NIDA Intensifies Focus on Marijuana Abuse

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NIDA Director, Dr. Nora D. Volkow

More than 96 million Americans have smoked marijuana at least once. Marijuana abuse is particularly prevalent among adolescents: Of the more than 2 million people who abuse the drug for the first time every year, two-thirds are between 12 and 17 years of age.

The damaging effects of marijuana fall heavily on adolescents and young adults. Half of all patients admitted to treatment for marijuana abuse are younger than 21. Cognitive impairments caused by marijuana linger a month or more after an individual's last exposure, and the damage is dose dependent—the more a person smoked prior to abstinence, the more marked are the deleterious effects on visual perception, verbal and visual memory, executive function, and manual dexterity, among other mental capabilities (see "Cognitive Deficits in Marijuana Smokers Persist After Use Stops," NIDA NOTES, Vol. 18, No. 5). Loss of social and intellectual growth because of these impairments may have a lifelong impact on a person's experience and achievement. As well, compared with teens who never smoke marijuana, a boy or girl who smokes marijuana before age 17 is more than twice as likely to abuse opioids, three times as likely to abuse cocaine or other stimulants, and nearly four times as likely to abuse hallucinogens later in life (see "Twins Study Links Early Marijuana Use to Increased Risk of Abuse or Dependence," NIDA NOTES, Vol. 18, No. 4).

NIDA is intensifying efforts to fully understand the effects of marijuana exposure from the earliest ages through adolescence and young adulthood. This research (based on RFA DA-04-016, "Consequences of Marijuana Use on the Developing Brain,") will provide new insight into the mechanisms by which marijuana affects brain development, a continuum that begins before birth and lasts into early adulthood. We are encouraging research projects that focus on the effect of marijuana during all phases of neurological development, from the neurogenesis and cell differentiation that takes place in the womb to the refinement of connections among cells that continues past adolescence. Our research initiative will produce a fuller understanding of normative brain development. It also will illuminate the importance of family and social contexts in adolescence as well as the differing biological and environmental factors that precede marijuana use or nonuse.

NIDA also is expanding support of research to develop treatments for marijuana abuse (RFA DA-04-014, "Medications Development for Cannabis-Related Disorder,"). There is a clear public health need for interventions to alleviate withdrawal symptoms and to help chronic abusers deal with social and other factors that make stopping marijuana abuse difficult. NIDA's expanded research agenda will encourage development of medications to counter marijuana dependence through animal studies as well as Phase I and Phase II clinical trials with humans. Some medications will be aimed at marijuana-associated disorders such as intoxication, delirium, psychosis, and anxiety. Other medications may address specific aspects of addiction recovery, such as withdrawal, craving, relapse, and complications such as cognitive impairment, sleep disorders, and depression and other mood disorders that often accompany marijuana abuse.

Successful comprehensive treatment of marijuana-related disorders will require a multidisciplinary approach. Therefore, NIDA's marijuana medications development initiative will encourage investigation of treatments that include behavioral intervention. This broad focus, building on the insights to be gained through increased understanding of marijuana's developmental impact, will help reduce the health costs and alleviate the damage inflicted by widespread abuse of this dangerous drug.