Scientists reverse Alzheimer's damage in mouse brains by restoring energy

Researchers at the Pieper Laboratory have identified a fundamental problem in Alzheimer's disease — and shown it can be fixed, at least in animal models. The brain, it turns out, runs on a molecule called NAD+, and in Alzheimer's patients, this crucial energy source depletes far more severely than it does in healthy aging.

The study, published in Cell Reports Medicine in December 2024, examined brain tissue from people with Alzheimer's alongside mice genetically engineered to develop the disease. What they found was striking: by restoring NAD+ balance using a compound called P7C3-A20, the researchers not only prevented Alzheimer's from developing in healthy mice — they reversed significant brain damage in mice that already had advanced disease.

The Energy Crisis in Alzheimer's

NAD+ naturally declines as we age, but in Alzheimer's brains, the drop is dramatic. Without enough NAD+, brain cells lose the ability to carry out basic maintenance tasks. Damage accumulates: the blood-brain barrier breaks down, nerve fibers deteriorate, inflammation spreads, and the formation of new neurons slows to a crawl. The mice in this study developed memory and thinking problems that closely mirrored human Alzheimer's.

But here's where the research pivots from problem to possibility. When the team restored NAD+ levels in mice with advanced disease, the cognitive recovery was complete. Blood tests showed normalized levels of phosphorylated tau 217 — a biomarker now used to diagnose Alzheimer's in people — suggesting that the disease process itself had been halted and reversed.

"The key takeaway is a message of hope," said Dr. Rajiv Pieper, who led the research. "The damaged brain can, under some conditions, repair itself and regain function."

This isn't the first hint that Alzheimer's might be reversible. The same laboratory showed in earlier research that restoring NAD+ balance could help brains recover from severe traumatic injury. But applying that finding to Alzheimer's — a disease that's been considered progressive and irreversible — represents a significant shift in how researchers think about the condition.

What Happens Next

The obvious question is whether this works in humans. The researchers are careful not to overstate: mice and people are different, and a drug that works in a controlled laboratory setting may behave entirely differently in the complexity of a living human brain. But the work is already moving toward the clinic. A Cleveland-based company called Glengary Brain Health, co-founded by Dr. Pieper, is commercializing the technology.

Dr. Kalyani Chaubey, who led the study, identified candidate proteins in human Alzheimer's brains that may relate to the ability to reverse the disease — clues that could guide the next phase of research. The laboratory is also exploring whether this approach works for other age-related neurodegenerative diseases beyond Alzheimer's.

Carefully designed human clinical trials will determine whether the mouse results translate to people. That's the essential next step — and the one that will either confirm this as a genuine breakthrough or reveal that animal models, once again, don't tell the whole story.