Smell Lasts Longer Than Vision and Hearing

The human being is considered fundamentally an audio-visual being.

During the monkey stage in their evolution, humans needed good vision for assessing distances while moving through trees and a good color vision to select the ripest fruits. In a forest, hearing is also important, as you cannot detect predators using vision inside a forest with limited visual field. But the olfactive sense was neglected and today human olfaction is considered a little more than vestigial.

But new research suggests that while eyesight and hearing deteriorate constantly with the normal aging process, the sense of smell may actually persist till advanced ages in healthy individuals.

The researchers at Griffith University's School of Nursing and Midwifery and the Eskitis Institute of Cell and Molecular Biology, Australia, tested about 1000 subjects, males and females of all ages, for their olfactive ability (by detecting or identifying a spectrum of different odors at different concentrations).

They discovered that the olfactory function impairs at low pace with age in non smokers, those without severe medical problems or have a history of nasal problems like sinusitis. But olfactory sensibility decreases sharply in older people taking medications that show chronic or severe health issues. "However our sense of smell is vulnerable to both the direct effects of some medications and changes associated with a number of neurodegenerative illnesses. Exposure to these factors typically increases with age", said researcher Dr Amy Johnston.

The drugs used as anticholesterol and to lower the blood pressure proved the most harmful for the smell power. "Conditions such as Parkinson's disease and Alzheimer's disease were also associated with impairment in the sense of smell," she said.

Smell degradation could further deteriorate the health. "People who lose their sense of smell, particularly the elderly, are at risk of poor appetite and subsequent poor nutrition. Smell is also an important warning sense -- telling people when food is not fit for consumption."

Women appeared to possess a sharper olfaction than men, but the sex bias was canceled by smoking, drugs or nasal problems history.