Changes in incidence of hospital diagnoses of mental disorders among children and adolescents over the past 3 decades.

Authors

Pernille B Hansen, Andreas Moses Appel, Elisabeth Wreford Andersen, Soren Dalsgaard, Michael E Benros

Published in

BMJ mental health. Volume 29. Issue 1. Sep 15, 2026. Epub Sep 15, 2026.

Abstract

WHO considers mental disorders a significant disease burden among children and adolescents. However, there is a lack of population-based studies on the time trends of mental disorder diagnosis in this group.
To investigate changes in the incidence of clinical diagnoses of mental disorders among all Danish children and adolescents in the past 3 decades.
In this retrospective cohort study, we included all Danish-born individuals from 1976. Follow-up started in 1994 until first diagnosis of a mental disorder, 18th birthday, emigration from Denmark, death or end of study on 30 June 2023. Sex-specific cumulative incidences of diagnosis by age 18 were calculated in 5-year birth cohorts from 1976-1980 to 2001-2005 using the Kaplan-Meier estimator. Poisson regression was used to estimate the age-specific and sex-specific incidence rates.
From 1994 to 2023, a total of 193 354 children and adolescents received a mental disorder diagnosis. Over 3 decades the cumulative incidence of any mental disorder diagnosis before age 18 increased from 1.46% (95% CI 1.40% to 1.52%) to 14.56% (95% CI 14.36% to 14.76%) among females and from 1.22% (95% CI 1.16% to 1.27%) to 14.77% (95% CI 14.57% to 14.96%) among males. A lower mean age at first diagnosis accounted for an estimated 15-22% of the observed incidence in the most recent years.
This study demonstrates a large increase in mental disorder diagnoses. Observed rates were in part accounted for by decreasing age at first diagnosis. While some of the remaining increase may reflect a true rise in the underlying prevalence of mental disorders, changes in diagnostic practice and greater awareness of mental disorders are probable contributors.
Estimates of specific diagnostic rates are essential for appropriate healthcare planning and resource allocation to accommodate the increasing number of mental disorder diagnoses among children and adolescents.

PMID:
42744585
Bibliographic data and abstract were imported from PubMed on 16 Sep 2026.

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