One determinant of brain health is iron levels, where higher iron levels in the brain had been linked to disease of the brain associated with cognitive morbidity in aging such as Alzheimer’s diseases and Parkinson’s disease. A large study published in PLOS Medicine showed that even moderate drinking helps this process along.

The study lead by researchers from University of Oxford reviewed self-reported alcohol consumption of 20,965 particpants from the UK Biobank. Additional information from participants also included brain MRIs, liver MRIs, and cognitive and motor assessments.

The average self-reported alcohol intake was approximately 18 units per week, which is approximately 7.5 cans of beer per week or 6 large glasses of wine per week.

Their analysis indicated that 7 units of alcohol per week was associated with elevated iron in the basal ganglia, a part of brain that plays multiple critical roles such as in movement, procedural learning, cognition, and emotion to name a few. This elevated iron accumulation was associated with worse than normal cognitive function.

The study is limited to MRI of the brain assessing iron levels and self-reported alcohol intake, which is normally likely underreported. Therefore, between no looking at other effects of the brain and likely underreportedness of alcohol intake, it is most likely the results are on the conservative side and that even the most moderate alcohol intake can lead to larger damages to the brain than can be estimated.

A Topiwala et al. Associations between moderate alcohol consumption, brain iron, and cognition in UK Biobank participants: Observational and mendelian randomization analyses. PLOS Medicine. DOI:10.1371/journal.pmed.1004039