Just 4 alcoholic drinks a week could contribute to cognitive decline

Concerning if confirmed! Even regular light and moderate consumption of beer or wine can cause harm according to this study. However, if the study is correct, would the prevalence of cognitive decline in the population be much larger than it actually is.

There are indeed some possible issues with this study: "The main limitations of the study include that χ and T2* can reflect changes in myelin as well as iron, alcohol use was self-reported, and MR estimates can be influenced by genetic pleiotropy."

So don't feel guilty yet drinking your next beer! Cheers!

"... The hypothesis driving the research arose from studies associating high brain iron levels with neurodegenerative diseases such as Alzheimer’s and Parkinson’s. Abnormal accumulations of iron in the brain have been detected in the brains of heavy alcohol drinkers ...
“In the largest study to date, we found drinking greater than seven units of alcohol weekly associated with iron accumulation in the brain,” ...
“Higher brain iron in turn linked to poorer cognitive performance. Iron accumulation could underlie alcohol-related cognitive decline.” ...
One unit of alcohol is defined here as 10 milliliters of pure alcohol. A big glass of wine, for example, could be anywhere from two to three units of alcohol, while a regular can of beer can contain between 1.5 and two units of alcohol. ...
“Alcohol suppresses hepcidin production, the major hormone-regulating iron homeostasis,” the researchers explained. “This suppression increases intestinal absorption of dietary iron and limits export of iron from hepatocytes.” ..."

Just 4 alcoholic drinks a week could contribute to cognitive decline

Associations between moderate alcohol consumption, brain iron, and cognition in UK Biobank participants: Observational and mendelian randomization analyses (open access)