One of the most painful experiences for families of people living with Alzheimer’s is the moment when a loved one no longer recognises them. A new study from the University of Virginia School of Medicine offers a compelling explanation for why this happens and hints at a way to stop it. The research reveals that social memory loss—specifically the ability to remember faces and relationships—may be caused by the deterioration of a protective structure inside the brain, rather than by general memory decline alone.
The study is led by Harald Sontheimer, PhD, along with graduate student Lata Chaunsali. Together, they focused on specialised protective sheaths surrounding neurons known as perineuronal nets. These delicate, mesh-like structures support communication between brain cells and help retain long-term memories. In healthy brains, the nets act as a scaffolding, protecting neural activity essential for recognising the people who matter to us. The UVA team discovered that when these nets break down, the brain becomes unable to store or retrieve social memories. Crucially, this effect is distinct from the ability to recognise objects or remember other kinds of information.
To test their theory, the researchers studied mice whose perineuronal nets were damaged. Those mice could still remember objects but failed to recognise other mice they had interacted with before. This division between object memory and social memory mirrors what clinicians often observe in Alzheimer’s patients: they may recognise belongings and familiar places, yet still forget their spouses, children, or caregivers. The study suggests that it is not all memory that fails at once, but specifically the brain’s system for protecting memories of people.
Even more promising was the team’s attempt to protect these nets. They used a class of drugs called MMP inhibitors, compounds already under study for potential use against cancer and arthritis. When mice were treated early with these inhibitors, the perineuronal nets remained intact, and the mice retained their social memories. This did not reverse damage once it had occurred, but it prevented the loss of recognition in the first place. Such a result points toward preventative treatment strategies that could one day safeguard memory before deterioration begins.
Sontheimer emphasised that identifying a structural change tied to a specific form of memory loss marks a crucial turning point. Chaunsali echoed this, noting that protecting these nets could offer a non-traditional way to prevent Alzheimer’s. What makes their findings particularly significant is that the deterioration they observed appears to be independent of amyloid plaques—the protein deposits long thought to drive the disease. If social memory loss can occur without amyloid involvement, then current theories about Alzheimer’s may need to be re-evaluated.
More research will be needed before these drug candidates can be used safely on people, but the implications are substantial. With Alzheimer’s affecting 55 million people worldwide and numbers rapidly rising, a treatment that protects identity-defining memories could change the course of the disease. Rather than simply slowing decline, future therapies may help preserve the relationships that give life meaning.
More information: Lata Chaunsali et al, Degradation of perineuronal nets in hippocampal CA2 explains the loss of social cognition memory in Alzheimer’s disease, Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association. DOI: 10.1002/alz.70813
Journal information: Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association Provided by University of Virginia Health System
