Adults with a history of ADHD who use drugs started using substances one to two years earlier than those with no ADHD history, according to a new University of Florida.
The findings highlight the need for earlier substance-use-prevention interventions in adolescents with ADHD, researchers say.
"The take-home message of this study shouldn't be that children with ADHD are more likely to become drug users, rather, seemingly 'normal' teenage behavior, such as experimenting with tobacco or alcohol use, may occur at younger ages for individuals with ADHD and so this might serve as a red flag for an accelerated gateway to illicit drug use." said Eugene Dunne, the study's lead author.
The findings appeared the December issue of the journal Addictive Behaviors.
Experts believe that people with ADHD who use drugs may be trying to self-medicate some of the symptoms associated with the disorder.
"Stimulant drugs such as nicotine and cocaine might be used to counter symptoms of inattention, while alcohol and marijuana may be used to counter feelings of hyperactivity or impulsivity," said Dunne, a third-year doctoral student in clinical and health psychology at UF's College of Public Health and Health Professions and a predoctoral fellow at UF's Substance Abuse Training Center in Public Health, funded by the National Institute on Drug Abuse.
While previous studies have found that adolescents with ADHD are at an increased risk for substance use and for starting at an earlier age than teens who do not have ADHD, the UF study is the first to compare the age of first use by individual substance among a group of adults with and without a history of ADHD who use drugs. It also included a comprehensive assessment of HIV risk behaviors.
ADHD is most often diagnosed in children and symptoms may continue into adulthood. The 2011 National Survey of Children's Health estimated that 11 percent of U.S. children ages 4 to 17 have been diagnosed with ADHD. A National Institute of Mental Health 2006 study found that 4 percent of adults ages 18 to 44 experience some ADHD symptoms.
For the UF study, researchers analyzed data collected as part of a National Institute on Drug Abuse-funded study on HIV prevention led by William Latimer, Ph.D., the dean of Lehman College's School of Health Sciences, Human Services and Nursing at The City University of New York and former chairman of UF's department of clinical and health psychology. Participants included more than 900 adults who had used illicit drugs in the past six months. They completed questionnaires that collected information on demographics, drug use and sexual risk behaviors. Among participants, 13 percent said they had previously received a diagnosis of ADHD from a health care provider.
"As hypothesized, we found the progression of participants' adolescent substance use to be similar to that in the gateway theory of substance use, with alcohol being the first reported, followed very closely by cigarettes, then leading to marijuana and eventually more illicit drugs such as cocaine and heroin," Dunne said.
On average, participants with a history of ADHD said they began using alcohol at age 13 - about 1 ½ years earlier than their counterparts. Those who injected cocaine began doing so, on average, at age 22 - two years earlier than the average age of participants who did not have a history of ADHD.
"Our study also found that current risk behaviors for HIV, such as injection drug use and needle sharing, were associated with ADHD history, so perhaps impulsivity and other ADHD symptoms might continue to be a factor in adult decision-making," Dunne said.