Epidemiological studies of smell: discussion and perspectives.

The critical epidemiological data for estimating the prevalence of chemosensory disorders in the United States are lacking. Several reasons for this will be discussed, including the time-consuming nature of many existing tests, stimulus delivery in a large-scale study, and the rationale for inclusion in a large-scale epidemiological study. The opportunity to include measures of chemosensory function in ongoing population-based studies has greatly facilitated the collection of recent data that establish the high prevalence of olfactory impairment in older adults in the U.S. population and the inability of self-report measures to capture this impairment. Epidemiological studies of the complete range of the population that involve chemosensory testing pose considerable challenges, but are critical to establishing prevalence rates. These studies have the potential to suggest prevention or intervention strategies for chemosensory impairment. Key issues, including cross-cultural issues in stimulus design, testing of special populations, cohort effects, and optimal analyses of population-based chemosensory data, are considered.