ADHD and substance abuse: Is there a link?

ADHD often lasts into adulthood, and several studies have shown a strong connection between ADHD, drug abuse and alcoholism. ADHD is five to 10 times more common among adult alcoholics than it is in people without the condition. It is also more common for children with ADHD to start abusing alcohol as teenagers. In one study, 14% of 15 to 17-year-olds with ADHD had problems with alcohol, compared to none of their peers without ADHD.

Researchers have also found links between ADHD and the use of marijuana and other recreational drugs, particularly in people who also have other psychological disorders (such as obsessive-compulsive disorder). What’s more, people with ADHD typically start having problems with drugs and alcohol at an earlier age than people without the condition.

Why are people with ADHD more likely to abuse drugs and alcohol?

People with ADHD tend to be more impulsive and likely to have behavioural problems, both of which can contribute to substance-abuse, say researchers. Also, both ADHD and alcoholism tend to run in families. A child with ADHD who has an alcoholic parent is more likely to develop an alcohol-abuse problem. Researchers have pointed to common genes shared between ADHD and alcoholism.

Are stimulant medications for ADHD addictive?

Parents sometimes worry whether the stimulant drugs their children are taking to treat ADHD (such as methylphenidate) are themselves addictive. Stimulant medications work by raising levels of a chemical messenger called dopamine in the brain, which helps improve focus and attention - skills people with ADHD often find difficult to master.

Dopamine also affects emotion and the feeling of pleasure, creating a  “high” that makes people want more. Because cocaine and other street drugs also raise dopamine levels, there has been concern that ADHD stimulants might be similarly addictive.  Methylphenidate’s ability to increase energy and focus has even led some people to refer to it as the ”poor man's cocaine”.

There have been reports of people using ADHD stimulant drugs that weren’t prescribed for them. People have crushed and snorted methylphenidate tablets, or dissolved the drug in water and taken it intravenously. Studies show that abusing methylphenidate can lead to dependence on the drug. When taken as prescribed, though, methylphenidate is not addictive in children or adults.

In large doses,  methylphenidate does have effects similar to those of cocaine. However, researchers have found marked differences between the two drugs. One of the factors that leads to addiction and abuse is how quickly a drug raises dopamine levels. The faster dopamine levels go up, the greater the potential for abuse. One researcher found methylphenidate takes about an hour to raise dopamine levels in the brain, compared to only seconds with inhaled cocaine. The doses of methylphenidate and other stimulants used to treat ADHD tend to be lower and longer-acting, which reduces the risk of addiction.