Flashcards in B06W12 Deck (376):
Compare and contrast the typical features suggestive of syncope vs seizure
Syncope: typically trigger (like vasovagal or postural hypertension), typical prodrome (weak, light headed, vision fading), crumple to ground and tend to break fall, brief or no convulsions or confusion; Seizure: no warning, no focal neurological disturbance, heavy fall, prolonge stiffening/convulsions over 1 minute, post-ictal confusion
What is the typical prodrome for syncope?
Weak, light-headedness, fading vision
Paroxysmal cerebral event resulting from abnormal, involuntary, rhythmis neuronal discharges (usually) causing altered behaviour, sensations or awareness
What are provoked seizures?
Seizure occuring in a previously normal brain because of an abnormal physiological stress (metabolic insult, drugs, acute neurological illness)
What are unprovokes seizures?
A seizure occuring in the absence of an identifiable acute insult
What is epilepsy?
A disorder predisposing to recurrent (more than 2) unprovoked seizures
Focal epilepsy is more common in _____, and generalised epilepsy is more common in _____
Give at least 3 examples of structures that might be altered in patient's with seizures
Developmental processes (age-related receptor/channel changes), ion channels and receptors, NTs, second messenger systems, synaptic number/morphology, synaptic plasticity (the same mechanisms that allow learning might reinforce epileptic pathways, neuronal size/shape/number and connectivity
What is the first step in classifying a seizure?
Descide whether there is a focal epilepsy (starting in one area and spreading) or generalised (whole brain affected at the same time)
Briefly discuss the pathophysiology of partial seizures
Focal/regional cortical abnormality causing a local imbalance between excitation and inhibition
What are the 2 main causes of partial seizures?
Structural lesions or regionally expressed genetic defects (i.e., channellopathy)
How are partial seizures defined?
By focal onset, regardless of eventual extent or severity
Describe how partial seizures can become generalised (secondary generalisation)
Because many neurons send excitatory inputs to neightbouring neurons, excessive firing at the focus may recruit normal brain into the seizure
Discuss the clinical features of partial seizures
Consciousness is usually preserved at the onset of partial seizures (because most of the brain is still unaffected), the intial symptoms depend on the part of the brain serving as the focus, spread by produce new symptoms or loss of consciousness and may be too rapid to allow identification of the focal phase.
List at least 2 common and potentially localising symptoms of a seizure of the temporal lobe
Altered awareness or memory-related phenomena (dŽjˆ vu), olfactory/visceral sensations
List a common and potentially localising symptoms of a seizure of the motor cortex
List a common and potentially localising symptoms of a seizure of the somatosensory cortex
List a common and potentially localising symptoms of a seizure of the occipital cortex
When do localising symptoms of seizure provide the best value?
Early in the seizure
Compare positive vs negative symptoms in neurology
Positive = experience of something extra (unwanted movements, sensations, etc.) - implied part of CNS is overactive; Negative = lack of movement/sensation, e.g., numbness, blindness - implies CNS is underactive
Transient positive focal brain symptoms strongly imply what underlying pathology?
Seizures (and sometimes migraine)
Transient negative focal brain symptoms strongly imply what underlying pathology?
Define primary generalised seizures
Seizures that involve the entire cortex from the onset
What neurological changes occur in generalised seizures?
Neuronal firing excessively synchronised rather than excessive in terms of absolute number of action potentials - many neurons firing at the same time in synchrony over a broad area is abnormal
What is the main difference in imaging in patients who have had a focal vs generalised seizure?
Can sometime see focal lesion in focal/partial seizures, but often no causative lesions can be found on scanning for generalised seizures
Discuss what is currently understood about the aetiology of generalised seizures
Not certain, but may be due to a system-wide instability in cerebral rhythms, with a tendency to undergo abnormal corical synchronisation, probably involving genetic abnormalities in thalamocortical cricuits
Discuss the classical clinical features of generalised seizures
Consciousness is lost at the onset of a generalised seizure, so seizure onset is not remembered (unlike partical seizures, there is not unaffected cortex to observe the abnormality)
What are the major subtypes of generalised seizures?
Primary generalised tonic-clonic seizures, tonic seizures, clonic seizures, myoclonic s, absence s, atypical absence, atonic s, infantile spasms
What are absence seizures?
Brief (1-10s) bursts of synchronised activity, with transitory loss of awareness (often not noted by patient), no post-ictal drowsiness. Often a condition of childhood that subsequently resolves
What are primary generalised tonic-clonic seizures?
Excessive firing of entire cortex, causing sudden loss of consciousness, full body stiffness, jerking of limbs
What are myoclonic seizures?
Brief generalised cortical discharges causing lightening-like muscular jerks bilaterally
If there is a loss of consciousness at the onset of a siezure, what seizure classification is most likely?
Generalised seizures (e.g., absences and primary generalised tonic clonic seizures)
Suppose someone has a seizure that did not have loss of consciousness at onset, but did have alteration of consciousness at onset. What sort of seizure classification would be most likely?
Complex partial seizure
Suppose someone has a seizure that did not have loss or alteration of consciousness at onset. What sort of seizure classification would be most likely?
Simple partial seizure
What questions would you ask a patient presenting with a seziure to determine what sort of seizure they had?
Ask whether the patient lost consciousness at the beginning of the seizure (generalised) or if they have any awareness of the event at the beginning (focal)
Compare and contrast the characteristics of absence seizures vs complex partial seizures
Absence = childhood, seconds in duration, automatism rare, no post-ictal confusion, up to 100 episodes per day; Complex partial = all ages, 30-50s duration, automatism common, post-ictal confusion present and weekly-monthly in frequency
What are the 2 main axes of classification of epilepsy?
Generalised and partial
What seizure types are most common in culdhood absence epilepsy?
Absence and generalised tonic-clonic
What seizure types are most common in juvenille myoclonic epilepsy?
Myoclonic and generalised tonic-clonic
List at least 5 differential diagnoses of epilepsy
Syncope (simple or convulsive), peudoseizures (psychogenic), TIA, migraine with focal deficits, sleep disorder (sleep walking), movement disorder (dyskinesia), retrograde amnesia from head infury
What provoking factors of epilepsy should be asked about in history?
Alcohol, drugs, sleep-deprivation, hypoglycaemia, metabolic disturbance
What seizure types are most common in temporal lobe epilepsy?
Complex partial seizure and secondary generalised seizures
What investigations should be ordered for a patient who has had a first seizure?
CT to ensure there are no acute neurological emergencies, metabolic screen (glucose, electrolytes, FBC, EEG)
What is the gold standard for diagnosing seizures?
EEG (useful in about 50% of newly diagnosed epilepsy patients)
Briefly describe how EEG can be used to measure electrical activity inside the skull?
Needs amplification: 1. Major cortical neurons are aligned perpendicular to the cortical surface (allowing spatial summation - all voltage changes are aligned). 2. Neuronal activity is often synchronised (allowing temporal summation)
What are the main events events seen in EEG?
Synaptic potentials (excitatory/inhibitory post-synaptic potentials)
What information is given in an EEG 'spike'?
Just telling you that all the neurons in that area fired at the same time - which is abnormal - correspons with highly synchronised synaptic events and therefore follow volleys of action potentials
List the 4 main treatment aims in epilepsy
Reduce seizures, manage cause, harm minimisation and reduced side effcets
What sort of treatment options are availabe to reduce seizures in epilepsy?
Remove/minimise provoking factors, antiepileptic drugs, epilepsy surgery (useful for refractory cases when there is a definite lesion), ketogenic diet and vagal nerve stimulation
When are antiepileptic drugs indicated?
When there is good evidence that seizures will be an ongoing problem (i.e., in post patients with epilepsy - 2 or more seizures), rather than for anyone after the first isolated seizure
What sort of harm minimisation strategies should be advised for patients with epilepsy?
Avoid driving, swimming, bathing and other dangerous activities
Why do anti-epileptic drugs have so many side effects?
Because they affect normal neurons as well as epileptic ones
What are the 2 main modes of action of anti-epilepsy drugs?
1. Reduce excitation 2. Promote inhibition
What is the MOA of Valproate and phenytoin in epilepsy?
Blocks sodium channels to reduce excitation (also blocks low-threshold voltage-dependent calcium currents
What is the MOA of benzodiazapines in epilepsy?
Promote inhibition by actong on GABA receptors
What is the MOA of anti-absence drugs in epilepsy?
Block low-threshold voltage-dependent calcium currents (i.e., valproate)
Which anti-epileptic drug can be used for primary generalised seizures, absence seizures and partial seizures?
Why is it important to start and stop anti-epileptic medications slowly?
Starting slowly avoids excessive sedation and may reduce side effects, stop slowly because rapid weaning can cause drug-withdrawal seizures
A 43 year old man with a recent diagnosis of lung cancer has prolonged jerking of right upper limb. What is the most likley cause?
Brain mets in motor cortex secondary to lung cancer
A 23 year old man has a single major convulsive seizure after heavy binge drinking for 5 days. What is the most likely cause?
Alcohol-induced seizure in a normal brain
A 10 year old girl has up to 100 brief starting spells each day. What is the most likley cause?
A 33 year old woman has an episode of feeling light-headed, going pale, slumping to the ground, jerking several times, remaining unconscious for one minute and then waking up promtpy without confusion. What is the mostly likley cause?
A 42 year old man has a 2 year Hx of going 'vague' for 3 minutes about once per month, often associated with olfactory hallucinations. What is the most likley cause?
Complex partial seizure arising from the temporal lobe
What is the largest lobe of the brain?
What are the 5 components of normal behaviour?
1. Motivation 2. Inhibition 3. Appropriateness 4. Interpretation 5. Insight
List the 5 functions of the frontal lobe that are tested in the examination of higher cortical centres
1. Frontal reflexes 2. Proverb interpretation 3. Comparison/contrast 4. Expressive aphasia 5. Sequences
What tests are use to examine frontal lobe reflexes?
P-m, pout, snout and grasp
What test is used to examine frontal lobe sequences?
Luria's test (pantomime)
What are the 5 broad functions of the temporal lobe?
Memory, emotion, language (in the dominant hemisphere only), olfaction and hearing
List the 2 functions of the temportal lobe that are tested in the examination of higher cortical centres
1. Memory (immediate recall, short-term and long-term) 2. Language
Which 3 components of memory are tested in the temporal lobe examination of higher cortical function?
Immediate recall (3 objects), short-term memory (3 objects at 5 minutes) and long-term (names, dates of birth of children etc.)
List 4 abnormalities of the parietal lobe
1. Sensation 2. Sensory inattention 3. Visual inattention 4. Constructional aprexia
What is apraxia?
A neurological disorder characterised by loss of the ability to carry out learned (familiar) movements, despite having the desitre and physical ability to perform the movements
List at least 3 types of apraxias
Ideomotor (poor spatial orientation), limb kinetic, conduction, dressing
What is agnosia?
Loss of ability to recognise objects, persons, sounds, shapes or smells whilst the specific sense is not defective nor is there any significant memory loss
What is alexia?
Acquired inability to read
What is agraphia?
Acquired inability to write
What is nominal aphasia?
Inability to name
What is conductive aphasia?
Inability to repeat
What is the difference between alexia and dyslexia?
Alexia refers to an acquired reading diability where reading ability had previously been developed, while dyslexia refers to developmental reading disability
List the 7 functions of the parietal lobe that are tested in the examination of higher cortical centres
Sensation, neglect, construction, acalculia, L-R disorientation, finger agnosia and agraphia
What is alcalculia?
loss of the ability to perform simple calculations, typically resulting from disease or injury of the parietal lobe of the brain
What test is used to examine parietal lobe construction?
What test is used to examine parietal lobe acaculia?
What are the 3 available tests for higher cortical function?
Montreal cognitive assessment, Addenbrook's cognitive examination (ACE-R) and mini mental state examination (MMSE)
Lst at least 5 of the functions tested in the MMSE
Orientation to time, place, attention, memory, naming, repeating, reception, written expression and visuo-spatial
List the corticl functions not tested by the MMSE
Lacks abstract resoning, calculations, long-term memory and does not test frontal lobes, is also education dependent
Which lobes are not tested via use of the MMSE? Why is this significant?
Frontal - MMSE will be normal in frontal lesions
Aside from level of education, list some of the other confounders of the MMSE
Age, language, crude testing, normal in right hemisphere and frontal lesions, does not distinguish between diffuse and focal lesions, is unhelpful in cases of acute confusion and cultural background may have an impact
List the advantages of the MMSE
Well standardised (English), easy to administer (if you have a cooperative patient), good inter-rater reliability, good for monitoring, ultility in global neurodegenerative conditions like Alzheimer's
Which standartised test of higher cortical function can differentiate between different forms of dementia?
Addenbrooke's Cognitive Examination (ACE-R)
What 5 functions are tested in the ACE-R?
Attention and orienta, memory, verbal fluency, language and visuospatial skills
Which 6 functions are tested in a bedside language examination?
1. Spontaneous speech (informal interview, structured talk and automatic sequences) 2. Naming 3. Auditory comprehension 4. Repetition 5. Reading (aloud and comprehension) 6. Writing (spontaneous, to dictation, copying)
List at least 4 of the bedside features of Broca's (expressive) aphasia
Spontaneous speech non-fluent/mute, naming imapired, comprehension in tact, repetition impaired, writing impaired with poor grammar and may have associated right hemiparesis and hemisensory loss
List at least 4 of the bedside features of Wernicke's aphasia
Spontanteous speech fluent but with paraphrasic errors, imapired naming and bizzaire mis-naming, impaired comprehension, impaired repetition, impaired reading, well-formed and paragraphic writing and may have associated hemianopia
What is the peripheral cortex?
Folded, multilayered sheet of grey matter on the surface of the brain that is thrown into folds forming gyri and sulci
List the three types of cerebral cortex (telencephalon)
1. Paleocortex 2. Archicortex 3. Neocortex
The hippocampus is part of which cerebral cortex type?
What structures make up the paleocortex?
Olfactory cortex + entorhinal
What is the function of the paleocortex?
Incorporates representations of pain and emotional sensations (interoceptive self)
The principle input to entorhinal cortex is from which area?
The principle output from the enterohinal cortex is via which pathways?
Hippocampus and limbic pathways
What is the deep nucleus for the archistriatum? Which part of cortex is this strongly connected with?
Amygdala; archicortex = hippocampus
What is the deep nucleus for the paleostriatum? Which part of cortex is this strongly connected with?
Globus pallidus; pelocortex ; entorhinal cortex
What is the deep nucleus for the neostriatum? Which part of cortex is this strongly connected with?
Caudate/putamen; neocortex = everything other than hippocampus and entorhinal cortex
Where is the hippocampus located?
Medial part on interior durface of temporal lobe
List the 3 main parts of the hippocampus
Uncus, fornix, dentate gyrus
All cortical input to the dentate gyrus/hippocampus comes via which cortex?
Entorhinal; especially from multimodal association areas between neocortex and hippocampus
The entorhinal cortex receives direct projections from which structure?
Which cortex is known as the place where the 'interoceptive self' meets the 'exteroceptive self'?
Which part of the human cortex is strongly affected in Alzheimer's disease?
Which structures make up the limbic lobe?
Parahippocampal gyrus, septal area and cingulate gyrus
The entorhinal cortex and hippocampus are the mediators of what functions?
The limbic lobe is comprosed of which types of cortex?
Archicortex and paleocortex
The limbic lobe is on the medial aspect of the brain and it's components encircle which structures?
Corpus callosum and diencephalon
The cingulate gyrus contains separate maps for which human experiences?
Pain and emotion
List at least 3 functions of the hippocampus
1. Formation and retrieval of sptial memory 2. Processing and categorisation of new information 3. Differentially modulates aggression and rage 4. Modulates endocrine functions of the hypothalamus
Hippocampal lobectomy results in what outcomes?
Inability to form new memories but long-term memories and intellectual skills not affected
Stimulation of the pole of the hippocampus closest to the amygdala promotes ______ behaviour; activation of he pole nearest the septal area suppresses ______ behaviour
List the 3 areas providing afferent information to the archicortex and paleocortex
1. Entorhinal cortex 2. Cortex (prefrontal, anterior cingulate gyrus) 3. Brainstem
Lateral and medial perforant pathways from the entorhinal cortex carry what sort of tertiary fibres to the hippocampus?
High order multisensory (olfactory, somatosensory, visual and auditory)
What are the 2 main efferent pathways from the hippocampus?
1. Via the fornix (projecting to septal area, diencephalon and contralateral hippocampus) 2. Cortex (entorhinal, cingulate and parts of the pre-frontal
What is the septal area of the limbic lobe?
A relay nucleus of the hippocampus to the hypothalamus
List the 3 afferents from the septal area of the limbic lobe
Hippocampus, brainstem monoaminergic systems, amygdala
List the 4 efferents from the septal area of the limbic lobe
Prefrontacl cortex, medial hypothalamus, medial thalamus and hippocapus (indirectly)
List at least 3 functions of the septal area of the limbic lobe
Control of aggression and rage, regulation of endocrine functions, reward/pleasure centre (self-stimulation; drinking behaviours), regulates the discharge of hippocampal neurons during learning of new tasks/goal-directed behaviour
Which brain strcuture is also known as the brain's alarm system?
What are the 3 subcortical afferents to the amygdala?
(from interoceptive self) Brainstem monoaminergic systems, thalamus, brainstem control centres including solitary nucleus and carioresp centres
What are the cortical afferents to the amygdala?
Olfactory areas (entorhinal) and visual, auditory and somatosensory areas
What are the 2 major functions of the amygdala?
1. Mediates adaptive responses 2. The most powerful regulator of the hypothalamus/endocrine functions
Which brain structure is the most powerful regulator of the hypothalamus/endocrine fucntions?
Unlike primary areas of the cortex, association areas project to which other cortex?
Which type of human cortex is comprised of 6 layers?
What is primary neocortex?
Main input from a particular modality (i.e., vision, touch on skin, sound waves) = one function. All information must go through thalamus, and these two areas are reciprocally connected.
What is secondary neocortex?
Limited to particular modality but may be limited to a speicifc feature of that modality (i.e., specific area of visual cortex dealing with colour)
What is association neocortex?
Area that gets inputs from a number of different modalities (e.g., visual and auditory like Wernicke's).
The majority of cells in the neocortex are whay types of cells?
Large excitatory pyramidal cells with very long axons (and most non-puramidal cells are inhibitory GABAergic)
All sensory input enters which layer of the neocortex?
Why is layer 4 of the neocortex also known as the striatal layer?
So many axons come into this layer and synapse that a dark stripe can be seen on sectioning
Different cortical areas interact with each other through cells located in which layers of neocortex?
II and III
Primary sensory cortex has high density of inputs into which layer of the neocortex?
Primary motor cortex has high density of inputs into which layer of the neocortex?
Pyramidal cells in layers V and VI
What is the name of the structure comprised of alternating columns of striate cortex receiving inputs from one eye and then the other?
Ocular dominance columns
What process results in amblyopia?
Visual deprivation involving one eye results in the non-deprived eye taking over the territories of the deprived eye
Within each ocular dominance column, there are ____ columns
____ sensicite regions are regulary spaces within each ocular dominance column
Projection (a) fibres originate in which layer of neocortex? What is their target?
V; striatum, brainstem, spinal cord
Projection (b) fibres originate in which layer of neocortex? What is their target?
Commisural fibres originate in which layer of neocortex? What is their target?
III; contralateral cortex
Association fibres originate in which layer of neocortex? What is their target?
III; ipsilateral cortex
List the 5 major association bundles of cortical white matter
1. Uncinate fasisculus 2. Superior occipitofrontal fasisculus 3. Superior longitudinal (arcute) fasisculus 4. Inferior occipitofrontal fasisiculus 5. Cingulum
What are the 2 most common categories of mental disorders?
Anxiety and mood disorders
List at least 4 types of anxiety disorders
Post traumatic stress disorder, social phobia, generalised anxiety disorder, panic disorder, obsessive-compulsive disorder
List at least 2 types of mood disorders
Major depressive disorder, unipolar depressive episodes, bipolar disorders
What is anhedonia in depression? What parts of the patient experience can this effect?
Patients have genuine inability to experience reward; impairs motivation and incentive based learning
MDD (major depressive disorder) is associated with polymorphisms in which genes? (name at least 2)
1. Glucocorticoid receptor gene 2. Monoamine oxidase A gene 3. Gene for glycogen synthase 4. Metabotropic glutamate receptor genes
Give one example of a poymorphism in depression that has been shown to improve liklihood of treatment
People with polymorphic variant to serotonin-transporter-linked-polymorphic region which affects the promotoer of the serotonin-transporter gene > show increased response to certain antidepressant treatment and reduced side effects
What are the characeristics of anxiety disorders?
Characterised by chronic and persistent worry coupled with non-specific physical health compaints (major depression is a common coexisting condition)
What is needed for a diagnosis of MDD accodring to the DSM-V?
2 or more major depressive episodes - depressed mood and/or loss of interest or pleasure in life for over 2 weeks with 5 of the following: depressed mood for most of day, unintentional weight change, insomnia, sleeping too much, agitation, fatigue, feelings of worthlessness, diminished ability to think, thoughts of death
What is needed for a diagnosis of anxiety disorder according to the DSM-V?
Excessive anxiety and worry about events more days than not for a period of 6 months plus 3 of the following: restlessness, on edge, difficulty concentrating, easily fatigues, muscle tension and sleep disturbance. Anxiety must cause significant distress/impairement, not be due to substances or medical conditions and not better accounted for by another disorder
Discuss the normal HPA axis physiology in stress responses
Stress is perceived by the brain and transmitted to the hypothalamus (limbic system). Hypothalamus released CTRH onto pituitary, which results in secretion of corticotropin into the plasma and stimulation of receptros in adrenal cortex. This then releases cortisol into the blood. In homeostasis, hypothalamic cortisol receptors respons by reduced CTRH secrection (neg. feedback)
Discuss the changes in the HPA axis in mood disorders
In stress responses in depression, prefrtonal cortex and amygdala sense the stress and there is a significantly increased basal CTRH and cortisol level observed in these patients
Discuss some evidence supporting the HPA-axis theory of mood disorders
Increased levels of monoamines in the brain affect the HPA axis and can reverse some long-term effects of stress (ST, NA). Also, depressed patietns have elevated plasma cortisol levels and elevated PTRH levels in CSF
Discuss some evidence that refutes the HPA-axis theory of mood disorders
Stress = depression link not perfect - patients can be depressed with no signs of HPA-axis dysfunction
Which structures are considered in the 'default mode network'?
Anterior medial prefrontal cortex, cingulate cortex and angular gyrus
Describe the changes seen in the default mode network of a depressed patient in resting-state fMRI
Functional overactivation and hyperconnectivity
Which structures are included in the positive effect circuit (in relation to mood disorders)
Striatal nucleus accumbens and ventral tegmental areas with medial prefrontal cortices and anterior cingulate
What is the funciton of the 'default mode network' in regards to mental health?
Neural networks that modulate normal emotional behaviour implicated in mood disorders (medial and orbital prefrontal cortices, cingulate cortex and angular gyri are active in patients with depression, even whilst they are at rest)
Manifestations of increased default mode circuit activation are associated with what behaviours?
Maladaptive rumination about depressive thoughts
Describe the changes seen in the positive affect circuit of an rs-fMRI of a depressed patient
Distinct hypoactivation to ventral sitratal areas when viewing rewarding stimuli > may contribute to anhedonia
Anxiety disorders often focus on pathology of which brain structure in particular?
List some of the key regions identified in anxiety research
Limbic structures and areas linked to prefrontal cortex and anterior cingulate cortex
What is the fucntion of corticolimbic circuits in anxiety?
Mediate the interpretation of environmental stimuli producing an anxiety-like response (major determinant of whether environmental stimuli are interpreted as threatening happens at the amygdala - i.e., sensory stimuli imbued with emotional value). Hyperactivity of amygdala caused by white matter disruptions in inputs can lead to manifestations of anxiety where sensory information is inappropriately perceived as threatening and leads to emotion and behvaioural responses like panic diroders, phobias and GAD
What is the monoamine hypothesis?
Symptoms of mood and anxiety disorders can result from insufficiency levels of serotonin, noradreneline, dopamine and melatonin > agents that alter metabolism of these can relieve symptoms (monoamine oxidase inhibitors MAOIs and tricyclic antidepressants)
What are SSRIs?
Selective serotonin reuptake inhibitors
What are the advantages of SSRIs and SNRIs vs monoamine oxidase inhibitors and tricyclic antidepressants?
Specific, reducing symtoms and causing less side-effects
How are SSRIs believed to work?
By increasing extracellular level of serotonin > limits reasbsorption into the presynaptic cell > increase binding to the post-synaptic receptor
What is the aim of CBT?
Replace maladaptive interprettions of events with more helpful ones > thus angaging neural plasticity
Pharmacological therapy in anxiety disorders targets what?
Serotonergic and noradrenergic neurotransmission (SSRIs or SNRIs)
Give an example of a common SSRI or SNRI used in treatment of anxiety disorders
Benzodiazepines, alprazolam (xanax) and diazepam (valium) and medazepam
What are the main pharmacological treatments for depression?
Anti-depressants targeted at monoaminergic neurotransmission (serotenergic and noradrenergic): SRIs most sommonly prescribes as well tolerated and non-sedating; SNRIs often prescribed for more severe depression; Tricyclic antidepressants; MAOIs only under exceptional circumstances
Modifications to which neural circuits are hypothesised to cause rumination and anhedonia in depression?
Rumination: increased connectivity of default mode circuit - maladaptive self-referential rumination of depressive thoughts; Adhedonia: decreased activity of positive affect circuit - inability to feel pleasure
Describe the neural circuitry and changes hypothesised to contribute to anxiety?
Corticolimbic: symptoms may relate to loss of moderation fro mPFC and ACC over the amygdala > results in hyperactivity of the structure and a misinterpretation of ambiguous environmental stimuli as threatening - anxiogenic
Define the plaques and tangles seen in Alzheimer's disease
Plaque = extracellular deposit of beta-amyloid in centre and dystrophic nerve derminals filled with hyperphosphorylated tau around it; Tangle = intracellular deposit of hyperphosphorylated microtubule-association protein tau assembled into paired helical filaments
What is the typical 'incubation period' for Alzheimer's?
Which brain system is first affected in Alzheimer's? What specific structures are involved?
Limbic system (hippocampus, amygdala)
Which cortices are typically spared in Alzheimers?
Visual cortical areas, and somatosensory areas
What causes cognitive dysfunction in the late stages of Alzheimer's disease?
Neuromodulatory systems (NA, 5-HT) in brainstem affected later in disease
Describe the location and composition of plaques seen in Alzheimers
In nerve tissue as well as around blood vessels; consist of extracellular protein (beta-amyloid in precipitated/insoluble form) with high content of heavy metals like aluminium, zinc and copper
Beta-amyloid is assembled from which other protein?
Discuss the pathophysiology of plaque emergence in Alzheimer's disease
Can emerge within days (i.e., fast), followed by microglial activation and recruitment (1-2 days) and progressive neuritic changes, leading to increasingly dysmorphic neurites/axons (days- weeks)
What is tau protein responsible for in the brain? What happens if it becomes hyperphosphorylated?
Stabilizing neurofilaments (cytoskeletal structures); if hyperphosphorylated, tau assembles into intracellular tangles, which causes neurofilaments to destabilise and break apart > axonal transport of mitochondria to and from synapse breaks, causes a mitochondrial energy and calcium homeostasis crisis at the synapse
Tangles in Alzheimer's are made from what protein? What is this protein notmally responsible for?
Made out of tau protein (crucial in making up normal microtubules in cytoskeleton)
What happens if tau protein is hyperphosphorylated?
Stabillity of cytoskeleton and microtubules decay > axonal transport severely impaired > form intracellular deposits (Alzheimer's)
Which type of Alzheimer's has early onset and a mutated gene?
Familial autosomal dominant
Sporadic Alzheimer's disease has similar risk factors to which other significant disease?
Atherosclerotic (i.e., in BP, lipids etc)
List the 3 main theories of disease generation in Alzheimer's disease
1. Amyloid hypothesis 2. Vascular hypothesis 3. MAM (mitochondria associated membrane) hypothesis
Briefly outline the amyloid hypothesis for Alzheimer's disease
Abnormal Amyloid precursor protein cleavage causes Amyloid-beta deposition > formation of senile plaques > neurodegeneration > disease
Briefly outline the vascular hypothesis for Alzheimer's disease
Advanced ageing and vascular risk factors lead to brain hypoperfusion > produces neuroglial energy crisis >mild cognitive impairement > neurodegeneration > disease
Briefly outline the MAM hypothesis for Alzheimer's disease
Altered lipid raft formation causes altered calcium homeostasis > altered Amyloid precursor protein/tau processing > plaques/tangles/lipid droplets form > neurodegeneration > disease
If Amyloid Precursor Protein proteolysis is done via alpha-secretase, what is produced?
Which particular Amyloid-beta is cytotoxic? What events does it promote?
Amyloid-beta42; aggregtion (oligomers), excitotoxicity, oxidation, inflammation and tau hyperphosphorylation
Amyloid-beta is produced in the ____ of a cell, and stored in ____
Vesiscular secretion of Amyloid-beta is controlled by what chemical at what time?
Orexin; under circadian control (decreased in sleep and increased when awake)
What are the protperies of Amyloid-beta?
Monomers may be neurotrophic, oligomers are toxic (escp A-beta42), produced in ER and stored in vesicles which are secreted via orexin and circadian control - secretion goes down during sleep and increases throughout the day)
What is the physiological role of the head of Amyloid Precursor Protein (N-terminus)?
Development - axonal pruning via DR6 that activates capsase 6 > apoptosis
What is the physiological role of Amyloid Precursor Protein's Amyloid-beta?
Secreted as a monomer and maintains synapses, also form amyloid sheets as oligomers in vesicles for storage
What is the physiological role of the tail of Amyloid Precursor Protein (AICD)?
Calcium homeostasis, ATP availability (mitochondria) and transcriptional modulation
The gamma-secretase complex comsists of which components?
Presenilin (PS1 PS2) as catalytic core and 3 accessory proteins (nicastrin, Alph1-1 and Pen-2)
List some of the ways that presenilin plays a central role in calcium homeostasis
Modulate SERCA pump, IP3 receptor and ryanodine receptor (in SER membrane), interact with calcium binding proteins like calpain, form calcium channels in expression system (SER calcium leak channels) and are essential for regulating transmitter release (presynaptic calcium stores)
Release of which ion from storage actives beta-secretase?
What happens to the number of synapses and number of cells in Alzheimers?
What changes in synaptic efficacy are seen in Alzheimer's disease?
AMPA-type fEPSPs are reduced, NMDA-dependent LTP may be affected
Spines are the sites of _____ synapses in the hippocampus
When exposed to control and Amyloid-beta42 monomers, spine density is _______. When exposed to Amyloid-beta42 oligomers, spine density _____
Alzheimer's plaques are made from ______
List the 3 drug classes approved for use in Alzheimers in Australia? Give an example of a drug within each class.
1. Anticholinesterases (donezepil) 2. Cholinomimetics (galantamine) 3. Glutamate (NMDA) receptor antagonists (memantine)
List at least 4 synaptic-related changes seen in Alzheimer's disease
Fewer synapses and cells, synapses with smaller efficacy, larger NMDA receptor currents at synapses, larger NMDA receptor-dependent spine loss, activity-dependent synaptic Amyloid-beta secretion
Why is the length of amino acid chain important? i.e., beta-amyloid in Alzheimer plaques
Because amino acid chains longer than 42 are toxic (but reason is unknown)
The amyloid see in Alzheimer's plaques is realted to which other amyloid deposit in human disease?
Pancreatic amyloid in diabetes
What is the result of exposing mitochondria in an axons to amyloid beta?
Axonal transport stops
Why is the incidence of Alzheimer's disease higher in people with Down's syndrome?
Because chromosome 21 abnormality is known to be implicated, and down's syndrome is a tripling of this chromosome
Familial Alzheimer's shares which 3 genes? What is clinically significant about this?
Amyloid precursor protein, PS1 and PS2 - if any one of these is mutated, the person WILL get the disease - there is no prevention
How does the cognittive decline of Alzheimer's relate to number of plaques?
Why is gamma-secretase difficult to use as a drug target for Alzheimer's disease?
Involved in a number of different signalling cascades (not just neuronally in Alzheimers), therefore if blocking this with drug - also block other cascades, such as the Notch pathway in enteric cells - don't re-generate as per normal and causes diarrhoea
What is the Aboriginal definition of health?
Aboriginal health means not just the physical well-being of an individual but refers to the social, emotional and cultural well-being of the whole community in which each individual is able to achieve their full potential as a human being thereby bringing about the total well-being of their community
List some of the associations of low birth weight in Indigenous populations
Lack of antenatal care, poor meternal nutrition, maternal smoking, alcool or drug use, extremes of maternal age, limited birth spacing and socioeconomic disadvantage
List 4 roles of a doctor in improving ATSI health
Be aware of the inequalities in healthcare, cultural awareness, knowledge of preventative activities unique to ATSI people, knowledge of the programs available to ATSI people
What are some of the secondary complications of scabies in indigenous populations?
Secondary bacterial infection (MRSA or GAS), post-strep glomerulonephritis, acute rheumatic fever
Low birth weight can lead to what complications?
Increased risk of diabetes, chronic renal disease, ischaemic heart disease etc.
How can low birth weight be prevented in Indigenous communitites?
Support women to present early and often, support women's diet during pregnancy, limit supply of alcohol in community, offer effective contraception to teenagers and following delivery
What immunisations are provided for preventative health in ATSI populations?
BCG (tuberculosis), Hep A, booster of pneumococcal vaccine at 2 years old, influenza (everyone over 18 for free and 6months-5years for free), pneumococcal (everyone over 50 or over 18 wth risk factors gets it for free
List some preventative screening practices used in ATSI populations
Anaemia in childhood, hearing loss in childhood, sexual health (gonorrhoea and pyphilis higher prevalence - recommended up to 35 years old), diabetes, chronic kidney disease and CVD (begins at younger age)
How does Closing the Gap progam impact GP practice?
ATSI populations encouraged to have yearly health check, better access to allied health care, cheaper medications, access to care coordinators and transport, access to funds to pay for private specialises and expensive imaging and GPs encouraged to see patients regularly
List some specific PBS for ATSI people
Antifungal creams, terbinafine, ciprofloxacin ear drops, nicotine patches, folic acid, magnesium and thiamine, paracetamol and aspirin
Which cells line the ventricles of the brain?
Astrocytes I the brain connect which structures?
Neurons with blood vessels
What are neurodegenerative diseases?
Degeneration of neurons and their synapses that affect brain function
List some of the basic principles/characteristics of neurodegenerative disorders
Progressive loss of neurons causing grey matter changes; pattern of neuronal loss is selective (in certain areas of the CNS); occur in previously healthy patients; development of abnormal interneuronal protein aggregates (can cause cofnromational changes in normal proteins surrounding - works similarly to a prion); protein aggregates are resistant to cellular mechanisms of degradation; protein aggregates are cytotoxis to neurons
Where do abnormal interneuronal protein aggregates originate from in Huntingtons, Alzheimers and Parkinsons?
Huntingtons = genetic mutation (abnormal protin aggregatces in the nucleus and kills the cell); Alzheimer's = peptide derived from large amyloid precursor protein; Parkinson's = unexplained alteration in a normal cellular protein
What is Alzheimer's disease?
Cortical degenerative disease with progressive loss of cognitive function (causing dementia)
List some of the characteristics of Alzheimer's disease
Insidious onset, disorders of thought content/perception/affect, behavioural disturbances, personality changes, can cause amnesia, aphasia and immobility
Genes on which chromosomes are thought to be implicated in familial forms of Alzheimer's disease?
21 (amyloid precursor protein is on this chromosome), 14, 1
Amyloid precursor protein is located on which chromosome?
What combination of techniques allow correct diagnosis of Alzheimer's disease?
Clinical assessment and radiology (definitive diagnosis autopsy)
List at least 4 macroscopic features of Alzheimer's disease seen in autopsy specimens?
Cortical atrophy, widened sulci, narroweed gyri, ventricular dilatation, thinned cortical ribbon
What are the 3 main hitological findings in Alzheimer's disease?
Neuritic plaques, neurofibrillary tangles and amyloid angiopathy (extracellularly)
Where are neuritic plaques best seen in Alzheimer's disease?
Seen in hippocampus, amygdala, neocortex
What are neuritic plaques of Alzheimer's comprised of?
Central amyloid core, surrounded by dilated tortuous dystrophic neurites > all surrounded by reactive astrocytes (macrophages of the CNS - causing scarring) and microglia are present at the periphery
Where are neurofibrillary tangles of Alzheimer's best seen?
Hippocampus and amygdala (intracellularly)
What are neurofibrillary tangles in Alzheimer's disease?
Intracellular bundles of filament in the cytoplasm encircling or displacing the nucleus - appearing as elongated flame-shaped or basket weave patterns.
Neurofibrillary tangles may persist as ______ after the death of neurons
What are neurofibrillary tangles in Alzheimer's composed of?
Paired helical filaments, hyperphosphorylated protein tau and mictotubule associated protein
What histo stain may be used to view neurofibrillary plaques as well as background axons in Alzheimers?
What is cerebral amyloid angiopathy? What disease may this be associated with?
Intramural deposits of amyloid in small arterieal vessels - may be sporadic or associated with Alzheimer's disease
What histo stain may be used to highlight amyloid as brick-red colour within the wall of a small artery?
Congo red stain (can then also apply polarised light to make briefringement of amyloid appear green)
What histo stain may be used to highlight amyloid as brown colour within the wall of a small artery?
Beta amyloid immunohistochemical
What are Hirano bodies, and in which disease state can they be seen?
Elongated glassy eosinophilic beaded bodies; Alzheimer's
In what disease may granulovacuolar degeneration of neurons (GVD) be seen?
List 5 main changes seen in an aging brain
1. Atrophy (decrease in brain weight, shrinkage of gyri/expansion of sulci, enlargement of ventricles) 2. Vascular changes 3. Accumulation of pigment (lipofuchsin) 4. Loss of pigment (substantial nigra) 5. Senile plaques (neuritic in deep cortex and non-neuritic in superficial cortex)
What mnemonic can be used to remember the clinical features of Parkinsons
TRAP - tremor, rigidity, akinesia and postural instability
There is a minor proportion of Parkinsons disease that have a familial form. Which 2 inheritance patterns do these follow?
Autosomal dominant, autosomal recessive
What change is seen in the histology of the substantia nigra in Parkinson's disease?
Loss of pigmented neurons in the substantia nigra
What macroscopic change can be seen in a cross section of the pons vs midbrain in Parkinsons disease?
Pons = Loss of pigmentation of locus ceruleus; Midbrain = Loss of melanin pigmentation of substantia nigra
List the histopathological changes seen on a H&E stain of the substantia nigra in Parkinson's disease
Loss of pigmented catecholaminergic neurons, lewy bodies in the remaining neurons (round to elongated cytoplasmis eosinophilic inclusions)
What are lewy bodies composed of?
Tightly packed fine filaments of alpha-synuclein, parkin and ubiquitin
Which chromosome(and protein) is thought to be implicated in Huntington's disease, and how?
Chromosome 4: protein Huntingtin; triplet nucleotide repeat expansion > exhibits anticipation
Huntington's disease results from a degeneration of what type of neurons?
List at least 4 clinical features of Huntingtons
Insidious onset (35-45 years), chorea, dementia, emotional symptoms, occassionally present with parkinsonian dynsrome, depression
What is chorea?
Arrythmix involuntary movements that are typically sudden and brief and that seem to flow from one part of the body to another
Dicuss the macroscopic changes that can be seen in the brain specimen of a patient with Huntington's disease
Atrophy of the caudate and putamen, widespread cerebral atrophy of the striatum and cerebral cortex
What is needed for the diagnosis of Huntingtons?
Distinguish from other causes of chorea, demetia and psychosis; genetic testing; MRI and PET scans
What pathological processes occur in amyotrophic lateral sclerosis?
Destruction and loss of upper and lower motor neurones and denervation and atrophy of the corresponding muscle fibres
In the few cases of hereditary amyotrophic lateral sclerosis, which 4 genes have been implicated?
SOD1, ALS2, NEFH, VAPB
What is the SOD1 gene (implicated in amyotrophic lateral sclerosis) responsible for?
Coding for superoxide dismutase hence it is proposed that the neuronal cell death in ALS may be related to excess of free radicals
Which functions are spared in amyotrophic lateral sclerosis?
Mental functions and physical sensation
List at least 3 clinical features of amyotrophic lateral sclerosis
Progressive loss of voluntary muscle contraction; progressive wasting and atrophy of affected muscles; spontaneous twitching of motor units (fasisculations); difficulty with chewing, swallowing and movements of the face and tongue; progressive phsyical disability
List the 2 macroscopic features of amyotrophic lateral sclerosis that can be seen on a cauda equina and filum terminae specimen
Withered nerve roots and thinned spinal chord
What sort of histo stain can be used to stain myelin blue?
Luxol fast blue
What changes are seen on a luxol fast blue histo stain of the spinal cord in amyotrophic lateral sclerosis?
Degeneration of lateral columns of spinal cord (pale due to loss of anterior horn)
Discuss the pathophysiology of the CNS seen in amyotrophic lateral sclerosis
Motor neurons undergo shrinkage with accululation fo lipofuscin pigment > presence of spheroids (focal accumulations of neurofilaments) > thinning of corticospinal tracts due to loss of cortical motor neurons > loss of fibres in the lateral columns of the spinal cord and replacement by filbrillary gliosis imparting some firmness (lateral sclerosis) > gliosis (the term for scarring of the CNS: astrocytes + their processes proliferate instead of fibroblasts. Collagen is not laid down as in a normal scar)
What is gliosis?
The term for scarring of the CNS - astrocytes and their processes proliferate instead of fibroblasts, so collagen Is not laid down as in a normal scar (as there is no fibroblasts in the brain)
What are the clinical manifestations of amyotropic lateral sclerosis in peripheral muscles?
Denervation and atrophy of corresponding muscle fibres - clinically recognised muscle wasting (amyotrophy)
List some of the differential diagnoses of amyotropic lateral sclerosis
Mass lesions, infections, toxins and drugs (lead poisoning), motor neuropathy with conduction block, paraneoplastic syndromes and hyperthyroidism
Which neurodegenerative disease is inherited as an autosomal dominant condition?
In an STPase stain at a pH of 9.4, how do type 1 vs type 2 muscle fibres appear?
Type 1 = light; Type 2 = dark
List at least 4 symptoms of muscle/NMJ disease
Muscle pain, weaknes, cramp, fatigue, wasting, family history, (note important of absence of sensory symptoms)
A 26 yo presents with proximal lower limb weakness for 6 months (avoiding stairs), fatigue worse later in day, also affects proximal upper limb muscles. She was previously good at sports, has no medial or family history and appears skinny with small muscle bulk, lower limb weakness and mild ptosis. What is the differential diagnosis?
List some investigations used for muscle/NMJ diseases
Bloods (CK, antibodies, TFTs), genetic studies, neurophysiology, muscle biopsy and imaging
What changes would be expected on a nerve conduction study of a patient with myasthenia gravis?
Electrical fatigue - successive decreases in muscle repsonse to stimuli over time
List at least 3 neuromuscular disorders
Myasthenia gravis (most common), Labert-Eaton (associated with lung cancer), botulism, congenital myasthenic syndromes, drugs/toxins (poisonous animals)
Discuss the pathogenesis of myasthenia gravis
Autoimmune disease of the NMJ caused by antibodies that attack components of the postsynaptic membrane, impair neuromuscular transmission, and lead to weakness and fatigue of skeletal muscle. The pathogenesis depends upon the target and isotype of the autoantibodies. Most cases are caused by immunoglobulin IgG1 and IgG3 antibodies to the acetylcholine receptor (AChR). They produce complement-mediated damage and increase the rate of AChR turnover, both mechanisms causing loss of AChR from the postsynaptic membrane. The thymus gland is involved in many patients.
Myasthenia gravis is mediated by ___ cells and
How do AChR antibodies contribute to disease in myasthenia gravis?
Block ACh binding site, cross linking of AChR on postsynaptic receptor, complement activation with destruction of postsynaptic receptor
What is MUSK, what does it do and in which disease is it implicated?
Muscle-specific tyrosine kinase; reduced AChR clustering; myasthenia gravis
What are the clinical features of myasthenia gravis
Ocular or generalised forms (ocular weakness in diplopia or ptosis), limb weakness or generalised weakness of proximal muscles (can include bulbar muscles); fluctuating weakness exacerbated by exercise and improved with rest (fatigue)
What are the exacerbating factors for myasthenia gravis?
Intercurrena illness, especially infection and drugs (like anaesthetics)
List 4 investigations for myasthenia gravis
1. Antibodies 2. Neurophysiology (repetivie stimulation or single fibre study) 3. Pharmacology testing (administering adrophonium which reverses weakness) 4. Imaging (chest CT for thymoma or hyperplasia)
List some of the treatment options for myasthenia gravis
Cholinesterase inhibitors, corticosteroids, azathioprine, plasmaphareses in myasthenic crisis, IVIG (acute setting), thymectomy if thymic hyperplasia present and a number of other immunosuppresants
What is the MOA of cholinesterase inhibitors?
Reduce breakdown of acetylcholine at NMJ
Why are cholinesterase inhibitors not the ideal treatment for myasthenia gravis?
Do not modify disease - progressive loss of AChR antibodies over time
What type of drug is pyridostigime? Which disease may it be used for?
Cholinesterase inhibitor (myasthenia gravis)
What side effects are elicited by increasing dose of cholinesterase drugs?
GIT motibility, salivation/lacrimation and hyperhidrosis - can also promote cholinergic crisis
Lambert Eaton myasthenic syndrome is characterised by antibodies against what channels?
Presynaptic volatge gated channels at the NMJ
List at least 3 types of botulism
Food borne, wound, overdose for treatment, infantile
List the 3 most common clinical features of botulism
Pupillary involvement, autonomic involvement, reflexes may be depressed
List 3 ways that botulism may be diagnosed
Wound culture, serum antibodies and toxin in food
Describe how Duchene's muscular dystrophy typically presents over time
X-linked: Normal at birth, clumsy in first year, arise using Gower's procedure, child does not run or jump, by 6-7 years child starts to fall, wheelchair usually needed by age 12, scoliosis and cardiac involvement common and death usually occurs in early adulthood or late teens
State the inheritance pattern for Duchene's and Becker's muscular dystrophies
List at least 3 treatments for Duchene's muscular dystrophy
Physiotherapy, bracing, predisolone (slows progression) and reconstructive surgery
Describe how Becker's muscular dystrophy typically presents over time
Weakness usually appears in first decade but may not present until 30s. Calf hypertrophy and contractures are common, as are leg muscle cramps. Cardiac disease can present later
What is facioscapulohumeral dystrophy (FSHD)? What are the clinical features
Autosomal dominant disease that is characterised by facial weakness, scapula weakness, biceps and triceps affected but deltoid spared, ankle dorsiflexors and abdo msucles may be affected. Asymmetry is common
What are the 2 types of myotonic dystrophy?
Distal and proximal
Discuss the inheritance pattern and genetics of myotonic dystrophy
Autosomal dominant; chromosome 19 affected and causes trinucleotide repeat of CTG
What are the clinical features of myotonic dystrophy?
Hand weakness, foot drop, ptosis and facial weakness, neck weakness and myotonia (may also include frontal balding, cardiac, daytime sleepiness, diabetes, cataracts and other endocrine involvement)
List some of the clinical features of polymyositis and dermatomyositis
Painles weakness, eyes spared and face rarely involved, proximal weakness of gradual onset, may have systemic features
List at least 3 drugs than can cause drug-induced myopathies
Corticosteroids, statins, gemfibrozil and chemo agents
List the common clinical positive symptoms of schizophrenia
Hallucinations, delusions, thought disorder
List the common clinical negative symptoms of schizophrenia
Decreased motivation, altered expressions of emotions, decreased amount or content of speech, anhedonia
List the common clinical cognitive deficit symptoms of schizophrenia
Impairements in attention, verbal learning, verbal fluency, executive function and working memory
What are the diagnostic criteria for schizophrenia in the DSM V?
1. 2 or more characteristic symptoms present for 1 month of delusions, hallucinations, disorganised speech (formal thought disorder), grossly disorganised or catatonic behaviour, negative symptoms; 2. Reduced functioning (occupational/social/self-care); 3. Duration: continuous signs of the disturbance for at least 6 months
On average, people with schizophrenia die ____ years earlier than the general population
List the 8 steps in normal neurodevelopment
1. Induction of neural plate (3 weeks post-conception) 2. Neuronal proliferation 3. Neuronal migration and aggregation 4. Axon and dendrite growth 5. Synaptogenesis 6. Myelination 7. Pruning 8. Apoptosis/synapse rearrangement
List at least 5 neuropathological findings in schizophrenia
1. Reduced brain weight 2. Enlarged lateral/third ventricles 3. Decreased markers of synapses and dendrites 4. Absence of neurodegenerative changes 5. Absence of gliosis (suggests prenatal brain insult) 6. Cytoarchitectural abnormalities (pyramidal cell disaray)
Describe the changes in white matter in a diffusion tensor MRI of a patient with schizophrenia
Thinning in corpus callosum, long intrahemispheric fibre tracts and subcortical projection systems. Abnormal functional lateralisation, impaired interhemipheric transfer, intrahemispheric processing and corticosubcortical information processing loops are affected
What is the main neurochemical finding in schizophrenia?
Abnormal dopaminergic neurotransmission
List the arguments for the dopamine hypothesis of schizophrenia
Illicit drugs which increase sopamine release (e.g., amphetamines and cocaine) may lead to psychosis; mediation which blocks dopamine receptors reduce schizophreniz symptoms; cannabis increases dopamine release can cause or exacerbate schizophrenia
List the arguments against the dopamine hypothesis of schizophrenia
Amphetamines don't act only on dopaminergic neuron; antipsychotics targeting dopamine neurons don't have an immediate effect; antipsychotics have little effect on negative symptoms; hyperdopaminergic state can be a consequence of NMDA hypofunction
What changes in GABA are seen in schizophrenia?
GAD (glutamic acid decarboxylase) is the enzyme responsible for the synthesis of GABA, and this enzyme is decreased in the cerebral cortex of patients with schizophrenia
Genes involving which 5 chromosomes have been identified in schizophrenia?
1, 2, 8, 13 and 22
Which 2 neurotransmitter systems are implicated in schizophrenia?
dopaminergic and glutamatergic
Compare positive vs negtive symptoms in neurological disorders
Positive symptoms are experiences that should not be there in a healthy state, whereas negative symptoms tend to be an absence of norma things (i.e., decrease in motivation which would be normal in a healthy person)
List some reasons why there is such an excess of death rates in patients with schiozphrenia when compared to the normal population
Diet high in saturated fats and high in fibre, more likey to be smokers etc., poorer access to health care (paranoid, lack of motivation, lack of services etc), life style factors, psychotropic medications
Compare the cause of death for men vs women with schizophrenia
Men tend to die more from unnatural
What is the chance of developing schizophrenia if you have an identical twin with the disease?
Almost exactly 50%
What are the two largest contributors to development of schizophrenia?
Genetics and evironment
Screening is a form of what sort of prevention?
What is screening?
Process of using tests on large scale to identify the presence of disease in apparently healthy people
List 4 different types of screening tests?
1. Mass screening 2. Multiple of multiphasic screenin 3. Targeted screening 4. Case-finding or opportunistic screening
What is mass screening?
Aims to screen the whole population or subset of
What is multiple or multiphasic screening?
Using several different screening tests
What is targeted screening?
Screening of groups with specific exposures, e.g., workers in lead bettery factories, is often used in environmental and occupational health
What is case-finding or opportunistic screening?
Aimed at patients who consult a health practicitioner for some other purpose
List at least 3 reasons to screen patients
1. Reduce morbidity, mortality and disability (heelprick test for CF) 2. Protection of other members of the public (screening of immagrants for HIV and Hep B) 3. Prevention of severe diseases in individuals
Screening in prevention is effective if what precention types are not available?
Primordial or primary prevention
Discuss the level of prevention provided by HPV vaccination
May prove effective as primary prevention for cervical cancer, but currently secondary prevention of pap smear testing continues
What are the 4 requirements for a screening program?
1. Characteristics of disease 2. Quality and acceptability of screening test 3. Disease treatable 4. Net benefit to community from program
What are the disease characteristics needed for effective screening?
Disease should be serve and perceived as a problem; High prevalence of pre-clinical disease (not essential if disease severe and test simple); Early intervention must improve outcome (understanding of natural hisotry important); Long lead time (slow progression of disease)
At what point during the natrual history of diease is screening ideal?
Critical point 2 - this is the point between the early diagnosis possible and the time that the usual clinical diagnosis would have been make (i.e., screening before the earliest diagnosis or after the clinical diagnosis is not helpful)
What are the screening test factors for effective screening?
Safety, acceptable and impose minimal discomfort, easy to administer, inexpensive, accurate and reliable
What treatment charactersists are needed for effective screening?
Diagnostic confirmatory testing must be available, treatment must be safe and effective and acceptable, and there must be resources available for screening and follow-up
Which measures determine the accuracy of a screening test?
Sensitivity and specificity
Is sensitivy or specificity more important in a screening test?
Specificity - don't want to miss anyone
When is a test considered to be reliable?
If it provides consistent results
When is a test considered to be valid? What measures are used to determine this?
If it correctly cateorises people into groups with and without disease (as measured by its sensitivity and specificity)
What is sensitivity?
The proportaion of people with the disease in a screened population who are identified as having the disease by the test (i.e., when the disease is present, how often does the test detect it)
What is specificity?
The proportion of disease-free people who are identified as not having disease by a test (when the disease is absent, how often does the test provide a negative result?)
If an entire population was screening, prevalence would euqal what other measure?
The pre-test probablity of the test about to be used =
post-test probability (post predictive value) of the tests just done
What is pre-test probability?
The probability that the patient had the condition on the basis of information available before the test was undertaken.
How do pre-test probability and PPV relate?
Higher pre-test probability gives higher PPV
PPV and NPV change with ____ probability
The accuracy of a screening test is defined by what measures?
Positive and negative predictive values
What is a high positive predictive value?
The probability of a person having a disease when the test is positive (true positives)
What is a high negative predictive value?
The probability of a person not having a disease when the test is negative (true negatives)
What factors determine predictive values?
The sensitivy and specificity of the test
When the prevalence of a disease in a population is applied to an individual, what is it called?
When is test with high sensitivity most important?
When a disease is serious and definitive treatment exists, when the disease can be spread, when there is minimal cost and risk of subsequent diagnostic evaluations
When is a test with high specificity most important?
When costs or risks of subsequent disagnostic evaluations are substantial, when false positives could harm the patient
Discuss the usual situation of PPV in general population screening
Probability that a positive test reflects the true disease (PPV) is very low
Discuss the positives and negatives of screening tests used in the general population
Most negatives are true negatives, but most positives are false positives
List at least 6 things that make a good screening test
Sensitive and specific, not harmful, acceptable, minimal discomfort, cheap, easy to perform, repeatable (reliable) and appropriate in a given situation regarding predictability
Which 3 questions should be considered when determining whether screening is worthwhile?
1. What is the evidence of effectiveness? 2. Does the benefit outweigh the harm? 3. Does the burden of the illness justify the effort?
What is the ideal study design for the evaluation with a screening program? How would it be carried out?
RCT; use current screening as control, plus the new screening as the experimental group. If no current program, randomise people to screening vs not screening at the individual level and follow up over time until outcomes are seen (i.e., death or diagnoses). Use intention-to-treat analysis to retain the benefits of randomisation
What 3 cancer screening programs exist in Australia?
Colorectal, breast cancer, cervical