Self-medication of anxiety symptoms with drugs or alcohol associated with increased risk of developing substance use disorders

"Self-medication of anxiety symptoms with alcohol, other drugs or both has been a plausible mechanism for the co-occurrence of anxiety disorders and substance use disorders," the authors write as background information in the article. "Given the significant consequences of mental illness comorbidity [coexistence with another illness] and its high prevalence in the general population, clarifying the underlying mechanisms through which comorbidity develops will have considerable implications for prevention and treatment."

Jennifer Robinson, M.A., and colleagues from the University of Manitoba, Winnipeg, Canada, examined data collected during two waves of the National Institute on Alcohol Abuse and Alcoholism survey to measure the occurrence of substance use disorders in individuals with anxiety disorders and new-onset anxiety disorders in those with substance use disorders. The first wave was conducted in 2001-2002, and the second wave was conducted three years later from 2004-2005. A total of 34,653 U.S. adults completed both waves of the survey and participants were separated into three categories: no self-medication, self-medication with alcohol only or self-medication with drugs (with or without the use of alcohol also).

Of participants who reported any substance use during the prior year, 12.5 percent reported self-medicating with alcohol and 24.4 percent with other drugs. Of participants with diagnosable substance use disorders at baseline, 23.3 percent self-medicated with alcohol and 32.7 percent with drugs. Additionally, 12.6 percent of individuals who met criteria for a baseline anxiety disorder and self-medicated with alcohol developed an alcohol use disorder, while 4.7 percent and 1.7 percent of those who did not self medicate developed an alcohol use or drug use disorder, respectively.

In participants with a baseline alcohol use disorder, the prevalence of incident anxiety disorders (including panic, social phobia, specific phobias, generalized anxiety disorder or any anxiety disorder) ranged from 5.7 percent (panic disorder) to 9.9 percent (specific phobia) for those who self-medicated with alcohol. For participants who self-medicated with other drugs, incidence rates ranged from 8 percent (panic disorder) to 13.5 percent (specific phobia). While 6.9 percent of new-onset social phobia was attributable to self-medication with alcohol, 20.4 percent was attributable to self-medication with drugs.

The authors also found that in participants with preexisting anxiety and alcohol use or drug use disorders, reported self-medication was associated with the persistence of alcohol use and drug use disorders, but not anxiety.

"Given the high percentage of incident substance use disorders and social phobia that can be attributed to self-medication, the reduction of self-medicating behavior may lead to a significant decrease in incident comorbidity in the general population," the authors conclude. "These results not only clarify several pathways that may lead to the development of comorbidity but also indicate at-risk populations and suggest potential points of intervention in the treatment of comorbidity."