Alcohol consumption and MRI markers of brain structure and function: Cohort study of 25,378 UK Biobank participants.
Level 3 - non-randomized controlled study
Prospective observational cohort study measuring baseline exposure against neuroimaging outcomes at follow-up.
PubMed 35653911 · doi:10.1016/j.nicl.2022.103066
What was done
Researchers analyzed data from 25,378 UK Biobank participants (mean age 54.9 ± 7.4 years, 12,254 female) who underwent multi-modal MRI (T1-weighted, diffusion-weighted, and resting-state functional MRI) an average of 9.6 ± 1.1 years after baseline. Alcohol intake was self-reported at baseline (2006–2010). The authors evaluated associations between alcohol consumption and structural and functional brain markers, as well as modifying effects of binge drinking, blood pressure, and BMI.
What was found
Lower total grey matter volumes were observed at alcohol intakes as low as 7–14 units (56–112 g) weekly. Higher alcohol intake was associated with widespread white matter microstructural differences, including lower fractional anisotropy and higher mean and radial diffusivity, as well as altered functional connectivity in the default mode, central executive, attention, salience, and visual networks. The relationship with total grey matter volume was stronger for alcohol than for blood pressure or smoking. Frequent binging, higher blood pressure, and higher BMI steepened the negative association with grey matter volume. Specific numerical effect sizes and confidence intervals were not reported in the abstract.
Why it matters
This study provides large-scale epidemiological evidence that even moderate alcohol consumption is associated with adverse structural and functional brain markers across mid- to late-life, challenging notions of a safe threshold for brain health.
Limits
The observational design cannot prove causality. Alcohol consumption relied on baseline self-reports subject to recall and reporting bias. Brain imaging occurred almost a decade after baseline without baseline scans to track longitudinal change within individuals. UK Biobank participants are unrepresentative of the broader population due to healthy volunteer bias.