Loss of Smell Warning May Signal Early Alzheimer’s Risk
A loss of smell warning may be one of the earliest signs of Alzheimer’s disease. It can appear even before memory problems become clear. However, many people often overlook this early change.
A new study published in Nature Communications supports this finding. Researchers explain that early brain changes can affect how the body processes sensory signals. As a result, smell function may decline long before cognitive symptoms begin. Therefore, this warning sign deserves more attention in early diagnosis efforts.
Early brain changes linked to smell
Scientists from the DZNE research institute and Ludwig-Maximilians-University Munich in Germany studied how Alzheimer’s may begin in the brain. They found that the brain’s immune system may play a key role. In addition, they observed unusual activity in immune cells called microglia.
These cells normally protect the brain. However, in early Alzheimer’s, they may behave differently. They may mistakenly attack nerve fibers that support smell processing.
How smell pathways are disrupted
The study shows that microglia interfere with communication between two important brain areas. These are the olfactory bulb and the locus ceruleus. The olfactory bulb processes smell signals from the nose. Meanwhile, the locus ceruleus helps regulate this system through nerve connections.
For example, when these pathways weaken, smell signals cannot travel properly. As a result, people may slowly lose their ability to detect scents. This change may happen quietly and without pain.
Evidence from human and animal studies
Researchers tested their findings using both mice and human brain samples. In addition, they used brain tissue analysis and PET scans. These tools helped them observe early structural changes in detail.
The results suggest that smell loss may reflect early Alzheimer’s activity in the brain. Therefore, scientists believe smell tests could support early detection in the future.
