Associations Between DAT1 Gene VNTR Polymorphism and Impulsivity Dimensions in Individuals with Behavioural Addictions

Background/Objectives: Impulsivity is a key psychological construct implicated in the onset and maintenance of behavioural addictions. Dysregulation of impulsivity is central to behavioural addictions, yet its genetic basis remains unclear. This study examined the association between the DAT1 variable number tandem repeat polymorphism and impulsivity in individuals with behavioural addictions. Methods: A total of 328 males (128 with behavioural addictions and 200 controls) completed the Barratt Impulsiveness Scale. DAT1 genotyping was performed via PCR and gel electrophoresis. Statistical analyses included chi-square tests, Mann–Whitney U-tests, and two-way ANOVA. Results: No differences in DAT1 genotype frequencies were found between groups. However, a significant interaction emerged for attentional impulsivity: individuals with behavioural addictions and the 9/9 genotype had the highest BIS-AI scores (F2, 322 = 5.48; p = 0.0046). Conclusions: The DAT1 9/9 genotype may increase vulnerability to attentional impulsivity, but only in the context of behavioural addictions. These findings highlight a gene–environment interaction and support the role of dopaminergic mechanisms in cognitive dysregulation. Future studies should validate these findings using longitudinal designs and neurobiological methods.