Consumption of lower-risk amounts of alcohol has been associated with a decreased risk of dementia, although a mechanism for this effect beyond the presumed effects on cardiovascular disease is unclear. Investigators randomly selected 527 adults from the population-based Whitehall II study of cardiovascular health to investigate the association between weekly alcohol consumption (determined 6 times over 30 years), grey matter density and white matter integrity (magnetic resonance imaging after 30 years), and cognitive dysfunction (a variety of tests 6 times over 30 years).
- Compared with no drinking in analyses adjusted for potential confounders, alcohol consumption—starting at any use—was associated with hippocampal atrophy in a dose-dependent fashion:
- non-significant increases at 0.6–<4 (14g) drinks/week (odds ratio [OR], 1.5) and 4–<8 drinks/week (OR, 2.0).
- significant increases at the other levels of drinking: 8–<12 drinks/week (OR, 3.4), 12–<17 drinks/week (OR, 3.6), and ≥17 drinks/week (OR, 5.8).
- Greater consumption was associated with smaller hippocampal volume, less anterior corpus callosum white matter integrity, and lower lexical fluency. The latter decreased by 14% over 30 years among those drinking 4–8 drinks/week and there were no benefits of lower amounts compared with abstinence.
Comments: Recent studies with improved methods have suggested that the benefits of lower-risk amounts of alcohol seen in many observational studies for cardiovascular disease and total mortality do not exist. This study now calls into question benefits from alcohol on dementia. Alcohol has long been known to be a neurotoxin. These findings—bolstered by a dose-response association and plausible mechanism—suggest that at just over 1 drink a day, there is hippocampal atrophy and cognitive dysfunction. As methodologically improved research emerges, it is folly to continue to trust prior observational studies suggesting that a carcinogenic neurotoxin has widespread health benefits. At the very least, this current study should raise concerns that “moderate” and heavier drinking might harm the brain.
Richard Saitz, MD, MPH
Reference: Topiwala A, Allan CL, Valkanova V, et al. Moderate alcohol consumption as risk factor for adverse brain outcomes and cognitive decline: longitudinal cohort study. BMJ. 2017;357:j2353.