We compared 7 mildly affected Huntington's
disease (HD) patients to 7 age- and education-matched healthy
controls (NC) on an odor detection test, the California
Odor Learning Test, and the California Verbal Learning
Test. Results demonstrated that odor detection sensitivity,
but not group membership, accounted for significant variance
in total olfactory learning. Both groups learned fewer
items in the olfactory modality compared to the verbal
modality, but retained a similar amount following a delay.
No group differences were demonstrated for verbal recognition
discriminability, but the HD group demonstrated significantly
impaired odor recognition discriminability. Finally, odor
detection provided excellent classification sensitivity
and specificity between the patients and controls, suggesting
that olfactory testing may provide a sensitive measure
of the early disease process in HD. (JINS, 1999,
5, 609–615.)