Psychosis - Diagnosis

Diagnosis

Diagnosing the presence and/or extent of psychosis may be distinguished from diagnosing the cause of psychosis.

The presence of psychosis is typically diagnosed by clinical interview, incorporating mental state examination. Its extent may be established by formal rating scales. The Brief Psychiatric Rating Scale (BPRS) assesses the level of 18 symptom constructs of psychosis such as hostility, suspicion, hallucination, and grandiosity. It is based on the clinician's interview with the patient and observations of the patient's behavior over the previous 2–3 days. The patient's family can also provide the behavior report. During the initial assessment and the follow-up, both positive and negative symptoms of psychosis can be assessed using the 30 item Positive and Negative Symptom Scale (PANSS).

Establishing the cause of psychosis requires clinical examination, and sometimes special investigations, to diagnose or exclude secondary causes of psychosis; if these are excluded, a primary psychiatric diagnosis can be established.