The effects of tobacco on the brain

Nicotine and other tobacco substances adversely affect various parts of the brain.

Lighting up and smoking a cigarette are actions that millions of people carry out on a regular basis every day, even though they know that smoking and tobacco use have a large on a regular basis every day, even though they know that smoking and tobacco consumption have a lot of harmful and detrimental effects on our survival.

By now most people are aware of the relationship between smoking and lung cancer, respiratory problems, the aging of our tissues or the shortening of life expectancy. However, there are other organs and affectations that are not so often taken into account by the population and that are nevertheless fundamental: for example, the effects of tobacco on the brain.

In this article we will give a brief overview of what smoking entails, how smoking affects the brain and the effects and risks that tobacco use can have on the king organ.

Tobacco and nicotine

Tobacco is a product made from the tobacco plant (Nicotiana tabacum), specifically from its leaves and stem, which after being chopped or cut are prepared in different formats and some of which are mixed with other substances to make cigarettes, rolling tobacco or to use in a pipe, and which is generally consumed by inhaling the smoke from its combustion.

The main active ingredient of tobacco, which gives it its psychoactive properties, is nicotine. This substance has activating and stimulating effects on the organism.It binds to the body's nicotinic acetylcholine receptors. However, with chronic consumption and the progressive habituation that this substance generates, the effects are less and less activating and tend to be perceived as depressing and even relaxing.

But habituation to nicotine ends up generating dependence to its external acquisition, in such a way that little by little greater quantities are needed to obtain the same effects: with the passage of time smoking becomes a necessity and smoking or nicotine dependence is established. smoking or nicotine or tobacco dependence is established..

The consumption of tobacco and the inhalation of its smoke also means that other components are incorporated into the body, such as carbon monoxide, carcinogenic substances, free radicals and oxidants such as the hydroxyl radical, carcinogenic gases such as formaldehyde or nitric oxide, or metals such as cadmium or beryllium (and even arsenic). (and even arsenic).

In addition, this consumption has harmful effects on multiple parts of our organism, regardless of whether we are talking about tobacco in the form of cigarettes or in other forms: smoke aspiration is irritating and is deeply linked to respiratory problems (being one of the most common reasons for chronic obstructive pulmonary disease, emphysema and other respiratory problems) and to the development of respiratory tumors or tumors of the intestinal and oropharyngeal tract.

It also affects, among others, the heart and vascular system, generating vasoconstriction and may facilitate severe problems in this system. It can generate liver and pancreas problems, cause damage to eyes and skin and alter the metabolism and Gastrointestinal system. It also reduces physical capacity due to lack of oxygenation.

How does smoking act on our brain?

Upon inhalation, most of this substance is absorbed by the smoker through the lungs (and to a much lesser extent through the mucous membranes and tongue). (and in much smaller quantities through the mucous membranes and the tongue), and after being processed by the alveoli and taken into the bloodstream in about eight seconds it reaches our brain after passing through the blood-brain barrier.

Once there, it binds to the acetylcholine receptors called nicotinic receptors, in which it generates the opening of calcium channels but prevents the acetylcholine already existing in the brain from entering. This will cause the organism to try to generate higher levels of acetylcholine, which will also provoke the activation of the dopaminergic of the brain reward system. Nicotine affects different parts of the brain, but some of the most relevant are the brain's some of the most relevant are the limbic system and the basal ganglia, as well as the mesocortical pathway.as well as the mesocortical and mesolimbic pathways.

This system is the reason why tobacco consumption gradually becomes appetizing and promotes addiction. Dopamine in this area increases at the same time that other components of tobacco block the action of MAO which would decrease it. It also affects the locus coeruleus, stimulating it and causing an increase in energy levels while contributing to generate feelings of tranquility in stressful situations.

Likewise, a desensitization of the nicotinic receptors to this substance is gradually generated through positive regulation, to which the body will respond by forming a greater number of receptors where the union between nicotine and receptor can occur. A tolerance to the substance is being formedThis will result in more and more nicotine being needed to produce the same effects. And this tolerance also partly explains why chronic smokers feel relaxation rather than activation when they smoke: they are actually relieving the anxiety of withdrawal.

At the same time, it affects the hypothalamic-pituitary axis in such a way as to increase the release of adrenocorticotropic and corticotropin-releasing hormones, which in turn contributes to the stimulation of the adrenal glands in such a way as to cause in such a way that it provokes the synthesis and emission of adrenaline or epinephrine. This hormone will generate vasoconstriction and increases in pressure and heart rate and in turn feeds back the activation of the organism. It also hinders the synthesis of pancreatic enzymes.

Effects of tobacco on the brain

Beyond how it acts, it is also relevant to know some of its effects. In the short term, and with the first consumption, it is common that the initial consumption of small doses can alleviate depressive symptoms and increase mood.

Activation of the locus coeruleus also facilitates arousal and increases in wakefulness levels may appear to occur. and may appear to produce increases in levels of wakefulness, ability to concentrate and the feeling of being able to cope with situations. However, it can also cause palpitations, dizziness and respiratory problems.

However, as consumption becomes more frequent, worse and worse consequences are seen. First of all, the progressive tolerance to nicotine results in the development of a dependence on the substance, initially physical and later also psychological.

The lack of tobacco will generate abstinence, usually in the form of discomfort and anxiety.. Increased appetite, apathy, headaches and sleep problems are also observed. In abstinence, concentration problems may also appear. It also alters the ability of olfactory and taste perception, impairing these senses.

The effect of nicotine on the neocortex has been observed, especially in the long term, as problematic and negative. Several studies suggest that tobacco consumption weakens and causes deterioration of nerve cells in this part of the brain, leading to a reduction in their thickness due to increased mortality of nerve fibers. This factor may be linked to an increased likelihood of cognitive impairment and even dementia. The formation of new neurons has also been shown to be reduced..

In case of pregnancy, it has been observed that smoking can cause prematurity and low weight, as well as delays in the growth and cognitive development of the child.

It also greatly affects the vasoconstrictive capacities of nicotine, something that has been shown to reduce the formation of new neurons. can facilitate the onset of stroke. However, nicotine (not smoking) seems to have positive effects in the prevention of Parkinson's disease, although this is still under study.

If we also take into account the possible effect of the presence of carbon monoxide (common in the combustion of tobacco), it also hinders the oxygenation of the brain and can cause demyelination of the nervous system (loss of myelin, which results in a loss of speed in the transmission of information between neurons).

Likewise, although in the initial moments it generated stimulation, in the long run it can generate problems such as depression. At a less biological and more psychological level, if unsuccessful efforts are made to quit, there may also be a feeling of helplessness or ineffectiveness, or even resort to other more harmful substances.

Bibliographical references:

• Dani, J.A. (2001). Overview of nicotinic receptors and their roles in the central nervous system. Biol. Psychiatry 49, 166–174.
• Karama, S., Ducharme, S., Corley, J., Chouinard-Decorte, F., Starr, J.M., Wardlaw, J.M., Bastin, M.E. & Deary, I.J. (2015). Cigarette smoking and thinning of the brain’s cortex. Molecular Psychiatry, 20: 778-785.
• Martín, A., Rodríguez, I., Rubio, C. Revert, C & Hardisson, A. (2004). Efectos tóxicos del tabaco. Rev. Toxicol.,21: 63-71.
• Tanja, A.J., Quintero, L.C.M. (2015). Efectos neurobioquímicos de la nicotina en el cerebro humano. Revista 16 de Abril; 54 (260): 31-41.