BS42017 L6,7,8 Flashcards
(50 cards)
what is the criteria for a depressive episode in ICD-10 criteria?
At least two of the following: - Depressed mood - Loss of interest and enjoyment - Reduced energy - Fatigue - Diminished activity Plus at least three of: - Reduced concentration and attention - Low self-esteem and confidence - Ideas of guilt and unworthiness - Pessimism - Ideas or acts of self harm - Disturbed sleep - Reduced appetite For at least 2 weeks!
what can you say about the diagnostic bar for depression?
it is set too low
how long does an uncomplicated moderate episode of depression last?
4-6 months
what can be used to quantify illness severity? (3)
long established rating scales eg. Beck Depression Inventory, 17-item Hamilton, MADRS.
what could be used to treat “mild” illness?
cognitive behavioural therapy (CBT)
what could be used to treat moderate-severe illness?
antidepressants and ECT?
what does an “adequate trial” of antidepressants include?
prescriptions of specific antidepressant above a specific minimum dose for a minimum of 6 weeks with reasonable certainty the patient took the medication as prescribed
what determines treatment-resistance?
number of failed adequate trials
what are the five research domain criteria (RDoC)?
- Negative valence system- e.g. fear, anxiety, loss, non-reward
- Positive valence system- e.g. reward learning and valuation, habits
- Cognitive system- e.g. attention, memory, cognitive control
- Social system- e.g. attachment, communication, perception of self/others
- Arousal/modulatory system- e.g. circadian rhythm, sleep/wake cycle.
what does positive valence do and what systems contribute to it? (7)
Positive valence system- function to mediate seeking and approach behaviours (incl. pleasure)
- Ascending dopamine systems; mesolimbic/cortical projection
- Endogenous opiate system (mu opioid receptors)
- Ventral striatum/accumbens
- Dorsal striatum (movement)
- Amygdala (conditioning/learning)
- Anterior cingulate (attention/conflict response selection)
- Orbitofrontal cortex (relative reward preference/rule learning)
what does negative valence do and what systems contribute to it? (7)
Negative valence system- functions to promote survival in the event of threat (fear/pain)
- Endogenous opioid systems (kappa receptors)
- Ascending serotonin systems
- Noradrenaline/CRF/ peptide transmitters.
- Central nucleus of amygdala
- Hippocampus
- Ventral anterior and medial hypothalamus
- Periaqueductal grey matter
how do you describe depression? (6)
- Difficulty identifying “rewarding” stimuli
- Reduced contact with previously rewarding stimuli
- Increased contact with aversive stimuli
- Overall reduction of behaviour
- Move less, eat less, lose weight, less interest in sex etc.
- Low mood
how do you describe mania? (7)
- Previously neutral stimuli become “rewarding”
- Increased exploration/overall activity
- Increased “appetite” for food, activity, sex, etc
- Intolerant of “aversion”/boredom
- Intolerant of frustration
- Elevated/elated mood
- Could be irritable
Is it possible to diagnose depression by only using a brain scan?
Many neuroimaging studies of mood disorder reporting abnormal brain structure and function show statistical differences based on standard statistical tests e.g. t-test. there is a highly significant group level difference between patients and controls (e.g. reduced hippocampal volume in MDD cf controls).
what is the problem with classical univariate statistics?
Group level (t-test) difference that is highly significant (p«0.05) may have lots of overlap on single measure e.g. hippocampal volume for individual patients. This means a single measure on its own is clinically useless.
Classical significance level (p<0.05) approach is not useful in psychiatry and there has bee no progress for over half a century as evidence of this. what is the solution to this?
a multivariate approach so instead of one measure, use lots of variables and statistical frameworks (machine learning)
Multi-centre study (Edinburgh and Aberdeen) using structural brain scans (T1 weighted) showed machine learning to be what?
machine learning based approach has 90% accuracy in diagnosis of depression.
where does the evidence of D&G’s theory come from?
- mainly animal model evidence
- a few psychopharmacology tests on humans
There is considerable evidence by the early 70s for dopamine being involved in reward. It is thought that serotonin might have what effect?
a “complementary” role (or “mirror opposite”).
what did D&G propose dorsal raphe nucleus neurons do?
functioned in opposition to dopaminergic projections, being engaged by distal cues predictive of aversive reinforcers, functioning as a “stop” or negative reinforcement signal, guiding the animal away from threats (passive avoidance) and towards dopaminergic safety cues (active avoidance).
what did D&G propose median nucleus neurons do?
mediate a disconnecting “unlearning” function during extinction or punishment of instrumental learning.
later suggested that MRN projections prevent consolidation of aversive memories allowing tolerance to chronic adversity (resilience).
what are the two roles of 5-HT in anxiety?
different behavioural requirements for responding to proximal vs distal threats.
what does the brain system responsible for responding to aversive threats include? (3)
amygdala –> (medial) hypothalamus –> periaqueductal grey matter (PAG).
what structure responds to distal threats?
amygdala
