WEDNESDAY, April 18, 2012 (Health.com) — The short-lived high teenagers get from using amphetamines or the club drug MDMA—better known as Ecstasy—could lead to longer-lasting depression later on, a new study suggests.
Researchers in Canada interviewed 3,880 teenagers from low-income neighborhoods in Québec. Compared to their peers who used neither drug, teens who reported taking MDMA or amphetamines at least once in the tenth grade had 70% and 60% higher odds, respectively, of experiencing depression symptoms in the eleventh grade. Using both drugs nearly doubled the odds of depression.
The findings don't show a cause-and-effect relationship between drug use and later depression, but they do come close. Unlike much previous research, the study controlled for a wide range of factors that might influence both drug use and depression, including problems at school and at home, a prior history of depression and anxiety, the strength of a teen's social networks, smoking, and alcohol use.
"This doesn't ensure causality, but that's the closest we can get with this kind of study," says Jean-Sébastien Fallu, Ph.D., a study coauthor and an associate professor of educational psychology at the University of Montréal, in Quebec.
The only way to establish cause and effect would be to create a randomized controlled trial in which one group of teens took MDMA or amphetamines and a similar group took placebo pills, but that would be impossible for ethical reasons, says Jeffrey T. Parsons, Ph.D., the chair of psychology at Hunter College, in New York City.
Other researchers have reported similar links between MDMA and amphetamine use and subsequent depression, says Parsons, who was not involved in the new study. "We're starting to be convinced that this, in fact, causal," he says.
The study was published this week in the Journal of Epidemiology and Community Health.
The use of MDMA and amphetamines—including methamphetamine, or meth—is increasingly common among youths, and not just those who frequent clubs and rave parties, the authors say. In this group of teens, 8% said they used MDMA and 12% said they used amphetamines (or "speed") in the tenth grade, when they were 15 or 16 years old. Seven percent of teens said they used both drugs at least once.
Notably, the authors did not specifically ask the kids about prescription stimulants such as Adderall (also known as amphetamine salts) or Ritalin, both of which are prescribed for attention deficit hyperactivity disorder (ADHD) and can have amphetamine-like effects when taken in high doses or otherwise misused. Studies have shown that children with ADHD are more prone to depression.
When the tenth graders were interviewed again in the eleventh grade, 15% reported symptoms of depression, such as feelings of hopelessness and sadness, loss of appetite, and trouble concentrating. The fact that using both MDMA and amphetamine increased depression risk more than using either drug alone suggests that the two drugs may interact in harmful ways, the authors note.
The study does have some important limitations. Although the authors did their best to control for the use of other drugs (including alcohol and marijuana), they can't completely rule out the possibility that such drugs are contributing to the association, Fallu says.
In addition, the study may present an incomplete picture because it excluded high-school dropouts and focused on relatively young teens who are likely to be experimenting with drugs rather than using them regularly. The link between drug use and depression may be different—and perhaps stronger—among older, frequent users and teens who aren't in school, Fallu says.