Moderate drinking may cause dementia and Alzheimer's. In this photo, a bottle of Corona beer is displayed on the a shelf at a supermarket in San Rafael, California, April 6, 2017. Getty Images

There have been numerous research and surveys to find out the effect of drinking on the human body. Most of those studies have concluded that moderate drinking is good for one’s health. Physicians even recommend a glass of wine or a beer as part of diets – Mediterranean Diet and DASH Diet – which help keep our heart and brain healthy. But a new study, published in the BMJ, originally called the British Medical Journal on Wednesday, contradicts this theory.

As part of this study, researchers studied a sample’s alcohol intake from the Whitehall II study, which has been tracking ailments and social behavior of a group of British civil servants for the past three decades. The BMJ study, conducted by scientists from University of Oxford and University College London, analyzed the brain functions of the participating sample through regular tests and MRIs.

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Heavy drinkers ran a high risk of hippocampal atrophy, a type of brain damage that can cause Alzheimer’s disease and dementia due to an impact on the spatial navigation. The researchers noticed a speedy decline in their vocabulary and language skills and degrading white matter integrity. This can hamper with the ability to quickly process thoughts.

"Higher alcohol consumption over the 30 year follow-up was associated with increased odds of hippocampal atrophy in a dose dependent fashion. While those consuming over 30 units a week were at the highest risk compared with abstainers. Even those drinking moderately (14-21 units/week) had three times the odds of right sided hippocampal atrophy," the study said.

But what came as a surprise was the test results of the light and moderate drinkers. "We were surprised that the light to moderate drinkers didn't seem to have that protective effect," said co-researcher and clinical lecturer at the Department of Psychiatry of the University of Oxford Dr. Anya Topiwala. "These are people who are drinking at levels that many consider social drinkers, so they are not consuming a lot."

Even the heaviest drinkers in the study had a more than two medium glasses of wine or two beers a night. The moderate drinkers had a glass of wine or one beer a night and little more on weekends. Even these people, whom we consider social drinkers, have shown signs of degeneration compared to those who do not drink at all.

"There was no protective effect of light drinking (1-<7 units/week) over abstinence. Higher alcohol use was also associated with differences in corpus callosum microstructure and faster decline in lexical fluency. No association was found with cross sectional cognitive performance or longitudinal changes in semantic fluency or word recall," the study analyzed for moderate and light drinkers.

Overall the study concludes that drinking, even socially might cause degenerative disorders of the brain, "Alcohol consumption, even at moderate levels, is associated with adverse brain outcomes including hippocampal atrophy. These results support the recent reduction in alcohol guidance in the UK and question the current limits recommended in the US."

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But there are those who disagree to this. Eric Rimm, director for the program in cardiovascular epidemiology at Harvard T.H. Chan School of Public Health and a professor of medicine, argues, "There are so many other lifestyle factors that are not taken into account in this study, like nutrition. Eating whole grains and fruits and vegetables have been linked with slower cognitive decline."

Carl Heneghan, director of the Centre for Evidence-Based Medicine at the University of Oxford, agrees with Rimm, "These type of studies also cannot account for all the (factors), and therefore they cannot, and should not, conclude causation. Using all the available evidence provides a much more balanced approach for the public on deciding how much to drink."