Association of DRD2 and BDNF Genetic Polymorphisms with Exercise Addiction

Exercise addiction is described in the literature as a compulsive behavior associated with adverse health symptoms. Currently, knowledge about the biological and social factors that trigger the development of this behavior is still lacking, and there are no published studies on genetic variants associated with the disorder. Because of this, we genotyped specific polymorphisms in the genes DRD1 (rs265981), DRD2 (rs1800497), BDNF (rs6265), HFE (rs1799945), ACTN3 (rs1815739), PPARA (rs4253778), PPARGC1A (rs8192678), and AMPD1 (rs17602729) to investigate whether they were associated with exercise addiction. In total, 469 men and women, comprising athletes and non-athletes between the ages of 18 and 50, were enrolled in the study. Each participant provided an oral swab sample for genetic analysis and completed the Negative Addiction Scale questionnaire that tests for physical exercise addiction. For the DRD2 polymorphism, there was a significant association of the GG genotype with asymptomatic participants and of the AA genotype with participants symptomatic for exercise addiction. Additionally, for the BDNF polymorphism, the CC genotype was associated with symptomatic participants, and the T allele was associated with asymptomatic individuals. However, all associations were found by evaluating the SNP individually, and this demonstrates the difficulty in studying variables related to behavioral phenotypes.