Does Age at Schizophrenia Diagnosis Actually Vary by Sex?

In a poster featured at the American Psychiatric Association 2023 Annual Meeting, researchers characterized demographic variables associated with age at time of diagnosis of schizophrenia in patients enrolled in controlled clinical trials. The authors performed the study to review exploratory findings that the age of diagnosis of schizophrenia (AOD) followed a bimodal and trimodal distribution for male and female patients, respectively.

However, according to the study’s lead author, Vijay Singh, DO, the team found instead that AOD followed a unimodal distribution for both male and female patients with schizophrenia. By proxy, the report noted, this finding suggested that sex likely affects age of onset (AOS) as well.

The retrospective analysis assessed patient-level data of 7881 individuals from 15 randomized, controlled trials on paliperidone extended-release, paliperidone palmitate 1-month, and paliperidone palmitate 3-month tablets in the Yale Open Data Access Initiative database. Authors used multivariable linear regression, with race and sex as predictor variables and AOD as the outcome variable.

The cohort included 4962 male patients and 2919 female patients, of which 4769 self-identified as white, 1692 as Black, 949 as Asian, 17 as Southeast Asian, three as Hispanic, and 343 as other. Using a chi-square test, researchers found a statistically significant association between sex and AOD (x2=295.61; df=68; P<.0001).

Specifically, male sex was statistically significantly associated with a lower AOD (P<.0001). Additionally, while the histograms based on AOD for male and female patients were unimodally distributed and skewed right, the AOD for male patients was 25.44 years compared with 28.79 years for female patients.

“Our findings not only call for a re-evaluation of previous epidemiological understandings of AOD,” the presenters concluded, “but may support future efforts in understanding the origins and typical clinical presentations of patients with newly developed symptomatology of schizophrenia, as well as support clinicians’ perspectives as part of clarifying differential diagnoses.”