Religious Involvement, the Serotonin Transporter Promoter Polymorphism, and Drug Use in Young Adults

We examine whether the genetic basis for religious involvement is common to the genetic basis for drug use/abuse, helping to explain the inverse relationship between religiosity and drug use. To test this hypothesis, we analyzed data on 2,537 young adult siblings participating in Wave III of the National Longitudinal Study of Adolescent Health on whom both genetic characteristics and religious participation were collected. Religion/spirituality was assessed with four measures: frequency of attendance at religious services and other religious youth meetings, frequency of private prayer, self-rated importance of religion and spirituality, and self-reported history of a life-changing spiritual experience. Each religious measure was examined individually and combined together into a summary scale. Illicit drug use (including prescription drug abuse) was assessed. Polymorphisms of the promoter region of the serotonin transporter gene, SLC6A4 (i.e., LL, SL, SS genotypes) were determined. Results indicated that (1) all religious measures were inversely related to drug use/abuse, (2) the SLC6A4 genotypes SS and SL were less common among those who were more religious, especially among non-whites, and (3) SS/SL genotypes were less common among those who used illegal drugs. Despite being less likely to have the protective SS/SL genotype, religious adolescents were still less likely to use drugs. (4) There was no evidence that the serotonin transporter genotype mediated the relationship between religiosity and illegal drug use. These findings suggest that genetic factors play a role in religiosity, especially in non-whites, and that both genotype and religiosity independently predict substance abuse.