Olfactory identification deficits and increased mortality in the community

Devanand, Davangere P.; Lee, Seonjoo; Manly, Jennifer J.; Andrews, Howard; Schupf, Nicole; Masurkar, Arjun V.; Stern, Yaakov; Mayeux, Richard; Doty, Richard L.

doi:10.1002/ana.24447

Cited by 116 publications

(122 citation statements)

References 50 publications

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“…40 Odour memory may therefore be a salient olfactory domain to monitor over time, as it may differentiate those at risk from those with frank dementia, and changes over time may signal disease progression. Recent evidence indicates that impaired olfaction is associated with the progression from MCI to dementia, 23 which corroborates other longitudinal studies, 194445 but, these studies are limited to odour identification. If AD is signified by the loss of odour identification and odour recognition memory, additional longitudinal studies of odour memory are needed for determining the utility of this deficit as a potential biomarker of transition.…”

Section: Discussionsupporting

confidence: 77%

A quantitative meta-analysis of olfactory dysfunction in mild cognitive impairment

Roalf

M²,

Turetsky³

et al. 2016

J Neurol Neurosurg Psychiatry

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Background The connection between Alzheimer’s disease (AD) and olfactory deficits is well documented and further, alterations in olfactory functioning may signal declines in functions associated with dementia. The aim of the present comprehensive meta-analysis was to investigate the nature of olfactory deficits in mild cognitive impairment (MCI). Methods Articles were identified through computerised literature search from inception to 30 June 2016 using PubMed, MEDLINE and PsychInfo databases. In order to control for differences in sample size during effect size computation, studies were weighted according to their inverse variance estimates. Results 31 articles (62 effects) were identified, which included 1993 MCI patients and 2861 healthy older adults (HOA). Included studies contrasted odour identification, discrimination, detection threshold and/or memory between cases and controls. Moderate to large and heterogeneous effects were seen for olfactory deficits in MCI relative to HOA (d=−0.76, 95% CI −0.87<δ<−0.64). Moderator analysis revealed that tests of odour identification yielded larger effect sizes than those of odour detection threshold or memory. In addition, a potential interaction between age and sex was observed, with male patients carrying a larger burden of olfactory deficit and older female patients performing better on olfactory tests. Conclusions and relevance Olfactory deficits are present and robust in MCI. Odour identification is most impaired in MCI, which parallels the most prominent sensory deficit seen in AD. As such, a simple-to-administer test of odour identification warrants inclusion in the screening of individuals at risk for developing AD.

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Section: Discussionsupporting

confidence: 77%

A quantitative meta-analysis of olfactory dysfunction in mild cognitive impairment

Roalf

M²,

Turetsky³

et al. 2016

J Neurol Neurosurg Psychiatry

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“…In a multiethnic community cohort, 349 of 1,169 individuals (29.9%) died during an average follow-up period of 4 years. 32 The association between lower UPSIT scores and increased mortality remained even after controlling for age, gender, education, depression, dementia diagnosis, alcohol abuse, head injury, medical comorbidity, smoking, body mass index, and vision and hearing impairment. The hazard ratios for mortality risk increased with decrease in UPSIT scores from 1.58 for the second quartile to 3.81 for the lowest quartile for UPSIT scores.…”

Section: Increased Mortality Riskmentioning

confidence: 94%

“…To date, three of four published studies have found this association to be significant. 32–35 The one study that did not find a significant association also reported the association of odor identification impairment with increased mortality, but it lost significance after controlling for serum cholesterol and cognitive performance. 35 Possible explanations for the association between impaired odor identification and mortality include an increase in the risk of eating spoiled food, cooking-related accidents, and inability to smell gas fumes or fire.…”

Section: Increased Mortality Riskmentioning

confidence: 99%

Olfactory Identification Deficits, Cognitive Decline, and Dementia in Older Adults

Devanand

2016

The American Journal of Geriatric Psychiatry

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Several recently developed biomarkers of Alzheimer disease (AD) are invasive, expensive, and difficult to obtain in most clinical settings. Olfactory identification test performance represents a noninvasive, inexpensive biomarker of AD that may have predictive accuracy comparable with neuroimaging measures and biomarkers assessed in cerebrospinal fluid. Neurofibrillary tangles in the olfactory bulb are among the earliest pathologic features of AD and are also seen in the projection pathways from the olfactory bulb to secondary olfactory brain regions, including the piriform and medial temporal cortex, orbitofrontal cortex, and other limbic regions. Odor identification impairment characterizes AD and predicts the clinical transition from mild cognitive impairment to AD in both clinical and community samples. Epidemiologic data indicate that in cognitively intact older adults, impairment in odor identification predicts cognitive decline but that episodic verbal memory impairment does not predict cognitive decline. Odor identification impairment has also been shown to predict mortality in older subjects with mortality risk increasing with greater severity of impairment in odor identification. The exact cause of this association is not known, but olfactory deficits may lead to an increase in accidents in the home, because of the inability to smell and taste food that is unsafe or not smelling a gas leak or fire, and this may increase mortality risk. Standardized tests of odor identification ability are widely available and may provide a useful tool to improve diagnostic and predictive accuracy for cognitive decline, AD, and mortality in older adults.

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“…It is now well established that a disproportionate number of the elderly experience smell dysfunction that has direct consequences for health and safety 35 6 For example, in one longitudinal study of 1162 non-demented older persons, the mortality rate over a 4-year period was 45% for those with lowest baseline olfactory test scores, when compared with a rate of 18% in those with the highest test scores, even after controlling for age and other confounders 7…”

Section: Introductionmentioning

confidence: 99%

Prevalence and risk factors of taste and smell impairment in a nationwide representative sample of the US population: a cross-sectional study

et al. 2016

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ObjectivesTo estimate the prevalence of, and explore potential risk factors for, taste and smell dysfunction in the general population of the USA.DesignA cross-sectional study.SettingA cross-sectional analysis of data collected in the National Health and Nutrition Examination Survey (NHANES 2013–2014).ParticipantsA total of 3519 men and women aged 40 years and older who participated in NHANES 2013–2014.Main outcome measuresUsing the NHANES Pocket Smell Test, smell impairment was defined as failing to correctly identify 6 or more of the 8 odours. Taste impairment was defined as failing to correctly identify quinine or sodium chloride.ResultsThe estimated prevalence was 13.5% for smell impairment, 17.3% for taste impairment and 2.2% for taste and smell impairment. For smell, but not taste, prevalence estimates increased with age and were higher in men and ethnic minorities. In backward stepwise logistic regression, low educational attainment, low family income and a history of asthma or cancer were independently associated with a higher prevalence of smell impairment, whereas light-to-moderate alcohol consumption (1–3 drinks/day) was associated with a lower prevalence of this condition. After multivariate adjustment, being non-Hispanic Black Americans, consuming ≥4 drinks of alcohol per day and having a history of cardiovascular disease (CVD) were independently associated with a higher prevalence of taste impairment.ConclusionsBased on a nationally representative multistage probability survey among the US population aged 40 years and older, smell and taste dysfunction affected ∼20.5 million (13.5%) and 26.3 million (17.3%) individuals, respectively. Age, gender, ethnicity, educational attainment, family income, light-to-moderate alcohol consumption and history of asthma or cancer were significant risk factors for smell dysfunction, whereas only ethnicity, heavy alcohol consumption and CVD history were associated with a higher prevalence of taste dysfunction.

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Olfactory identification deficits and increased mortality in the community

Cited by 116 publications

References 50 publications

A quantitative meta-analysis of olfactory dysfunction in mild cognitive impairment

A quantitative meta-analysis of olfactory dysfunction in mild cognitive impairment

Olfactory Identification Deficits, Cognitive Decline, and Dementia in Older Adults

Prevalence and risk factors of taste and smell impairment in a nationwide representative sample of the US population: a cross-sectional study

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