Impaired olfaction predicts cognitive decline in nondemented older adults.
In 1992, the twelve-item Brief Smell Identification Test((R)) and, in 1992 and 1996, a variety of measures of verbal learning and memory, executive control, and global function were administered to a total of 359 individuals (286 men and 73 women; mean age in 1992 74.3 years). Individuals with a history of stroke or impaired cognition at baseline were excluded from analyses. Impaired olfactory function (present or absent) was related to a greater 4.5-year decline on several indices of verbal memory, but not to a decline on measures of executive control or of global functioning after adjustment for baseline cognitive performance, age, education, gender, and history of smell difficulties. Olfactory loss remained associated with a decline in components of verbal memory, independently of the apolipoprotein E epsilon4 status. The predictive utility of impaired smell identification in older adults appears to be specific to a decline in components of verbal memory.