Your nose knows death is imminent | Mo Costandi | Science | theguardian.com
Loss of the sense of smell predicted death more accurately than did a diagnosis of cancer, heart failure or lung disease, the only other common cause of predicting it more accurately being severe liver damage. But the researchers stress that it is unlikely to be a cause of death itself, arguing only that it is a harbinger for what is to come, and suggesting two possible reasons why this might be so.
The tip of the olfactory nerve, which contains the smell receptors
, is the only part of the human nervous system that is continuously regenerated
by stem cells
. The production of new smell cells declines with age, and this is associated with a gradual reduction in our ability to detect and discriminate odours
. Loss of smell may indicate that the body is entering a state of disrepair, and is no longer capable of repairing itself.
The olfactory nerve is also the only part of the nervous system that is exposed to the open air. As such, it offers poisons and pathogens a quick route into the brain, and so losing smell could be an early warning of something that will ultimately cause death.