Figure 4.

Early (a) pleasurable and (b) unpleasant sensations of initial smoking experience, grouped by sex and OPRM1 genotype. Male G allele carriers identified an initial smoking experience as more pleasurable than male homozygous A allele carriers, female G and female homozygous A allele carriers (a), with no differences in unpleasant sensations between the groups (b). Data represent mean (±s.e.m.) scores on the Early Smoking Experiences questionnaire adjusted by the inclusion of age of initial exposure to nicotine and psychosocial adversity as covariates. **P<0.005.