Most common functional mental illness characterised by a pervasive lowering of mood, reduced enjoyment and negative patterns of thinking – may be experienced by up to 30% of the population during their lives. Assumed to be high incidence of underdiagnosis and undertreatment.
1) Unipolar – episode of depression only
Bipolar – tends to upswings and downswings of mood
Unclear. Family history can be positive. Neurochemical and neuroendocrine mechanisms may play a role. Monoamine hypothesis – suggests that depression is due to a functional deficiency of monoamine neurotransmitters (norepinephrine and serotonin). Adverse life events and circumstances increase risk. Some medications increase risk for depression – amphetamines, antineoplastic agents, Parkinsonism agents, barbiturates, benzodiazepines, digoxin
Depressed mood, loss of pleasure or interest in usual activities, feelings of sadness, hopelessness, apathy, despair, lack of enjoyment from everyday activities, sleep pattern changes, withdrawal from friends, reduced appetite/weight loss, reduced libido, pessimistic thoughts about self, the world and the future, cognitive function may be impairs (reduced attention and/or concentration)
Differential diagnosis – normal sadness (eg bereavement)
• Risk assessment (eg for suicide, self-neglect
• Drugs (tricyclic antidepressants (TCA’s); selective serotonin reuptake inhibitors (SSRI’s); monoamine oxidase inhibitors (MAOI’s); lithium)
• ECT – electroconvulsive therapy (indicated for severely depressed; those at risk of starvation from loss of appetite; failure to respond to drugs)
• Psychotherapy (supportive)
Most single episodes last up to 8 months – 20% last up to 2 years; 50% have recurrences.
Poorer outcome is related to younger age of onset, severity of initial symptoms and the presence of co-morbidity (psychiatric or physical).