Mental-substance comorbidities in the ICPE surveys

Abstract

Data are presented from seven community epidemiology surveys carried out in six countries in North America (Canada and the United States), Latin America (Brazil and Mexico), and Europe (Germany and the Netherlands) exploring patterns of comorbidity between mental disorders and substance use disorders. The surveys have a combined sample size of 28,658 respondents. Results are consistent across the surveys in showing that strong comorbidities exist between mental disorders and substance use disorders, that mental disorders are typically temporally primary (i.e., have earlier ages of onset than substance use disorders) in these comorbid pairs, and that primary mental disorders are significant predictors of the subsequent first onset of substance use disorders. Only active mental disorders, not remitted disorders, predict subsequent substance use, problems, and dependence, arguing indirectly that there is something about the mental disorders themselves rather than about determinants of these disorders, that promotes substance disorders. Decomposition shows that mental disorders are less powerful predictors of first drug use than of progressing from use to problem use and from problem use to dependence. Simulations suggest that primary mental disorders are associated with 54.7% of all drug dependence among men and 47.8% among women in these surveys. Conduct disorder and adult antisocial behavior are responsible for these cases among men, while anxiety disorders and mood disorders are also important among women. These results suggest that early interventions to treat mental disorders might be affective in reducing the number of people who would otherwise become dependent on drugs.