Co-morbidity of drug addiction: An analysis of epidemiological data and possible etiological models

This review summarizes the literature on psychiatric co-morbidity of substance use. The author overviews general population epidemiological surveys as well as clinical studies, and discusses both DSM axis I and axis II disorders. After presenting epidemiological data the author analyzes the nature of relationship between psychoactive substance use and other mental disorders, and-through examples-four possible models of this relationship are examined. Despite the lack of precisely determined prevalence rates, some definite tendencies could be observed along the consistent results of the studies. Due to methodological problems, however, many questions remain unanswered. Although there are relatively comprehensive studies on psychiatric disorders associated with drug use and drug addiction, the question of causality is relatively unresolved. Theoretically possible relations regarding causality seem to overlap in practice, and in most cases linear type connection is unlikely. It can be concluded that general questions, such as which disorders have a great significance in connection to drug use, can be answered. Additional research is needed, however, to examine the effects of different drug types, race, and gender. Understanding causality also requires further research.