In this newsworthy study, Pinto and colleagues investigated the hypothesis that olfactory dysfunction could be an early indicator of death in older adults. The most remarkable feature of the olfactory system is its unique capacity for neurogenesis and replacement of degenerating olfactory receptor neurons long after development. Aging does impair this capacity and results in reduced olfactory function in older adults. In addition, the intimate links between neurodegenerative disorders, including Parkinson’s disease (PD) and Alzheimer’s disease (AD), and olfactory function, which have been established by clinical, postmortem, and functional and structural imaging data support the idea that impaired olfactory function may be a candidate biomarker, indicative of impaired cellular regeneration and physiological decline.
One of Pinto et al.'s most interesting findings was that the likelihood of death is significantly increased for anosmic and hyposmic older adults even after controlling for several potentially confounding variables, such as age, gender, race, education, and known comorbidities. Intriguingly, the five-year mortality was three times higher in anosmic and still 1.5 times higher in hyposmic subjects compared to normosmic subjects. The effect of higher mortality was present in all age groups and was not driven by subjects with a severe olfactory deficit.
The results shed completely new light on the significance of olfactory impairment in older subjects as it pertains to cellular processes related to aging. However, it has to be noted here that olfactory function is reduced in the elderly as a consequence of normal aging. Whether this process can be accelerated by toxic environmental exposure needs to be investigated in further studies. In the same vein, I agree with the authors that a more extensive clinical test of olfactory function might help differentiate subjects with normal age-related decline of olfaction from those with severe impairment. Furthermore, although statistical analyses controlled for cognitive deficits, subjects in the study group were in an age range at which PD or AD may develop. Such potential confounds were additionally considered by excluding subjects with severe olfactory deficits, as it is known that even in early, pre-clinical stages of PD, olfaction is often dramatically reduced.
In summary, the article by Pinto et al. shows clearly that olfactory dysfunction is a strong predictor for five-year mortality in elderly subjects. The study has important implications for future research. Considering olfactory impairment is a stronger risk factor for death than heart failure, diabetes, and stroke, research and routine clinical care should be more focused on olfactory decline, because it may provide important insight to into age-related physiological processes.
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University of Basel
In this newsworthy study, Pinto and colleagues investigated the hypothesis that olfactory dysfunction could be an early indicator of death in older adults. The most remarkable feature of the olfactory system is its unique capacity for neurogenesis and replacement of degenerating olfactory receptor neurons long after development. Aging does impair this capacity and results in reduced olfactory function in older adults. In addition, the intimate links between neurodegenerative disorders, including Parkinson’s disease (PD) and Alzheimer’s disease (AD), and olfactory function, which have been established by clinical, postmortem, and functional and structural imaging data support the idea that impaired olfactory function may be a candidate biomarker, indicative of impaired cellular regeneration and physiological decline.
One of Pinto et al.'s most interesting findings was that the likelihood of death is significantly increased for anosmic and hyposmic older adults even after controlling for several potentially confounding variables, such as age, gender, race, education, and known comorbidities. Intriguingly, the five-year mortality was three times higher in anosmic and still 1.5 times higher in hyposmic subjects compared to normosmic subjects. The effect of higher mortality was present in all age groups and was not driven by subjects with a severe olfactory deficit.
The results shed completely new light on the significance of olfactory impairment in older subjects as it pertains to cellular processes related to aging. However, it has to be noted here that olfactory function is reduced in the elderly as a consequence of normal aging. Whether this process can be accelerated by toxic environmental exposure needs to be investigated in further studies. In the same vein, I agree with the authors that a more extensive clinical test of olfactory function might help differentiate subjects with normal age-related decline of olfaction from those with severe impairment. Furthermore, although statistical analyses controlled for cognitive deficits, subjects in the study group were in an age range at which PD or AD may develop. Such potential confounds were additionally considered by excluding subjects with severe olfactory deficits, as it is known that even in early, pre-clinical stages of PD, olfaction is often dramatically reduced.
In summary, the article by Pinto et al. shows clearly that olfactory dysfunction is a strong predictor for five-year mortality in elderly subjects. The study has important implications for future research. Considering olfactory impairment is a stronger risk factor for death than heart failure, diabetes, and stroke, research and routine clinical care should be more focused on olfactory decline, because it may provide important insight to into age-related physiological processes.
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