Jennifer Robinson, who is working on her PhD in clinical psychology and is a research associate for the department of psychiatry from the University of Manitoba in Winnipeg, Canada, told APA attendees that anxiety disorders and substance use disorders are common comorbidities as determined by clinical and community-based research and that comorbidity results in increased mental health treatment utilization,more severe symptomatology, and increased disability.1
A 2009 study by Robinson and colleagues2 examined the prevalence and comorbidity of self-medication for anxiety disorders. Rates of self-medication with alcohol were highest for those with generalized anxiety disorder (18.5%) and social phobia (16.9%). Highest rates for self-medication with drugs (with our without the use of alcohol additionally) were social phobia (4.5%) and generalized anxiety disorder (5.1%).
Because of the cross-sectional nature of previous studies, Robinson noted that an unanswered question was whether self-medication for anxiety symptoms is a risk factor for the development of incident substance use disorder—or whether it is a correlate of substance use.
To seek an answer, Robinson and colleagues performed logistic regression analyses of the National Institute on Alcohol Abuse and Alcoholism’s National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). It is a nationwide household comorbidity survey that assessed DSM-IV psychiatric disorders, self-medication, and sociodemographic variables at 2 time points. Adult US participants (n= 34,653) completed both waves of the survey. Wave 1 was conducted between 2001 and 2002 and wave 2 between 2004 and 2005.
The objective of Robinson and colleagues most recent study (in press) was to examine whether self-medication confers risk of comorbidity. The main outcome measures were incident substance use disorders among those with baseline anxiety disorders and incident anxiety disorders among those with baseline substance use disorders.
Their analysis revealed that self-medication conferred a heightened risk of new-onset substance use disorders among those with baseline anxiety disorders. Adjusted odds ratios (AOR) ranged from 2.08 (p < .01) to 4.33 (p < .001). The research team concluded in a summary that “self-medication with anxiety disorders confers substantial risk of developing incident substance use disorders. Conversely, self-medication within substance use disorders is associated with incident social phobia.”
Other important findings were the results of Population Attributable Fractions that indicate the maximal proportion of incident substance use disorders that could be prevented by eliminating self-medication from the baseline population. The researchers found that 17.1% of incident alcohol dependence could be attributed to self-medication with alcohol at baseline, and 20.6% of incident drug abuse was attributable to self-medication with drugs.
“These findings underscore the importance of targeting self-medication in order to prevent future comorbidity,” Robinson said.
