Not only does alcohol disrupt short-term memory (i.e., recall of recent events) but repeated use of alcohol can cause cognitive learning and memory problems even if one is not actually drinking. This observation suggests that repeated alcohol use or binging can cause damage specifically to the hippocampus in adolescents.

While most research on alcohol-induced cell death has been performed in animals newer technologies have enabled us to detect damage in the human brain. The brain can be visualized with imaging technologies such as magnetic resonance imaging or MRI. MRI detects the energy given off by spinning protons in hydrogen atoms (most of these are in water and fat) in the tissues throughout the body. Using MRI scans scientists have shown that people who began drinking alcohol as adolescents have significantly smaller hippocampi than their non-drinking peers.

Learn more how an MRI scan works.

When studying the MRI scans, scientists noted that there is an association between the (smaller ) size of the hippocampus and the number of years of alcohol abuse, suggesting that the earlier that a teen begins abusing alcohol, the greater the risk of harm to the hippocampus. Most strikingly, the damage that alcohol causes in the developing brain can last through adulthood. These data provide compelling evidence that the adolescent hippocampus is highly sensitive to the neurotoxic effects of alcohol and that the damage can be long-lasting. Scientists are now assessing whether the damage is irreversible.

Similarly, MRI has also been used to show that the early stages of Alzheimer’s disease are marked by physical changes in the hippocampus. Researchers have found that the reduction in hippocampal size is associated with an increased risk for the development of Alzheimer’s disease. Thus, those who start drinking alcohol as adolescents may have an increased risk for developing Alzheimer’s disease when they get older.

Figure 3.7 MRI scans show a smaller hippocampus (in the red circles) in a person with adolescent alcohol-use disorder (right) compared to a healthy person of the same age (left). (Adapted from M.D. De Bellis with permission).