Risk of dementia and death in very-late-onset schizophrenia-like psychosis: A national cohort study

Knowledge is limited regarding the risks of death and dementia in very-late onset schizophrenia-like psychosis (VLOS). This study aims to scrutinize the associations between VLOS with the risks of death and dementia. Based on a prospective Israeli cohort study with national coverage, 94,120 persons without dementia or schizophrenia diagnoses aged 60 to 90 in 2012 were followed-up for the risks of dementia or death from 2013 to 2017. VLOS was classified as present from the age of the first ICD-9 diagnosis during follow-up, otherwise as absent. Hazard ratios (HR) with confidence intervals (95% CI) were computed with survival models to quantify the associations between VLOS and the risks of death and dementia, without and with adjustment for confounding. Nine sensitivity analyses were computed to examine the robustness of the results. The group with VLOS, compared to the group without, had higher death (n = 61, 18.5% vs. n = 7028, 7.5%, respectively) and dementia (n = 64, 19.5% vs. n = 5962, 6.4%, respectively) rates. In the primary analysis, the group with VLOS compared to the group without had increased risks of death (unadjusted HR = 3.10, 95% CI = 2.36, 4.06, P <.001; adjusted HR = 2.89, 95% CI = 2.15, 3.89; P <.001) and dementia (unadjusted HR = 3.81, 95% CI = 2.90, 4.99, P <.001; adjusted HR = 2.67, 95% CI = 1.82, 3.91; P <.001). The results remained statistically significant (P <.05) in all sensitivity analyses, including among persons without antipsychotic medication. The results may support notions of increased dementia risk and accelerated aging in VLOS, or that VLOS is a prodromal state of dementia.