A new study has found that the loss of smell could be an early warning sign of Alzheimer’s disease, and the timing of diagnosis could help at-risk patients receive more effective treatment.
The research, conducted by DZNE and Ludwig-Maximilians-Universität München (LMU), found that Alzheimer’s can cause the brain’s immune cells, called microglia, to mistakenly target healthy nerve fibers in the brain that are crucial for smell. This means an Alzheimer’s patient will likely struggle to smell years before they are formally diagnosed with the disease.
The connection between scent and Alzheimer’s has been theorized for years, but the study’s findings are a promising sign that neurologists may start testing the sensitivity of smell in patients, Dr. Dale Bredesen, a neurologist at Apollo Health with a focus on Alzheimer’s disease, told HuffPost.
“The question has always been, ‘Why is [smell loss] such an early change in Alzheimer’s?’” Bredesen said. “I think this [study] will help to let neurologists know we should be more sensitively testing smell in people routinely before they ever have any cognitive complaints.”
One of the earliest sites degenerated in Alzheimer’s disease is called the locus coeruleus, which is a spot in the brain stem that provides the brain with norepinephrine, Bredesen explained. Norepinephrine helps regulate functions like smell, sleep and blood flow.
