The impact of alcohol on the brain could be more serious than previously thought

Alcohol abuse could damage the brain through microglia, a type of immune cell residing in the central nervous system, according to a recent study led by researchers at the Cleveland Clinic.

The research, published in the journal Immunity, examined how microglia react to alcohol. While these cells typically monitor the brain and clear away waste, the scientists observed that, in this context, they can also contribute to the deterioration of nervous tissue.

 To test this, they administered oral doses of ethanol to mice, either as single doses or repeatedly over several days, and monitored the effects on microglia and neurons using microscopy and other imaging techniques. They found that, in the presence of alcohol, these cells began to break down the extracellular matrix—the network that surrounds and supports neurons, enabling them to communicate effectively.

The researchers observed distinct changes in the microglia as little as one hour after intense alcohol exposure. The cells’ branches retracted, and they began to strip away this protective matrix—even before the onset of sedation. Consequently, neuronal activity declined, which was linked to drowsiness, a loss of coordination, and alterations in consciousness.

According to the study, a single episode of excessive consumption is enough to damage this structure and eliminate connections between neurons. When such consumption is repeated, the damage progresses, leading to neuronal loss in the frontal cortex, a region essential for judgment and impulse control. Furthermore, samples from human brains affected by alcohol use disorder showed the same alteration in the extracellular matrix; according to the researchers, this provides the first direct evidence of this mechanism in humans.

The team also identified a protein, called MyD88, that regulates the microglia response. Deleting the gene associated with this protein before exposing the animals to alcohol blocked much of the harmful reaction, protected the brain, and reduced both sedation and behavioral disturbances—even when blood alcohol levels were high. 

The authors believe these findings could pave the way for new strategies to prevent brain damage linked to alcohol consumption, as well as other neurological conditions.

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