Analysis of HR measurements revealed a significant main effect for trial (F(4, 136)=6.75, p<0.0001). A 2 (Trial) × 2 (Genotype) mixed ANCOVA with baseline HR included as a covariate indicated that, 15 m after smoking, A/A and A/C individuals had significantly higher HR than C/C individuals (F(1, 37)=4.36, p=0.04; see Fig. 3). HR did not differ between genotype groups 5, 10, 30, or 60 m after smoking. Withdrawal severity did not predict HR changes after marijuana.
