In ADHD, Psychiatric Comorbidity May Raise Premature Death Risk
New study data point to an association between psychiatric comorbidities and all-cause and cause-specific mortality risks among individuals with attention-deficit/hyperactivity disorder (ADHD).1
Associations with premature mortality were observed in both children and adults with ADHD, and risk was found to increase in conjunction with the number of psychiatric comorbidities present.
“In adulthood, early-onset psychiatric comorbidity contributed primarily to the association with death due to natural causes, whereas later-onset psychiatric comorbidity mainly influenced death due to unnatural causes, including suicide and unintentional injury,” the authors of the study wrote.
ADHD has been diagnosed in approximately 6.1 million (9.4%) US children aged 2 to 17 years at some point in their lives, according to 2016 data from the CDC’s National Survey of Children’s Health.2 Data from the same survey indicated that every 2 out of 3 children with current ADHD in 2016 had at least 1 other mental, emotional, or behavioral disorder, with anxiety in particular affecting every 1 in 3 children with ADHD.2 Depression, autism spectrum disorder, and Tourette syndrome also affect some US children with ADHD.2
Prior to this study, little was known about the direct association between ADHD and premature mortality and whether psychiatric comorbidities impacted this association, the authors wrote.
In their prospective cohort study, Shihua Sun, MD, from the Department of Medical Epidemiology and Biostatistics at Karolinska Institutet, and colleagues evaluated Swedish national registry data of 2,675,615 individuals born in Sweden between January 1, 1983, and December 31, 2009. Exposures, including first clinical ADHD diagnosis, first prescription of ADHD medications, and clinical diagnosis of psychiatric comorbidity, were taken into account.
Upon study entry, mean patient age was 6.4 years. Follow-up lasted until December 31, 2013. During this period, ADHD had been diagnosed in 86,670 of 2,675,615 individuals, or 3.2% of the study population.
A total of 424 individuals with ADHD and 6231 without ADHD had died over the course of the study, translating to mortality rates of 11.57 and 2.16 per 10,000 person-years, respectively. The association between mortality and ADHD was found to be stronger in adulthood than in childhood (hazard ratios [HRs] 4.64 and 1.41, respectively), and was found to increase significantly with the number of psychiatric comorbidities present. HRs were 25.22 for individuals with ADHD with at least 4 comorbidities compared with 1.41 for those with ADHD alone.
The associations for death due to unintentional injury or other external causes remained significant following adjustment for later-onset psychiatric disorders (HRs 2.14 and 1.74, respectively).
However, several associations were rendered statistically insignificant following adjustment for certain factors, the researchers noted. The association between ADHD and mortality due to natural causes was significantly attenuated following adjustment for early-onset psychiatric comorbidity (HR 1.32), and the association with mortality by suicide was attenuated after adjustment for later-onset psychiatric disorders (HR 1.13)
“These findings suggest that health care professionals should closely monitor specific psychiatric comorbidities in individuals with ADHD to identify high-risk groups for prevention efforts,” the researchers wrote.
1. Sun S, Kuja-Halkola R, Faraone SV, et al. Association of psychiatric comorbidity with the risk of premature death among children and adults with attention-deficit/hyperactivity disorder [Published online August 7, 2019]. JAMA Psychiatry. doi:10.1001/jamapsychiatry.2019.1944.
2. Data and statistics about ADHD. Attention-deficit /hyperactivity disorder (ADHD). Centers for Disease Control and Prevention. https://www.cdc.gov/ncbddd/adhd/data.html. Page last reviewed September 21, 2018. Accessed August 7, 2019.