Recently, a team of researchers led by Prof. Cheil Moon (Daegu Gyeongbuk Institute of Science and Technology, Korea) published an article in Alzheimer's Research and Therapy, identifying a potential mechanism that may explain why many people with Alzheimer's disease experience abnormal olfaction.
Olfactory dysfunction, or difficulty with smelling, is thought to affect almost 90% of people with Alzheimer's disease (AD), with individuals reporting either loss of smell (anosmia) and/or difficulty identifying particular smells. Smell processing involves several areas of the central nervous system, with olfactory sensory neurons (OSNs) playing a particularly prominent role in propagating 'smell' signals to the olfactory bulb in the brain.
In their article, Prof. Cheil Moon and colleagues report on the results of studies performed in the 5xFAD mouse model of AD, revealing that the OSNs of these mice show reduced responses to odorants. In particular, they observed reduced activation in the glomerulus of the olfactory bulb, a specialised region of the brain that deals with smell. Looking more closely at the distribution of amyloid-beta proteins, a key driver of AD, the researchers saw that the regions with higher levels of amyloid-beta coincided with the regions that showed reduced activation after exposure to smells. Together, these results suggest that olfactory dysfunction in AD may be linked to amyloid-beta accumulation in regions of the brain that are responsible for detecting and identifying smells.
https://alzres.biomedcentral.com/articles/10.1186/s13195-020-00730-2
