An aromatic cup of coffee accompanied by a lit cigarette is a classical combination.
Why do these two seem to complement each other so well? Does it depend on environmental or genetic factors? In what was to become the largest twin study of its kind, scientists at the Department of Biological Psychology at the University of Amsterdam attempted to answer the latter questions.
Their research was carried out in multiple steps:
• Applying bivariate genetic models on data of over 10 000 registered twins.
• Calculation of genetic correlation using (LD-score regression) statistics obtained in meta-analyses of genome-wide association studies on smoking and caffeine.
• Mendelian randomization analysis was used on more 13 000 people including 6605 twin register participants to consider causal effects.
As it transpires, the results of the twin model analysis gave a correlation that pointed towards a genetic predisposition to caffeine and nicotine cravings, as did the calculations of the genetic meta-analysis. The Mendelian randomization analysis did not produce any evidence of causal effects. The overall results suggest genetic factors predispose individuals to form an association between consumption of coffee and cigarettes.
Individuals who smoke and drink coffee, will have a difficult path to lowering their nicotine dependence if they consume high levels of caffeine.
Consequently, individuals who smoke and drink coffee, will have a difficult path to lowering their nicotine dependence if they consume high levels of caffeine, as we see that in many individuals that co-dependency on both, caffeine and nicotine, is commonplace.
Considering the biochemical association of active the substances in coffee and cigarettes, a strange phenomenon can be witnessed. The nicotine affects the breakdown of caffeine shortening its half-life which means smokers may consume more coffee in order to reach the desired caffeine levels then, consume more cigarettes to counter the effects of peak caffeine in plasma.
Author: Dāvis Liepa
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