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15th February 2025
Psychosis secondary to other conditions
Medical causes of psychosis
It is important to rule out medical causes of psychosis before diagnosing it as a psychiatric condition, as these likely need different, time-sensitive management. A CT or MRI head is generally recommended in the first episodes of psychosis.
Factors suggesting a medical cause of psychosis include:
- Acute onset
- Onset at >40 years
- Non-auditory hallucinations (e.g. visual, olfactory, tactile)
- No family history of psychosis and no premorbid or prodromal symptoms
Key medical causes are summarised in Table 5.
Table 5 Key medical causes of psychosis and associated clinical features and investigations
| Condition | Clinical features | Investigations |
|---|---|---|
| Delirium | Cognitive decline, behavioural change, reversed night-day sleep-wake cycle and altered consciousness. Acute onset with fluctuating course. Common medications implicated in delirium include anticholinergic drugs, benzodiazepines, antihistamines, dihydropyridine calcium channel blockers, diuretics, and opioids. | Determine underlying cause, including pain, infection, nutrition, constipation, hydration, medication, environment (‘PINCH ME’). First line: haloperidol. |
| Structural brain problems, e.g. tumour, stroke | Symptoms depend on the territory affected.
E.g. peduncular hallucinosis, a relatively rare neurological disorder that causes vivid visual hallucinations following damage to the midbrain. There may be Lilliputian hallucinations featuring smaller-than-life people or animals. |
Neuroimaging. |
| Epilepsy | Ictal psychosis: associated with non-convulsive status epilepticus. Postictal: develops following a lucid phase, up to 7 days following cessation of a seizure; associated with temporal lobe epilepsy and generalised tonic-clonic seizures. Interictal: not related to the timing of seizures; typically associated with partial epilepsy; may indicate the presence of small brain tumours.Psychosis may also be caused by seizure medications. |
Clinical history of two seizures is needed for a diagnosis of epilepsy. EEG may help confirm the diagnosis.
Insomnia is usually the first sign of postictal psychosis, so preventative antipsychotic treatment may be started. |
| Neurodegenerative, e.g. dementia, Parkinson’s, CJD | Progressive cognitive decline, memory loss, functional difficulties, language deficit, personality changes. Can cause anxiety/depression and psychosis.
With Parkinson’s: tremor, rigidity, bradykinesia, postural instability, hyposomnia, sleep disorders. With CJD: muscle weakness, involuntary movements, poor co-ordination, peripheral neuropathy, visual disturbance. |
Neuroimaging and neurocognitive testing. More specialised tests if prion disease is suspected. |
| Demyelinating disease, e.g. MS | Fatigue, visual disturbance, peripheral neuropathy, muscle spasms, mobility problems. Associated with psychosis, some MS medications also induce/exacerbate psychosis. | Neuroimaging, evoked potential test, LP. |
| Inflammatory, paraneoplastic or infectious CNS disease | Fever and rapid progression. Encephalitis: flu-like symptoms may progress to seizures, weakness/paralysis and cognitive deficits. HSV commonest cause. | Neuroimaging and LP or rheumatology investigations if indicated. |
| Wilson disease | Liver and kidney disease and, more rarely, cardiomyopathy. Kayser-Fleischer rings. Neuropsychiatric symptoms include Parkinsonian features, dystonia, cognitive disorders (frontal lobe disorders and subcortical dementia) and psychosis. | Caeruloplasmin (low), 24 h urine copper (high), serum copper (low, except in acute liver failure). |
| Acute porphyria (cutaneous porphyrias do not affect CNS) | Abdominal pain, chest pain, peripheral neuropathy, nausea, bowel changes, red or brown urine, hypertension, tachycardia, seizures and cognitive defects. | Urine porphyrin precursor porphobilinogen (PBG). Genetic testing. |
| Lead poisoning | Tremor, headache, abdominal pain, bowel changes, muscle pain/weakness, memory problems, fatigue, cognitive defects and delirium. Burton’s line: blue tinge around the gums. Acute lead poisoning may progress to encephalopathy, seizure and death. | Heavy metal screen. Blood film may show basophilic stippling, microcytosis and hypochromia. |
| Vision loss | May trigger visual hallucinations, often with insight (Charles Bonnet syndrome). | Ophthalmology investigations. |
Substance and alcohol-induced psychosis
Prescription drugs and illicit substances (e.g. cannabis, spice, meth, MDMA, LSD [lysergic acid diethylamide]) can cause symptoms of psychosis, but can also worsen underlying mental health conditions. Alcohol can also cause psychosis and is perhaps most dangerous during withdrawal. Delirium tremens affects approximately 5% of people in alcohol withdrawal and can be fatal.
Alcohol withdrawal
The general timeline of alcohol withdrawal is as follows:
- 6-12 hours: anxiety, shaking, nausea, headaches, sweating and insomnia
- 12-48 hours: hallucinations and seizures
- 48-72 hours: delirium tremens (hallucinations, confusion, seizures, sweating, tachycardia and hypertension)
Management of alcohol withdrawal includes CIWA (clinical institute withdrawal scale) scoring to assess severity, consideration of benzodiazepine or carbamazepine, and thiamine to prevent Wernicke’s encephalopathy.
For delirium tremens, first-line management is with oral lorazepam; second-line options include IV lorazepam or haloperidol. Ideally, the patient should be managed in the ICU in a well-lit room.
References
- Ellul M, Solomon T. Acute encephalitis – diagnosis and management. Clinical Medicine. April 2018. 18(2):155–159
- Epilepsy Foundation. Psychosis. Online [cited 28 January 2022]. Available from: https://www.epilepsy.com/learn/challenges-epilepsy/moods-and-behavior/mood-and-behavior-101/psychosis
- Fordham S. RCEM Learning. Delirium in the Elderly. Online [cited 28 January 2022]. Available from: https://www.rcemlearning.co.uk/reference/delirium-in-the-elderly
- Liaison Psychiatry. In: Oxford Handbook of Psychiatry. 4th ed. Ed. Semple D and Smyth R. Oxford: Oxford University Press; 2019. Pp. 839-880.
- Marder S. Psychosis in adults: Epidemiology, clinical manifestations, and diagnostic evaluation [Internet]. Stein M, Friedman M, editors. UpToDate. 2021 [cited 18 January 2022]. Available from: https://www.uptodate.com/contents/psychosis-in-adults-epidemiology-clinical-manifestations-and-diagnostic-evaluation
- National Institute for Health and Care Excellence. Alcohol-use disorders: diagnosis and management of physical complications [Internet]. NICE. 2017 [cited 16 January 2022]. Available from: https://www.nice.org.uk/guidance/cg100
- Orrin Devinsky. Postictal Psychosis: Common, Dangerous and Treatable. Epilepsy Currents. March 2008. 8(2):31-34.
- Epilepsy Society. Seizure types. Online [cited 5 November 2022]. Available from: https://epilepsysociety.org.uk/about-epilepsy/epileptic-seizures/seizure-types
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