Mood disorders Flashcards
Prevalence of MDD
increasing rate of Major depressive disorder (MDD), wth an earlier age of onset
Classification of mental disorders
DSM-V (NICE guidelines)
ICD-10 (WHO system)
What is the Kraepelinian definition of MDI?
Any recurrent mood episodes of any kind (depressive or manic)
Definition of mood disorders ICD-10
Recurrent change in mood/affect to either depression or elation accompanied by a change in overall level of activity
onset related to stressful events
What is a depressive episode?
2 weeks or more of a depressive mood, associated with: sleep alterations, change in diet, anhedonia, anergia, low concentration and agitation
How would you diagnose Major Depressive Disorder?
Major depressive episode with no manic or hypomanic episodes in the past
What are the three groups of features in major depressive disorder?
Atypical (increased sleep, appetite, and mood reactivity) //
Melancholic (anhedonia, blunted affect, decreased mood reactivity and psychomotor retardation) //
Psychotic (delusions/hallucinations)
Core symptoms of depression
Low mood
anhedonia
anergia
What are the biological symptoms of depression?
sleep
loss of libido
changes in appetite
What are the psychological features of depression?
Attitudes towards the world, oneself and about the future
What is a manic episode?
Euphoric or irritable mood associated with: less need for sleep, distractibility, inflated self-esteem, impulsivity
How would you diagnose Type 1 Bipolar Disorder?
Manic episode for at least 1 week with notable functional impairment
What is hypomania?
A milder form of mania - when the symptoms of a manic episode occur for at least 4 days without notable functional impairment (ie psychotic behaviour). It is NOT underactive behaviour
How would you diagnose Type 2 Bipolar Disorder?
Hypomanic episodes (no manic episodes), with at least one major depressive episode
What is the diagnosis for manic symptoms that occur for less than 4 days?
Unspecified Bipolar Disorder
Exceptions to diagnosis of hypomania
Psychotic features
Hospitalised patient
What is cyclothymia?
Milder version of bipolar disorder - fluctuating mania and depressive episodes but not as severe amplitude
How does Type 1 Bipolar Disorder compare to cyclothymia with changes in mood?
Much more significant amplitudes in fluctuations between manic and depressive episodes
How does Type 2 Bipolar Disorder compare to other bipolar disorders with changes in mood?
Similar amplitude of manic episode to cyclothymia // Similar amplitude of depressive episode to Type 1 Bipolar Disorder
What will the majority of first episodes in Type 1 Bipolar Disorder be?
Depressive (85%)
Differences between bipolar and unipolar conditions.
- Age of onset, (earlier in bipolar)
- Shorter depressive episodes in bipolar
- Recurrent course, (more frequent episodes in bipolar)
- Genetic specificity, (manic episodes seem to run in families)
- Differential treatment, (antidepressants for unipolar depression vs neuroleptics/lithium for mania)
Describe the attention biases in depression
Prolonged maintenance of attention over negative material
reduced attention to positive stimuli
Describe the memory biases in depression
Preferential recall of negative material compared to positive
Seen in at risk individuals and those who are recovered
Describe the perceptual biases in depression
Preferential recognition of negative faces in a line of negative and happy faces
What 3 areas of the brain are responsible for this and why?
Sustained amygdala response to negative stimuli //
Prefrontal cortex: anterior cingulate cortex (mediates negative attention bias) / lateral inferior frontal cortex (impaired diversion from negative material)
Role of the amygdala in perceptual bias
Enhanced amygdala response to negative faces
Sensitive to detecting and triggering responses to arousing stimuli e.g. reward/punishment. Bias to detecting cues signalling potential threat such as fearful expression.
What is the monoamine deficiency hypothesis?
Depressive symptoms arise from insufficient levels of monoamine neurotransmitters: serotonin (5-HT), norepinephrine, dopamine
What are five indirect evidences for depression being caused by 5-HT hypofunction?
Anti-hypertensive drugs causes 5-HT depletion and was associated with depression //
Useful antidepressants increase synaptic monoamine concentrations//
Post-mortem lower levels of 5-HT in brainstem of those who commited suicide//
MDD has elevated monoamine oxidase A//
Tryptophan depletion triggers relapse in MDD that has be successfully treated with SSRIs
Why is there only indirect evidence that depression occurs from 5-HT hypofunction?
Difficult to measure serotonin levels in the brain
What is the main way of quantifying receptors in the living human brain?
Aka baseline scan
PET Imaging: inject a radioactive tracer which binds to a specific receptor - proportion of binding leads to stronger images on scan
How do we quantify the amount of transmitter in the human brain?
Second PET scan with radio tracer and amphetamine challenge which stimulates NT release. These competitively bind to receptor instead of tracer leading to a weaker image. Subtracting from the baseline scan shows the amount of NT released.
Issues with PET radiotracers
5HT antagonists are not sufficiently sensitive to pharmacological challenges
5HT2A agonist works but causes a psychedelic effect
Conclusion of radio tracer investigation
Reduced 5HT release capacity in people with depression
Tryptamine psychedelics
Psilocybin - 4/5hr oral, 1hr IV
DMT - 4/5hr oral, 10/20min smoke/IV
LSD - 10/12hr oral, Ihr IV
Psychedelic action
Act on serotonin system, similar to 5HT2A agonist
Different mechanism to SSRI’s
What are the effects of psychedelics?
Psychological peaks - spiritual experience, blissful state, deeply positive mood
How safe are psychedelics?
Non-addictive, low toxicity, good therapeutic index
Adverse effects of psychedelics
Dysphoria, anxiety, headache, nausea
Results of phase 2b trial of psychedelics
statistically sig reduction in depression symptoms
rapid onset action
sustained response at wk 12 .: high durability
