It is well known and well documented that alcohol addiction can lead to significant changes in the brain, causing the brain tissue of alcoholics to exhibit a variety of differences from the brain tissue of non-alcoholics. A new study, however, has revealed that there is more to these brain changes than what meets the eye. According to the study, while all alcoholics’ brains have some characteristics in common, some changes in the brain are exclusive to anxiety-prone (type I) alcoholics, and some changes are exclusive to impulsive (type II) alcoholics.

For the study, researchers at the University of Eastern Finland examined post-mortem brain tissue of both alcoholics and non-alcoholics. Alcoholic brain tissue was then divided into two categories based on Cloninger’s typology of type I and type II alcohol addicts.

Two Types of Alcoholics

Type I alcohol addicts are more prone to anxiety and typically develop alcohol addiction later in life. Type II alcohol addicts, meanwhile, typically exhibit more antisocial behavior and impulsivity, and they tend to develop alcohol addiction earlier in life.

Categorizing the Differences

In dividing the alcoholic brain tissue into two categories based on Cloninger’s typology, researchers recognized that not all alcoholics, of course, neatly fit into one of the two categories. The main goal of the categorization was to highlight the vast range of individuals suffering from alcohol addiction.

Before exploring the differences in brain tissue among alcoholics, it is helpful to first explore the many similarities that alcoholic brains share. All alcoholics seem to exhibit increased levels of dehydroepiandrosterone, a steroid hormone that affects the central nervous system. These increased hormone levels explain why alcoholics tend to become tolerant to the feelings of pleasure they once had when consuming alcohol. In addition, all alcoholic brains tend to show decreased levels of serotonin transporters in regions of the brain related to the recognition of feelings and social cognitive processes.

Even with the many brain similarities that exist among alcoholics, researchers were able to detect brain differences between the two different types of alcoholics. Type I (anxiety-prone) alcoholic brains tended to exhibit changes in the endocannabinoid system, which modulates stress responses. These brains also saw increased levels of docosahexaenoyl ethanolamide—a lipid signalling molecule responsible for anti-inflammatory and organ protective activity. Type II (impulsive) alcoholic brains, meanwhile, saw increased levels of AMPA receptor, which are responsible for the learning and regulation of behavior.

Opening the Path for Further Research

Researcher Olli Kärkkäinen, M.Sc. (Pharm) highlighted the important of these findings when he stated, “These findings enhance our understanding of changes in the brain that make people prone to alcoholism and that are caused by long-term use. Such information is useful for developing new drug therapies for alcoholism, and for targeting existing treatments at patients who will benefit the most.” These findings could additionally help tailor treatment to individuals recovering from alcohol addiction, depending on which type of alcoholism more closely resembles their own.