Some are addicted to their smartphones or video games, others are addicted to chocolate, and still others cannot do without cigarettes, sports or sex. More annoying are those who are addicted to alcohol, medication or other drugs.

What do all these interests have in common and what causes these addictions from a scientific point of view?

If we refer to the official definition of the site[i] "Inter-ministerial mission to fight against drugs and all addictive behaviors" (Mild and Ca), we read:

"From a scientific and medical point of view, addictions are brain pathologies defined by a dependence on a substance or an activity, with deleterious consequences.

Addictions include tobacco(nicotine), alcohol, cannabis, opiates(heroin, morphine), cocaine, amphetaminesand synthetic derivatives. Among non-substance addictions, only pathological gambling is clinically recognized as a behavioral addiction in international diagnostic classifications (DSM 5, ICD 10). "

If we refer to the encyclopedia Larousse[ii]It is defined as :

"Process of more or less alienating dependence on toxicants or behaviors.

Addiction is a process by which a human behavior allows access to immediate pleasure while reducing a feeling of internal discomfort. It is accompanied by an inability to control this behavior despite the knowledge of its negative consequences. "

It seems to us that the essential point evoked in this last definition is the notion of access to immediate pleasure, because it is indeed that which the people seek during these various practices on which they are dependent. Whether it's drinking a glass of wine or smoking a joint, the goal sought (often unconsciously) by this act is the feeling of well-being or betterment. Could it be to escape, as the Larousse encyclopedia suggests, from a feeling of internal malaise? This statement seems questionable and varies greatly from person to person.

As for the scientists, if they define addiction as a cerebral pathology, they have undoubtedly hidden the spark of activation that precedes the cerebral. This spark is purely hormonal. In fact, the neurotransmitters responsible for pleasure or any other sensation or behavior will only be released if they are activated by a hormone, a hormone that is itself carried in the bloodstream. The feeling of pleasure brought by the addictive act is therefore not directly caused by the brain. The brain is only the hard disk of our organism, a disk in which all our sensations have been recorded. These sensations are brought back to consciousness and revived through the endocrine system. It is therefore the latter that causes the addiction phenomenon and not our nervous system.

The common factor between the use of alcohol, drugs and excessive sex is the feeling of euphoria that comes from it. Euphoria, well-being, pleasure are rather positive emotions and depend essentially on our thyroid gland. This butterfly-shaped gland located at the base of the neck is the gland of communication and sensitivity. All our sensations and perceptions (visual, auditory, gustatory, sensations of pleasure or well-being, but also those of displeasure or sadness, etc.) depend on the activation of our senses by thyroxine, the main thyroid hormone.

What does this have to do with the substance or the additive act, you might ask?

All of these potentially addictive activities have one thing in common: they all trigger thyroid excitement. Thyroid excitement increases the rate of thyroxine release in the body, which is accompanied by a feeling of euphoria and well-being. Conversely, sad situations or painful actions tend to exhaust this gland which, tired, will secrete less thyroxine. We then witness a state of fatigue, dejection or depression[iii] in the most advanced cases. One thing is certain, all these moods, whether sad or happy, are directly related to the state of excitement or not of our thyroid gland and therefore to the rate of imbibition of the body by the thyroid hormone (thyroxine).

Activated by the pleasurable act, alcohol or drugs, the thyroid releases thyroxine, this circulating thyroxine will itself awaken the sensations of well-being that our brain will have previously registered in similar situations.

Thus, a person who feels his life is sad or monotonous will quickly understand that a small drink, a small joint, a small square of chocolate or a good video game brings him a feeling of pleasure, excitement and euphoria. Whenever the thyroid gland tends to be tired and exhausted, the person may turn to this type of activity to compensate and regain that pleasant state.

The addiction is therefore endocrine or glandular at first. It is cerebral only in a second time, insofar as the thyroid excitation reactivates the sensations of well-being recorded beforehand. These sensations are brought back into the body's memory thanks to thyroxine, which in turn activates the neurons or brain areas in which these memories of well-being lie dormant.

While the state of well-being or excitement is much less evident in drug dependence, the phenomenon of thyroid boosting is similar. In this case, it is the chemical molecules that stimulate the thyroid. And it is no coincidence that the most addictive drugs are psychotropic drugs (altering emotions), antidepressants (activating the thyroid to prevent sadness and drowsiness) and sleeping pills (inducing sleep to allow the thyroid gland to regenerate during the night). In fact, these three families of drugs all act through the glandular intermediary in order to modify the moods or the behavior of the person who consumes them.

[i] http://www.drogues.gouv.fr/comprendre/l-essentiel-sur-les-addictions/qu-est-ce-qu-une-addiction

[ii] http://www.larousse.fr/encyclopedie/medical/addiction/185204

[iii] http://www.dailymotion.com/video/xhanid