The Neurobiology of Mood Disorders Flashcards
what is involved in the appetitive system (mediate seeking and approach behaviours incl pleasure)?
ascending dopamine systems
mesolimbic / cortical projections (ventral striatum)
dorsal striatum (movement)
amygdala (conditioning / learning)
anterior cingulate (attention / conflict / response selection)
orbitofrontal cortex (relative reward preference / rule learning)
what is involved in the aversive system (promote survival in event of threat - fear / pain)?
ascending serotonin systems NA / CRF / peptide transmitters central nucleus of amygdala hippocampus ventroanterior and medial hypothalamus periaqueductal gray matter
how can depression be conceptualised?
an altered sensitivity / accuracy of brain systems evaluating rewards and cues predicting reward within the environment
how can anxiety be conceptualised?
an altered sensitivity / accuracy of brain systems evaluating threat and cues predicting threat within the environment
what 6 things could contribute to mood disorders being recurrent?
abnormal brain development genetic and developmental effects endocrine/metabolic causes adverse life events psychological resilience/ or lack of cultural aspects
what neurotransmitters are thought to be deficient in the hypothesis of depression?
serotonin norepinephrine dopamine gamma-aminobutyric acid (GABA) brain-derived neurotrophic factor (BDNF) somatostatin
what neurotransmitters are thought to be in excess in the hypothesis of depression?
acetylcholine (toxic)
substance P
corticotrophin releasing hormone (CRH – stress hormone)
what pathway becomes more active in depression?
one that connects amygdala to cortex
what changes occur in serotonin in depression?
decrease in receptor binding through cortical and subcortical regions
what changes occur in norepinephrine in depression?
decrease neurotransmission (MFB) leading to anergia, anhedonia and decrease libido
what changes occur in dopamine in depression?
hypoactive D1 receptor
increase binding of D2/D3 receptors in striatal regions
consistently low CSF level of HVA
how is GABA involved in depression?
principal neurotransmitter mediating neural inhibition
reductions in GABA observed in plasma and CSF
GABA receptors upregulated by antidepressants
how can the HPA axis be involved in depression?
the NF of cortisol to hypothalamus, pituitary and immune system impaired - this causes continual activation of HPA axis and excess cortisol release
cortisol receptors become desensitised leading to increased activity of the pro-inflammatory mediators in disturbances in neurotransmitter transmission
what does cortisol do to blood glucose?
raises it
cortisol basically effects every organ in body - reduces size of brain and therefore reduces neurotransmission
what explains why 80% of patients have recurrences of major depressive episodes?
serotonin function is abnormal before, during and after episodes of depression
what receptor plays a major part in how 5-HT communicates with rest of brain?
5HT1A
how can corticosteroids cause depression (study in animals)?
corticosteroids reduce hippocampal 5-HT1A receptor sites in animal studies and may explain reduced hippocampal damage in depression
what neurotransmitter dysfunction is thought to cause hopelessness?
norepinepherine
what is the difference in NE in patients who have not have depression vs those who have?
in situations that most people may not find too stressful, the vulnerable depressed individual does feels very stressed and may deplete NE
depletion of NE causes depression in recovered patients but not unaffected people
what system is involved in control of motivation and rewarding experiences?
mesolimbic dopaminergic system
what neurotransmitter dysfunction is thought to cause loss of interest / pleasure?
dopamine
deficiency of what neurotransmission has been hypothesised as a factor in mania AND depression and why?
serotonergic neurotransmission - because it contributes to GABA deficit
increased NE and DA activity may underline mania
