Stimulant Drugs Are Not the Culprit

Stimulant medications do not foster substance abuse or other addictive behavior in patients with ADHD, says a team of researchers from York University in Toronto.¹ This has been a sticking point considering that addiction disorders have long been known to be more common in persons with ADHD than the general population. Davis and colleagues¹ also found that, contrary earlier findings, women with ADHD were not at higher risk for addiction than their male counterparts.

The suspicion that stimulant drugs put patients with ADHD at risk for substance abuse disorders is certainly plausible, given their effect on dopamine. Studies examining the impact of ADHD drugs on dopamine transport have been equivocal, though, and preclinical research suggests that emotional factors play a stronger role than stimulant therapy in fostering addictive behaviors.  Because both ADHD and addiction disorders are associated with impulsivity, reward seeking, anxiousness, and negative affect, the Canadian research team hypothesized that personality characteristics were at the crux of increased risk of addiction disorders in ADHD.

To test their hypotheses, they used a moderator-mediation model in which symptomatic persons who had not yet received an ADHD diagnosis were compared with persons with ADHD who were taking stimulant medication (methylphenidate or amphetamines) and with persons who had no or minimal symptoms.

The study population included a community sample of 213 men and women between the ages of 17 and 32 years. Among these, 46 participants had received a diagnosis of ADHD and were either currently taking or had previously taken stimulant medications. The remaining participants were selected for placement into an ADHD high-symptom (n = 83) or low-symptom group (n = 84) based on their Connors Adult ADHD Rating Scale scores.

Three personality factors: impulsivity, reward sensitivity, and addictive personality traits were respectively assessed using the Barratt Impulsivity Scale, the Sensitivity to Punishment and Sensitivity to Reward Questionnaire, and the Addiction Scale of the Eysenck Personality Questionnaire-Revised. Addictive behaviors were assessed using the Shorter PROMIS Questionnaire. Mediation was demonstrated when statistically significant relationships were drawn between the independent variable (ADHD status) and the proposed mediator (personality risk), the proposed mediator and the dependent variable (addictive behaviors), and the independent variable and the dependent variable.

After controlling for ADHD status, the researchers found no male-female differences regarding personality risk or addictive behaviors in general. Also, although ADHD status strongly correlated with addictive behaviors, no difference in addictive behaviors regarding substance abuse or any other personality characteristics were seen between the nontreated  high-symptom group and the ADHD-medicated group. The personality-risk scores of these groups, however, distinctly differed from those of the low-symptom group (P < .0001).

These results confirm that a high-risk personality profile for addictive behaviors is common in ADHD. They also counter assumptions about sex differences in ADHD and add support to the emerging contention that current or past treatment with stimulant medication does not particularly impact addiction-disorder/substance-abuse risk.

References:

1. Davis C, Cohen A, Davids M, Rabindranath A. Attention-deficit/hyperactivity disorder in relation to addictive behaviors: a moderated-mediation analysis of personality-risk factors and sex. Front Psychiatry. 2015;6:47.