Objective Huntington disease (HD) is an autosomal dominant neurodegenerative disease involving motor disturbances, cognitive decline and psychiatric symptoms. Psychotic symptoms occur in a significant proportion of patients. We sought to characterise the clinical outcomes of this group of patients.

Methods Data were drawn from the Cooperative Huntington Observational Research Trial, a prospective, multi-centre observational study. 1082 patients with HD were recruited. Measures of cognition, function, behavioural disturbance and motor function were completed annually over 5 years.

Results Overall, 190 patients (17.6%) displayed psychotic symptoms. These patients demonstrated worse cognition, function and behavioural disturbances than patients without psychosis over time. Patients with psychosis also demonstrated lower levels of chorea than patients without psychosis, despite adjusting for concurrent antipsychotic and tetrabenazine use.

Conclusions Psychosis in HD is associated with poorer outcomes in cognition, function and behavioural symptoms. Patients with psychotic symptoms may also have less chorea. Altogether, the findings suggest patients with psychosis have a distinct clinical course.