Studies have shown a strong connection between ADHD and substance abuse. Data show that one in four (25%) people being treated for alcohol and substance abuse have ADHD. Teens with ADHD are more likely to start abusing alcohol than peers who don’t have ADHD. One study found that 40% of teens with ADHD started abusing alcohol around age 15, compared to just 22% of their non-ADHD peers. Experts have also found links between ADHD and the use of marijuana and other recreational drugs. This link is even stronger when a person has other psychological disorders, such as obsessive-compulsive disorder.