Genetic and Environmental Influences on Smoking and Motives for Smoking

Gynther, Lynn

Graduate Thesis Or Dissertation

Genetic and Environmental Influences on Smoking and Motives for Smoking Público Deposited

Analytics

Citations

Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/hm50tt36r

Abstract

Earlier twin studies have shown a genetic component to smoking, but a greater characterization of these influences is necessary to determine possible mechanisms of action. The relative importance of genetic and environmental influences on cigarette use, years of smoking, and motives for smoking were examined in a volunteer sample of 4,119 twins aged 50 years and older.

A factor analysis of motives for smoking in 1,790 current and former smokers recovered five coherent factors that accounted for 37% of the variance in amount smoked and 21% of the variance in years of use. Pharmacological smoking was the primary predictor of both indices of smoking behavior. Former smokers scored loweron Pharmacological smoking and higher on Psychological smoking than current smokers. The Fagerstrom Tolerance Questionnaire differentiated between current and formersmoking in women but not in men.

Analyses partitioned variance among the indices of smoking behavior into components due to genes, shared environment, and non-shared environment. Environmental factors alone were sufficient to explain whether someone ever smoked a cigarette, and 68% of the variance of ever smoking was due to shared environment. However, genetic influences explained 38% of the variance of self-defined smoking status. Shared environment contributed 35% to the variability of smoking status.

Multivariate structural modelling on 400 twin pairs indicated that both genes and shared environment affect the relationship among years of use, amount of use, and smoking motives. There were no significant sex differences in the genes or shared environment influencing this set of smoking behaviors or in the magnitude of those effects.

The results suggest a dual pathway to addiction through both genes and environment. The relationship between years of use and Pharmacological smoking was primarily genetic, whereas the relationship between amount of use and Pharmacological smoking was primarily environmental. Only 15% of the variance in daily consumption was due to genetic influences, compared to 48% of the variation in years of use. These differential genetic effects on amount of use and years of use may partially account for why it is easier to modify cigarette consumption than to quit smoking completely.

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