Synopsis
Recognise a depressive syndrome through sustained mood, interest, energy, cognition and biological change, assess suicide and psychosis directly, and distinguish clinically significant illness from ordinary sadness without reducing diagnosis to a questionnaire score.
- Core depressive experiences include sustained low mood, reduced interest or pleasure and reduced energy, but the person's language may emphasise emptiness, irritability, numbness or inability to care.
- Biological or somatic changes include sleep disturbance, appetite or weight change, psychomotor slowing or agitation, reduced libido, fatigue and sometimes early-morning or diurnal worsening.
- Cognitive features include impaired concentration and decision making, guilt, worthlessness, hopelessness, negative expectations and recurrent thoughts of death.
- Establish duration, persistence, reactivity, baseline and functional change; a clinically significant episode is more than a bad day and commonly persists for at least two weeks.
- Ask directly about self-harm, suicide, neglect, psychosis, mania or hypomania, substances, trauma, pain, pregnancy or postpartum context and risk to dependants.
- Observe appearance, speech, psychomotor activity, affect, thought form and content, perception, cognition and insight while distinguishing observation from the patient's report.
- Use validated measures to support baseline and monitoring, not as a standalone diagnosis, severity decision or predictor of suicide.
- Consider grief, bipolar disorder, anxiety, trauma, substance or medicine effects, endocrine and neurological disease and sleep disorders according to phenotype.
- Share the working diagnosis and uncertainty, agree treatment from severity, function and preference, and safety-net early change or emergent suicidal thoughts.
Key red flags
Suicidal planning, rehearsal, available means, recent self-harm, severe hopelessness or the belief that others are better off after the person's death requires an immediate scenario-based formulation.
Mood-congruent delusions of guilt, poverty, nihilism or deserved punishment, accusatory voices or command hallucinations indicate psychotic depression until alternatives are assessed.
Marked slowing, mutism, stupor, posturing, negativism, excitement or autonomic disturbance may indicate catatonia and needs urgent medical and psychiatric evaluation.
A previous period of elevated or irritable mood with reduced need for sleep and increased activity may indicate bipolar disorder, changing antidepressant risk and treatment.
Fluctuating attention, altered arousal, focal neurology, fever, new seizure, late abrupt onset or rapid cognitive decline suggests delirium or neurological disease rather than uncomplicated depression.
Investigation priorities
Establish mood, interest, energy, cognition, biological change, persistence and previous baseline.
Management branches
A person reports persistent low mood, reduced motivation, fatigue or loss of interest.
- Establish core, cognitive and biological symptoms, duration, baseline and concrete functional consequences using the person's own language.
- Ask directly about suicide, self-harm, psychosis, catatonia, mania, substances, physical illness and dependants.
- Formulate severity, immediate risk, leading diagnosis and alternatives and arrange urgent or routine care with named follow-up.