Abstract
BACKGROUND: Pathological gambling (PG) frequently co-occurs with anxiety disorders. However, the extent to which the co-occurrence is related to genetic or environmental factors across PG and anxiety disorders is not known. METHOD: Data from the Vietnam Era Twin Registry (n=7869, male twins) were examined in bivariate models to estimate genetic and shared and unique environmental contributions to PG and generalized anxiety disorder (GAD) and PG and panic disorder (PD). RESULTS: While both genetic and unique environmental factors contributed individually to PG, GAD, and PD, the best fitting model indicated that the relationship between PG and GAD was attributable predominantly to shared genetic contributions (r(A)=0.53). In contrast, substantial correlations were observed between both the genetic (r(A)=0.34) and unique environmental (r(E)=0.31) contributions to PG and PD. LIMITATIONS: Results may be limited to middle aged males. CONCLUSIONS: The existence of shared genetic contributions between PG and both GAD and PD suggests that specific genes, perhaps those involved in affect regulation or stress responsiveness, contribute to PG and anxiety disorders. Overlapping environmental contributions to the co-occurrence of PG and PD suggest that common life experiences (e.g., early life trauma) contribute to both PG and PD. Conversely, the data suggest that distinct environmental factors contribute to PG and GAD (e.g., early onset of gambling in PG). Future studies should examine the relationship between PG and anxiety disorders amongst other populations (women and adolescents) to identify specific genetic and environmental influences that account for the manifestation of these disorders and their co-occurrences.