Smell Loss Predicts Mortality Risk Regardless of Dementia Conversion.
OBJECTIVE
To determine whether dementia could explain the association between poor olfactory performance and mortality risk within a decade-long follow-up period.


METHODS
Prospective cohort study.


METHODS
Betula Study, Umeå, Sweden.


METHODS
A population-based sample of adult participants without dementia at baseline aged 40 to 90 (N = 1,774).


METHODS
Olfactory performance using the Scandinavian Odor-Identification Test (SOIT) and self-reported olfactory function; several social, cognitive, and medical risk factors at baseline; and incident dementia during the following decade.


RESULTS
Within the 10-year follow-up, 411 of 1,774 (23.2%) participants had died. In a Cox model, the association between higher SOIT score and lower mortality was significant (hazard ratio (HR) = 0.74 per point interval, 95% confidence interval (CI) = 0.71-0.77, P < .001). The effect was attenuated, but remained significant, after controlling for age, sex, education, and health-related and cognitive variables (HR = 0.92, 95% CI = 0.87-0.97, P = .001). The association between SOIT score and mortality was retained after controlling for dementia conversion before death (HR = 0.92, 95% CI = 0.87-0.97, P = .001). Similar results were obtained for self-reported olfactory dysfunction.


CONCLUSIONS
Poor odor identification and poor self-reported olfactory function are associated with greater likelihood of future mortality. Dementia does not attenuate the association between olfactory loss and mortality, suggesting that olfactory loss might mark deteriorating health, irrespective of dementia.
Gösta Ekman Laboratory, Psychology Department, Stockholm University, Stockholm, Sweden.
Ingrid
I
Ekström
Gösta Ekman Laboratory, Psychology Department, Stockholm University, Stockholm, Sweden.
Sara
S
Sjölund
Department of Psychology, Umeå University, Umeå, Sweden.
Steven
S
Nordin
Department of Clinical Sciences, Umeå University, Umeå, Sweden.
Annelie
A
Nordin Adolfsson
Department of Clinical Sciences, Umeå University, Umeå, Sweden.
Rolf
R
Adolfsson
Gösta Ekman Laboratory, Psychology Department, Stockholm University, Stockholm, Sweden.
Lars-Göran
LG
Nilsson
Gösta Ekman Laboratory, Psychology Department, Stockholm University, Stockholm, Sweden.
Maria
M
Larsson
Gösta Ekman Laboratory, Psychology Department, Stockholm University, Stockholm, Sweden.|Swedish Collegium for Advanced Study, Uppsala, Sweden.
Jonas K
JK
Olofsson
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003704:Dementia / Q000175:diagnosis*; D005500:Follow-Up Studies; D006306:Health Surveys; D006801:Humans; D008875:Middle Aged; D009026:Mortality; D000857:Olfaction Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D011159:Population Surveillance / Q000379:methods; D011446:Prospective Studies; D012307:Risk Factors; D012903:Smell / Q000502:physiology*; D013548:Sweden
Alzheimer disease; longitudinal studies; mortality; olfaction disorders; smell