Temporal trends of psychiatric disorders incidence by sex, education and immigration status among young and middle-aged adults in Sweden, 2004-2019.
Level 3 - non-randomized controlled study
Nationwide population-based open cohort registry study
PubMed 40001096 · doi:10.1186/s12888-025-06596-8
What was done
A nationwide open cohort study included 5,051,875 individuals born between 1958 and 1994 residing in Sweden during 2004–2019 (aged 25–61 years, followed for ~56–58 million person-years). Researchers identified incident psychiatric disorders from inpatient and outpatient specialist care registries. Individuals were categorized across 18 strata combining sex, education level (low, medium, high), and immigration status (first-generation, second-generation, native). Temporal trends in age-standardized incidence rates (ASIRs) were quantified as average annual percent changes (AAPCs) using Joinpoint regression.
What was found
Autism spectrum and other pervasive developmental disorders showed a significant rise (AAPC 11.8%, 95% CI: 9.5 to 15.8), as did attention-deficit/hyperactivity and conduct disorders (AAPC 18.8%, 95% CI: 16.6 to 25.0). In contrast, other disorders remained flat or declined; AAPCs ranged from 0% for substance use disorders to -5.7% for schizophrenia and acute/transient psychotic disorders. First-generation immigrants had lower overall ASIRs and more favorable secular trends (greater declines or smaller increases) compared to second-generation immigrants and native Swedes, a pattern most pronounced among women and those with low education.
Why it matters
This study highlights sharp increases in adult neurodevelopmental diagnoses alongside stable or declining incidence for other major psychiatric conditions, with substantial variation across socioeconomic and immigrant backgrounds.
Limits
The registry captures only specialist inpatient and outpatient consultations, omitting disorders managed exclusively in primary care. Upward trends in neurodevelopmental diagnoses likely reflect changes in diagnostic awareness and coding practices rather than pure changes in underlying pathology. Lower rates in first-generation immigrants may reflect barriers to accessing specialist care rather than lower true morbidity.
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