Scientists have uncovered a surprising reason why people with Alzheimer’s disease often struggle to sleep, and the discovery could eventually lead to new treatments.
Instead of blaming sticky protein plaques alone, researchers found that the brain’s own immune cells may be responsible for keeping the brain awake. The study was published in Alzheimer’s & Dementia.
Alzheimer’s disease is the most common cause of dementia. It slowly damages memory, thinking, and the ability to carry out daily activities.
Years before memory problems become obvious, many people begin experiencing poor sleep, but scientists have never fully understood why this happens.
For many years, researchers believed that amyloid plaques directly disrupted brain cells and caused sleep problems. Amyloid plaques are clumps of abnormal protein that build up between nerve cells.
The new study suggests the plaques may instead trigger an overactive immune response that becomes the real cause of sleep loss.
The research was led by Dr. Shannon Macauley and colleagues at the University of Kentucky. They focused on microglia, special immune cells that normally protect the brain by removing damaged cells and harmful material. Under healthy conditions these cells are essential, but in Alzheimer’s disease they can become overactive.
The researchers compared healthy mice with mice that developed amyloid plaques similar to those seen in Alzheimer’s disease. Tiny sensors measured brain waves and muscle activity so the scientists could accurately identify deep sleep, dreaming sleep, and wakefulness. Advanced imaging techniques then showed exactly where plaques and immune cells were located inside the brain.
The team found that sleep problems appeared early, when plaques first formed, and did not become much worse even after plaque levels more than doubled. This suggested that the first wave of immune activity was causing most of the damage. The researchers described this as a ceiling effect, meaning the problem reached its maximum early in the disease.
To test their idea, the scientists temporarily removed most of the mice’s microglia using a drug called pexidartinib. The results were remarkable. The mice gained more than two extra hours of sleep each day, even though the amyloid plaques remained in their brains.
The restored sleep mainly involved non-rapid eye movement sleep, also called NREM sleep. This stage is important because it helps the brain repair itself, store memories, and remove waste that builds up during the day. Losing this deep sleep may create a harmful cycle that speeds Alzheimer’s disease.
The discovery suggests that calming harmful inflammation could become a new treatment strategy. Rather than trying only to remove amyloid plaques, future therapies might also focus on controlling the brain’s immune response. The researchers are already studying whether existing medicines such as metformin or stiripentol could safely reduce excessive microglial activity.
Study analysis: This research provides strong evidence in animal models that overactive immune cells play a major role in Alzheimer’s-related sleep loss.
However, the findings come from mice, so human studies are still needed before new treatments become available. Even so, the work changes how scientists think about Alzheimer’s disease and may open a promising new path for improving sleep and possibly slowing cognitive decline.
If you care about Alzheimer’s disease, please read studies about the protective power of dietary antioxidants against Alzheimer’s, and eating habits linked to higher Alzheimer’s risk.
For more health information, please see recent studies that oral cannabis extract may help reduce Alzheimer’s symptoms, and Vitamin E may help prevent Parkinson’s disease.
Source: University of Kentucky.
