Clinical studies of olfaction.

Disorders of the senses of taste and smell are not uncommon, occurring in over three million adults in the United States alone. Olfactory dysfunction occurs in about half of the population between the ages of 65 and 80 years and in about three-quarters of those 80 years of age and older (Figure 1). Although rarely appreciated, taste and smell disorders have significant consequences for the patient, including (i) impaired quality of life; (ii) increased health or safety risks from spoiled foods and dangerous vapors (e.g. leaking natural gas); (iii) compromised vocational abilities; and (iv) altered food choices and consumption patterns that can adversely impact health or worsen underlying illnesses (e.g. decreased body weight, impaired immunity, overuse of salt in hypertension or sugar in diabetes mellitus). A major focus of our Center over the last 25 years has been on the development of reliable, valid and easy-to-use tests for evaluating the senses of taste and smell. Quantitative testing is needed to (i) determine what specific cranial nerves are affected; (ii) accurately assess function (patient subjective reports can be misleading); (iii) communicate valid information to patients regarding the level of dysfunction and whether it is normal for their age and sex; (iv) monitor disease progression; (v) determine treatment efficacy; (vi) provide objective information regarding worker’s compensation and other insurance or legal claims; (vii) detect early signs of tumors and neurological disorders that may not be discerned otherwise; (viii) maximize efficacy of intervention or treatment; (ix) detect malingering; and (x) provide state-of-the-art medical surveillance and care. Most of the olfactory tests we have developed, including tests of odor detection, identification and memory, are commercially available and some, such as the University of Pennsylvania Smell Identification Test (UPSIT), have been translated into multiple languages and administered to hundreds of thousands of persons. Among the findings of our Center is the close relationship between a test’s length (e.g. number of items) and its reliability, a key index of its sensitivity (Figure 2).