brain conditions Flashcards
what are the hypotheses for MDD?
monoamine hypothesis
glumatate (NMDA) hypothesis
GABAergic hypothesis
neurogenesis hypothesis
corticotrophic (glucocorticoid) hypothesis
HPA axis hypothesis
what are the hypotheses to explain SZ?
altered dopamine hypothesis
neurodevelopment hypothesis
NMDA-receptor hypothesis
diathesis-stress response axis
what is the 2-hit model for SZ?
it is a proposition that in neurodevelopment, there are 2 times in the patients life where the brain develops wrong, the first one is as early as the first or second trimester and the second is during puberty due to too much synapse elimination and loss of plasticity
what regions of the brain are affected with schizophrenia?
the mesolimbic dopamine neurons coming from the VTA and the prefrontal cortex (specifically the dorsolateral PFC)
the hippocampus is also affected (where learning and memory is)
amygdala where emotional stress and learning is
where does cell loss happen in SZ patients?
theres deficits in olgiodendrocytes in the PFC and limbic system inc anterior cingulate gyrus (ACC), and hippocampus
what is the modified dopamine hypothesis SZ?
its the hypothesis that theres significantly less dopaminergic neurons present in the PFC (hypodopaminergia) and too much dopaminergic activity in the mesolimbic regions (hyperdopaminergia)- negative and positive symptoms respectively
what can electroconvulsive therapy be used for?
parkinsons
treatment-resistant MDD
SZ
epilepsy
it works by non-focal and intense stimulation of the entire brain, usually causes a generalised seizure then shows greatly reduced symptoms for a long period of time, exact mechanism unknown
what parts of the brain are involved in MDD?
hyperactive anterior cingulate cortex
lower neural activity in PFC, hypothalamus, striatum and amygdala
explain the HPA axis
hypothalamus has neuroendocrine neurons which produce vassopressin and corticotrophin-releasing hormone which then act on the pituritary to release adrenocorticotrophic hormone which signals to the adrenal glands in the adrenal cortex to produce glucocorticoids inc cortisol (hypersecretion of which is thought to be a risk factor for depression)
what does clozapine target?
D1 and 2 receptors, M1 and 5-HT 2a + alpha-adrenoceptor (according to NICE) its 2nd gen
what is the first gen SZ med?
and what does it target?
cloropramazine- targets D2,3+5, H1 +M1 antagonist
what is the first choice SZ med and how does it work?
amisulpride- selective D2+3 receptor antagonist
how does olanzapine work?
it targtes the D1-5 receptors, 5-HT2, H1 and M1 receptors and antagonises them
what makes up the mesolimbic pathway?
the ventral-tegmental area (VTA) and the ventral striatum
what genes are involved in SZ?
DISK-1 - a truncated gene on chromosomes 1 and 11, need to associate with other genes and non-genetic factors to actually cause an effect
3q29 deletion- highest risk allele associated with SZ
22q11 deletion - associated with the immunodeficient DiGeorge syndrome, 25% of people with this also have SZ
where is there loss of grey matter in SZ?
superior temporal gyrus
the amygdala and hippocampus
why is the thalamus smaller in SZ patients?
becuase of loss of cell bodies in the mesodorsal neucleus of the thalamus and a loss of axonal terminals which contribute to the loss of cortical dendrites and the dendritic spines
what novel treatment targets both the positive and negative symptoms of SZ?
KarTX
trospium - peripheral muscarinic antagonist
xanomeline- M1/4 agonist crosses BBB to cause central effects whilst not being used up in the periphery - also means theres less side effects
what causes physiological anxiety?
the hypothalamus and the amygdala signal to the adrenal glands in the adrenal medulla to release adrenaline to cause the physiological symptoms of anxiety
what are the hypotheses explaining anxiety?
HPA axis- involved in the second part of the stress response
GABAergic altered sensitivity
5-HT implicated
what part of the brain is most affected in parkinsons and whats its role?
the substantia nigra which is responsible for much of the brains dopamine production leading to less positive motor control and more negative motor inhibition
what is the main treatment of parkinsons? and what is also given to help this?
levodopa - increases levels of dopamine in the brain
given with catechol-o-methyltransferase to stop peripheral breakdown of the drug
what are the effects of the inability to clear protein aggregates in parkinsons?
alpha-synuclein are associated with protein misaggregation and impaired protein cleavage to form lewy bodies which disrupt cell pathways leading to synaptic loss and glial damage and neuronal death