Drinking seven units of alcohol per week may cause cognitive decline

cognitive decline
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Emerging research from the University of Oxford suggests that consuming more than seven units of alcohol per week could increase your risk of experiencing cognitive decline and conditions such as Alzheimer’s disease.

The University of Oxford study, which analysed more than 20,000 people involved in the UK Biobank study, discovered that consuming in excess of seven units of alcohol is linked to higher levels of iron in the brain.

Accumulation of iron in the brain has long been associated with neurodegenerative diseases, including Alzheimer’s and Parkinson’s, with the new findings highlighting that it may be a potential mechanism for alcohol-related cognitive decline.

Anya Topiwala of the University of Oxford said: “In the largest study to date, we found drinking greater than seven units of alcohol weekly associated with iron accumulation in the brain. Higher brain iron, in turn, is linked to poorer cognitive performance. Iron accumulation could underlie alcohol-related cognitive decline.”

The study is published in the open-access journal PLOS Medicine.

Adverse effects of alcohol

Previous research demonstrates that alcohol use can lead to various health implications, with estimates that around 24% of adults in England and Scotland regularly drink alcohol. Moreover, a 2018 survey found that 5% of men drank over 50 units, and 3% of women drank over 35 units. Those living in the least deprived areas were more likely to consume more than 14 units a week than those in the most deprived.

Consuming alcohol has been linked to more than 60 conditions, including high blood pressure, liver cirrhosis, mouth, stomach, throat, liver and breast cancers, and depression. There is now increasing evidence that alcohol can adversely impact brain health.

Alcohol consumption and cognitive decline

The team examined 20,965 participants from the UK Biobank to investigate the relationship between alcohol consumption, brain iron levels, and cognitive decline. The individuals reported their alcohol consumption, and their brains were scanned using magnetic resonance imaging (MRI).

Around 7,000 had their livers imaged using MRI to monitor systemic iron levels, with everyone completing a series of tests to measure cognitive and motor function. The mean age of the participants was 55 years, and 48.6% were female. 2.7% identified as non-drinkers, with the average intake of the cohort being around 18 units per week – roughly seven and a half cans of beer or six large glasses of wine.

The results demonstrated that consuming more than seven units of alcohol per week was associated with markers of higher iron in the basal ganglia, brain regions crucial for controlling motor movements, procedural learning, eye movement, cognition, emotion and more. The team discovered that iron accumulation in specific brain areas was linked to worse cognitive decline.

Study limitations

The team noted that a limitation of their study was that MRI-derived measures are indirect representations of brain iron, meaning they could conflate brain changes seen due to alcohol consumption with changes in iron levels.

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