Damaged brains may be able to recover as scientists successfully complete treatment on mice.

American researchers say they have fully reversed Alzheimer’s disease in laboratory mice, a result that challenges the long-held belief that the illness is irreversible once it takes hold.

In a study published in Cell Reports Medicine, scientists from Case Western Reserve University, University Hospitals, and the Louis Stokes Cleveland VA Medical Center reported that mice with advanced Alzheimer’s regained normal brain function after treatment with an experimental compound called P7C3-A20. 

“For more than a century, people have considered Alzheimer’s disease an irreversible illness,” the researchers noted in a statement. As a result, most efforts have focused on slowing decline rather than restoring lost brain function. 

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The team tested the drug on two different mouse models of Alzheimer’s: one driven by amyloid protein mutations and another by tau protein mutations.

Both models develop severe brain damage and cognitive impairment similar to that seen in people with the disease.

The treatment works by restoring levels of NAD+, a molecule essential for cellular energy and survival. NAD+ naturally declines with age, but the drop is far more severe in the brains of people with Alzheimer’s. Without it, brain cells struggle to function and inflammation increases.

When the researchers gave P7C3-A20 to young mice, it prevented the disease from developing. More strikingly, when they treated mice that already had advanced Alzheimer’s, the animals showed both pathological and functional recovery. Their cognitive abilities returned, and key biological markers of the disease normalized.

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The findings suggest recovery might one day be possible in people. The key takeaway is a message of hope—the effects of Alzheimer's disease may not be inevitably permanent. The damaged brain can, under some conditions, repair itself and regain function.

The study also confirmed disease reversal using a blood biomarker already approved for Alzheimer’s patients, strengthening its relevance for future clinical trials.

Researchers caution that the results are limited to animal models, and human trials are still needed.

If successful, the work could mark a major shift in how Alzheimer’s is treated — away from slowing decline and toward restoring lost brain function.

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