Attention deficit/hyperactivity disorder (ADHD) is a common developmental disorder. This study aims to clarify the timing of diagnosis of ADHD in working-age workers with psychiatric comorbidities using large claims data in Japan. Based on a literature survey, we identified 10 typical comorbidities of ADHD. Among 3064162 participants with social insurance, 215060 working-age workers who were diagnosed with the 10 typical comorbidities of ADHD were included. Cohort 1 consisted of 96994 patients…