Study Finds Overlap in Genetic Factors Contribute to Pathological Gambling and Major Depression

Approximately one-third (34 percent) of the genetic factors that contribute to pathological gambling in middle-aged men also contribute to major depression in the same demographic, according to the results of 
a recently released study led by Dr. Marc Potenza of Yale University.

Published in the September issue of the Archives of General Psychiatry, the study, "Shared Genetic Contributions to Pathological Gambling and Major Depression in Men," (Potenza, M., Xian, H., Shah, K., Scherrer, J., & Eisen, S.) sought to estimate the environmental and genetic contributions to pathological gambling and major depression, as well as the lifetime co-occurrence of the conditions.

The study's authors observe that "pathological gambling and major depression frequently co-occur," but that hardly any information exists regarding which contributing genetic and environmental factors affect the co-development of the disorders. In order to examine the genetic, unique environmental and shared environmental factors contributing to pathological gambling and major depression, the study analyzed interviews from a 1992 survey of 7,869 members of the Vietnam Era Twin (VET) Registry, a national sample of male twins who served in the military from 1965 to 1975 and were born between 1939 and 1957.  
Identifying 112 (1.4 percent) of the survey subjects who met the lifetime criteria for pathological gambling and 775 (9.6 percent) who met the lifetime criteria for major depression, the study results also found high rates of lifetime co-occurrence between the two disorders.

Specifically, the overlap of 34 percent of contributing genetic factors to both disorders - a more significant overlap than initially hypothesized - has important implications for future research and treatment possibilities. According to the study, the genetic overlap between the disorders may indicate that treatments that have proven effective for individuals with major depression might also be helpful for those with pathological gambling. Additionally, the overlap may prove helpful in determining the specific gene variants contributing to both disorders and therefore allow for more targeted treatments. 

While the genetic overlap between pathological gambling and major depression observed in this study is significant, the authors note a number of limitations on the study's results. Since the VET Registry is comprised mostly of well-educated, Caucasian male twins whose average age is 42, the results may not be accurately applied to other demographics such as women, adolescents and other racial/ethnic groups.

For further study, the authors recommend an examination of the specific genetic factors contributing to both disorders to allow for a more accurate categorization of pathological gambling as a psychiatric disorder and the development of improved prevention and treatment methods.