Can smoking make you less “intelligent”? What is the link between cigarettes and dementia

Many studies have established that the habit of smoking has biological roots driven by genetic factors, with hundreds of loci genes that influence daily cigarette consumption or cessation of the habit, contributing in the order of 44% to the first blonde to light up.

Parkinson

Studies on addictive behaviors (not just for cigarettes) indicate that, in the development of the nervous system of some people, there are predisposing risk conditions that promote certain addictions. An emblematic case is Parkinson's disease, which presents an alteration of the dopaminergic nervous system and where, already in 2010, a study published in Neurology indicated that the risk of developing it among smokers is almost half that of those who have never smoked.

A future therapy?

This does not mean that smoking avoids Parkinson's disease – says Professor Alfredo Berardelli of the La Sapienza University of Rome and past president of the Italian Society of Neurology -, but that smoking aversion could be considered an independent feature of this disease, which precedes the appearance of its cardinal symptoms by years. A study published in New England Journal of Medicine from the University of Nantes proposes to consider any form of exposure to nicotine as possible anti-Parkinson treatment, but, mind you, we are not talking about cigarette smoking but rather exposure to this vegetable alkaloid which is also found in peppers. Another Anglo-German study shows that nicotine patches fail to slow the onset of the disease. It will still take time to perfect this therapybut I am confident in the development of a new line of treatment, based on a direct action on nicotinic receptors.

Smoking and the brain

In addition to the personal response of each smoker's nicotinic receptors, many factors are involved in the habit of smoking, ranging from the different metabolism of the inhaled substances to theabnormal functioning of the dopaminergic systemas happens precisely in parkinsonians. The association between smoking and lower development of the white and gray matter of the brain is now well establishedbut there are still ongoing debates about its nature and that is whether it is a less developed brain that predisposes to smoking or, vice versa, whether it is smoking that causes the brain to shrink.

The chicken and the egg

Using data from the UK Biobank, which collects health history, genetic and imaging data from 40 thousand peopleresearchers from the Washington University School of Medicine in St. Louis and the Research Triangle Institute International in North Carolina, directed by Yoonhoo Chang, tried to understand whether smoking, so to speak, Which comes first, the chicken or the egg. They published in the magazine Biological Psychiatry a large review of 2,019 cases, which shows that a history of daily smoking is strongly associated with reduction in brain volume, more evident with increasing cigarette consumption. The smokers had 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. The risk of starting to smoke is instead associated with a reduction in gray matter ten times lower (2,424 cubic millimetres) and therefore the result is in favor of the hen, because the brain declines especially as the habit continueseven if those born as potential smokers are at a disadvantage.

The most affected areas

To suffer the most chronic smoking they are the superior frontal cortex of both cerebral hemispheres, the rostral middle frontal cortex, the medial orbital frontal cortex in the left hemisphere, and the precentral cortex in the right hemisphere. All areas implicated in the so-called executive functionsin which attention, working memory (working memory), problem solving (problem solving), planning and behavioral adaptation to achieve a goal in a structured and flexible way. With smoking, pieces of the neuronal substrate that underlies complex cognitive behaviors are therefore lost such as decision-making, expression of personality or social conduct.

Alzheimer's

It is calculated a 14% association between Alzheimer's disease and smoking: Dementia is accelerated because it is affected above all the hippocampus
, a pivotal brain region in this disease. Various studies have indicated that smoking cessation represents a modifiable risk factor in Alzheimer's, but the results of the research published in Biological Psychiatry I'm against the trend: smoking damage appears to be long-lasting and, after quitting the habit, no evidence of recovery of the lost brain volume has been found. Considering gray matter, white matter and cerebrospinal fluid, no significant association was found between the number of years since quitting smoking and total brain volume. In other words, To keep dementia away, it's best not to start smokingbecause even if you stop, the damage will already be done.

Corriere della Sera also on Whatsapp. sufficient click here to subscribe to the channel and always be updated.