Study Results Show Moderate Drinking May Cause Cognitive Decline

Consumption of 7 or more units of alcohol per week has been associated with higher iron levels in the brain, which has been linked with Alzheimer and Parkinson diseases and is also a potential mechanism for alcohol-related cognitive decline, according to the results of a study posted in PLOS Medicine.¹

Growing evidence has shown that moderate alcohol consumption can adversely affect the brain, so the investigators explored the relationship between alcohol consumption and iron levels in the brain.¹

They included 20,965 individuals from the United Kingdom Biobank, who reported their own alcohol consumption, and had their brains scanned using magnetic resonance imaging (MRI). Approximately 7000 individuals also had their livers imaged using MRI to assess levels of systemic iron.¹

All participants underwent a series of tests to assess cognitive and motor functions. They had a mean age of 55 years, and approximately 48.6% were female.¹

Although 2.7% classified themselves as non-drinkers, the average intake of alcohol was about 18 units per week, which equates to about 7.5 cans of beer or 6 large glasses of wine.¹

The investigators found that above 7 units of alcohol per week was associated with markers of higher iron in the basal ganglia, which is a group of brain regions associated with control of cognition, emotion, eye movement, motor movements, and procedural learning.¹

Additionally, the iron accumulation in some brain regions was associated with worse cognitive function.¹

“In the largest study to date, we found drinking greater than 7 units of alcohol weekly associated with iron accumulation in the brain. Higher brain iron in turn linked to poorer cognitive performance,” Anya Topiwala of the University of Oxford, said in a statement.¹

“Iron accumulation could underlie alcohol-related cognitive decline,” she said.¹

This is the largest study of moderate alcohol consumption and iron accumulation to date, according to the statement.¹

Limitations of the study could be that drinking was self-reported and could be underestimated. However, this was considered the only feasible method to establish such a large cohort’s alcohol intake.¹

Additionally, another limitation could include that MRI-derived measures are indirect representations of brain iron and could conflate other brain changes observed with alcohol consumption with changes in iron levels.¹

Two in 3 individuals who drink report drinking above moderate levels at least once a month, according to the CDC.

The agency also said that most adults in the United States who drink do not drink every day, which makes the amount consumed per day more important to monitor than the number of days they drink.²

although past studies have indicated that moderate alcohol consumption could have health benefits, such as reducing the risk of heart disease, it is unclear whether this is because of alcohol consumption or whether it is related to a difference in behavior or genetics, according to the CDC.²

Reference

1. Moderate drinking linked to brain changes and cognitive decline. EurekAlert. News release. July 14, 2022. Accessed July 15, 2022. https://www.eurekalert.org/news-releases/957671

2. Dietary guidelines for alcohol. CDC. Updated April 19, 2022. Accessed July 15, 2022. https://www.cdc.gov/alcohol/fact-sheets/moderate-drinking.htm#:~:text=Two%20in%20three%20adult%20drinkers,at%20least%20once%20a%20month.