Sex differences in clinically diagnosed psychiatric disorders over the lifespan: a nationwide register-based study in Sweden.

Background: Limited studies exist on sex differences in incidence rates of psychiatric disorders across the lifespan. This study aims to analyze sex differences in the incidence rates of clinically diagnosed psychiatric disorders over the lifespan.

Methods: We conducted a nationwide register-based cohort study, including all individuals who were born in Sweden and lived in Sweden between 2003 and 2019, including 4,818,071 females and 4,837,829 males. We calculated sex- and age-specific standardized incidence rates for any and 10 major types of psychiatric disorders. Multivariable-adjusted incidence rate differences (IRDs) for diagnosed psychiatric disorders between females and males were estimated.

Findings: During a follow-up of 119,420,908 person-years, males showed a higher incidence rate of any diagnosed psychiatric disorder than females at age 5-9 (IRD = -8.93; 95% CI: -9.08 to -8.79; per 1000 person-years), whereas females showed a higher rate than males at age 15-19 (IRD = 9.33; 95% CI: 9.12-9.54) and onwards (except age 60-69). Specifically, among females, excess rates were apparent for depressive, anxiety, eating, stress-related and bipolar disorders at age 10-54, whereas among males, excess rates were pronounced for autism and attention deficit hyperactivity disorders before age 14, drug use disorders at age 15-54, and alcohol use disorders in adulthood. For schizophrenia, the male excess at age 15-49 shifted to female excess at age 60-79. The magnitude of IRDs were greater in recent years and individuals with lower socioeconomic status.

Interpretation: Knowledge about the lifespan and socioeconomic variations in the sex differences in rates of diagnosed psychiatric disorders may inform targeted screening/intervention strategies.

Funding: Vetenskapsrådet, FORTE, Karolinska Institutet Strategic Research Area in Epidemiology and Biostatistics, and Icelandic Research Fund.