Risk of Dementia in Patients Suffering From Psychosis-A Danish Register-Based Cohort Study

OBJECTIVE: To investigate the association of psychosis with subsequent risk of dementia and to explore any impact of age at psychosis onset.

METHODS: Using the Danish National health registries, a total of 39,022 patients with a diagnosis of psychosis and a matched sample of 195,109 individuals without psychosis were included in the study. All individuals were born between 1910 and 1959 and were a minimum of 18 years of age in 1969. The risk of being diagnosed with dementia was analyzed using Cox proportional hazard regression with adjustment for sociodemographic variables and alcohol use disorder. Analyses were stratified by age of psychosis onset (< 45/45+ years) and age at follow-up in three categories (60-70, 70-80, and 80 or above).

RESULTS: During mean 16.8 years of follow-up, 18,653 (12.55%) of all individuals developed dementia. Patients with psychosis had a higher risk of dementia at all ages of follow-up, with the highest risk estimate at follow-up before age 70 (hazard ratio (HR) adjusted 4.44 CI (4.01-4.91)). However, the risk also varied with age at psychosis onset, being highest at late-onset (adjusted hazard ratio: 5.16 (95% confidence interval: 4.59-5.81)).

CONCLUSION: Patients with psychosis had a higher risk of developing dementia than individuals without psychosis. The risk varied with age at psychosis onset and age at follow-up.