Urge ratings and response times during the task are presented in Table 2. The mean length of abstinence from alcohol prior to scanning was 1.63 days (SD = 0.83). No group differences were observed across OPRM1 genotype in subjective urge ratings during the task or response times as analyzed by independent t-tests (ps > 0.10). Across all subjects, urge to drink alcohol and rating response time following cue presentation were unrelated to alcohol dependence indices (ps > .10). There was a trend toward greater alcoholism severity among A-allele homozygotes [t(15) = −1.763, p = .09], and alcoholism severity was controlled for in subsequent analyses.
