The Neurobiology of Mood Disorders

Question 1

what is involved in the appetitive system (mediate seeking and approach behaviours incl pleasure)?

Answer 1

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)

Question 2

what is involved in the aversive system (promote survival in event of threat - fear / pain)?

Answer 2

ascending serotonin systems
NA / CRF / peptide transmitters
central nucleus of amygdala
hippocampus 
ventroanterior and medial 
hypothalamus
periaqueductal gray matter

Question 3

how can depression be conceptualised?

Answer 3

an altered sensitivity / accuracy of brain systems evaluating rewards and cues predicting reward within the environment

Question 4

how can anxiety be conceptualised?

Answer 4

an altered sensitivity / accuracy of brain systems evaluating threat and cues predicting threat within the environment

Question 5

what 6 things could contribute to mood disorders being recurrent?

Answer 5

abnormal brain development
genetic and developmental effects
endocrine/metabolic causes 
adverse life events
psychological resilience/ or lack of
cultural aspects

Question 6

what neurotransmitters are thought to be deficient in the hypothesis of depression?

Answer 6

serotonin
norepinephrine
dopamine
gamma-aminobutyric acid (GABA)
brain-derived neurotrophic factor (BDNF)
somatostatin

Question 7

what neurotransmitters are thought to be in excess in the hypothesis of depression?

Answer 7

acetylcholine (toxic)
substance P
corticotrophin releasing hormone (CRH – stress hormone)

Question 8

what pathway becomes more active in depression?

Answer 8

one that connects amygdala to cortex

Question 9

what changes occur in serotonin in depression?

Answer 9

decrease in receptor binding through cortical and subcortical regions

Question 10

what changes occur in norepinephrine in depression?

Answer 10

decrease neurotransmission (MFB) leading to anergia, anhedonia and decrease libido

Question 11

what changes occur in dopamine in depression?

Answer 11

hypoactive D1 receptor
increase binding of D2/D3 receptors in striatal regions
consistently low CSF level of HVA

Question 12

how is GABA involved in depression?

Answer 12

principal neurotransmitter mediating neural inhibition
reductions in GABA observed in plasma and CSF
GABA receptors upregulated by antidepressants

Question 13

how can the HPA axis be involved in depression?

Answer 13

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

Question 14

what does cortisol do to blood glucose?

Answer 14

raises it

cortisol basically effects every organ in body - reduces size of brain and therefore reduces neurotransmission

Question 15

what explains why 80% of patients have recurrences of major depressive episodes?

Answer 15

serotonin function is abnormal before, during and after episodes of depression

Question 16

what receptor plays a major part in how 5-HT communicates with rest of brain?

Answer 16

5HT1A

Question 17

how can corticosteroids cause depression (study in animals)?

Answer 17

corticosteroids reduce hippocampal 5-HT1A receptor sites in animal studies and may explain reduced hippocampal damage in depression

Question 18

what neurotransmitter dysfunction is thought to cause hopelessness?

Answer 18

norepinepherine

Question 19

what is the difference in NE in patients who have not have depression vs those who have?

Answer 19

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

Question 20

what system is involved in control of motivation and rewarding experiences?

Answer 20

mesolimbic dopaminergic system

Question 21

what neurotransmitter dysfunction is thought to cause loss of interest / pleasure?

Answer 21

dopamine

Question 22

deficiency of what neurotransmission has been hypothesised as a factor in mania AND depression and why?

Answer 22

serotonergic neurotransmission - because it contributes to GABA deficit

increased NE and DA activity may underline mania