Lecture 8 - depression Flashcards
what is depression?
central to depression it is depressed mood and/ or loss of both pleasure in most activities
Severity of the disorder is determined by both the number and severity of symptoms.
Two diagnostic systems: ICD-10/11 and the DSM-5 classification system.
Symptoms should be present for at least 2 weeks and each symptom should be present at sufficient severity for most of every day
what does ICD-10 look at ?
section V: mental and behavioural disorders
what does ICD-11 look at?
mental, behavioural or neurodevelopment disorders
what is bipolar disorder I, II, cyclothymia and euthymia?
Bipolar I disorder is where a person has had at least one manic episode and periods of significant depression, each usually lasting for an extended period.
Bipolar II disorder, the person has never had a manic episode, but has had at least one hypomanic episode and at least one period of significant depression.
Strong genetic component – inheritability. Usually diagnosed in late teens
Cyclothymia – similar to bipolar but with lower extremes
Euthymia – period without mood disturbances.
what is lithium used as?
lithium used to calm manic patients and prophetically as a mood stabiliser. the results observed relatively quick and are considered safe - no overdose potential
what is the mechanism of action of lithium and side effects?
modulation of glutamate, GABA and dopamine neurotransmission
inhibition of inositol triphosphate formation
interference with cAMP formation
accumulation of lithium in the cell, leading to sustained depolarisation
side effects: long half life leads to common side effects such as nausea, thirst, tremor, mental confusion
what are key symptoms and associated symptoms of major depressive disorder?
key symptoms:
persistent sadness or low mood
loss of interests or pleasure
fatigue or low energy
associated symptoms: disturbed sleep, poor concentration or indecisiveness, low self-confidence, poor or increased appetite, suicidal thoughts or acts
agitation or slowing of movements, guilt or self-blame. symptoms should be present for at least 2 weeks and each symptom should be present at sufficient severity for most of every day.
what are the degrees of depression?
not depressed(<4)
mild depression(4 symptoms)
moderate depression(5 or 6 symptoms)
severe depression(>7 symptoms, with or without psychotic symptoms)
what is the hypothesis for the pathophysiology of depression?
monoamine hypothesis.
suggests that depression results from deficient monoamine transmission.
conceived by observation that a monoamine oxidase inhibitor developed to treat tuberculosis, elevated the mood of the treated patients.
Other animals models, including reserpine, also highlight a role for monoamines.
Thus, the amine hypothesis proposes that depression occurs due to decreased levels of amines (NA, 5-HT & DA) in the CNS
what are problems associated with the monoamine hypothesis?
Drug action is relatively fast (hours) but relief of symptoms takes longer (weeks)
Antidepressants have differing mode of action (i.e. 5-HT v NA), but work similarly on symptoms.
describe synaptic transmission vs volume transmission.
synaptic transmission - high speed and precise eg glutamate
volume transmission: temporarily slower, anatomically broader eg monoamines
what are treatments for depression?
Cognitive behavioural therapy (CBT)
Identify and address triggers / causes
Antidepressants
Selective serotonin reuptake inhibitors (SSRIs)
Serotonin noradrenaline reuptake inhibitors (SNRIs)
Monoamine Oxidase Inhibitors (MAOIs)
Tricyclic antidepressants (TCAs)
Electroconvulsive Shock Treatment (ECT)
what is non pharmacological treatment for depression?
Psychotherapies:
Behavioural therapy
Interpersonal psychotherapy
Group therapy
Cognitive-behavioural therapy (CBT)
Mindfulness-based cognitive therapy (MBCT)
Brain stimulation methods
Electroconvulsive therapy (ECT)
Vagus nerve stimulation (VNS)
Transcranial magnetic stimulation (TMS)
Deep brain stimulation (DBS)
explain what the mechanism of action of monoaminase oxidase inhibitors are as antidepressants.
MAOIs is to inhibit the enzyme MAO. MAO is breaks down monoamine neurotransmitters, such as serotonin, norepinephrine, and dopamine, in the brain. By inhibiting MAO, these drugs slow down the breakdown and so an increase of these neurotransmitters.
ncreased neurotransmitter levels, there is enhanced neurotransmission, which can help regulate mood, improve emotional stability, and alleviate symptoms of depression
what is the mechanism of action of TCAs?
TCAs inhibit the presynaptic alpha2 receptors and block the reuptake pumps responsible for removing serotonin and norepinephrine from the space between nerve cells (synaptic cleft). By doing so, they allow these neurotransmitters to stay in the synapse for a longer time, enhancing their effects.
