As with many controversial health topics these days, medical opinion about the benefits and risks of alcohol seems to whip back and forth more quickly than tennis balls at Wimbledon. Is it good or bad for you?

The answer: both. Duke research suggests that moderate drinking earns a qualified maybe for older adults and a more marked thumbs-down for young people. More conclusive are the adverse effects of drinking too much in a single evening, which is an emphatic no-no.

Mixed Results for Older Drinkers

Over the past few years, several highly publicized studies have suggested that senior citizens who drink wine regularly may lower their risk of heart disease, hypertension, and diabetes, and even increase bone mass. But geriatric specialist Heidi White, MD, says seniors who enjoy alcoholic beverages should proceed with caution.

According to White’s research, drinkers older than 50 who have more than a single drink at a time are more likely to become disabled and have memory problems than non-drinkers. White adds that seniors’ illnesses and medications may not mix well with alcohol, and excessive drinking can lead to dementia. “Part of this may be due to changes in body composition,” she speculates, “because alcohol is distributed in body fat.”

Another study led by Duke psychologist John Barefoot, PhD, suggests that some of the healthy effects often attributed to wine consumption may be due to other factors entirely. The study of 4,000 college alumni in their 60s compared those who named wine as their beverage of choice to those who drank harder stuff or abstained entirely.

The wine-drinkers ate more healthfully than either of the other groups, and were both more likely to exercise and less likely to smoke than other drinkers. “These healthier lifestyles may at least partially explain their better general health,” Barefoot says. "But there are also plausible reasons to think that wine is particularly good for you."

Memory Loss in Young People

For young people, the detrimental effects of alcohol seem to outweigh any health positives. In the first human study to assess alcohol's effects on memory in young adults, researchers at Duke and the Durham VA Medical Center found that just two drinks can dampen the ability of college-age students to learn and remember new information. According to Duke neuropsychologist Scott Swartzwelder, PhD, alcohol disrupts a key process within the hippocampus, the portion of the brain responsible for building long-term memories, much more powerfully in the young brain than in the adult brain.

Just as dangerous is the trouble young people can get into while under alcohol’s influence. According to another study coauthored by Swartzwelder, significant numbers of college students, especially young women, experience regular or sporadic memory “blackouts” during evenings of heavy drinking, which are associated with highly risky behaviors. These activities, such as having unprotected sexual intercourse, vandalizing property, or driving a car, could lead to serious health or legal consequences.

“Alcohol consumption is often viewed tolerantly as a rite of passage, but the hazards it poses are too significant to be ignored,” Swartzwelder says. He and his colleagues hope that sobering study results like these will lead to more intensive education for incoming college students about the dangers of alcohol.

Moderation is Essential

One thing is certain among alcohol research findings: drinking too much is bad for your health, especially large amounts in a single sitting.

Researchers have long known about the associations between high alcohol intake and liver cirrhosis and cancer. But Barefoot points to recent Danish research showing higher mortality rates among those who consolidate their drinking into episodes of all-out inebriation.

Those differences in drinking patterns may correlate with other lifestyle factors, as with Barefoot's research on wine drinkers. Indeed, the confluence of factors at play can make it difficult to discern the overall effect of alcohol on health. Nonetheless, the message is clear -- for those who do choose to drink, moderation is key.

"If you have seven glasses of wine a week, that may be fine," Barefoot says. "But if you drink all of them on Saturday night, you may be damaging your health."