June 2, 2000 -- Researchers have just come up with another reason to warn teen-agers not to drink alcohol: Specialized brain imaging studies have shown that teens and young adults, who drank heavily over long periods of time, showed shrinkage of an area of the brain that is responsible for memory and learning. This shrinkage was not seen in teens who did not drink.
The risk of this type of damage is greatest in those who begin drinking at a younger age and those who drink for longer periods of time, according to the study.
"Only in recent years have we known the extent of brain development during adolescence," says co-author of the study, Duncan B. Clark, MD, PhD. "The hippocampus is one of the areas that's rapidly changing at this time and may be particularly affected by alcohol."
But Clark also suggests that the toxic effects of alcohol on the brain might be reversible, especially if the alcohol use is discontinued early.
Susan F. Tapert, PhD, a research scientist with the Veterans Medical Research Foundation and the University of California at San Diego, reviewed the study for WebMD. "We still need more studies, but it looks like there's a good possibility that drinking heavily during the teen-age years could affect your ability to remember things and learn new things," she says. "If you want to do well in school and be able to remember all kinds of things that you learn, it's best to avoid any kind of heavy drinking."
Many people may be surprised to learn that the brain is still developing during the teen years. "Adolescence is a period during which we now know the brain continues to rapidly develop," Clark says. "We know that alcohol can damage the brain. Adolescent alcohol abuse and dependence may have a damaging effect on adolescent brain development, and it is possible that these effects have lifelong adverse consequences.
"The effects of alcohol problems on adolescent brain development have not received much attention, in part because the technology for examining the brain has only recently been developed to the point where we can see the small differences we would expect in the adolescent period. ... This technology [for seeing the brain] provides us with a method for examining areas of the brain that may be affected by alcohol," says Clark, who is director of the Pittsburgh Adolescent Alcohol Research Center.
In this report in the June issue of the American Journal of Psychiatry, a special brain scan, called an MRI, was used to measure differences in the sizes of various brain regions in 12 adolescents and young adults who used alcohol excessively, and 24 healthy youngsters who had no drinking problems.
The researchers focused on measuring the size of an area of the brain, the hippocampus, which is known to be sensitive to the effects of alcohol in adults. The hippocampus is associated with learning and memory functions, Clark says. Two hippocampi are found in the brain, one on the right side and the other on the left side.
Both the right and left hippocampi were smaller in teens with drinking problems in comparison with the normal controls. "The difference was fairly substantial, about a 10% difference, which for this area of the brain is a major difference," Clark says. The shrinkage was limited to the hippocampus; no differences were found in other brain areas.
The shrinkage of the hippocampus was greatest in those who began drinking at an early age and in those individuals who were long-time abusers. The authors say the findings suggest that, during adolescence, the hippocampus may be particularly susceptible to the effects of alcohol.
Clark says that studies conducted in animals, as well as on adults with longstanding alcohol use disorders, suggest that alcohol consumption causes the brain damage. Other explanations, however, may be possible. For instance, the brain changes may have preceded the alcohol consumption and contributed to the onset of the alcohol abuse. Or another risk factor may have caused both the drinking behavior and brain changes.
Clark says that at this early stage, it is difficult to say whether brain changes or alcohol abuse come first. He says that longitudinal studies are needed to confirm and expand the findings.
- The brain still is developing during the teen years. A new report suggests drinking alcohol during this time may damage vulnerable areas in the brain. More study is needed to determine the significance of the damage and if it's reversible.
- In the study, doctors took images of teen drinkers' brains and compared them with images from nondrinking peers. Drinkers showed smaller brain regions in charge of memory and learning.
- Drinkers also showed more signs of other mental conditions like depression, conduct disorder, post-traumatic stress disorder, and attention deficit hyperactivity disorder.