A study found that schizophrenia onset among men had a 2-modal peak pattern and among women, a 3-modal pattern. These findings were published in the Journal of Psychiatric Research.
Investigators at the University of Melbourne in Australia evaluated data collected for the 2010 Australian Survey of High Impact Psychosis (SHIP) study. SHIP was a population-based study of nearly 1.5 million adults and was conducted at 7 sites across Australia. Participants were screened for psychosis and the subset of participants with schizophrenia underwent an additional interview and data collection phase. For this study, age- and gender-based predictors of schizophrenia onset were evaluated using a hierarchical clustering method.
Study participants (N=857) were stratified by gender. Men (n=612) and women (n=245) were aged mean 34.1±9.0 and 39.0±11.5 years with the earliest recall of schizophrenia symptoms at 21.7±10.9 and 25.5±9.7 years of age, respectively.
Men were observed to have a 2-cluster solution for age at onset with early onset occurring at a mode of 18 years and late onset at 40 years. For women, early onset occurred at a mode of 21 years, intermediate onset at 26 years, and late onset at 42 years.
Stratified by early and late onset, significant group differences among men with schizophrenia were observed for parental separation in childhood (42.4% vs 15.8%; P =.002), cannabis abuse (80.8% vs 50.0%; P =.004), age at school leaving (mean, 16.2 vs 16.4 years; P =.009), childhood temperament or personality difficulties (64.8% vs 45.9%; P =.033), and family history of psychosis (52.4% vs 34.2%; P =.044), respectively.
For women, early, intermediate, and late onset cohorts differed for migration status (10.6% vs 27.5% vs 18.2%; P =.005), family history of psychosis (63.6% vs 47.3% vs 36.4%; P =.010), alcohol or drug abuse (40.9% vs 39.6% vs 9.1%; P =.015), poor premorbid social adjustment (43.9% vs 27.5% vs 22.7%; P =.017), poor premorbid work adjustment (35.6% vs 24.2% vs 9.1%; P =.018), premorbid personality disorder (12.9% vs 3.3% vs 4.5%; P =.033), and first-degree or other close relative death in childhood (48.1% vs 47.8% vs 19.0%; P =.039), respectively.
The major limitation of this study was recruiting participants through specialized mental health services, so individuals who could manage their disease using less intensive services were likely not represented.
The study authors concluded, “Distal factors occurred more commonly in the early onset group of both sexes, and somewhat more frequently in early onset males. Genetic effects, early developmental difficulties and psychosocial trauma contributors may possibly sensitize individuals to a future onset of psychosis. […] Proximal factors occurred somewhat more commonly in earlier rather than later onset females, but there were mostly no statistically significant differences in the occurrence of proximal factors between the early and late onset male groups. A slightly different pattern of characteristics with less premorbid impairment may be evident in middle to later onset female cases.”
Selvendra A, Toh WL, Neill E, et al. Age of onset by sex in schizophrenia: Proximal and distal characteristics. J Psychiatr Res. 2022;151:454-460. doi:10.1016/j.jpsychires.2022.05.010