Cognitive decline and dementia risk in older adults with psychotic symptoms: a prospective cohort study

Objectives: To study the temporal association between psychotic symptoms with cognitive decline and incident dementia.

Design: Population-based prospective cohort study.

Setting: General population in England and Wales.

Participants: A subsample of 2,025 participants of the Medical Research Council Cognitive Function and Ageing Study, representing a study sample of 11,916 nondemented adults age 65 years or older.

Measurements: Baseline presence of psychotic symptoms was assessed with the Geriatric Mental State. Cognitive decline (Cambridge Cognitive Examination) and incident dementia (Automated Geriatric Examination for Computer Assisted Taxonomy diagnosis) were evaluated at 2, 6, and 10 years from baseline.

Results: A total of 330 participants reported baseline symptoms of paranoid delusions, misidentification, or hallucinations, estimated to represent 13.4% of the older general population without dementia. Psychotic symptoms were cross-sectionally associated with worse cognitive functioning, and individuals with psychotic symptoms displayed more rapid cognitive decline from baseline to a 6-year follow-up, especially in nonmemory functions, than people without such symptoms. They further carried an increased overall risk of later dementia (odds ratio = 2.76, 95% confidence interval = 1.75-4.36). The risk increment was observed independently of baseline cognition, depression, anxiety, and vascular risk factors, increased with increasing numbers of psychotic symptoms, and was highest in people age 65-74 years.

Conclusions: Older adults with psychotic symptoms are vulnerable to develop dementia and might be a promising target for indicated prevention strategies. Their neuropsychological functioning should be evaluated on a regular basis.