Hospital-treated psychosis and suicide in a rural community (1877-2005). Part 1: Incidence rates

The incidence of very late-onset psychotic disorders: a systematic review and meta-analysis, 1960-2016

A substantial subset of people with psychotic disorders are first diagnosed in old age, yet little is known about the epidemiology of very late-onset schizophrenia-like psychosis. We investigated the incidence of affective and non-affective psychotic disorders in those aged 65 and above, and examined variation related to potential risk factors via systematic literature review. We searched PubMed, PsychInfo, Web of Science and bibliographies and directly contacted authors to obtain citations published between 1960 and 2016 containing (derivable) incidence data. Cases were those diagnosed with non-organic psychotic disorders after age 65. Findings were presented narratively, and random-effects meta-analyses were used to obtain pooled incidence rates. From 5687 citations, 41 met inclusion criteria. The pooled incidence of: affective psychoses was 30.9 per 100 000 person-years at risk (100 kpy) [95% confidence interval (CI) 11.5-83.4; I2 = 0.99], and schizophrenia was 7.5 per 100 kpy (95% CI 6.2-9.1; I2 = 0.99), with some evidence of higher schizophrenia rates in women [odds ratio (OR) = 1.6; 95% CI 1.0-2.5, p = 0.05]. We found narrative evidence of increasing incidence rates of non-affective psychoses with age, and higher rates amongst migrants than baseline populations, but no evidence that incidence varied by study quality or case ascertainment period (quality OR = 1.04; 95% CI 0.74-1.48; time period OR = 1.00; 95% CI 0.95-1.05). Substantial heterogeneity in the incidence of very late-onset schizophrenia-like psychoses was observed. No identified studies examined possible risk factors which may account for such variation, including socio-economic status, sensory impairment, traumatic life events, or social isolation.

Hospital-treated psychosis and suicide in a rural community (1877-2005). Part 2: Genetic founder effects

OBJECTIVE

To demonstrate the existence of genetic founder effects in hospital-treated cases of psychosis and self-harm in historical cohorts of a small rural population.

METHOD

These cohorts consist of named persons born after 1845. The cumulative case registers were linked to the purported pedigrees of three presumed mentally ill founders living in the community in the 17th and 18th centuries. We compared the incidence of psychosis and self-harm in the genetically unexposed population and in three exposed founder populations.

RESULTS

We found a preponderance of organic mental disorders and schizophrenia in the twice-exposed founder population and of other non-organic psychosis and self-harm in the thrice-exposed founder population.

CONCLUSION

The genetic impact of the founders seems to have affected the incidence rates of severe psychiatric disorders of their descendants in two ways. A founder effect is detected in organic mental disorders and schizophrenia, and it seems to run independently of that detected in affective psychotic disorders and intentional self-harm.