Neuropathological changes in olfactory areas of the brain in patients with AD suggest the theoretical importance and potential diagnostic utility of investigating functional changes in olfaction in these patients. A series of investigations utilizing psychophysical, neuropsychological, and electrophysio-logical techniques have been conducted to assess olfaction function in both patients with AD and those at risk for the disease. Both Alzheimer's patients and those at risk for AD show significant impairment in olfactory threshold sensitivity, odor identification, and odor memory, with some measures showing more impairment than others in the early stages of the disease process (Murphy, 1999). Functional testing in AD revealed deficits in olfactory threshold (Murphy et al., 1990; Nordin and Murphy, 1996: Bacon et al., 1998), odor identification (Morgan et al., 1995; Murphy et al., 1998), odor memory (Murphy et al., 1999; Nordin and Murphy, 1996; Niccoli-Waller et al., 1999), odor fluency (Bacon et al., 1999) and olfactory event-related potentials (Morgan and Murphy, in preparation).
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