Longitudinal Scandinavian population registries provide an extensive data source that has given new insights into attention-deficit/hyperactivity disorder and its associated risks of suicidal behavior, accidents, and early mortality. The studies allowed comparisons of rates between ADHD patients and control patients, as well as treated and non treated ADHD patients.
The studies looked at suicide rates in ADHD patients, with further screening for comorbidities. Swedish national registry study identified 51,707 patients with ADHD matched by sex and birth year to 258,535 controls. The ADHD patients had significantly higher rates of both attempted and completed suicide. The risk after adjustment for socioeconomic status was increased 12.3-fold in individuals with ADHD, compared with controls, but the risk dropped to 5.91-fold after further adjustment for comorbid psychiatric disorders. They found clear improvement to suicide related risk when ADHD patients are identified and treated with medication. Patients on stimulant medication had a significant 19% lower risk of suicide-related events than when they were off medication. While on non stimulant ADHD medications, their suicidality risk was no different from when off medication.
ADHD is associated with an increased potential to engage in risk-taking behaviors, including substance abuse, criminality, risky sexual behavior, and accidents, which are themselves associated with early mortality.
When Danish investigators looked at their national registries, they identified 32,061 individuals with ADHD born during 1981-2011, and followed them through 2013 They found that the mortality rate was 5.85 deaths per 10,000 person-years in individuals with ADHD, compared with 2.21 deaths per 10,000 person-years in controls, resulting in a fully adjusted mortality rate ratio of 2.07. Swedish studies looked at adults with ADHD for serious transport accidents involving a trip to the emergency room or death during 2006-2009. The risk was increased by an adjusted 1.47-fold in men with ADHD and by 1.45-fold in women with the disorder.
The numbers related to early mortality due to accidents improved when the patients were placed on ADHD medication treatment. Males in the study group with ADHD were 58% less likely to have a serious transport accident when they were on ADHD medication than when off medication. The investigators estimated that 41%-49% of transport accidents in men with ADHD could have been avoided had they been on drug therapy continuously throughout the follow-up period. Similar data showing that being on ADHD medication reduces the elevated risk of serious accidents – have been reported in other independent studies conducted in Denmark, Germany, Hong Kong, and most recently in a U.S. These findings collectively highlight the public health importance of diagnosing and treating ADHD.