Neighborhood-level factors have previously been associated with the risk of smoking initiation. In order to test whether genetic factors and social context influence cigarette use, one molecular study investigated the interaction between an aggregated genotypic risk score (GRS) combining the top genetic variants (i.e. all SNPs reaching a p-value threshold of <5 × 10−7) from a meta-analysis previously conducted on African Americans, and neighborhood-level effects on smoking behavior. Among individuals who had ever smoked cigarettes, the GRS significantly predicted the number of cigarettes smoked per day (measured by “In the past 30 days, on those days when you smoked, on average, how many cigarettes did you smoke per day?”) and accounted for ~3% of the variance. Significant interactions were observed between the GRS and number of traumatic events experienced and average neighborhood social cohesion, but not neighborhood physical disorder. The association between the GRS and cigarettes per day increased with increasing number of traumatic events and decreased with increasing levels of neighborhood social cohesion (98).
