The brains of alcohol-dependent individuals are affected not only by their own heavy drinking, but also by genetic or environmental factors associated with their parents? drinking, according to a new study by researchers at the National Institute on Alcohol Abuse and Alcoholism (NIAAA), part of the National Institutes of Health (NIH). Researchers found reduced brain growth among alcohol-dependent individuals with a family history of alcoholism or heavy drinking compared to those with no such family history. Their report has been published online in Biological Psychiatry at http://www.sciencedirect.com/science/journal/00063223 as an article in press.

"This is interesting new information about how biological and environmental factors might interact to affect children of alcoholics," notes George Kunos M.D., Ph.D., Scientific Director, Division of Intramural Clinical and Biological Research, NIAAA.

Many studies have shown that alcohol-dependent men and women have smaller brain volumes than non-alcohol-dependent individuals. It is widely believed that this is due to the toxic effects of ethanol, which causes the alcoholic's brain to shrink with aging to a greater extent than the non-alcoholic's.

"Our study is the first to demonstrate that brain size among alcohol-dependent individuals with a family history of alcoholism is reduced even before the onset of alcohol dependence," explains first author Jodi Gilman, B.S., a NIAAA research fellow and Ph.D. candidate at Brown University working with senior author Daniel Hommer, M.D., of the NIAAA Laboratory of Clinical and Translational Studies (LCTS) and co-author James Bjork, Ph.D., also of the NIAAA/LCTS.

Children of alcoholics are known to have a greater risk for alcohol dependence than individuals without a parental history of alcohol dependence. In addition to inheriting genes that predispose them to alcoholism, children of alcoholics may experience adverse biological and psychological effects from poor diets, unstable parental relationships, and alcohol exposure before birth, all of which could contribute to their increased risk for alcoholism.

In a search for direct physical evidence of these assumed genetic and environmental mediators of family-transmitted alcoholism, the NIAAA researchers used magnetic resonance imaging (MRI) techniques to measure the volume of the cranium — the part of the skull that encloses the brain — in a group of individuals being treated for alcohol dependence. The intracranial volume (ICV), they note, is determined by skull growth, which occurs as the brain expands to its maximum size around puberty. Because ICV does not change as the brain shrinks with age, it provides a good estimate of the lifetime maximum volume of the brain.