ABSTRACT
BACKGROUND: No evidence exists on the association between genocide and the incidence of schizophrenia. This study aims to identify critical periods of exposure to genocide on the risk of schizophrenia. METHOD: This population-based study comprised of all subjects born in European nations where the Holocaust occurred from 1928 to 1945, who immigrated to Israel by 1965 and were indexed in the Population Register (N = 113 932). Subjects were followed for schizophrenia disorder in the National Psychiatric Case Registry from 1950 to 2014. The population was disaggregated to compare groups that immigrated before (indirect exposure: n = 8886, 7.8%) or after (direct exposure: n = 105 046, 92.2%) the Nazi or fascist era of persecutions began. The latter group was further disaggregated to examine likely initial prenatal or postnatal genocide exposures. Cox regression modelling was computed to compare the risk of schizophrenia between the groups, adjusting for confounders. RESULTS: The likely direct group was at a statistically (p < 0.05) greater risk of schizophrenia (hazard ratio = 1.27, 95% confidence interval 1.06-1.51) than the indirect group. Also, the likely combined in utero and postnatal, and late postnatal (over age 2 years) exposure subgroups were statistically at greater risk of schizophrenia than the indirect group (p < 0.05). The likely in utero only and early postnatal (up to age 2 years) exposure subgroups compared with the indirect exposure group did not significantly differ. These results were replicated across three sensitivity analyses. CONCLUSIONS: This study showed that genocide exposure elevated the risk of schizophrenia, and identified in utero and postnatal (combined) and late postnatal (age over 2 years) exposures as critical periods of risk.
Subject(s)
Adult Survivors of Child Adverse Events/statistics & numerical data , Emigration and Immigration , Exposure to Violence/statistics & numerical data , Genocide/statistics & numerical data , Holocaust/statistics & numerical data , Prenatal Exposure Delayed Effects/epidemiology , Registries , Schizophrenia/epidemiology , Adult , Adult Survivors of Child Adverse Events/psychology , Aged , Aged, 80 and over , Europe/ethnology , Exposure to Violence/psychology , Female , Genocide/psychology , Holocaust/psychology , Humans , Incidence , Israel/epidemiology , Middle Aged , Pregnancy , Prenatal Exposure Delayed Effects/psychology , Proportional Hazards Models , Risk FactorsABSTRACT
BACKGROUND: A reduced risk of cancer has been noted among people with schizophrenia. Given that genetic causes have been proposed as an explanation of this finding, one would expect that the risk of cancer among first-degree relatives would be equally reduced. AIMS: To investigate the risk of cancer among the biological parents and full siblings of people receiving in-patient care for schizophrenia. METHOD: Linkage analysis was conducted between national population, psychiatric and cancer databases. Standardised incidence ratios for all cancer sites were calculated by comparing the incident rates among first-degree relatives with national incidence rates. RESULTS: A reduced cancer risk was found across all groups examined. Among parents, whose numbers were adequately large, the findings reached statistical significance. For index cases and siblings--a markedly younger population--only a trend was elicited. CONCLUSIONS: The genetic hypothesis--namely, the presence of a gene with the dual effect of reducing the cancer risk and disrupting neurodevelopment--is a plausible explanation for these findings.
