Scientists have discovered an unexpected reason why Alzheimer's disease disrupts sleep, and their findings suggest that the problem may be reversible. In experiments involving mice with Alzheimer's-like brain changes, researchers restored more than two hours of sleep per day without removing the amyloid plaques associated with the disease. The surprising discovery points to an overlooked culprit: the brain's own immune cells.
Rather than simply protecting the brain from damage, these cells can trigger inflammation that interferes with healthy sleep. Researchers at the University of Kentucky found that temporarily eliminating most of these immune cells allowed the mice to sleep longer and spend more time in the deep, restorative stages of sleep. The results suggest a potential new approach to treating one of the most disruptive symptoms of Alzheimer's disease.
The findings, published in the journal Alzheimer's & Dementia, were reported by a team led by Shannon L. Macauley, Ph.D., an associate professor of physiology at the University of Kentucky College of Medicine, and first author Nicholas J. Constantino, Ph.D., a recent doctoral graduate.
Macauley described the discovery as "paradigm-shifting" because it challenges the prevailing understanding of why people with Alzheimer's often experience severe sleep problems. How the Brain's Immune System Can Disrupt Sleep To understand what the researchers uncovered, imagine a small fire breaking out in a kitchen. Instead of containing the flames, the building's sprinkler system activates everywhere, flooding the entire house and causing widespread damage.
Something similar may happen in the brain during Alzheimer's disease. Amyloid plaques are deposits of sticky protein fragments that accumulate between nerve cells. They are one of the characteristic features of Alzheimer's and have long been investigated for their role in the disease.
The brain also contains specialized immune cells known as microglia. These cells normally protect the nervous system by removing debris, responding to injuries, and helping maintain a healthy environment for neurons. However, when microglia detect amyloid plaques, their defensive response can become excessive.
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