Alzheimer’s disease erodes memory progressively, starting with short-term recall and eventually leading to the heartbreaking loss of recognition – even of family and friends. Recent research suggests that a structural change in the brain, specifically the deterioration of specialized support structures around neurons, may be a key driver of this devastating symptom.
The Role of Perineuronal Nets
Healthy brains contain structures called perineuronal nets (PNNs). These mesh-like formations stabilize connections between neurons, protect against cellular stress, and regulate how memories are formed and retained. Essentially, PNNs help neurons communicate effectively, enabling the brain to record and store experiences.
The Study: Mice and Social Memory
Scientists at the University of Virginia and Virginia Tech investigated the link between PNN deterioration and memory loss in mice. They discovered that when PNNs broke down in the CA2 region of the hippocampus (a brain area crucial for social memory), mice lost the ability to remember other mice, despite retaining object-based memory. This pattern mirrors what happens in Alzheimer’s patients, where social memory often fades before other cognitive functions.
How Deterioration Occurs
The breakdown of PNNs is linked to enzymes called matrix metalloproteinases (MMPs). These enzymes dissolve proteins within the extracellular matrix, including those that form PNNs. In Alzheimer’s, MMP activity increases, leading to PNN degradation and subsequent memory loss.
Blocking Enzymes Restores Memory
Researchers tested whether inhibiting MMPs could prevent memory loss. They used MMP inhibitors, compounds also studied as potential cancer drugs, to block enzyme activity. Mice treated with inhibitors showed less PNN degradation and retained more social memory function, even with Alzheimer’s-like symptoms.
Implications for Humans
While this study was conducted on mice, the findings have significant implications for humans. Alzheimer’s affects an estimated 55 million people worldwide, with numbers expected to rise sharply as populations age. If PNN degradation is confirmed as a critical factor in human Alzheimer’s, it could open new avenues for treatment and prevention.
Next Steps
Researchers caution that more studies are needed to confirm these results and assess the safety and effectiveness of MMP inhibitors in humans. However, the findings represent a promising step toward understanding and combating this devastating disease.
The research suggests that preserving brain structures responsible for memory retention may be a viable approach to delaying or even preventing Alzheimer’s-related memory loss.
