Numerous studies have established that smoking has biological roots driven by genetic factors that influence 44% of people starting to smoke.
Studies on addictive behaviors (not just tobacco) indicate that, in the development of the nervous system of some people, there are predisposing risk conditions that favor certain addictions. An example is Parkinson’s disease, which has altered the dopaminergic nervous system and where, already in 2010, a study published in Neurology indicated that smokers’ risk of developing it is almost half that of those who had never smoked.
“This does not mean that smoking prevents Parkinson’s disease,” says Professor Alfredo Berardelli, of Sapienza University in Rome and former president of the Italian Society of Neurology, “but that aversion to tobacco could be considered an independent characteristic of this disease, which precedes the appearance of its symptoms by years. “A study published in New England Journal of Medicine by the University of Nantes proposes to consider any form of exposure to nicotine as a possible antiparkinsonian treatment, but, be careful, we are not talking about cigarette smoke, but rather exposure to this plant alkaloid that is also found in peppers. Another Anglo-German study shows that nicotine patches cannot, however, slow down the onset of the disease. “It will still take time to perfect this therapy, but I am confident in the development of a new line of treatment, based on direct action on nicotinic receptors.”
In addition to the personal response of each smoker’s nicotinic receptors, many factors are involved in smoking, from the different metabolism of inhaled substances to the abnormal functioning of the dopaminergic system, as occurs in Parkinson’s patients. The association between smoking and less development of the white and gray matter of the brain is now well established, but it is still debated whether it is a less developed brain that predisposes one to smoking or, on the contrary, whether it is smoking that shrinks brain.
Using data from the UK Biobank, which collects the health history, genetic and imaging data of 40,000 people, researchers at Washington University School of Medicine in St. Louis and the Research Triangle Institute International in North Carolina, led by Yoonhoo Chang, have tried to find out if smoking, so to speak, comes first with the chicken or the egg. They published an extensive review of 2,019 cases in the journal Biological Psychiatry, in which they showed that a history of daily smoking was strongly associated with a reduction in brain volume, which became more evident as cigarette consumption increased. Smokers lost 22,964 cubic millimeters of brain, equivalent to 0.001 grams of gray matter, and the loss increased proportionally to the number and strength of cigarettes smoked. On the other hand, it was found that the risk of starting to smoke is associated with a tenfold reduction in gray matter (2,424 cubic millimeters), so the result favors the “chicken”, since the brain deteriorates especially as the habit continues, although those who are born as potential smokers start at a disadvantage.