Taste and Smell

Smell losses with age are most often linked to upper respiratory infections, and may represent accumulated damage over time. Head trauma can cause sudden loss of the ability to smell. This may occur in whiplash-like accidents that cause a tearing of olfactory filaments near the cribiform plate. More rarely, head trauma may damage nerves involved in taste perception.

Alzheimer’s disease is associated with a reduced sense of smell. This may result from a loss of nerve cells in the olfactory bulb that is sometimes observed prior to the onset of clinical dementia. Smell losses may therefore help in the early diagnosis of Alzheimer’s disease. Patients with Parkinson’s disease are also less able to perceive and identify odors.

Reduced odor perception through the back of the mouth has been observed in older subjects, even though odor perception through the nose is normal. This may be due to dentures that cover the roof of the mouth. Dentures may block the retronasal transport of odors from the mouth to the olfactory receptors, producing a decrease in the perceived flavor of food.