Even moderate drinking linked to changes in brain structure

Drinking even moderate amounts ofalcohol is linked to changes in brain structure and an increasedrisk of worsening brain function, scientists say.

In a 30-year study that looked at the brains of 550middle-aged heavy drinkers, moderate drinkers and teetotallers,the researchers found people who drank more alcohol had a greaterrisk of hippocampal atrophy a form of brain damage thataffects memory and spatial navigation.

People who drank more than 30 units a week on average hadthe highest risk, but even those who drank moderatelybetween14 and 21 units a week were far more likely than abstainers tohave hippocampal atrophy, the scientists said.

"And we found no support for a protective effect of lightconsumption on brain structure," they added.

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The research team from the University of Oxford andUniversity College London said their results supported arecent lowering of drinking limit guidelines in Britain, butposed questions about limits recommended in the United States.

The researchers defined aunit as 10 millilitres (ml) of pure alcohol.

U.S. guidelines suggest that up to 24.5 units of alcohol aweek is safe for men, but the study found increased risk ofbrain structure changes at just 14 to 21 units a week.

Canada's Low-Risk Alcohol Drinking Guidelinessay to reduce long-term health risks, no more than two drinks a day, five times a week or 10 drinks total a week for women are recommended and no more than three drinks a day, five times a week or 15 drinks total a week are recommended for men.

In the Canadianguidelines, "a drink" means:

• 341 ml (12 oz.) bottle of 5% alcohol beer, cider or cooler.
• 142 ml (5 oz.) glass of 12% alcohol wine.
• 43 ml (1.5 oz.) serving of 40% distilled alcohol (rye, gin, rum, etc.)

Killian Welch, a Royal Edinburgh Hospital neuropsychiatristwho was not directly involved in the study, said the results,published in the BMJ British Medical Journal, underlined "theargument that drinking habits many regard as normal have adverseconsequences for health."

"We all use rationalizations to justify persistence withbehaviours not in our long term interest. With [these results] justification of 'moderate' drinking on the grounds of brainhealth becomes a little harder," he said.

The study analysed data on weekly alcohol intake andcognitive performance measured repeatedly over 30 years between1985 and 2015 for 550 healthy men and women with an average ageof 43 at the start of the study. Brain function tests werecarried out at regular intervals, and at the end of the studyparticipants were given a MRI brain scan.

After adjusting for several important potential confounderssuch as gender, education, social class, physical and socialactivity, smoking, stroke risk and medical history, thescientists found that higher alcohol consumption was associatedwith increased risk of brain function decline.

Drinking more was also linked to poorer "white matterintegrity" a factor they described as critical when it comesto cognitive functioning.

The researchers noted that with an observational study likethis, no firm conclusions can be drawn about cause and effect.They added, however, that the findings could have importantpublic health implications for a large sector of the population.