Time trends in the incidence of diagnosed depression among people aged 5–25 years living in Finland 1995–2012

Background: Knowledge of time trends for depression is important for disease prevention and healthcare planning. Only a few studies have addressed these questions regarding the incidence and cumulative incidence of diagnosed depression from childhood to early adulthood and findings have been inconclusive.

Aim: The aim of this national register-based Finnish study was to report the time trends of the age-specific and gender-specific incidence and cumulative incidence of diagnosed depression.

Methods: The study sample included all 1,245,502 singletons born in Finland between 1 January 1987 and 31 December 2007 and still living in Finland at the end of 2012. The participants were divided into three cohorts by birth year: 1987–1993, 1994–2000 and 2001–2007. Depression diagnoses (ICD-9: 2961; ICD-10: F32, F33) given in 1995–2012 were available and identified from the Care Register for Health Care.

Results: Ten percent of the females and five percent of the males were diagnosed with depression in specialized services by age 25 years. The cumulative incidence of depression by age 15 years rose from 1.8% (95% CI 1.8–1.9) to 2.9% (95% CI 2.8–3.0) in females and from 1.0% (95% CI 1.1–1.2) to 1.6% (95% CI 1.6–1.7) in males when the cohorts born 1987–1993 and 1994–2000 were compared.

Conclusions: A larger proportion of young people in Finland are diagnosed with depression in specialized services than before. This can be due to better identification, more positive attitudes to mental health problems and increased availability of the services.