DOn: INFLUENCE OF AGE AND AGE.RELA TED DISEASES 77 now relations within the nasopharynx resulting from changes in such behaviors as the speed and amount of chewing or swallowing. COMMON CAUSES OF SMELL LOSS IN THE ELDERLY

Major changes in the ability to smell occur as a function of aging and a number of age-related neurologic degenerative disorders. Although such changes are less obvious than the changes that may occur in vision. hearing. balance. or tactile sensation (which can dramaticaUy innuence such everyday activities as locomotion and social interaction). they are of considerable consequence to the people who experience them and are commonly irrevenible. In addition to adversely altering the &vor of foods and beverages. loss or distortion of smeU function increases the chance of accidental poisoning from toxic fumes and spoj)ed foodstuffs. Thus. it is not surprising that a disproportionate number of elderly persons succumb to accidental gas poisonings each year ,1 Age-related alterations in smeU function are observed in tests of odor identification. discrimination. threshold detection. suprathreshold intensity perception. and perceived pleasantness,1-8 Unfortunately. it is not known to what degree such alterations represent aging processes per se or changes in the olfactory system brought about by facton correlated with age (for example. cumulative viral insults or repeated exposures to air poUutants), The relationship between age and scores on a standardized 40.0dorant test of smeU function (the Univenity of Pennsylvania SmeU Identification Test or UPSIT) is presented in FIGURE I.' In general. I) peak performance occurs in the third through fifth decades of life and markedly declines after the seventh decade. 2) nonsmokers outperform smokers. and 3) women outperform men. particularly during the later yean. More than half of the subjects between the ages of 6S and 80 years. and more than three-quarters of those over the age of 80 yean. evidence major impairment on this test. Interestingly. the sex difference appears to occur in a number or cultural groups and is probably universal," Decrements in the perception of odors presented to the receptors from inside the oral cavity (as during chewing and swallowing) have also been reported in the elderly," Because the intensity or such retronasally perceived odor is innuenced by mouth movements occuning normally during deglutition.'2 some age-related alterations in retronasal odor perception may be due to alterations or pressurel