Moderate alcohol consumption may be good for your heart, but new research suggests that it doesn’t appear to offer the same protective benefits for the brain. While moderate amounts of alcohol don’t necessarily help the brain, regularly consuming more than two drinks a day can definitely harm it.

Habitual consumption of more than 14 alcoholic drinks per week actually causes the brain to shrink, according to the results of a study conducted by researchers at Wellesley College in Wellesley, Mass. The scientists found that the more alcohol an individual drinks on a regular basis, the lower his or her total brain volume.

For the study, the Wellesley researchers evaluated brain size and alcohol consumption patterns in more than 1,800 adults between the ages of 34 and 88 years. The subjects were enrolled in the Framingham Offspring Study, which includes children of the original Framingham Heart Study participants.

Magnetic resonance imaging (MRI) scans were performed and used to measure brain volume, a relatively reliable indicator of brain aging and health. Compared with those who abstained from alcohol, the subjects who habitually consumed more than 14 drinks per week had a 1.6 percent reduction in brain volume.

Although chronic drinking is detrimental to the entire brain, the cells of the hippocampus are especially vulnerable to damage from alcohol. The hippocampus is a small, curved structure in the brain that is vital to learning and memory formation.

When the structure is surgically removed, a person’s ability to store most new experiences in memory is permanently lost. In individuals with advanced, debilitating Alzheimer’s dementia, the hippocampus typically is the first brain structure affected, and often the one that is most profoundly damaged by the disease.

In an animal study supported by the National Institutes of Health, scientists at Scripps Research Institute in San Diego found that chronic alcohol consumption dramatically reduced the number of new brain cells that normally form in the hippocampus.

For the study, rhesus monkeys were allowed to voluntarily consume a sweetened beverage containing 6 percent alcohol during one-hour sessions, five days a week for five months. A control group of monkeys had equal access to a similar, alcohol-free beverage.

Analysis of brain tissue revealed that alcohol consumption significantly reduced new brain cell growth and proliferation in the hippocampus. Compared with the non-drinking monkeys, those consuming alcohol exhibited a 58 percent decrease in the number of new brain cells formed in the hippocampus and a 63 percent reduction in cell survival.

Based on the results of their study, the researchers concluded that chronic alcohol consumption not only causes existing cells of the hippocampus to die off, it also keeps new cells from forming. These findings have important implications for humans, since shrinkage of the hippocampus is known to coincide with declines in cognitive abilities, such as memory and learning, and can ultimately lead to dementia.

Although the hippocampus typically shrinks with age, the rate at which it becomes smaller differs substantially among individuals. While regular physical activity and continued learning have been shown to enhance the size of the structure, chronic alcohol consumption appears to reduce it.

In the earliest stages, loss of brain volume is associated with temporary, minor lapses in memory, such as forgetting a doctor’s appointment or the name of a casual acquaintance, according to the results of a study published in the medical journal Neurology.

If you’re determined to keep your hippocampus healthy and your mind sharp as you grow older, don’t stop exercising or learning new things. And if you enjoy drinking alcohol, continue to do so only in moderation.

Dr. Rallie McAllister is a family physician in Kingsport, Tenn.