Olfactory dysfunction for pyridine and dementia progression in Alzheimer disease.
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.


METHODS
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.
Nordin
S
S
Department of Psychology, Stockholm University, Sweden.
Almkvist
O
O
Berglund
B
B
Wahlund
L O
LO
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009812:Odorants; D011725:Pyridines; D012903:Smell / Q000502:physiology*
D011725:Pyridines; C023666:pyridine