Measurement of sensitivity to olfactory flavor: Application in a study of aging and dentures

Olfaction involves a dual sensory process for perceiving odors orthonasally (through the nostrils) and retronasally (through the mouth). This investig ation entailed developing a measure of sensitivity to an odor delivered in an orally sampled food (orange flavoring in a sucrose-sweetened gelatin) an d examining sensitivity in the elderly. In experiment 1, olfactory flavor s ensitivity was 49 times lower in elderly (n = 21) than in young (n = 28) su bjects. In experiment 2, with 73 elderly women, higher olfactory flavor sen sitivity correlated significantly with higher orthonasal perception (Connec ticut Chemosensory Clinical Research Center test). Some women, however, exh ibited low olfactory flavor sensitivity despite high orthonasal perception; none had high olfactory flavor sensitivity and low orthonasal perception. Those who wore complete or palatal covering dentures had lower olfactory fl avor sensitivity than those who were dentate or wore dentures that did not cover the palate. Through multiple regression analysis, orthonasal percepti on and denture status were found to be independent contributors to predicti ng olfactory flavor sensitivity, in summary, elderly subjects showed depres sed olfactory flavor sensitivity (i.e. retronasal sensitivity) that related to poor orthonasal olfactory perception and denture characteristic. Thus, while good orthonasal olfaction may be necessary for good olfactory flavor sensitivity, it is not sufficient. Other factors, some associated with oral conditions, may impede release and retronasal transport of odors from the mouth to the olfactory receptors.