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O5‐03‐06: DO ODOR IDENTIFICATION AND REMOTE ODOR MEMORY TOGETHER PREDICT CONVERSION FROM MCI TO AD IN APOE ε4 CARRIERS?
Author(s) -
Murphy Claire,
Wheeler Paul
Publication year - 2019
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2019.06.4851
Subject(s) - odor , receiver operating characteristic , predictive value , identification (biology) , olfaction , medicine , psychology , neuroscience , biology , botany
Background: Like odor identification, remote odor memory, reflected in familiarity ratings, is impaired in AD (Murphy, Nature Reviews Neurology, 2019). We investigated the relative abilities of standard screening (MMSE), odor identification and remote odor memory to predict transitions from amnestic MCI (aMCI) to AD in a sample from the UCSDADRC.Methods: The sample contained 170 controls, 210 AD, 26 aMCI converters to AD and 42 aMCI non-converters. A receiver operating characteristic (ROC) curve plots the trade-off between sensitivity and specificity. The area under the curve (AUC) indicates how well a marker discriminates patients from controls. Results: Analyses showed higher predictive value for converting from aMCI to AD in ApoE ε4+ carriers for odor familiarity, odor identification and for the combination than for the MMSE. ROC/AUCs for the conversion from aMCI to AD have ranged from .63 .67 for CSF biomarkers. Odor familiarity and odor identification had similar AUC values; however, combining odor familiarity and odor identification produced an ROC/AUC value of 1.0 in ε4 carriers, appreciably higher than for MMSE alone (.58). Conclusions: Olfactory biomarkers show real promise as early, non-invasive indicators of disease, particularly in samples enriched with ε4 carriers. Although odor identification has been the focus of olfactory biomarker work, the results suggest that other measures of olfactory function have the potential to enhance prediction. Combining odor familiarity and odor identification produced a predictive value of 1.0 in ε4 carriers. The results warrant further investigation into the potential for enhancing drug trials and clinical screening. Supported by NIH grants R01AG004085-26 (CM) and P50AG005131 (UCSD ADRC). We thank the UCSD ADRC and particularly Drs. Douglas Galasko and David Salmon.