Moderate drinking linked to brain changes and cognitive decline

Consumption of seven or more units of alcohol per week is associated with higher iron levels in the brain, according to a study of almost 21,000 people publishing July 14th in the open access journal PLOS Medicine. Iron accumulation in the brain has been linked with Alzheimer's and Parkinson's diseases and is a potential mechanism for alcohol-related cognitive decline.

A total of 20,965 participants from the UK Biobank reported their own alcohol consumption, and their brains were scanned using magnetic resonance imaging (MRI). Almost 7,000 also had their livers imaged using MRI to assess levels of systemic iron. All individuals completed a series of simple tests to assess cognitive and motor function.

Although 2.7% classed themselves as non-drinkers, average intake was around 18 units per week, which translates to about 7½ cans of beer or 6 large glasses of wine. The team found that alcohol consumption above seven units per week was associated with markers of higher iron in the basal ganglia, a group of brain regions associated with control of motor movements, procedural learning, eye movement, cognition, emotion and more. Iron accumulation in some brain regions was associated with worse cognitive function.