title: Olfactory phenotypic expression unveils human aging.
abstract: The mechanism of the natural aging of olfaction and its declinein the absence of any overt disease conditions remains unclear. Here, we investigated this mechanism through measurement of one of the parameters of olfactory function, the absolute threshold, in a healthy population from childhood to old age. The absolute olfactory threshold data were collected from an Italian observational study with 622 participants aged 5-105 years. A subjective testing procedure of constant stimuli was used, which was also compared to the 'staircase' method, with the calculation of the reliability. The n-butanol stimulus was used as an ascending series of nine molar concentrations that were monitored using an electronic nose. The data were analyzed using nonparametric statistics because of the multimodal distribution. We show that the age-related variations in the absolute olfactory threshold are not continuous; instead, there are multiple olfactory phenotypes. Three distinct age-related phenotypes were defined, termed as 'juvenile', 'mature' and 'elder'. The frequency of these three phenotypes depends on age. Our data suggest that the sense of smell does not decrease linearly with aging. Our findings provide the basis for further understanding of olfactory loss as an anticipatory sign of aging and neurodegenerative processes.
authors.affiliation: Department of Neuroscience, Imaging and Clinical Science, 'G. d'Annunzio' University of Chieti-Pescara, Chieti, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Mazzatenta
authors.affiliation: Scuola Normale Superiore, Pisa, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Cellerino
authors.affiliation: Neuroscience Institute, CNR-Pisa, Pisa, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Origlia
authors.affiliation: Neuroscience Institute, CNR-Pisa, Pisa, Italy.|Department di Medicina Clinica e Sperimentale, Sezione di Neurologia, e Dai di Neuroscienze, Pisa, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Barloscio
authors.affiliation: Department di Medicina Clinica e Sperimentale, Sezione di Neurologia, e Dai di Neuroscienze, Pisa, Italy.
authors.forename: Ferdinando
authors.initials: F
authors.lastname: Sartucci
authors.affiliation: Department of Neuroscience, Imaging and Clinical Science, 'G. d'Annunzio' University of Chieti-Pescara, Chieti, Italy.
authors.forename: Camillo
authors.initials: C
authors.lastname: Di Giulio
authors.affiliation: Neuroscience Institute, CNR-Pisa, Pisa, Italy.|Department of Applied Clinical Science and Biotechnology (DISCAB), School of Medicine, l'Aquila University, L'Aquila, Italy.
authors.forename: Luciano
authors.initials: L
authors.lastname: Domenici
mesh_terms: D020001:1-Butanol / Q000494:pharmacology; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D000857:Olfaction Disorders / Q000175:diagnosis / Q000503:physiopathology; D055696:Olfactory Perception / Q000187:drug effects / Q000502:physiology*; D012680:Sensitivity and Specificity; D012684:Sensory Thresholds / Q000187:drug effects / Q000502:physiology*; D012903:Smell / Q000187:drug effects / Q000502:physiology*; D055815:Young Adult
chemical_list: D020001:1-Butanol
keywords: Gerotarget; absolute threshold; aging; olfaction; olfactometry; olfactory phenotype