Consistent with the DEQ findings, we found that smokers Val/Val genotype had greater withdrawal severity following an overnight abstinence, as measured by the MNWS and the BQSU. Further analysis of the individual MNWS items showed that smokers with the Val/Val genotype had greater craving, more difficulty concentrating and more irritability than Met carriers. To our knowledge, these findings are the first to demonstrate that the COMT Val158Met variation moderates withdrawal severity in smokers. In a previous study, smokers with the Val/Val genotype had greater blood flow to prefrontal cortical regions that are associated with cigarette craving upon abstinence from smoking (17). More severe withdrawal in smokers with the Val/Val genotype may have important treatment implications (see below).
