Researchers from the University of Oxford and University College London have found that drinking between 14-21 units of alcohol per week -- the equivalent of a medium glass of wine each night, plus a little more on the weekends, according to CNN -- can result in hippocampal atrophy, a form of brain damage that affects memory and spatial navigation. This is a startling finding, since current federal guidelines say that drinking even more than this amount is safe for some consumers.
“Our findings…call into question the current US guidelines, which suggest that up to 24.5 units a week is safe for men, as we found increased odds of hippocampal atrophy at just 14-21 units a week, and we found no support for a protective effect of light consumption on brain structure,” the researchers said.
Causes brain damage
The study used data that measured weekly alcohol intake and cognitive performance over the course of 30 years for approximately 550 healthy men and women who took part in the Whitehall II study, with the researchers adjusting for factors like age, sex, education, social class, physical and social activity, smoking, stroke risk, and medical history.
Over the study period, the researchers found that higher consumption of alcohol was associated with higher incidences of hippocampal atrophy, decreased language skills, and poorer white matter integrity, which is essential for the brain to process information.
While the heaviest drinkers had the greatest risks in all of these cases, the researchers say that even moderate drinkers were causing lasting damage to their brain function; participants who drank moderately were found to be at three times the risk of hippocampal atrophy when compared to light drinkers or those who abstained from alcohol.
"Normal" habits could be harmful
While the study is only observational and cannot produce any firm conclusions about cause and effect, the researchers say they also found no protective effect of light drinking on brain structure. In a linked editorial, neuropsychiatrist Killian Welch said the findings “strengthen the argument that drinking habits many regard as normal have adverse consequences for health.”
“We all use rationalizations to justify persistence with behaviours not in our long term interest. With publication of this paper, justification of moderate drinking on the grounds of brain health becomes a little harder,” he said.
The full study has been published in The BMJ.