Children with attention-deficit/hyperactivity disorder (ADHD) may be at significant risk for later substance abuse, new research suggests.
A cohort study of more than 600 children showed that those with a diagnosis of ADHD at baseline (mean age, 8.5 years), regardless of their sex, had significantly higher rates of substance use or a substance use disorder (SUD) 6 to 8 years later compared with their age-matched peers who did not have ADHD.
However, substance use/SUD rates at the 8-year follow-up point did not differ significantly between any of the ADHD treatment subgroups.
“Medication for ADHD did not protect from, or contribute to, visible risk of substance use or SUD by adolescence,” write the investigators.
Overall, “this study underscores the significance of the substance use risk for both boys and girls with childhood ADHD,” said lead author Brook Molina, PhD, professor of psychiatry and psychology at the University of Pittsburgh School of Medicine in Pennsylvania, in a release.
The researchers note that the findings suggest that alternative or adjunctive adolescent-focused interventions are needed, “especially given [these kids’] increased risk for use and abuse of multiple substances that is not improved with stimulant medication.”
The study was published online December 28 in the Journal of the American Academy of Child and Adolescent Psychiatry.
According to the researchers, stimulants such as methylphenidate and amphetamine are the most commonly prescribed treatment for ADHD.
“These medications reliably decrease ADHD symptoms for more than 80% of diagnosed children, sometimes dramatically,” they write. However, questions have remained as to whether these stimulants decrease risk for substance addiction vulnerability in these patients.
The original Multimodal Treatment Study of Children with ADHD (MTA) enrolled 579 participants and randomly assigned them to 1 of 4 ADHD treatments for 14 months to assess “whether medication at follow-up, cumulative psychostimulant treatment over time, or both relate to substance use/SUD.”
Evaluations were conducted at 3, 9, and 14 months after randomization, as well as at 2-, 3-, 6-, and 8-year follow-ups.
For this analysis, the investigators compared 436 of these participants with 261 of their classmates without ADHD at each of the follow-ups starting at the 24-month postrandomization point (mean age of the participants at the last follow-up, 16.8 years).
Increased Substance Use
Results showed that 35% of the participants with ADHD at the 6-year follow-up reported using 1 or more substances vs 19.5% of those without ADHD; and 17.8% vs 8%, respectively, reported using 2 or more substances.
Overall, the group with ADHD had significantly greater rates of substance use than the non-ADHD group at each checkpoint (2 years, P < .01; 3 years, P = .01; 6 years, P < .01; 8 years, P = .04).
At the 8-year follow-up, there were significantly more daily cigarette smokers within the ADHD group than within the non-ADHD group (16.7% vs 7.9%, respectively; P < .01) and significantly more marijuana users (P < .01).
Alcohol use at the 8-year point was high in both groups (47% vs 45%, respectively).
In addition, 10% of the adolescents with ADHD met criteria for any SUD compared with only 3% of their peers without ADHD at the 6-year point (P < .01). The between-group difference was no longer significant at the 8-year point.
The original study’s treatment subgroups did not differ significantly on rates of substance use/SUD at any checkpoint, and neither medication at follow-up nor cumulative treatment played any part in predicting use.
“We Need to Do Better”
Dr. Molina reported that the investigators are now working on understanding the cause of the link found between ADHD and increased risk for drug use.
“Our hypothesis, partly supported by our research and that of others, is that impulsive decision making, poor school performance, and difficulty making healthy friendships all contribute,” she explained.
She added that “some of this is biologically driven,” because it is commonly known that ADHD runs in families.
“However, similar to managing high blood pressure or obesity, there are nonmedical things we can do to decrease the risk of a bad outcome,” said Dr. Molina.
“As researchers and practitioners, we need to do a better job of helping parents and schools address these risk factors that are so common for children with ADHD.
The study was funded by grants from the National Institute of Mental Health and the National Institute on Drug Abuse and by the Office of Special Education Programs of the US Department of Education and the Office of Juvenile Justice and Delinquency Prevention of the Justice Department.