Attention-deficit/hyperactivity disorder and subsequent diagnoses of major psychiatric disorders: a nationwide...

We evaluated the risk of being diagnosed with various psychiatric disorders after an attention-deficit/hyperactivity disorder (ADHD) diagnosis using data from South Korea's National Health Insurance Service from 2002 to 2019, which covers approximately 97% of the country's population. ADHD and control groups were selected after propensity score matching was performed for individuals diagnosed with ADHD and their age- and sex-matched counterparts from the general population. Comorbid psychiatric disorders included depressive disorder, bipolar disorder, tic disorder, and schizophrenia. The incidence of newly diagnosed psychiatric disorders was compared between the groups. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated and adjusted for ADHD medication prescription. After matching, 353,898 individuals were assigned to each of the two groups. Compared to the control group, the ADHD group showed a significantly higher risk of being subsequently diagnosed with depressive disorder, bipolar disorder, schizophrenia, and tic disorder. The onset age of depressive disorder, bipolar disorder, and schizophrenia in the ADHD group was 16-17 years, approximately 5 years earlier than that in the control group. The risk for depression was the highest in individuals with high income levels, and that for schizophrenia was the highest among rural patients. The median length of the follow-up time until the diagnosis of each comorbid psychiatric disorder was 7.53, 8.43, 8.53, and 8.34 years for depressive disorder, bipolar disorder, schizophrenia, and tic disorder, respectively. Individuals with ADHD had an overall higher risk of being diagnosed with subsequent psychiatric disorders than did the controls. Hence, they should be carefully screened for other psychiatric symptoms from an early age and followed up for an extended duration, along with appropriate interventions for ADHD symptoms, including psychosocial treatments and educational approaches.