Odor Identification Ability Predicts PET Amyloid Status and Memory Decline in Older Adults.

ABSTRACT: BACKGROUND:Odor identification deficits occur in Alzheimer's disease (AD), as measured by the 40-item University of Pennsylvania Smell Identification Test (UPSIT). OBJECTIVE:To determine if UPSIT scores predict amyloid-? (A?) status, determined by 11C-Pittsburgh Compound B PET. We also compared UPSIT scores to A? status in predicting future memory decline. METHODS:Subjects were recruited into a longitudinal clinical prediction study. We analyzed data from those who had UPSIT, cognitive testing, PIB PET, and at least 12 months' clinical follow-up. Forty-six amnestic mild cognitive impairment patients and 25 cognitively normal controls were included. Amyloid-positivity was defined as composite PIB standardized uptake value ratio >1.5. Logistic regression and Receiver Operating Characteristic Curve analyses tested the predictive utility of impaired olfaction (defined as UPSIT score <35) and amyloid-positivity for memory decline. RESULTS:High UPSIT scores predicted absence of amyloidosis on PET, with negative predictive value of 100%. Positive predictive value of low UPSIT scores on positive A? status was only 41%. Both low UPSIT score (OR?=?4.301, 95% CI?=?1.248, 14.821, p?=?0.021) and positive PET scan (OR?=?20.898, 95% CI?=?2.222, 196.581, p?=?0.008) predicted memory decline. CONCLUSION:Individuals with high UPSIT scores are less likely to have cerebral amyloidosis or experience memory decline. Therefore, UPSIT has potential as a screening tool to determine utility of A? PET in clinical practice or enrollment in clinical trials. Low UPSIT score is a non-specific marker of neurodegeneration that could indicate further workup in patients with memory complaints.

SUBMITTER: Kreisl WC 

PROVIDER: S-EPMC6760657 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature