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Royal College of Psychiatrists, Section of Neuropsychiatry, Annual Conference 2011, Robison College, Cambridge, UK

The diagnosis of psychosis: a review and clinical guide to the diagnosis of conditions causing psychotic symptoms

Cardinal RN, Bullmore ET

In recent work [1], we first sought to describe all known causes of psychosis, including primary psychiatric diseases and psychosis secondary to other conditions. We compiled the set of causes iteratively through systematic review of secondary sources and non-systematic review of primary sources. We found >220 conditions that can produce psychotic symptoms, in addition to a large number of therapeutic and recreational drugs and other toxins. We categorized the causes in approximate groups as follows: neurodevelopmental disorders and chromosomal abnormalities; neurodegenerative disorders; focal neurological disease; malignancy; delirium (as an intermediate mechanism); infectious and postinfectious syndromes; endocrine disease; inborn errors of metabolism; nutritional deficiency; other acquired metabolic disorders; autoimmune rheumatic disorders and vasculitides; other autoimmune encephalopathies; poisoning; sleep disorders; sensory deprivation and impairment; catatonic disorders; primary psychiatric disease; normal experiences; and factitious disorder and malingering.

We then hand-reviewed all causes obtained. We gave disease characteristics, the frequency of psychosis in patients with that disease where this is known, and key investigations or diagnostic criteria. We emphasized the non-psychiatric phenotype for secondary psychoses, since there is no evidence that reliable exclusion of most such conditions can be made based on mental state.

Next, we sought to describe a practical approach to the diagnosis of a patient with psychosis, covering clues from the history, physical and mental state examination, plus initial and specialist investigations. Aides-mémoire include probe questions for psychosis, symptom/sign types seen in different psychotogenic disorders, reasons to order particular special investigations, and a classificatory approach with diagnostic criteria for primary psychoses. The work is intended for psychiatrists in training and as a reference for those with responsibility for patients with psychotic symptoms.

[1] Cardinal & Bullmore (2011), The Diagnosis of Psychosis, Cambridge University Press.


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