British researchers have found a causal relationship between Smoking and isolation. Using Mendelian randomization, which indicates the existence of direct dependence on data of the single-nucleotide polymorphisms, they showed that Smoking leads to the development of feelings of loneliness. Feedback was also observed, but was slightly weaker, but the connection between loneliness and alcohol consumption scientists have found. Article published in the journal Addiction.
Loneliness is associated with poor health and both mental and physical: loneliness and social isolation can be a cause of depression and its symptoms and their associated with an increased risk of heart attack and stroke. One of the reasons that loneliness leads to health problems, may lie in the fact that people who are dissatisfied with their social interactions, tend to favor unhealthy behaviors and habits: for example, Smoking and alcohol abuse.
The direction of the relationship between loneliness and bad habits is not always clear: the abuse of alcohol, for example, can be as a consequence of feelings of loneliness, and to lead him through the breaking of social ties due to alcoholism. The most effective way to assess the possibility of a causal relationship and its direction is the analysis of genetic data using Mendelian randomization, in which the marker polymorphisms are used as an instrumental variable affecting the emergence of a characteristic. Recently, with the help of this method Robin Wotton (Wotton Robyn) from Bristol University and his colleagues provedthat Smoking leads to the development of schizophrenia and depression.
In the new work, scientists have evaluated the Association between loneliness, Smoking and alcohol consumption. Scientists used to analyze data on the polymorphisms of four independent studies: in total, the analysis included the data 511280 people from the study on loneliness, 249171 from studies on Smoking and the frequency of consumption of tobacco, 143852 man from the study of attempts to quit Smoking and 46568 people from the study on alcohol dependence.
Scientists have identified 16 single-nucleotide polymorphisms associated with loneliness, 378 polymorphisms associated with tobacco use, 99 related to the amount of alcohol consumed per week of alcohol, and 11 polymorphisms that explain the risk of alcohol dependence.
Scientists have been unable to detect any connection between loneliness and alcohol consumption: in other words, with the genetic information could not be proved nor the fact that alcohol consumption and dependence lead to loneliness, nor the fact that loneliness leads to alcohol consumption and dependence. But the causal link between Smoking and loneliness to discover possible and reversible, according to the results of the analysis, Smoking caused a feeling of loneliness in humans (p = 0.28 × 10-13), and loneliness led to the fact that people have started Smoking (although the connection was much weaker).
The authors, therefore, first to indicate a causal relationship between Smoking and the feeling of loneliness. Mechanism, in their view, can be roughly the same as in the development of Smoking of depression: in a previous work, the researchers notedthat nicotine acting on acetylcholine receptors interferes with the synthesis of dopamine and serotonin (though it has yet to be explored). Regarding the fact that the relationship between loneliness and alcohol consumption could not be found, the authors noted that there might be insufficient statistical power (study participants about the consumption of alcohol was much less) — and it should be considered in future studies.
In addition to loneliness and depression, Smoking also contributes to the development of cardiovascular and oncological diseases, and for a lifetime no matter how much a person smokes even a rare, but regular Smoking increases the risk of premature death. For willing still to quit Smoking some news, too: throw a few years ago have shown scientists better dramatically, not gradually.