Moderate drinking linked to iron buildup in the brain

(ORDO NEWS) — Scientists conducted the largest multi-organ study to date of iron homeostasis associated with moderate alcohol consumption.

Scientists from the Universities of Oxford and Cambridge, Queen Mary University of London (UK) and Yale University (USA) were looking for evidence of a causal relationship between alcohol consumption and iron levels in the brain, as well as the resulting decline in cognitive abilities.

Previously, it was thought that moderate alcohol consumption could have almost no effect on health. Recently, however, more and more scientific works have appeared that refute this point of view.

It is especially important to understand how alcohol affects, for example, the deposition of iron in the brain, because it is known that its elevated levels, among other things, lead to neurodegeneration such as Alzheimer’s and Parkinson’s diseases.

But until now, researchers did not know whether iron accumulates in the brain due to moderate alcohol consumption, what are the mechanisms of this process and the clinical consequences of minor deviations.

The authors of the work analyzed data on 20,965 volunteers 40-69 years old (mean age 55 years, 48.6% women), data on which were collected from 2006 to 2010 and stored in the British Biobank. At the time of observation, none of the participants had dementia or other similar ailments.

They completed questionnaires about alcohol use, underwent MRIs of the brain and liver, and a series of tests to assess cognitive and motor function. Brain iron content was determined using quantitative magnetic susceptibility mapping, T2* gradient echo, and magnetic susceptibility-weighted sequences.

Although almost three percent of the participants identified as non-drinkers, on average volunteers consumed about 18 units of alcohol per week, which is equal to ten milliliters (eight grams) of ethanol, or about seven and a half cans of beer and six glasses of wine.

This is more than recommended by British experts – up to 14 units, although in the case of men, 21 units per week are allowed. Those who described themselves as never drinkers were mostly women with lower blood pressure, but diabetes was more common among them.

As an analysis of all the data showed, moderate alcohol consumption – above seven units in seven days – correlated with lower iron content in the thalamus, but higher – in the basal ganglia, that is, clusters of neurons in the basal regions of the forebrain and midbrain involved in the regulation of movement, cognition, emotions and so on.

Iron deposits in the brain went hand in hand with cognitive deterioration: in particular, a slow reaction rate and a decline in executive functions, the set of mental abilities necessary to control and self-regulate behavior.

“Consumption of more than 11 units of alcohol per week was associated with higher levels of iron in the liver, as measured by MRI. In women, this was observed when taking more than 17 units per week, ”the researchers added.

There was some evidence for a causal relationship between genetically predicted alcohol consumption and basal ganglia and hippocampus susceptibility, they said, but they were not corrected for by multiple tests.

Despite some deterioration, there were no clear clinical manifestations of neurodegeneration in the study participants, probably because the level of iron in the brain serves as an early marker of disease.

“In our work, higher systemic iron levels explained only 32% of the overall effect of alcohol on brain iron levels, suggesting other mechanisms may be involved.

Probably, among them is an increase in the permeability of the blood-brain barrier for iron, which, in turn, is mediated by a decrease in the level of thiamine . (this occurs in alcohol use disorders due to a combination of malnutrition, reduced absorption and metabolic changes).

In patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), iron leakage has been associated with blood-brain barrier permeability. Other possible mechanisms include dopamine release after alcohol ingestion or chronic inflammation.

The alternative is that people with higher iron content in the brain drink more alcohol, ”the scientists explained.

If it can be confirmed that alcohol consumption leads to cognitive decline through elevated levels of iron in the brain, existing treatments can be applied – for example, chelation therapy for patients with post-transfusion iron overload, the authors concluded.

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