Psychotic disorders a potentially modifiable risk factor for dementia

Individuals with nonaffective psychotic disorders appear to have a twofold higher risk of developing subsequent dementia compared with those who do not have such disorders, as reported in a recent study.

Researchers performed a systematic review and meta-analyses of studies that quantified the risk of dementia associated with psychotic disorders. They searched four electronic databases for relevant studies and identified 13 studies meeting the inclusion criteria. Of these, 11 were included in the meta-analysis.

The studies were conducted in Australia, Europe (Denmark, Finland, Sweden, and the United Kingdom), Israel, New Zealand, Taiwan, and the United States. Sample sizes ranged from 61 to 8,011,773 adult participants, with a total of 12,997,101. Study follow-up periods ranged from 1.57 to 33 years (median 11 years).

Nonaffective psychotic disorder diagnoses across studies included late-onset acute and transient psychosis and late-onset delusional disorder, late-onset and very late-onset schizophrenia-like psychoses, schizophrenia, psychotic disorders, and schizophrenia in older people. Most studies focused on the incidence of all-cause dementia, with only one study investigating the incidence of Alzheimer's disease.

Obtained using random-effects meta-analyses, pooled data showed that nonaffective psychotic disorders were associated with increased risk of all-cause dementia (pooled risk ratio [RR], 2.52, 95 percent confidence interval [CI], 1.67–3.80; I2=99.7%; n=12,997,101; 11 studies), with high heterogeneity between studies.

Subgroup analyses showed stronger associations in studies with shorter follow-up periods, conducted in non-European countries, published after 2020, and where ≥60 percent of the sample were female. The risk of subsequent dementia was higher in patients aged <60 years at baseline, in typical and late-onset psychotic disorders vs very late-onset psychosis, in broader psychotic disorders vs schizophrenia, and in prospective vs retrospective studies.

Of note, the associations persisted despite excluding low-quality studies (pooled RR, 2.50, 95 percent CI, 1.71–3.68; I2=99.0%).

The findings highlight the importance of closely monitoring individuals with psychotic disorders for cognitive decline in later life.