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By Richard Karel
Teenagers with prior, serious psychiatric problems can quickly progress from first use of marijuana to dependence, according to a recent study funded by the National Institute on Drug Abuse (NIDA).
The study, by psychiatrist Thomas Crowley, M.D., and colleagues at the Addiction Research and Treatment Service at the University of Colorado School of Medicine, was published in the spring issue of Drug and Alcohol Dependence ("Cannabis Dependence, Withdrawal, and Reinforcing Effects Among Adolescents With Conduct Symptoms and Substance Use Disorders").
Researchers looked at 165 boys and 64 girls who were between the ages of 13 and 19 and had been referred by social service or criminal justice agencies to a university-based treatment program for delinquent, drug-dependent adolescents. More than 80 percent of the boys and 60 percent of the girls met DSM criteria for marijuana dependence, and two-thirds of those who were dependent complained of withdrawal symptoms upon stopping use.
The study is significant and "tends to add weight to arguments against legalization of marijuana," said Sheldon Miller, M.D., chair of the APA Council on Addiction Psychiatry. But Miller cautioned that the findings cannot be generalized to all adolescents, since the criteria for inclusion in the study required participants to have at least one diagnosis of drug dependence and three symptoms of conduct disorder.
Lead author Crowley spoke with Psychiatric News about the implications of the study. The progression from first use to "regular use," defined as use at least once monthly, is "very significant," said Crowley. The rate of progression correlates with the degree to which a drug is reinforcing, which in turn correlates with the probability of progression to compulsive, uncontrolled use, he said.
"An important question is how effective is a drug at driving a progression of use," said Crowley. "When we looked at these kids who had alcohol, tobacco, and marijuana quite available to them and were using all three, and asked them how long it took them to go from their first use to monthly use, it turns out this drug is about as effective as tobacco in driving a progression to regular use. And the two of them drive this progression considerably faster than does alcohol."
Although other addiction researchers have asserted that marijuana is less reinforcing than tobacco or alcohol, "our data suggest otherwise," said Crowley.
The teenagers in this study reported significant withdrawal symptoms, including insomnia and restlessness, said Crowley. "Of the kids who qualify for diagnosis of cannabis dependence, 65 percent experience withdrawal, and 25 percent say it is severe enough to motivate further use," he added. "That suggests that marijuana withdrawal is a clinically significant phenomenon in this disorder."
Problems of conduct disorder and substance dependence tend to run in families, observed Crowley. Hence, a variety of substances is frequently available to troubled youngsters from a very early age. Crowley found some instances where youngsters said they first tried marijuana between the ages of 4 and 6.
"We're talking here about kids with very serious psychiatric problems, who in the main are being raised in families where other people have serious psychiatric problems," Crowley explained. "There is a very strong likelihood of finding relatives with serious substance problems in the families of these kids. Hence substances are unusually available in the families of these kids. If it were sold legally, I think it wouldn't have much impact on its availability within these families."
For society at large, however, legalization would increase cannabis dependence, said Crowley. "The more you make any substance available within a society, the more people are going to be exposed to it," and, if it is addictive, the higher will be the prevalence of addiction to that substance.
There has been a relative absence of rigorous research on cannabis, said Crowley. "Many people in this social debate [over cannabis] have suggested that cannabis has no adverse effects," he said. "The kids we've interviewed who are cannabis-dependent clearly report the drug has adverse effects on their lives. Henceforth, no one should be able to say without compelling data that this drug has no adverse effects. That's not to say it has adverse effects for everybody, but it clearly has adverse effects for some people."
The treatment of cannabis dependence in adolescence is virtually unexplored, said Crowley. "There is absolutely no research-based guidance on how to treat cannabis dependence in adolescents, and even less so for treatment of cannabis withdrawal. At the present time we don't know if treatment for cannabis withdrawal is even warranted."
Clinicians working with polysubstance-dependent youngsters should, however, be "extremely cautious" in using any abusable drug as part of treatment, he warned.
Another issue in this population is appropriate treatment of comorbid psychiatric disorders, particularly conduct disorder, observed Crowley. "Appropriate and thoughtful treatment of the conduct disorder is central to the treatment of the substance disorder," he noted.
David Fassler, M.D., chairs APA's Council on Children, Adolescents, and Their Families. "The findings clearly support our growing understanding that marijuana is an addictive drug," he remarked. "Clearly the adolescents are describing the accepted signs and symptoms of dependence and addiction. Hence, it reinforces the belief that marijuana is not an inconsequential drug."
The earlier youngsters start using drugs, whether alcohol, marijuana, or tobacco, the more likely they are to become dependent, said Fassler. Marijuana use by adolescents leads to multiple social and academic problems, he added.
The study highlights the importance of designing and funding studies to identify troubled youngsters at an early age in order to design effective interventions, Fassler said. "I would speculate that many of these adolescents began to show signs of antisocial behavior well before age 13, which was the cutoff point for this study."
He added, "One concern I have is that there does not appear to be a control group of teenagers who use marijuana and do not have prior, serious antisocial problems. It would be interesting to compare those groups with respect to the progression from first use of marijuana to regular use."
Crowley noted that he and colleagues are currently designing a controlled study that will address some of the issues raised by Fassler.
J. Thomas Ungerleider, M.D., is a member of APA's Committee on Training and Education in Addiction Psychiatry. As a clinician, he has for many years treated troubled youths whose problems have included marijuana use.
"I would agree with everything they say. I don't know anybody who says marijuana is safe for adolescents." The teenagers in this study appear to have been "self-medicating," he added.