Most Patients Who Report Smell Loss Are Over 50 Years Old. Why?
The answer to the question has not been seriously addressed. However, few patients in the pediatric, adolescent or adult age range have been recognized to complain of smell and taste loss except patients with congenital smell loss. Is this age relationship to older age meaningful in terms of sensory pathways?
Most patients evaluated at the Taste and Smell Clinic have an average age of about 55 years. While younger patients are evaluated at The Clinic the majority of patients are older aged. Is this a manifestation of the effects of age on these sensory systems in which younger people are “protected” from loss of smell by mechanisms that protect smell and taste function. Do these systems become more vulnerable to the various pathologies which injure taste and smell function with ageing?
Several investigators have measured smell function in older adults and reported that among elderly people reports of smell loss are more common than in young adults. In addition, there are few reports of spontaneous smell loss in children. Several investigators have also measured taste function in older adults and reported that as a group their sensory acuity is less than in younger adults. However, changes in smell function as people age can be such a subtle event overtime that people are not aware of a significant loss.
We have also measured smell function over a wide age range and measured specific changes in smell function. By test we have demonstrated that with age people can still detect and recognize tastants and odorants but the robust quality of the response has diminished. For example, older people can still taste and smell coffee but if they added one teaspoon of sugar to it early on as they get older they may add two teaspoons to get this same flavor as when they were younger. These results suggest that smell and taste receptor number decrease with age consistent with a decrease in growth factors that stimulate receptor stem cells to grow and mature.
For details see: Henkin, R.I. Taste loss in aging, in The Biomedical Role of Trace Elements in Aging, (Hsu, J.M., Davis, R.L., Neithamer, R.W., Eds.), Eckerd College Gerontology Center, St. Petersburg, FL, 1976, pp.221-236.