Your sense of smell is directed by a cranial nerve (that is, a nerve which runs from the brain to an extension of the brain called the olfactory bulb) called the Olfactory Nerve (Cranial Nerve I). read more
It's common for a person to lose the sense of smell due to the normal aging process. Brain injuries may cause anosmia, as can disorders that affect the nervous system, including Parkinson's disease, multiple sclerosis, Alzheimer's disease or Bell's palsy. Radiation treatment to the head and neck may also cause anosmia. read more
Loss of sense of smell was a stronger predictor of death than even a diagnosis of cancer, heart failure, or lung disease. 6 Loss of olfactory function is probably not a cause of death, but rather may "serve as a bellwether for slowed cellular regeneration or as a marker of cumulative toxic environmental exposure," the researchers said. read more