01Purpose and principlesWhat the assessment is for and the core concepts behind it.
Severity is multidimensional. Count and intensity matter, but so do persistence, distress, function, previous course, physical health, social circumstances and danger. NICE groups subthreshold and mild presentations as less severe and moderate and severe presentations as more severe for treatment discussions, while recognising that boundaries are not defined by one number. Describe what the person cannot do, what now requires help and whether essential needs or dependants are affected.
Functional assessment should include eating, washing, dressing, sleep, medicines, money, cooking, driving, work or study, relationships, parenting and ability to seek help. Ask how much prompting, time or informal care is hidden behind task completion. A professional who still attends work may be profoundly impaired through errors and exhaustion; a person not employed should not be judged less impaired. Use goals important to the person as later outcome markers.
Psychotic features usually occur during severe episodes but require differential assessment. Delusions may concern guilt, disease, poverty, punishment, persecution or nihilism; hallucinations are often accusatory but can be mood incongruent. Ask whether the person believes organs have stopped, food is deservedly forbidden or family would benefit from their death. Explore cultural and spiritual context. Check delirium, substance use, neurological disease and a primary psychotic or bipolar disorder before fixing subtype.
Catatonia and profound psychomotor change are emergencies. Record movement, speech, posture, response, intake, continence and autonomic observations and assess medical and medicine causes. Severe depression can impair capacity selectively, but diagnosis does not prove incapacity. A patient may understand treatment while refusing from a value, or may be unable to weigh because a delusion makes a consequence unreal. Record the exact decision and causal evidence.
Treatment intensity follows needs and preference. Less severe depression often begins with the least intrusive psychological option the person prefers; antidepressants are not routinely offered first unless that is informed preference. More severe depression warrants a discussion of individual CBT, behavioural activation, antidepressants and combination treatment, with specialist care for psychosis, high risk, catatonia or complex resistance. Safety and physical support proceed before a complete diagnostic label.
Key points
- NICE describes less severe and more severe depression using symptom severity and functional impairment rather than a questionnaire cutoff alone.
- Assess breadth, intensity, duration, persistence and trajectory of symptoms alongside self-care, relationships, work, caregiving, money and treatment use.
- Ask what support or effort makes apparent functioning possible; attendance or good grooming can conceal major impairment and carer burden.
- Validated scales can structure baseline and response measurement when interpreted with language, culture, physical illness and individual goals.
- Assess suicide, self-harm, neglect, nutrition, hydration, medicines, dependants, housing and ability to use help at every severity.
- Explore delusions by content, conviction, flexibility and behaviour and hallucinations by modality, commands, distress, control and suicide implications.
- Psychotic depression generally requires specialist mental-health care and consideration of combined antidepressant and antipsychotic treatment.
- ECT may be considered for severe depression when a rapid response is needed, other treatments have failed or the person has previously responded and prefers it.
- Document severity as a reasoned formulation with evidence, immediate actions and review timing, not merely mild, moderate or severe.
02Indications, selection and cautionsWhen it is useful, when urgency changes and important limitations.
Symptoms and impairment are clinically significant but essential function and safety remain sufficiently preserved for a lower-intensity option with active review.
Broader or more intense symptoms cause substantial functional loss, safety concern, marked biological change or need for combined and specialist care.
Delusions or voices amplify depressive themes such as guilt, disease, poverty, punishment, hopelessness or deserved death and influence behaviour.
Psychotic content does not clearly match depressive themes, widening consideration of bipolar, schizoaffective, primary psychotic, neurological or substance causes.
Stupor, mutism, posturing, negativism or marked excitement with physical risk requires urgent syndrome-specific medical and psychiatric assessment.
03Method and interpretationA systematic approach to the test and its findings.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Clinical severity assessmentFirst step - Why
- Integrate symptom intensity, duration, trajectory, distress, function, history, context and immediate danger.
- Interpretation and limitations
- Avoid deriving treatment from a single score. State concrete evidence for severity and factors that could make the interview under-represent illness.
- 02
Validated symptom measure - Why
- Provide a structured baseline and repeated measure of selected depressive symptoms.
- Interpretation and limitations
- Scores support but do not replace diagnosis, suicide assessment, psychosis enquiry or functional judgement; use consistent adapted administration.
- 03
Functional and carer assessment - Why
- Identify loss of essential and instrumental activities, roles, hidden support and caregiver strain.
- Interpretation and limitations
- Task completion can conceal unsustainable prompting or risk. Translate every serious deficit into an action and responsible clinician.
- 04
Psychosis and catatonia examination - Why
- Describe delusions, hallucinations, commands, psychomotor signs, intake, cognition and medical complications.
- Interpretation and limitations
- Behaviour and physiology determine urgency. Consider delirium, bipolarity, medicines, substances and neurological causes in parallel.
- 05
Decision-specific capacity assessment - Why
- Assess treatment, admission, nutrition or disclosure decisions when ability is genuinely in doubt.
- Interpretation and limitations
- A delusion may affect one decision without removing all capacity; record supported understanding, retention, weighing and communication.
04Clinical next stepsHow the result changes management or prompts escalation.
01Severity formulationCombine symptoms with real-world functionFirst stepA depressive syndrome has been identified and treatment intensity must be agreed.+
- 1Describe symptom breadth, intensity, duration and trajectory and use a validated measure only as supporting evidence.
- 2Map self-care, instrumental function, relationships, roles, safety, hidden support and the person's desired outcomes.
- 3EscalationClassify needs as less or more severe with reasons and agree treatment, review timing and escalation triggers collaboratively.
02Psychotic depressionProtect, exclude and obtain specialist careDepression coexists with delusions, hallucinations or impaired reality testing.+
- 1Assess commands, suicide, neglect, nutrition, hydration, capacity, dependants and urgent physical or neurological alternatives.
- 2Arrange specialist mental-health assessment and a safe setting, using voluntary care or lawful restriction according to criteria.
- 3Discuss antidepressant and antipsychotic combination, ECT indications and physical monitoring with the person using supported consent.
03Functional collapseRestore essentials while treating illnessThe person cannot reliably eat, use medicine, maintain housing, care for dependants or seek help.+
- 1Address fluids, nutrition, injury, infection, medicines, benefits, housing and safeguarding before waiting for mood treatment response.
- 2Assess capacity for the specific unmet need and mobilise family, social care or advocacy only with appropriate consent or lawful authority.
- 3Define observable recovery goals and review support burden and restrictions frequently as symptoms improve.
05Risks, monitoring and follow-upComplications, safety checks and further assessment.
- Review symptoms, function, psychosis, intake, self-neglect and suicide risk at a frequency matched to severity and after every major treatment change.
- Use the same accessible symptom measure where helpful but investigate discordance between score, collateral evidence and real-world function.
- Monitor metabolic, cardiovascular, movement and prolactin effects when an antipsychotic is used for psychotic depression.
- Reassess capacity and legal status as delusions, cognition, nutrition and willingness change.
- Track carer burden, dependants, housing and financial safety because discharge may remain unsafe after mood begins to improve.
06Special situationsVariants, exceptions and circumstances that change the usual approach.
Severity is not arithmetic
Two people with the same symptom count may require different care because function, psychosis, suicide risk, physical illness and support differ.
High function can conceal
Professional attendance or personal grooming may depend on extreme effort and extensive support while judgement, nutrition or safety is deteriorating.
Psychosis changes behaviour
A belief that food is undeserved or organs are dead can produce medical danger even without a conventional suicide plan.
Scores have context
Language, literacy, pain, culture, cognitive impairment and response style can raise or lower questionnaire totals without equivalent change in illness.
Recovery includes roles
Symptom improvement is incomplete when the person cannot resume essential self-care, relationships, caregiving or meaningful activity safely.
07Common pitfallsFrequent interpretation and management errors.
- 01
Calling depression mild solely because a questionnaire total lies below a threshold.
- 02
Assuming work attendance proves low impairment or no suicide risk.
- 03
Asking only about auditory hallucinations and missing nihilistic or guilt delusions.
- 04
Treating psychotic depression as uncomplicated low mood without specialist assessment.
- 05
Attributing stupor or mutism to refusal before assessing catatonia and physical illness.
- 06
Assuming severe diagnosis automatically removes capacity for every decision.
- 07
Improving symptoms while leaving food, housing, dependants and medicine support unaddressed.