Genetics Guard Against Alcohol-Induced Brain Damage

No one credits heavy drinking with making people smarter - the mind-numbing effects are well documented. Odds are that if you haven't experienced this personally, you've witnessed it in the foolish antics of others. The clear correlation between rapidly diminishing intelligence and rising alcohol consumption is no secret.

But the long-term effects may go deeper than a morning headache or a need to wear sunglasses inside. A new study conducted at Brookhaven National Laboratory reveals that genetic factors can make some individuals more susceptible than others to lasting neurological damage from drinking - alcohol can actually shrink critical areas of the brain, at least in mice.

MRI data mapped onto an existing atlas of a mouse brain to compare the effects of drinking ethanol and water on brain volume.

The study, which explored how alcohol consumption affects brain volume in mice, showed that the brain's dopamine receptors, responsible for registering signals from this "reward" chemical, provide protection. The mice missing those receptors were more damaged by drinking.

The study compared brain volumes overall and region-by-region in normal mice and a strain that lacked the gene for dopamine D2 receptors after six months of drinking a 20 percent ethanol solution. The results demonstrated the powerful defensive role of D2.

Magnetic resonance imaging (MRI) scans revealed that mice without those dopamine receptors experienced brain atrophy overall and shrinkage of the cerebral cortex and thalamus. The mice with D2, however, drank the same amount of alcohol without the resulting brain damage. The corresponding regions of the human brain are critical to processing speech, sensory information, and forming long-term memories.

"This study clearly demonstrates the interplay of genetic and environmental factors in determining the damaging effects of alcohol on the brain," said study author Foteini Delis, a neuroanatomist with the Behavioral Neuropharmacology and Neuroimaging Lab at Brookhaven.

And there's more bad news for mice with a drinking problem. Previous studies indicated that the absence of dopamine D2 receptors also increases the odds of alcohol addiction - meaning that without D2, alcoholism is both more likely and more dangerous.

Maybe in the future a simple genetic test will diagnose susceptibility to alcoholism and other conditions, and we'll have mice (and neuroscientists) to thank for it. Drinking still won't make people smarter, but this research may help keep its effects on the brain temporary.

Read the original press release from Brookhaven National Laboratory here.
The study was published in the May 2012 issue of Alcoholism: Clinical and Experimental Research.

This post was written by Brookhaven Lab science writer Justin Eure.