Psychosis and dementia: risk factor, prodrome, or cause?

BACKGROUND: Progression of dementia is often associated with the emergence of neuropsychiatric symptoms (NPS), though there is recent evidence that NPS may occur in prodromal dementia (PrD) and impact clinical course. Mood and anxiety symptoms are the NPS that tend to occur most frequently in PrD and thus have been most extensively studied. Comparatively, there has been little focus on psychotic symptoms in PrD.
METHODS: The authors review the existing literature on psychosis in PrD, including the functional psychosis of early and late onset, with a focus on epidemiology, phenomenology, and clinical course and treatment considerations.
RESULTS: Patients with psychotic disorders at baseline such as schizophrenia may be more at risk for developing dementia over time, although this is not completely clear. Psychotic symptoms are likely more common in PrD than previously understood based on factor analysis studies, although they are much more common in established dementia. Variability in findings may reflect the heterogeneous nature of PrD studies to date and the lack of inclusion of patients with late onset psychosis in most clinical studies. The presence of psychosis in patients with PrD may be associated with a worse prognosis in terms of mortality and conversion to dementia.
CONCLUSIONS: Research to date suggests that psychosis in PrD may be more common than previously thought and impact clinical course negatively. Future studies incorporating patients with late onset psychotic disorders, and focusing on the impact of early recognition and treatment, are required to more fully understand the role of psychosis in PrD.