Substance Abuse Risk in ADHD Relatives May be Genetic

A new study indicates that relatives of ADHD patients may be at higher risk for substance abuse — possibly due to shared genetic factors between the disorders.

The study, conducted by the Karolinska Institutet in Stockholm, Sweden, found that first-degree relatives of ADHDers had an increased risk of substance abuse — even when controlling for other factors like coexisting psychiatric disorders.

The study looked at data on more than 62,000 ADHD patients from the Swedish National Patient Register, and their relatives. The ADHD relatives were matched with unaffected control individuals with the same birth year, sex, and shared residential factors, then cross-referenced with national registries to determine their history of substance abuse diagnoses.

ADHDers themselves were much more likely to have suffered from substance abuse, as the researchers expected. Surprisingly, however, the first-degree relatives were at a significantly higher risk for substance abuse than the control group — even when disorders like depression, schizophrenia, or bipolar disorder were taken into account.

Previous research has indicated that ADHD and substance abuse are often linked, but the reason for the link was never fully determined. As many as 30 percent of ADHD adults will experience substance abuse in their lives — nearly triple the rate for non-ADHD adults. Theories include “self-medication” — ADHDers using drugs or alcohol to slow down a racing brain, calm social anxieties, or help them sleep. Some have also hypothesized that the increased risk for substance abuse among ADHD patients is linked to the use of stimulant medications to treat symptoms. But, the researchers write, their results show there’s something more going on.

“The main clinical implication is that the overlap between ADHD and SUD [substance use disorder] is likely not explained by harmful effects of stimulant medication,” the study concludes. “This is important, given that concerns around the safety of central stimulant treatment in ADHD might result in the withholding of essential and effective pharmacological treatment in affected individuals.”

The research suggests that if the genetic overlap between ADHD and substance abuse can be more fully understood, those who are at a higher risk for substance abuse can be identified — and treated — earlier.

A better understanding of the genetic overlap between ADHD and substance abuse may lead to wider acceptance of the two as real medical disorders — positive news for ADHDers and addicts alike who are tired of hearing that they lack willpower.