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

Source:

Topiwala A, Wang C, Ebmeier KP, Burgess S, Bell S, et al. (2022) Associations between moderate alcohol consumption, brain iron, and cognition in UK Biobank participants: Observational and mendelian randomization analyses. PLOS Medicine 19(7): e1004039. https://doi.org/10.1371/journal.pmed.1004039

Author summary

Why was this study done

• There is growing evidence that even moderate alcohol consumption negatively impacts the brain, but the mechanisms underlying this are unclear.
• One possibility is that accumulation of iron in the brain could contribute, as higher brain iron has been described in numerous neurodegenerative conditions including Alzheimer’s and Parkinson’s disease.
• To the best of our knowledge, there have been no studies investigating if brain iron levels differ by level of alcohol consumption.

What did the researchers do and find

• In 20,965 participants in a United Kingdom cohort study, we explored relationships between self-reported alcohol consumption and brain iron levels, measured using magnetic resonance imaging.
• We assessed the association of alcohol intake with blood and liver iron and cognitive measures associated with higher brain iron.
• Alcohol consumption above 7 units (56 g) weekly was associated with markers of higher iron in the basal ganglia, which in turn associated with worse cognitive function.
• These observational findings were further supported by analyses using genetic variants as proxies for alcohol consumption.

What do these findings mean

• These findings suggest that moderate alcohol consumption is associated with higher iron levels in the brain.
• Brain iron accumulation represents a potential mechanism for alcohol-related cognitive decline.
• Key limitations are that changes in myelin may also alter imaging markers and alcohol intake was self-reported. It is unclear how our findings generalize to other populations, particularly those which are more ethnically diverse and socioeconomically deprived.