The number of smokers has fallen dramatically in recent years. Public smoking bans, taxes on cigarettes and more information about the harmful effects of tobacco have clearly had a substantial effect.
Cultural and legislative factors are very important in whether people choose to quit or start smoking. But to continue reducing the vast number of health problems attributed to smoking or alcoholism, it’s also important to understand the biological factors that make certain people more prone to these addictions.
Last week, in a study published in the science journal Nature, an international group of scientists reported that they have found 4,000 genetic associations that have at least some influence on alcohol or tobacco consumption. The study took into account the age at which these substances began to be used, as well as the quantities that participants were consuming.
Of the three million people examined – 80% of them being of European descent – the study observed that, despite living in similar socio-economic environments, people with a greater genetic predisposition smoke more: “Individuals in the top 10% of genetic predisposition [to tobacco usage] smoke, on average, twice as many cigarettes per day as those in the bottom 10% (14 cigarettes vs. seven),” said Javier Costas, lead researcher in the Psychiatric Genetics Group of the Santiago de Compostela Health Research Institute.
The ability to predict smoking or alcohol use is much more accurate when examining people of European ancestry, as there are smaller number of samples available from other racial populations. However, the authors of the study highlight that the effects appeared in individuals from all backgrounds.
The analysis is the first step to begin identifying biological risk factors for smoking or alcoholism. By understanding them, it will be helpful to crafting public health policies. For instance, genetic variants can help predict the risk of relapse among at-risk groups of addicts.
In a similar study from 2019, various scientists – including some of the authors of the study published last week – looked for correlations between alcoholism and other mental disorders. In this genetic study, correlations between alcoholism and attention deficit disorder, schizophrenia and depression were observed. Something else that caught the attention of the authors was the weak overlap between the genes associated with alcohol addiction and those associated with moderate alcohol consumption.
According to Dr. Costas, the main limitations of the work published by Nature – as well as other similar studies – are the lack of specificity and the fact that participants self-reported their consumption. For instance, two very different patterns of alcohol consumption – such as regular drinking with meals or weekly binge drinking – can result in the same number of alcoholic beverages consumed per week.
“It’s well-known that people with health problems tend to under-declare their consumption of alcohol and tobacco,” he explained.
Experts point out that, while biological factors in addiction certainly require further study, it’s important not to downplay the role that public policies have played in modifying people’s behavior. As an example, 2014 marked the 50th anniversary of a report published by the US Surgeon General – the highest health authority in the country – that detailed the effects of tobacco on health. Over the course of half-a-century, the percentage of Americans who smoke fell from 42% to 18% – a massive cultural shift that prevented over eight million premature deaths, according to a study in JAMA.
According to statistics from the American Medical Association, this was not just an American phenomenon. From 1980 until 2014, the percentage of smokers worldwide fell from 41.2% to 31.1% among men and from 10.6% to 6.2% among women.
To better support the diffusion of information and the crafting of public health policy, the authors in Nature emphasize the importance of expanding the samples that are currently available. By increasing the number of people of non-European ancestry who are studied, it will be possible to better define the importance that genes have on the consumption of alcohol and tobacco. Modifying treatment methods and changing societal attitudes go hand-in-hand.
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