The acute effects of physical activity on cigarette cravings: exploration of potential moderators, mediators and physical activity attributes using individual participant data (IPD) meta-analyses.

RATIONALE: The effects of acute bouts of physical activity (PA) on Strength of Desire (SoD) and Desire to Smoke (DtS) using individual participant data (IPD) from 19 acute randomised controlled studies were quantified. However, there is a need to identify factors influencing this relationship. OBJECTIVES: To understand who most benefits from PA, whether changes in affect mediate these effects and whether any specific attributes of PA are associated with cigarette cravings. METHODS: IPD (n = 930) contributed to one-stage IPD meta-analyses. Participants engaging in PA were compared against controls, using post-intervention DtS and SoD (when DtS is not available) with baseline adjustments. The craving scales were linearly rescaled to 0-100 % (a mean difference between groups of -10 would indicate that post-intervention cravings were 10 % lower in the PA compared with the control group). Demographic, smoking and other characteristics were examined as predictors and potential moderators, whereas change in affect was considered as a mediator. PA was categorised according to type, duration and intensity, to determine PA attributes associated with cravings reduction. RESULTS: None of the included covariates were shown to moderate or mediate the effects of PA. Intensity of PA was significantly associated with a reduction in cravings; moderate and vigorous intensity PA offered the most benefits. A one-stage IPD meta-analysis yielded effect sizes of -9.22 (-15.24; -3.20) for light, -34.57 (-42.64; -26.50) for moderate and -31.29 (-38.00; -24.57) for vigorous intensity in comparison with controls. CONCLUSIONS: Moderate intensity PA could be recommended to all smokers regardless of demographic, smoking and other characteristics.

Variation in the α 5 nicotinic acetylcholine receptor subunit gene predicts cigarette smoking intensity as a function of nicotine content.

A single-nucleotide polymorphism (SNP) in the α5 nicotinic acetylcholine receptor subunit gene, rs16969968, has been repeatedly associated with both smoking and respiratory health phenotypes. However, there remains considerable debate as to whether associations with lung cancer are mediated through effects on smoking behavior. Preclinical studies suggest that α5 receptor subunit expression and function may have a direct role in nicotine titration during self administration. The present study investigated the association of CHRNA5 polymorphisms and smoking topography in 66 smokers asked to smoke four nicotine-containing (nicotine yield=0.60 mg) and four placebo (nicotine yield <0.05 mg) cigarettes, during separate experimental sessions. Genotype at rs16969968 predicted nicotine titration, with homozygotes for the major allele (G:G) displaying significantly reduced puff volume in response to nicotine, whereas minor allele carriers (A:G or A:A) produced equivalent puff volumes for placebo and nicotine cigarettes. The present results suggest that puff volume may be a more powerful objective phenotype of smoking behavior than self-reported cigarettes per day and nicotine dependence. Further, these results suggest that the association between rs16969968 and lung cancer may be mediated by the quantity of smoke inhaled.