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Moderate alcohol consumption associated with adverse brain outcomes

Adults who consume alcohol in moderate quantities have an increased risk for cognitive decline and abnormal brain structure, according to findings published in the BMJ.

“Alcohol use is widespread and increasing across the developed world,” Anya Topiwala, PhD, from the department of psychiatry at the University of Oxford in England, and colleagues wrote. “It has historically been viewed as harmless in moderation, defined variably from 9 to 18 units (72 to 144 g) a week… While chronic dependent drinking is associated with Korsakoff syndrome and alcoholic dementia, the long-term effects of nondependent alcohol consumption on the brain are poorly understood. Robust evidence of adverse associations would have vital implications for public health.”

Topiwala and colleagues conducted an observational cohort study to investigate how moderate alcohol consumption affects brain structure and function. They assessed the weekly alcohol intake and cognitive performance of 527 adults (mean age at baseline, 43 years) from the Whitehall II cohort study over the course of 30 years (1985 to 2015) at approximately 5-year intervals. All participants scored less than 2 on the CAGE screening questionnaire, indicating that they were nonalcohol dependent. In addition, it was safe for all participants to undergo MRI of the brain at study endpoint which was performed between 2012 and 2015.

Results indicated that higher alcohol consumption increased the risk of hippocampal atrophy, with participants consuming more than 30 units a week being at the highest risk compared with abstainers (OR = 5.8; 95% CI, 1.8-18.6; P ≤ .001). Participants who drank moderately, defined as 14 to 21 units per week, also had an increased likelihood of right-sided hippocampal atrophy (OR = 3.4; 95% CI, 1.4-8.1; P = .007). Light drinking, defined as 1 to less than 7 units per week, did not provide any protective effect compared with abstinence. Differences in corpus callosum microstructure and faster decline in lexical fluency was observed in those with higher alcohol intake. The researchers found no association between alcohol consumption and cross sectional cognitive performance or longitudinal changes in semantic fluency or word recall.

“Our findings support the recent reduction in U.K. safe limits and call into question the current U.S. guidelines, which suggest that up to 24.5 units a week is safe for men, as we found increased odds of hippocampal atrophy at just 14 to 21 units a week, and we found no support for a protective effect of light consumption on brain structure,” Topiwala and colleagues concluded. “Alcohol might represent a modifiable risk factor for cognitive impairment, and primary prevention interventions targeted to later life could be too late.” – by Alaina Tedesco

Disclosure: The researchers report funding from the UK Medical Research Council, the Gordon Edward Small’s Charitable Trust and the HDH Wills 1965 charitable trust.