Studies of adults with attention deficit hyperactivity disorder (ADHD) have consistently found that they are more likely to have drug problems. 17-45% of ADHD adults have histories of alcohol abuse or dependence, while 9-30% have histories of drug abuse or dependence. At the same time the levels of ADHD are much higher among drug abusers than the rest of the population. Some researchers have suggested that the amphetamine-based treatments for ADHD can cause drug problems while others suggest that treating the problem reduces the risks of later drug abuse. A U.S. study of 206 people with ADHD compared those who had had no treatment for the condition, those who had had treatment in the past and those who were being currently treated for it. No differences were found in the prevalence of cigarette smoking, alcohol or drug abuse or dependence between the groups and no differences were found in complications of drug or alcohol use.
Faraone, Stephen V. ... [et al] - A naturalistic study of the effects of pharmacotherapy on substance use disorders among ADHD adults Psychological Medicine 37(12), 1743-1752