Kathleen Louden

May 06, 2013

CHICAGO — Among teenagers with substance abuse, those who also have social anxiety disorder are significantly more likely to start using marijuana at an earlier age than those without the anxiety disorder, new research shows.

Teenagers with social anxiety disorder, also known as social phobia, start using marijuana at a mean age of 10.6 years, an average of 2.2 years earlier than other adolescents with substance use disorders, according to a study conducted by investigators at Case Western Reserve University School of Medicine, Cleveland, Ohio.

"This finding surprised us," said principal investigator Alexandra Wang, a third-year medical student at the university, in an interview with Medscape Medical News. "It shows we need to start earlier with prevention of drug and alcohol use and treatment of social phobia [in children]."

Wang presented the research as a scientific poster here at the American Society of Addiction Medicine (ASAM) 44th Annual Medical-Scientific Conference.

Which Comes First?

The researchers conducted the study to determine associations between anxiety disorders and substance use disorders, and which disorder started first in adolescents with this comorbidity.

The study included 195 youths (102 girls, 52%), aged 14 to 18 years, who met the current diagnosis of substance use disorder and had received medical detoxification if needed. Participants had no major health conditions requiring hospitalization.

Alexandra Wang

Assessment involved semistructured interviews, medical chart review, and reports from the adolescent, parent, and clinician. Using the Mini–International Neuropsychiatric Interview, the investigators assessed the participants' history of drug and alcohol use and their history of any of 3 anxiety disorders: social anxiety disorder, panic disorder, and agoraphobia. A clinician verified the participants' recalled age at onset of symptoms or substance use in 83% of cases, according to the poster. Each participant received $25 for completing the interview.

The drug most often used was marijuana. Of the 195 participants, 92% had marijuana dependence, with a mean age at onset of use of 13 years, the investigators reported; 61% were alcohol dependent, having started to drink at 13.5 years on average.

Teenagers with either social anxiety disorder or panic disorder were significantly more likely to have marijuana dependence (for each, P < .01, logistic regression), Wang said. Both of these disorders reportedly were likelier to occur before marijuana dependence (P < .01).

Approximately 80% of adolescents with social anxiety disorder and 85% with panic disorder had symptoms of that disorder before the onset of their substance abuse, the poster data showed.

In addition, panic disorder tended to start before alcohol dependence (P < .05) and occurred in 75% of alcohol-dependent adolescents.

There was no clear pattern as to whether agoraphobia preceded or followed either marijuana use or the first drink, according to the authors.

The investigators also evaluated whether presence of substance abuse lowered the age at onset of an anxiety disorder, but they noted no significant difference.

Rule, Not the Exception

A limitation of the study, according to the research team, was that 128 (66%) of the particpants were juvenile offenders who had received court-referred treatment of their substance abuse. In their poster, the authors wrote that their findings might not generalize to a less severely addicted population.

Still, coinvestigator Christina Delos Reyes, MD, told Medscape Medical News that interventions to reduce social anxiety might help prevent adolescents' marijuana use.

"We need to treat these young patients initially with nonpharmacologic means, such as cognitive behavioral therapy or mindfulness meditation," said Dr. Delos Reyes, a psychiatrist specializing in addictions at University Hospitals Case Medical Center, in Cleveland.

Asked to comment by Medscape Medical News, Patrick Bordeaux, MD, a child and adolescent psychiatrist in Quebec, Canada, said it is well known that "comorbidities tend to be the rule in adolescents, not the exception."

"Adolescents are more likely to have social and mental disorders that make them more likely to use drugs," said Dr. Bordeaux, who was not involved with the study.

Grants from the National Institute on Alcohol Abuse and Alcoholism and from the John Templeton Foundation in West Conshohocken, Pennsylvania, partly funded this study. Alexandra Wang and Dr. Delos Reyes disclosed no relevant financial relationships.

American Society of Addiction Medicine (ASAM) 44th Annual Medical-Scientific Conference. Poster 4. Presented April 26, 2013.


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