Psychopathology distinguishing secondary ("organic") psychoses: A systematic review and meta-analysis

A significant minority of patients who present with psychosis have an underlying medical ("organic") cause. Some of these secondary causes are reversible; therefore, early detection is critical. Psychopathology may be informative during initial assessment to determine which patients are at an increased risk of having an underlying medical cause and should be prioritised for enhanced investigation. Through a pre-registered (CRD42024511546) systematic review and meta-analysis, we compared the psychopathology of patients with psychosis secondary to a medical cause compared to patients with primary psychosis as reported in case-control studies using PubMed from inception to September 2025. We identified 13 studies and a pooled sample size of 1564 individuals (primary psychosis = 781, secondary psychosis = 783). Poverty of speech (RR = 18.18, 95% CI = 1.43-231.5) and visual hallucinations (RR = 1.35, 95% CI 1.02-1.80) were more likely to be features of psychosis that was secondary to an underlying medical cause compared to a primary psychotic disorder. Conversely, auditory hallucinations (RR = 0.55, 95% CI = 0.50-0.61), thought insertion (RR = 0.24, 95% CI = 0.12-0.48), thought broadcast (RR = 0.30, 95% CI = 0.09-0.98), unspecified delusions (RR = 0.44, 95% CI = 0.30-0.66), delusions of persecution (RR = 0.72, 95% CI = 0.62-0.84), olfactory hallucinations (RR = 0.34, 95% CI = 0.18-0.63), and tactile hallucinations (RR = 0.26, 95% CI = 0.19-0.35) were more likely to be features of a primary psychosis. Findings underscore the clinical value of a comprehensive psychiatric assessment in patients with undifferentiated psychosis. Secondary psychoses show psychopathological differences, with certain symptoms potentially serving as 'red flags' for secondary causes. These indicators may assist clinicians in prioritising patients for further investigation.