Genetic and Environmental Contributions to Pathological Gambling Symptoms in a 10-Year Follow-Up

Abstract

Problem (P) and pathological gambling (PG) symptoms wax and wane. Past symptoms are a risk for future symptoms even after controlling for familial influences. To address the genetic architecture of lifetime PG and current PG symptoms, we tested for common and unique genetic factors to lifetime PG symptoms at baseline and past year PG symptoms at 10-year follow-up. Diagnostic and Statistical Manual of Mental Disorders (3rd ed., Rev.; DSM-III-R; American Psychiatric Association, 1987) lifetime criteria of one or more PG symptoms were derived in 1992 and past year PG symptoms in 2002 from 1675 individual twins from the Vietnam Era Twin Registry. Cholesky decomposition models were fit to baseline and past year PG symptoms. Under the best fitting model we observed that 49% of the risk for one or more baseline PG symptoms in 1992 was due to a genetic factor and 51% of the risk was due to a unique environmental factor. All of the genetic variance (57.5%) in risk to past year PG symptoms in 2002 was common with baseline PG symptoms. Unique environment accounted for the remaining variance in past year PG symptoms with 13% common to baseline and 30% specific to past year PG symptoms. The genetic contributions to lifetime and past year gambling symptoms 10 years later are similar. There is no evidence for genetic contributions unique to past year PG symptoms. However, most of the unique environmental influences to past year PG are not shared with lifetime PG. This may reflect the changed social–cultural environment between 1992 and 2002, characterized by increasing access to legalized gambling.

Disordered Gambling: Etiology, Trajectory, and Clinical Considerations

“…Finally, studies among twins found that PG was higher among co-twins of individuals with PG than co-twins of individuals without PG (Slutske et al 2001;Slutske et al 2009;Xian et al 2007). In sum, genetic influences might not determine the development of a specific expression of addiction; however, genetics does influence the risk of addiction in general.…”

The Australian Twin Study of Gambling (OZ-GAM): Rationale, Sample Description, Predictors of Participation, and a First Look at Sources of Individual Differences in Gambling Involvement

“…The results of this study suggest that PG is as heritable as alcohol dependence, and that genetic factors, rather than social modeling, predominantly explain the familial transmission of PG. In a 10-year follow-up of the Vietnam Era twin cohort, Xian et al (2007) found that the same genetic factors accounted for variation in liability for problem gambling at both the baseline and at the 10-year follow-up and that the estimates of heritability at the two time points were similar (baseline: 49%; follow-up: 58%). The results of this follow-up study suggest that the changes in the availability of gambling that occurred in the United States between 1992 and 2002 did not alter the underlying genetic architecture of the liability to problem gambling.…”

The Genetics of Problem and Pathological Gambling: A Systematic Review

“…The studies relating to the Vietnam Era Twin Registry contained problem and pathological gamblers with a diagnosis based on the DSM-III-R or DSM-IV classification system carried out by telephone interview [21][22][23][24][25]. For participants of the Australian Twin Registry Cohort, the NODS (National Opinion Research Center DSM-IV Screen for Gambling Problems) was applied to assess gambling-related problems, and is a tool that utilizes the DSM-IV criteria for pathological gambling [26].…”