Over the past 50 years, alcohol consumption has steadily declined in France, a decline that is mainly attributed to the decline in wine consumption. Still, 10% of French adults still experience problems with alcohol.
Excessive alcohol consumption is not without damage to the brain. Numerous studies have shown that the volume of brain structures involved in cognition and learning is significantly reduced in people who are addicted to alcohol. This decrease is partially reversible after a prolonged discontinuation of consumption, but not all areas of the brain recover in the same way. Which benefit from stopping alcohol? And what are the consequences of those who do not benefit?
Alcohol lowers the brain volume
Even with moderate but regular drinkers, an overall reduction in brain volume has been observed. However, it is not definitive: when the alcohol stops, there is a partial recovery of the volume of the brain, which is accompanied by an improvement in cognitive skills. Many factors influence this recovery: age, gender, genetic factors, family history of alcohol addiction, smoking, etc.
Can alcohol-related brain damage itself influence behavior related to addictions? In other words, can it increase the risk of relapse? To find out, the first step was to determine which brain regions, among those involved in addiction, were most affected by these volume changes. The team of Timothy Durazzo and Dieter Meyerhoff, perhaps the best-known authors in the field of structural neuroimaging in alcohol dependence, recently addressed the issue.
An immediate recovery
The researchers brainstormed the brain of 85 people with alcohol restriction for a week, a month and seven months after they stopped using alcohol, and compared them with the brain images of control subjects who consumed little or no alcohol. alcohol, so without addiction.
The people who consumed more than 204 "standard" glasses of alcohol were considered addicted (a standard glass corresponds to about a "balloon" of 12 cl of wine or 10 g of ethanol) per month. in the last 8 years for men, and 108 glasses in the last 6 years for women. This difference is explained by the fact that men eliminate alcohol faster than women, and that the brain and body effect are greater in the latter, at equal doses.
As far as gender differences are concerned, it is interesting to note that while men born between 1891 and 1910 were three times more likely than women born at the same time to use problematic alcohol consumption, this ratio gradually diminished over the course of the twentieth century. To the point that there is no significant difference today between boys and girls born between 1991 and 2000.
In the study, MRI revealed that all areas studied (anterior cingulate cortex, insula, dorsolateral prefrontal cortex, orbitofrontal cortex) had changed when participants started their withdrawal period. However, after stopping alcohol, the volume of affected brain structures increased over time as soon as people stopped using it. The effects of discontinuation of consumption were indeed noticeable from the first week or the first month of discontinuation. These recoveries followed very different trajectories according to the individuals, some recovered less well than others.
Moreover, a structure has never been restored: the hippocampus. But this plays an important role in memorization, especially when forming new memories.
Differences that explain the inequality with alcohol
The neurobiological abnormalities that occur in the hippocampus therefore seem more persistent than those in the cortex. This can lead to learning disabilities, especially with regard to the new tasks needed to manage long-term abstinence. Combined with the fact that the plasticity of gray matter observed during abstinence varies from individual to individual, this suggests that some people have a greater risk of relapse.
However, the study had some limitations. First, no MRI was performed before the alcohol was stopped. Obtaining such recordings is of course difficult because of both technical and ethical limitations. Subsequently, most subjects did not pass the three consecutive registrations (one week, one month and seven months after stopping alcohol), which limits the value of the collected data. Last but not least, no cognitive measures have been realized (this issue is the subject of future research). This is unfortunate because they would have been needed to show that the attacks of brain structures have real clinical significance.
Looking for the origin of individual sensitivity
Studies of the same type that have already been performed on alcohol dependent persons have shown that they suffer from two types of seizures. On the one hand attacks that can be described as "irritation", both diffuse and frequent, but also reversible after stopping alcohol. On the other hand, attacks are "fixed", which continue to exist well after stopping alcohol.
Many questions remain unanswered in this context. First, even if one suspects the existence of a strong link with the cognitive disorders (which are in fact separated according to the same two types – "irritative" and "fixed"), it has not really been studied until now, while it is clearly important in practice. Then it is crucial to understand why some (most) attacks are reversible, while others are frozen and leave traces, if not indelible, at least lasting. Finally, it is essential to understand why some topics are exposed more than others to the fixed attacks.
Is it a matter of dose and duration of alcohol exposure? Too simplistic, without a doubt. The differences observed from patient to patient are probably explained by individual factors of neurobiological sensitivity to alcohol, still unknown. More information about these determinants will be the biggest challenge for researchers in the coming years.
This article is inspired by a publication of the Addict & Aide newsletter, which provides information about all addiction problems. The Addict & # 39; Aide portal is supported by MGEN, VYV Group.
Published in collaboration with The Conversation