Brain Health

Loss of Smell May Signal Alzheimer's Years Before Memory Problems Begin

Scientists have discovered why losing your sense of smell may be one of the earliest warning signs of Alzheimer's disease, appearing years before memory problems. Researchers found that the brain's immune cells called microglia mistakenly attack nerve fibers connecting smell-processing regions when they detect abnormal signals on neuron surfaces. This happens when phosphatidylserine, normally inside nerve cell membranes, flips to the outside, creating an 'eat-me' signal for immune cells. The study used evidence from mice, human brain tissue, and PET scans to confirm these findings. This discovery could lead to earlier Alzheimer's detection through simple smell tests.