UF Study Reveals Loss In Sensory Perception

September 11, 1997

GAINESVILLE–A University of Florida researcher says you can pick out a lemon at any age — at least if you smell it.

After six years of volunteers smelling lemons and some 40 other scents including natural gas and bubble gum, Dr. Marc Heft has determined that aging has little effect on smell, taste or touch.

“There is a belief that as you age, everything deteriorates. The truth is there is only a modest change in sensory functioning,” said Heft, director of the Claude Pepper Center for Research on Oral Health in Aging at UF’s College of Dentistry. “There are a number of older folks that can smell and taste just as well as many of the young.”

Ruling out various factors, including disease and whether the participants were smokers, the researchers found less than 10 percent of the differences in sensory perceptions are age-related.

Heft said the findings mean good news for older people, who are experiencing a higher quality of life and are living longer.

“In Florida alone there are more than a million people over the age of 75, and they are a fairly healthy, vivacious population,” Heft said. “What’s emerging is a more upbeat vision of aging.”

UF researchers recruited 180 healthy volunteers between the ages of 20 and 88 for the study. The researchers’ goal was to look at normal changes in the senses of taste, touch and smell as a person ages. They also tested the volunteers’ abilities to feel pain and tell differences in temperature.

The volunteers participated in five one-hour sessions to identify which stimuli they could perceive, their threshold level (the lowest amount of a stimulus a person could perceive and identify) and how well they perceived differences in sensations above their threshold level.

Using a probe about the size and shape of a pencil, the researchers asked the volunteers to identify various temperatures and pressures. The tests involved stimulating the area above the upper lip and the chin with the probe.

“The face is a wonderful model to look at sensory perceptions because day to day we sample our environment through our nose, eyes and mouth,” Heft said.

The researchers used a test known as the Pennsylvania Smell Identification Test, in which participants scratched and sniffed cards with different scents on them ranging from licorice to paint thinner.

The researchers noted that women are better smellers than men.

“The women were able to identify the different scents better, but we don’t know why that it is yet,” Heft said. “There were no differences between gender regarding the other senses.”

Heft said the body uses the senses in various ways, including protecting it from harm, and that may be why senses are stable throughout life.

“The take-home message is, there are going to be a number of immutable factors that to some degree will play a part in your sensory perception. Disease and your inherited genetic makeup are two factors,” he said.

“However, there are factors you can control to a degree, such as for your motor system, by the amount of exercise you get. Cognitive aging is affected by how you develop your mind through activities such as reading,” Heft said. “A big factor also is the amount of sun exposure you receive, which affects the skin’s aging and indirectly affects the skin’s senses.”

The UF research is funded by the National Institute of Dental Research.