Alzheimer’s May Not Start in the Brain: New Discovery Offers Hope

New research published in December 2025 suggests a fundamental shift in the approach to Alzheimer’s disease, moving from managing a permanent decline toward the possibility of early prevention and the reversal of existing damage.

Two distinct scientific developments have emerged from mouse models and human brain tissue analysis, targeting the disease at different stages: one focusing on stopping the disease before symptoms begin, and another aiming to restore cognitive function in advanced cases.

Targeting Toxic Proteins Before Memory Loss

Scientists at Northwestern University have identified a previously unknown, highly toxic sub-species of amyloid beta oligomers, which are clusters of peptides that drive early changes in the brain. This specific subtype has been identified as ACU193+.

According to research released on December 22, 2025, these toxic proteins appear to trigger the disease years before memory loss occurs. They are among the first markers to appear in stressed neurons, where they attach themselves to astrocytes, which are the brain’s support cells.

To combat this, researchers developed an experimental small-molecule compound called NU-9. In mouse models of Alzheimer’s disease, NU-9 decreased the presence of the ACU193+ subtype and reduced the resulting damage to the brain.

The treatment specifically targets the onset of the disease to prevent the cascade of toxic events that eventually destroy neurons. By deploying NU-9, researchers found that astrocytes remained in a calmer, healthier state, reducing the neuroinflammation linked to the early stages of the disease.

These results are stunning. NU-9 had an outstanding effect on reactive astrogliosis, which is the essence of neuroinflammation and linked to the early stage of [Alzheimer’s] disease.

William Klein, neurobiologist

Reversing Damage Through Energy Balance

While the NU-9 research focuses on early intervention, separate research from University Hospitals Cleveland Medical Center and Case Western Reserve University explores the possibility of reversing the disease in advanced stages.

Research released on December 24, 2025, indicates that Alzheimer’s is driven in part by a collapse in the brain’s energy balance. Specifically, the brain’s inability to maintain healthy levels of a vital cellular energy molecule known as NAD+ plays a major role in the progression of the disease.

By studying human Alzheimer’s brain tissue alongside multiple mouse models, researchers found that restoring and maintaining normal brain NAD+ levels could potentially reverse the disease’s effects.

In animal models, this approach resulted in several key outcomes:

• The repair of brain pathology.
• The restoration of cognitive function and memory, even in mice with advanced Alzheimer’s.
• The normalization of Alzheimer’s biomarkers.

For over a century, medical consensus viewed Alzheimer’s as a one-way decline that was permanent and untreatable once it began. These findings challenge that assumption, suggesting that the damage may not be irreversible if the brain’s energy supply is restored.

Current Status and Future Directions

Both the NU-9 and NAD+ studies were conducted using preclinical mouse models and the analysis of human tissue. While these results provide a new framework for treatment, they remain in the experimental phase.

The research into NU-9 emphasizes the importance of catching Alzheimer’s in its earliest stages, long before symptoms appear, to stall its development. Simultaneously, the NAD+ research suggests that recovery may be possible even after significant damage has occurred.

Together, these developments indicate a shift in Alzheimer’s research toward identifying hidden toxic triggers and correcting biological failures in brain energy to prevent or reverse neurological decline.