Altered Affective Evaluations of Smells in Alzheimer's Disease.
BACKGROUND
Studies of olfaction in Alzheimer's disease (AD) mainly focused on deficits in odor detection and identification, with very few investigations of olfactory emotional changes and their consequences for hedonics.


OBJECTIVE
The aim of the present study was to characterize affective evaluations of odors in AD patients.


METHODS
To this end, 20 AD patients and 20 matched controls were tested. Participants were screened for odor detection and identification ability and then asked to rate the intensity, pleasantness, and edibility of 20 odorants.


RESULTS
Results showed that, overall, AD patients had lower detection ability and perceived all odors as weaker than controls. As expected, they had lower identification ability on both cued and non-cued tasks. In addition, when smelling pleasant odors, patients had significantly lower hedonic ratings than controls (p <  0.02), whereas no group difference was found for neutral or unpleasant odors (p >  0.05 in both cases). Moreover, an analysis combining both intensity and pleasantness ratings showed that whereas intensity increased as a function of pleasantness and unpleasantness in controls, this quadratic relationship was not observed in AD patients.


CONCLUSIONS
The study suggests that the simplest categorization criteria of odors (intensity and hedonic valence) are impaired in AD patients (especially for pleasant odors).
CNRS UMR5292, INSERM U1028, Lyon Neuroscience Research Center, University Lyon, France.
Pauline
P
Joussain
CNRS UMR5292, INSERM U1028, Lyon Neuroscience Research Center, University Lyon, France.
Marion
M
Bessy
CNRS UMR5292, INSERM U1028, Lyon Neuroscience Research Center, University Lyon, France.
Arnaud
A
Fournel
CNRS UMR5292, INSERM U1028, Lyon Neuroscience Research Center, University Lyon, France.
Camille
C
Ferdenzi
CNRS UMR5292, INSERM U1028, Lyon Neuroscience Research Center, University Lyon, France.
Catherine
C
Rouby
Hospices Civils de Lyon, France.|Clinical and Research Memory Center of Lyon, France.
Floriane
F
Delphin-Combe
CNRS UMR5292, INSERM U1028, Lyon Neuroscience Research Center, University Lyon, France.|Hospices Civils de Lyon, France.|Clinical and Research Memory Center of Lyon, France.
Pierre
P
Krolak-Salmon
CNRS UMR5292, INSERM U1028, Lyon Neuroscience Research Center, University Lyon, France.
Moustafa
M
Bensafi
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000150:complications*; D000704:Analysis of Variance; D016022:Case-Control Studies; D004644:Emotions / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D019964:Mood Disorders / Q000209:etiology; D009812:Odorants; D000857:Olfaction Disorders / Q000209:etiology*; D011569:Psychiatric Status Rating Scales; D012903:Smell / Q000502:physiology; D011795:Surveys and Questionnaires
Alzheimer’s disease; emotion; intensity; olfaction; pleasantness