4.+Neurocognitive+Effects

=Neurocognitive Effects of Alcohol on Adolescents=



More than likely if you ever ask a group of teens if they thought drinking alcohol was damaging their brains they would collectively say no. They might tell you that they don't drink enough, or haven't been drinking long enough, for that to happen. Many teenagers (and adults) think that it takes massive amounts of alcohol, or drinking heavily over a long period of time, to cause brain damage. This is not true. Scientists can already see changes in the brains of teenagers who drink.

A study by Dr. Susan F. Tapert, of adolescent binge drinkers, has found that even relatively infrequent exposure to large amounts of alcohol during the teen years may compromise the integrity of the brain's white matter, or the cerebral cortex, which plays a key role in memory, attention, awareness, thought, and language (Kain, 2009). In the study, Tapert used an MRI machine to measure the integrity of white matter in the brains of 28 teenagers - 14 who had and 14 who did not have histories of binge drinking. According to Tapert, the teen binge drinkers exhibited lower levels of white matter fibre coherence (Kain, 2009). Dr. Tapert stated that, "Those who reported engaging in binge drinking showed lower levels of brain organization" (Kain, 2009). Binge drinking is defined as drinking 5 or more drinks in a couple of hours.

The overriding concern is that because the brain is still developing during adolescence, it may be more vulnerable to high doses of alcohol. Dr. Tapert admits that long-term studies that follow teens over time are necessary to clarify the cause and effect of these brain changes, but states that drinking to the point of being drunk may be harmful to the adolescent brain (Kain, 2009). The image to the left is an example of one of Dr. Tapert's MRI scans.

During adolescence, the hippocampus may be especially vulnerable to the negative effects of alcohol. The hippocampus is a major part of the limbic system in the brain, consisting of two mirror-imaged halves, and closely associated with the cerebral cortex. It plays an important role in memory, learning and spatial navigation. One study compared the hippocampal volumes of adolescents and young adults with adolescent-onset alcohol use disorders to those of healthy matched comparison subjects (De Bellis et al., 2000). MRI's were used to measure the subjects' comparative hippocampal volumes. The results showed that both left and right hippocampal volumes were much smaller in subjects with alcohol use disorders than in comparison subjects. It was also seen that the older someone was when they started drinking, the larger their total hippocampal volume was, and the longer they had been drinking, the smaller their total hippocampal volume was (De Bellis et al., 2000).

Figure 1, Figure 2

Figure 1. Hippocampal Volumes, Adjusted for Intracranial Volume, of Subjects With Adolescent-Onset Alcohol Use Disorders and Healthy Matched Comparison Subjects (De Bellis et al., 2000)

Figure 2. MRI Scans Depicting the Right Anterior and Left Posterior Hippocampus in a Subject With an Adolescent-Onset Alcohol Use Disorder and a Healthy Comparison Subject Matched for Age, Sex, and Handedness (De Bellis et al., 2000)

**The following video highlights some of the effects of alcohol on the adolescent brain**

media type="youtube" key="PGR4AzycAyU?fs=1" height="385" width="480" align="left"

As Dr. Aaron White discusses in the video, younger brains are more susceptible to alcohol because they are more sensitive. During adolescence the brain is very moldable and flexible, because of all the learning and changing it has to do. Alcohol is very effective at preventing these changes. The danger is that once a person is in their early 20's, the brain loses this flexibility. Therefore adolescence is the critical time for the brain to change and grow.