Some have worried that by giving stimulant medication to children and teens with ADHD, we increase their risk to abuse substances in adolescence and adulthood. However, there really is no research to support this, and in fact, long-term studies of those with ADHD show the exact opposite.

Do Stimulants Increase Risk for Substance Abuse in Adolescents?

Biederman et al (1999) studied a sample of over 200 Caucasian boys who were at least 11 years old. They followed them for four years (meaning all were at least 15 years old at follow up). The sample was divided into three groups:

• The first group was composed of 56 children and teens with ADHD who took medication. They generally took it for four and a half years, about two thirds of them were recruited from psychiatric clinics while the other third came from the larger community, and they were 13 years old on average at the start of the study.
• The second group was composed of 19 children and teens with ADHD who did not take medication. Most (84%) were recruited from the larger community, and they were 14.5 years old on average at the start of the study.
• The third group was composed of 137 children and teens who did not have ADHD. About a third of them were recruited from psychiatric clinics while the other two thirds came from the larger community, and they were 15 years old on average at the start of the study.

Four years later, they studied these teens again. They interviewed the teens and one of their parents (separately) about the teen’s substance use, with particular attention to signs of problematic use. This would include, for example, increasing use of substances over time, frequent intoxication, increased tolerance to substances, withdrawal, substance abuse treatment, decreased school performance because of substance use, and physically dangerous behavior while intoxicated.

First they examined whether the source of participants (psychiatric clinics versus the larger community) and age were related to substance use levels. They found these were not, and so the small differences in age and recruitment source were not important. As a result, they compared the three groups and examined the rate of problematic substance use:

• 18% of those without ADHD showed at least three signs of problematic substance use by age 19.
• 25% of those with ADHD who took medications showed at least three signs of problematic substance use by age 17.
• 75% of those with ADHD who did not take medications showed at least three signs of problematic substance use by age 18.

As you can see, by far, those with the greatest risk for problematic substance use were the children and teens with ADHD who were not treated with stimulants. In fact, they were three times more likely to show problematic substance use.

They included alcohol, marijuana, hallucinogens, cocaine, and stimulants in the figures above. However, they note that in 80% of cases, the substance used was primarily alcohol. As a result, they did not have enough participants who showed problems primarily with drugs to run multiple statistical analysis for the type of drug. However, they do report the percentages of drug use in the three groups:

• As for stimulants, 0%, 2%, and 5% of the non-ADHD, medicated ADHD, and unmedicated ADHD teens respectively showed signs of problematic use of stimulants.
• As for cocaine, 1%, 2%, and 12% of the non-ADHD, medicated ADHD, and unmedicated ADHD teens respectively showed signs of problematic use of cocaine.
• As for marijuana, 8%, 16%, and 42% of the non-ADHD, medicated ADHD, and unmedicated ADHD teens respectively showed signs of problematic use of marijuana.

In all three cases, those with the highest rate of problematic use of stimulants, cocaine, and marijuana were those with ADHD who were not prescribed stimulants. This is consistent with the findings for overall alcohol and drug use; those with ADHD who were not treated with stimulants were two to four times more likely to show problematic drug use.

Biederman and colleagues published a follow-up study in 2008. They were able to contact many (80%) of those with ADHD in the above study, and again interview them as well as one of their parents:

• For those who did take medication, most began taking it between 5 and 12 years of age, and they continued to take it for about six years. They noted that 22% were still taking it at the 10 year follow-up.
• Those who had been prescribed stimulants were no difference in risk for ongoing substance abuse than those never prescribed stimulants at follow up (both groups were in their early 20’s at the follow-up study).
• They found that the age at which the child/teen was first prescribed stimulant medication, and the length of time they took it, did not appear related to risk for problematic substance use.

More data is available in the online version, where they report a few more findings:

• Those with ADHD who did not take stimulants were significantly more likely to be diagnosed with Oppositional Defiant Disorder, Conduct Disorder, and Major Depressive disorders.
• Those with ADHD who did not take stimulants were significantly more likely to have been held back a grade at some point.

Thus… the prior study showed much higher rates of problematic substance use in adolescents with ADHD who were not treated with stimulants. It seems that by the time these teens reached their 20’s, their use of substances had decreased to normal levels. However, they still showed much greater risk of emotional, behavioral, and academic problems.

Does It Matter When Stimulants Are Prescribed?

Mannuzza et al 2008 wondered whether the age at which a child with ADHD starts taking stimulants might determine whether they abused substances. To study this further, they took 176 boys with ADHD taking methylphenidate twice a day, and compared them to 176 similar boys without ADHD. In comparing this study to the one by Beiderman, this means Mannuzza’s sample included twice as many people, although they were boys with ADHD who took medication and boys without ADHD. Mannuzza did not include boys with ADHD who did not take medication.

They began the study in 1970 when the boys were aged 6-12 years, and followed them into adulthood, evaluating them again at age 18 and 24 years:

• Most participants who took medication took it on average for two years. The age at which they stopped taking medications was not related to any risk. However, the age at which they started taking medication was:
  • They found that 27% of those with ADHD who began medication before age eight years, and 29% of those who were not ADHD, met criteria for drug abuse at some point over the course of the study. This was not a significant difference, and so children with ADHD who started stimulant medications before the age of eight years showed the same risk for substance abuse as those without ADHD.
  • However, 44% of those with ADHD who began medication after age eight years met criteria for drug abuse at some point over the course of the study.

In other words, those with ADHD who started medication after age eight years were at a 50% greater risk of developing a substance abuse problem. The researchers wondered whether this was the result of the stimulant medication, or perhaps might be due to some other factor:

• They first examined parental rates of substance use, as they wondered whether perhaps those who abused substances might have been more likely to have a parent who abused substances. However, they found no connection.
• Next, they examined rates of behavior problems, as they found those who began medication after age eight years were more likely to be diagnosed with Antisocial Personality Disorder. They examined this finding further, and saw that those with Antisocial Personality Disorder were responsible for most of the difference in rates of substance abuse.

In other words, it seems that those with ADHD who started taking stimulants after age eight years were at a greater risk for developing behavior disorders, like Antisocial Personality Disorder, and as a result of their behavior disorders theywere more likely to abuse substances.

Taken together, these studies do present a consistent picture. Based on three studies of over 500 boys followed for 10 to 12 years:

• Childhood stimulant medication is associated with lower risk in adolescence. Those with ADHD who take stimulants show no more risk than children without ADHD. However, those with ADHD who do not take stimulants are at a significantly greater risk of substance abuse, academic problems, and behavior problems in adolescence.
• Childhood stimulant medication is partially associated with lower risk in young adulthood.
  • Those with ADHD who began taking stimulants before age eight years show no more risk of substance abuse, academic problems, and behavior problems than those without ADHD.
  • Those with ADHD who began taking stimulants after age eight years show increased risk for behavior problems, which last into young adulthood, and increase the risk to develop substance abuse problems too.

Wilens et al (2003) identified six studies that followed medicated and unmedicated people with ADHD for at least four years (the 1999 Beiderman study was one of them), for a total of 1,000 participants:

• One study showed an increased risk of alcohol and drug abuse was associated with ADHD and stimulant use; however, the groups in the study showed different rates of substance abuse at the start of the study, so the ending differences are hard to interpret.
• One study showed no difference in alcohol and marijuana abuse rates associated with ADHD and stimulant use; however, in this study too the groups showed different rates of substance abuse at the start of the study, so the ending lack of a difference is hard to interpret.
• Three studies showed a decreased risk of alcohol and drug abuse was associated with ADHD and stimulant use (the 1999 Beiderman study is in this group).
• One study showed a decreased risk of drug abuse (alcohol use was not included in that study) was associated with ADHD and stimulant use.

Given the addition of the second Beiderman study and the Mannuzza study, we can summarize as follows:

• One questionable study has shown an increased risk of substance abuse associated with ADHD and stimulant use.
• One questionable study has shown no difference in risk of substance abuse associated with ADHD and stimulant use.
• Six studies have shown a decreased risk of substance abuse associated with ADHD and stimulant use. These six studies began with similar groups, followed them for 4 to 15 years, and found a 25-75% reduction in risk.

In conclusion… the majority of studies show that prescribing stimulant medication to children with ADHD does not increase their risk for any substance abuse problem, much less stimulant abuse.

References