Neurobiology of Mood Disorders Flashcards
What is meant by the appetitive and aversive systems?
Appetitive (Reward system)
Aversive (Brain avoids previously unpleasant stimuli)
How does depression affect the appetitive system?
Depression is a misunderstanding of rewards within the environment
How does anxiety affect the aversive system?
Anxiety is a misinterpretation of cues predicting threat within the environment
Patient thinks normal stimuli are threatening
Why are mood disorders difficult to diagnose in teenage/ young adults and old age?
confused with normal teenage behavior OR drug use
Elderly = confused with other psychiatric illnesses (i.e Alzheimer’s or Parkinson’s)
Why do many patients with mood disorders have such poor outcomes?
Treatment often started late
Long-term compliance to medication is poor due to long treatment duration
At what stages in life do depressive episodes present in unipolar disorders?
Usually teenage years = first episode and then again in early adult life (e.g. marriage age)
At what stages in life do manic and depressive episodes usually occur in bipolar disorders?
Manic and depressive episode whilst at school/ during teenage
Manic and depressive relapse into adult life
Why are mood disorders recurrent?
Abnormal brain development Genetic Endocrine/Metabolic causes Adverse life events Cultural aspects
What neurotransmitters are thought to be depleted in depression?
Serotonin 5HT
Noradrenaline
Dopamine
Gamma-aminobutyric acid (GABA)
What neurotransmitters in excess are thought to cause depression?
Acetylcholine (ACh)
Substance P
Corticotrophin Releasing Hormone (CRH)
A decrease in noradrenaline neurotransmission leads to what symptoms?
anergia
anhedonia
decrease libido
Why can cortisol be constantly raised in depression/ anxiety?
Perception of a stimulus as threatening causes the hypothalamic-pituitary axis to release cortisol for a fight or flight response
- if patient is suffereing from a mental disorder where stimuli are constantly deemed as threatening, their cortisol level is never suppressed by negative feedback
Serotonin Function is abnormal before, during and after episodes of depression. TRUE/FALSE?
TRUE
=> may explain why 80% of patients have recurrences of major depressive episodes
How can adverse childhood events cause changes in the noradrenaline system that lead to a depressive episode?
Adverse childhood experiences cause over-active responsiveness in noradrenaline system
Vulnerable depressed individuals can deplete noradrenaline and therefore find certain non-stressful situations VERY STRESSFUL
This depletion of noradrenaline only causes depression in recovered patients, NOT patients who were previously unaffected
Why has hypofunction of the dopamine system been hypothesised as the reason for loss of pleasure/interest in depression?
Mesolimbic dopaminergic system is involved in the control of motivation and rewarding experiences
