THE EPIDEMIOLOGY OF FUNCTIONAL PSYCHOSES OF LATE-ONSET

For the functional psychoses of late life, epidemiological information comes from two sources: studies of persons who have reached psychiatr ic services; and surveys of elderly persons sampled from the general p opulation. A conspectus of published data fr om both sources leads to the following conclusions: Stales phenomenologically similar to those found in clinics do occur In the community in non-trivial numbers. The re is no notable divergence in the information obtained from clinical series and from population-based surveys. These states are more common in women, they become more common with increasing age and are sometim es associated with decline in cognitive performance or with degenerati ve changes in the brain revealed by neuroimaging. Genetic factors appe ar to be less important than in early-onset psychoses but remain ill-d efined, and tile roles of social isolation and disorders of personalit y have not yet been sufficiently elucidated. Both clinical and communi ty-based studies have found an association with sensory impairment. Th e community-based data suggest that paranoid symptoms may be detectabl e at subclinical level, and an association between them and cognitive impairment is demonstrable in individuals who are not diagnosable case s either of psychosis or of dementia. Differences exist between late-o n set paranoid psychoses and affective psychoses in symptomatology and response to treatment. These observations confirm the importance of t he late-onset psychoses for research directed towards uncovering the o rigins of psychotic symptoms in any age group.