Previous studies have suggested that attention-deficit/hyperactivity disorder might be associated with an elevated risk of all-cause mortality. However, the potential associations of psychiatric comorbidities and cause-specific risks are not known. This study aims to examine the all-cause and cause-specific risks associated with ADHD, along with the role of psychiatric comorbidities.

This prospective cohort study included a total of 2,675,615 individuals, of whom 86,670 received a diagnosis of ADHD. The first clinical diagnosis of ADHD or the first prescription of ADHD was considered. The primary outcomes of the study were all-cause and cause-specific mortalities and hazard ratios (HR).

During the follow-up, a total of 6,655 deaths were reported (424 with ADHD and 6,231 without ADHD). The mortality rates were 11.57 per 10,000 person-years for individuals with ADHD and 2.16 per 10,000 person-years for individuals without ADHD. The findings suggested that the associations were more significant in adulthood (hazard ratio 4.64) compared with childhood (HR 1.41). When adjusting for early-onset psychiatric comorbidity in adulthood, the association between ADHD and natural death was alleviated substantially (HR 1.32).

The research concluded that individuals with ADHD were at a higher risk of premature death, with psychiatric comorbidities playing a vital role in increasing cause-specific risks.