Eighty-six percent of Italians make use of alcoholic drinks and statistics show that the first glass is drank around the age of 11 or 12. These data, gathered from the ISTAT (Italian National Institute of Statistics), are very important, especially if we think about the effects that alcohol has on our brain.
Alcoholism, in fact, affects several brain areas and behavior in many ways. This evidence has been gathered through post-mortem examination of alcohol abusers or thanks to more modern neuroimaging techniques that allow researchers to visualize the in vivo activity of the brain cortex.
The brain functioning is based on the communication between nervous cells (neurons). Each neuron connects to a variable number (up to thousands) of other nervous cells and converts the messages of other neurons in transient modifications (such as the possibility to respond faster to other impulses) or permanent modifications (such as the creation of new links). Alcohol interferes with this process called signal transduction1.
According to a validated hypothesis, alcohol produces a severe atrophy of both grey (neurons) and white (links between neurons) matter in the brain cortex2.
Despite the fact that this process may involve the whole brain, it has been demonstrated that specific cortical and sub-cortical structures are more affected than others. In a recent study, thanks to Magnetic Resonance, “photos” of the brain of two groups of subjects were taken: the first group comprised alcoholics while the second one comprised participants, matched by age and education to the first group, who never drank alcohol3. This study demonstrated that the continuous use of alcoholic drinks may lead to a reduction of the volume of the hippocampus, a structure located in the temporal lobe that is involved in the acquisition of new memories. This reduction may be the cause of the memory dysfunctions from which patients affected by chronic alcoholism suffer.
Frontal lobes, involved in executive functions (attention and problem solving skills among the others), are very vulnerable to alcohol4. These areas are connected with the other lobes (parietal, temporal and occipital) and exchange information with sub-cortical structures too, such as the amygdala, which is crucial to process emotions. More specifically, prefrontal cortex (the anterior part of the frontal lobes) seems to be subject to the effect of alcoholic substances5. The prefrontal cortex is fundamental to plan and regulate our actions; in other words to inhibit dangerous or inadequate behaviors. The destruction of this “control system” often causes the execution of impulsive or inappropriate actions as much as violent verbal or physical behaviors. Furthermore, these uninhibited behaviors may contribute to increase alcohol consumption.
Finally, it seems that alcohol acts in a deeper way in the right part of brain. Despite the fact that the two hemispheres are in close relationship and act in unison, each one of them is specialized in specific functions. Patients suffering from left hemisphere lesions have overshot language problems, while patients suffering from right hemisphere lesions often have spatial problems as well as impairments related to the expression and comprehension of emotions. Several neuroimaging studies pointed out that patients with a history of alcohol abuse may seem emotionally unresponsive, that is less sensitive to situations that can produce affective involvement. Furthermore these patients also have difficulties in processing emotional information such as the interpretation of facial expressions (for instance, distinguishing a happy expression from a sad one). This failed identification phenomenon seems to be connected to severe impairments in interpersonal relationships6.
We have to consider however that the processing of emotions doesn’t involve one hemisphere only but also sub-cortical areas such as the limbic areas (which include the hippocampus and the amygdala) and the frontal areas we mentioned above. That said, it is plausible to hypothesize that alcoholism affects this complex network as a whole.
The above-mentioned studies allow us to conclude that alcoholism is a dangerous pathology, especially because of the involvement of brain regions that can change our behavior making it less inhibited, slower and less careful to personal relationships.
[1] Alling, Christer, Ivan Diamond, Steven W. Leslie, Grace Y. Sun, and W. Gibson Wood, eds. Alcohol, Cell Membranes, and Signal Transduction in Brain. 1st ed. Springer, 1993.
[2]Lishman, W. A. “Alcohol and the Brain.” The British Journal of Psychiatry 156, no. 5 (May 1, 1990): 635–644.
[3] Beresford, Thomas P., David B. Arciniegas, Julie Alfers, Lori Clapp, Brandon Martin, Yiping Du, Dengfeng Liu, Dinggang Shen, and Christos Davatzikos. “Hippocampus Volume Loss Due to Chronic Heavy Drinking.” Alcoholism: Clinical and Experimental Research 30, no. 11 (November 2006): 1866–1870.
[4] Sullivan, Edith V. Human brain vulnerability to alcoholism: Evidence from neuroimaging studies. In Noronha, A.; Eckardt, M.; and Warren, K., Eds. Review of NIAAA’s Neuroscience and Behavioral Research Portfolio. NIAAA Research Monograph no. 34. Bethesda, MD: National Institutes of Health, 2000, pp. 473–508.
[5] Abernathy, Kenneth, L Judson Chandler, and John J Woodward. “Alcohol and the Prefrontal Cortex.” International Review of Neurobiology 91 (2010): 289–320.
[6] Kornreich, Charles, Pierre Philippot, Marie-Line Foisy, Sylvie Blairy, Emmanuel Raynaud, Bernard Dan, Ursula Hess, Xavier Noël, Isy Pelc, and Paul Verbanck. “Impaired Emotional Facial Expression Recognition Is Associated with Interpersonal Problems in Alcoholism.” Alcohol and Alcoholism (Oxford, Oxfordshire) 37, no. 4 (August 2002): 394–400.