Functional Psychosis: Assessment, Differential Diagnosis and Management

Functional psychosis describes psychotic symptoms arising primarily from a psychiatric disorder rather than an identified structural, metabolic, infectious, toxicological or neurological cause. It is a clinical description, not permission to skip a medical assessment. Hallucinations, delusions and disorganised thinking can occur in schizophrenia-spectrum illness, mood disorders, substance-related conditions, delirium and brain disease.

Learning objectives

• Define psychosis and distinguish functional psychosis from delirium, substance-induced and medical causes.
• Differentiate schizophrenia-spectrum, mood-related, brief/acute psychosis and delusional disorders.
• Complete a first-episode psychosis assessment including risk, collateral history, physical examination and investigations.
• Plan acute treatment, maintenance, psychosocial support, relapse prevention and follow-up.

1. Psychosis as a syndrome

2. Functional psychosis categories

Schizophrenia

A persistent or recurrent psychotic illness with positive symptoms, negative symptoms, cognitive change and functional decline. Duration and exclusion criteria differ by classification. Document course, remission, severity and treatment response rather than relying only on the label.

Schizoaffective disorder

Prominent mood episodes occur with schizophrenia-spectrum symptoms, with a period of psychosis also occurring outside a major mood episode. Establish the longitudinal timeline from collateral history; a single visit cannot reliably distinguish it from bipolar or depressive psychosis.

Brief or acute and transient psychotic disorder

Psychosis begins abruptly and lasts a limited period with eventual return toward baseline. Stress, sleep loss, substances and medical causes still need assessment. Relapse and later schizophrenia or mood disorder remain possible, so follow-up is essential.

Delusional disorder

One or more persistent delusions occur with relatively preserved functioning and without the pervasive disorganisation typical of schizophrenia. Assess risk, stalking/violence, mood, substance use, neurological causes and the cultural context of the belief.

Mood disorder with psychotic features

Psychotic symptoms occur during severe depression or mania. Determine whether psychosis is confined to mood episodes. Mania may include reduced need for sleep, increased energy, pressured speech, grandiosity and risky behaviour; psychotic depression may include guilt, nihilism or somatic beliefs.

3. Red flags for non-functional psychosis

• Acute or fluctuating onset, impaired attention or altered arousal.
• Fever, autonomic instability, severe headache, meningism, seizures or focal neurological signs.
• Visual/olfactory hallucinations, abnormal movements, marked cognitive decline or atypical age of onset.
• Recent stimulant, cannabis, hallucinogen, steroid, anticholinergic or other medicine exposure.
• Head injury, cancer, HIV/TB, autoimmune disease, pregnancy/postpartum state or endocrine illness.

4. First-episode psychosis assessment

1. Safety: suicide, violence, command hallucinations, access to weapons/pesticides, vulnerability, self-neglect, exploitation and ability to care for dependants.
2. History: onset, symptoms, mood, sleep, function, trauma, substances, medicines, medical/neurological symptoms and previous episodes.
3. Collateral: baseline personality and function, timeline, behaviour, adherence, substance exposure, sleep and family history.
4. Examination: observations, glucose, neurological examination, hydration, infection, movement disorder, head injury and pregnancy possibility.
5. Investigations: targeted blood tests, toxicology, ECG and metabolic baseline; CT/MRI/EEG/CSF for red flags.

5. Psychosis and risk

• Ask directly about suicidal thoughts, command voices, plans, intent, means, previous attempts and reasons for living.
• Assess violence risk: threats, persecutory beliefs, command hallucinations, weapons, intoxication, impulsivity, past violence and access to the alleged target.
• Assess vulnerability: homelessness, exploitation, unsafe relationships, neglect, inability to obtain food/medicines and risk to children.
• Use the least restrictive safe plan: collaborative de-escalation, safe room, observation, family support and urgent admission where necessary.

6. Immediate management

• Reduce noise and stimulation; introduce yourself, use short sentences, maintain safe distance and offer choices.
• Treat medical or substance-related causes; psychosis with delirium is not managed as routine schizophrenia.
• If severe agitation threatens safety, follow local emergency sedation protocol with airway, breathing, circulation, glucose, ECG and sedation monitoring.
• Assess capacity for treatment decisions; a diagnosis does not automatically remove capacity.

7. Antipsychotic treatment

Choose one antipsychotic after discussing previous response, metabolic risk, movement effects, prolactin, QT risk, sedation, pregnancy, cost and availability. Start low, titrate gradually, use an adequate trial and measure symptoms/function. Avoid routine polypharmacy.

Before treatment record weight/BMI, waist, blood pressure, pulse, glucose/HbA1c, lipids, movement examination, cardiac history and ECG when indicated. Monitor symptoms, adherence, sedation, akathisia, EPS, metabolic effects, prolactin symptoms and suicidality.

8. Clozapine and treatment resistance

Consider clozapine under specialist services when persistent symptoms continue despite adequate trials of two antipsychotics, or for persistent suicidality in appropriate patients. It requires full blood-count monitoring and education about fever, sore throat, infection, severe constipation, abdominal pain, chest pain, breathlessness and seizures. Smoking changes can rapidly alter levels. Never begin, stop or adjust it outside the local specialist system.

9. Psychosocial treatment

• Family psychoeducation and communication training.
• CBT for psychosis to reduce distress and improve coping, alongside medicine.
• Supported education/employment, occupational therapy, social-skills support and rehabilitation.
• Substance-use treatment, sleep/routine stabilisation and relapse-prevention planning.
• Trauma-informed care, housing, legal/safeguarding support and peer services.

10. Duration, adherence and relapse prevention

Explain expected time to benefit and the need for regular review. Explore reasons for missed doses without blame: adverse effects, cost, stigma, cognitive difficulty, transport, cultural beliefs and lack of support. Consider long-acting injectable treatment when clinically appropriate, after oral tolerability and informed consent. Create an early-warning plan for reduced sleep, social withdrawal, suspiciousness, voices, disorganisation, substance escalation or medicine interruption.

11. Differential diagnosis table

12. Worked cases

First episode with stimulant use

A 22-year-old develops persecutory beliefs and voices after stimulant use and several nights without sleep. Assess intoxication/withdrawal, glucose, vitals, neurological status, suicide/violence risk and collateral history. Do not diagnose schizophrenia until the timeline is clarified and medical causes are considered.

Psychotic depression

A patient has profound guilt, hopelessness, refusal of food and voices saying they deserve to die. Treat as high-risk severe depression: urgent containment, medical assessment, specialist pharmacotherapy and possible ECT.

Persistent symptoms despite two trials

A patient remains psychotic despite documented adequate trials and adherence. Confirm diagnosis, dose, duration, substance use and interactions; refer for clozapine assessment rather than adding unstructured polypharmacy.

13. Quick self-test

1. What is psychosis, and why is it not a diagnosis by itself?
2. Name five red flags for an organic cause.
3. What distinguishes mood-congruent psychosis from schizophrenia-spectrum illness?
4. What baseline tests are important before antipsychotics?
5. Why should antipsychotic polypharmacy be avoided?
6. When should clozapine be considered?
7. List four psychosocial interventions for functional psychosis.

Answers

1. Psychosis is a syndrome of delusions, hallucinations, disorganisation, negative/cognitive symptoms; it can arise from psychiatric, medical, neurological or substance causes.
2. Acute fluctuation, impaired attention, fever/autonomic instability, seizures, focal neurology, head injury, immunosuppression, atypical age and new drug exposure.
3. Mood-related psychosis occurs in the context of a major mood episode; schizophrenia-spectrum illness requires a longitudinal pattern in which psychosis is not explained only by mood episodes.
4. Weight/BMI, waist, pulse/BP, glucose/HbA1c, lipids, movement examination, medication/substance review and ECG when indicated.
5. It increases interactions and adverse effects, obscures response and makes it difficult to identify the cause of harm.
6. Persistent symptoms despite adequate trials of two antipsychotics or selected persistent suicidality, under specialist monitoring.
7. Family psychoeducation, CBT for psychosis, supported employment/education, rehabilitation, substance-use treatment, sleep/routine work and relapse planning.

References and further reading

• NICE: Psychosis and schizophrenia in adults.
• WHO mhGAP Intervention Guide.
• WHO mhGAP guideline 2023.
• WHO ICD-11 clinical descriptions and diagnostic requirements.
• Use Uganda Ministry of Health and hospital protocols for emergency sedation, referral, safeguarding and medicines monitoring.