Olfactory dysfunction for pyridine and dementia progression in Alzheimer disease
S. Nordin, O. Almkvist, B. Berglund and L. O. Wahlund
Department of Psychology, Stockholm University, Sweden.
OBJECTIVE: To investigate whether odor detection sensitivity for pyridine,
suggested by previous research not to be affected, is impaired in Alzheimer
disease (AD) and whether an association exists between odor threshold and
both degree of dementia and rate of dementia progression in AD. METHOD: The
method of constant stimuli was used to determine odor thresholds for
pyridine in 18 patients with AD (Diagnostic and Statistical Manual of
Mental Disorders, Third Edition, Revised and National Institute of
Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and
Related Disorders Association criteria) and 16 healthy elderly control
subjects. All participants were carefully examined with medical and
neuropsychological tests. RESULTS: Six patients with AD but none of the
controls were anosmic (total olfactory loss) to pyridine, and the 12
nonanosmic patients had significantly higher detection thresholds (50%
probability for detection, 323 parts per billion [ppb]) than did the
controls (50% probability for detection, 105 ppb). In addition, an
association was found between odor threshold and both degree of dementia
and rate of dementia progression in AD. CONCLUSIONS: In contrast to
previous findings, our results provide evidence that odor sensitivity in AD
is impaired for pyridine. Odor sensitivity, in addition to other suggested
predictors of progression rate, may be of interest for defining subgroups
of AD or for clinical prognostic judgments of single patients.
