Neuroimaging biomarkers and impaired olfaction in cognitively normal individuals

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Abstract

Objective: There is a need for inexpensive noninvasive tests to identify older healthy persons at risk for Alzheimer disease (AD) for enrollment in AD prevention trials. Our objective was to examine whether abnormalities in neuroimaging measures of amyloid and neurodegeneration are correlated with odor identification (OI) in the population-based Mayo Clinic Study of Aging. Methods: Cognitively normal (CN) participants had olfactory function assessed using the Brief Smell Identification Test (B-SIT), underwent magnetic resonance imaging (n = 829) to assess a composite AD signature cortical thickness and hippocampal volume (HVa), and underwent 11C-Pittsburgh compound B (n = 306) and 18fluorodeoxyglucose (n = 305) positron emission tomography scanning to assess amyloid accumulation and brain hypometabolism, respectively. The association of neuroimaging biomarkers with OI was examined using multinomial logistic regression and simple linear regression models adjusted for potential confounders. Results: Among 829 CN participants (mean age = 79.2 years; 51.5% men), 248 (29.9%) were normosmic and 78 (9.4%) had anosmia (B-SIT score < 6). Abnormal AD signature cortical thickness and reduced HVa were associated with decreased OI as a continuous measure (slope = −0.43, 95% confidence interval [CI] = −0.76 to −0.09, p = 0.01 and slope = −0.72, 95% CI = −1.15 to −0.28, p < 0.01, respectively). Reduced HVa, decreased AD signature cortical thickness, and increased amyloid accumulation were significantly associated with increased odds of anosmia. Interpretation: Our findings suggest that OI may be a noninvasive, inexpensive marker for risk stratification, for identifying participants at the preclinical stage of AD who may be at risk for cognitive impairment and eligible for inclusion in AD prevention clinical trials. These cross-sectional findings remain to be validated prospectively. Ann Neurol 2017;81:871–882.

Original languageEnglish (US)
Pages (from-to)871-882
Number of pages12
JournalAnnals of Neurology
Volume81
Issue number6
DOIs
StatePublished - Jun 1 2017

Fingerprint

Smell
Neuroimaging
Alzheimer Disease
Biomarkers
Amyloid
Olfaction Disorders
Linear Models
Confidence Intervals
Positron-Emission Tomography
Logistic Models
Magnetic Resonance Imaging
Clinical Trials
Odorants
Brain
Population

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology

Cite this

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title = "Neuroimaging biomarkers and impaired olfaction in cognitively normal individuals",
abstract = "Objective: There is a need for inexpensive noninvasive tests to identify older healthy persons at risk for Alzheimer disease (AD) for enrollment in AD prevention trials. Our objective was to examine whether abnormalities in neuroimaging measures of amyloid and neurodegeneration are correlated with odor identification (OI) in the population-based Mayo Clinic Study of Aging. Methods: Cognitively normal (CN) participants had olfactory function assessed using the Brief Smell Identification Test (B-SIT), underwent magnetic resonance imaging (n = 829) to assess a composite AD signature cortical thickness and hippocampal volume (HVa), and underwent 11C-Pittsburgh compound B (n = 306) and 18fluorodeoxyglucose (n = 305) positron emission tomography scanning to assess amyloid accumulation and brain hypometabolism, respectively. The association of neuroimaging biomarkers with OI was examined using multinomial logistic regression and simple linear regression models adjusted for potential confounders. Results: Among 829 CN participants (mean age = 79.2 years; 51.5{\%} men), 248 (29.9{\%}) were normosmic and 78 (9.4{\%}) had anosmia (B-SIT score < 6). Abnormal AD signature cortical thickness and reduced HVa were associated with decreased OI as a continuous measure (slope = −0.43, 95{\%} confidence interval [CI] = −0.76 to −0.09, p = 0.01 and slope = −0.72, 95{\%} CI = −1.15 to −0.28, p < 0.01, respectively). Reduced HVa, decreased AD signature cortical thickness, and increased amyloid accumulation were significantly associated with increased odds of anosmia. Interpretation: Our findings suggest that OI may be a noninvasive, inexpensive marker for risk stratification, for identifying participants at the preclinical stage of AD who may be at risk for cognitive impairment and eligible for inclusion in AD prevention clinical trials. These cross-sectional findings remain to be validated prospectively. Ann Neurol 2017;81:871–882.",
author = "Maria Vassilaki and Christianson, {Teresa J.} and Mielke, {Michelle M} and Geda, {Yonas Endale} and Kremers, {Walter K} and Machulda, {Mary Margaret} and Knopman, {David S} and Petersen, {Ronald Carl} and Val Lowe and Jack, {Clifford R Jr.} and Roberts, {Rosebud O}",
year = "2017",
month = "6",
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doi = "10.1002/ana.24960",
language = "English (US)",
volume = "81",
pages = "871--882",
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publisher = "John Wiley and Sons Inc.",
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T1 - Neuroimaging biomarkers and impaired olfaction in cognitively normal individuals

AU - Vassilaki, Maria

AU - Christianson, Teresa J.

AU - Mielke, Michelle M

AU - Geda, Yonas Endale

AU - Kremers, Walter K

AU - Machulda, Mary Margaret

AU - Knopman, David S

AU - Petersen, Ronald Carl

AU - Lowe, Val

AU - Jack, Clifford R Jr.

AU - Roberts, Rosebud O

PY - 2017/6/1

Y1 - 2017/6/1

N2 - Objective: There is a need for inexpensive noninvasive tests to identify older healthy persons at risk for Alzheimer disease (AD) for enrollment in AD prevention trials. Our objective was to examine whether abnormalities in neuroimaging measures of amyloid and neurodegeneration are correlated with odor identification (OI) in the population-based Mayo Clinic Study of Aging. Methods: Cognitively normal (CN) participants had olfactory function assessed using the Brief Smell Identification Test (B-SIT), underwent magnetic resonance imaging (n = 829) to assess a composite AD signature cortical thickness and hippocampal volume (HVa), and underwent 11C-Pittsburgh compound B (n = 306) and 18fluorodeoxyglucose (n = 305) positron emission tomography scanning to assess amyloid accumulation and brain hypometabolism, respectively. The association of neuroimaging biomarkers with OI was examined using multinomial logistic regression and simple linear regression models adjusted for potential confounders. Results: Among 829 CN participants (mean age = 79.2 years; 51.5% men), 248 (29.9%) were normosmic and 78 (9.4%) had anosmia (B-SIT score < 6). Abnormal AD signature cortical thickness and reduced HVa were associated with decreased OI as a continuous measure (slope = −0.43, 95% confidence interval [CI] = −0.76 to −0.09, p = 0.01 and slope = −0.72, 95% CI = −1.15 to −0.28, p < 0.01, respectively). Reduced HVa, decreased AD signature cortical thickness, and increased amyloid accumulation were significantly associated with increased odds of anosmia. Interpretation: Our findings suggest that OI may be a noninvasive, inexpensive marker for risk stratification, for identifying participants at the preclinical stage of AD who may be at risk for cognitive impairment and eligible for inclusion in AD prevention clinical trials. These cross-sectional findings remain to be validated prospectively. Ann Neurol 2017;81:871–882.

AB - Objective: There is a need for inexpensive noninvasive tests to identify older healthy persons at risk for Alzheimer disease (AD) for enrollment in AD prevention trials. Our objective was to examine whether abnormalities in neuroimaging measures of amyloid and neurodegeneration are correlated with odor identification (OI) in the population-based Mayo Clinic Study of Aging. Methods: Cognitively normal (CN) participants had olfactory function assessed using the Brief Smell Identification Test (B-SIT), underwent magnetic resonance imaging (n = 829) to assess a composite AD signature cortical thickness and hippocampal volume (HVa), and underwent 11C-Pittsburgh compound B (n = 306) and 18fluorodeoxyglucose (n = 305) positron emission tomography scanning to assess amyloid accumulation and brain hypometabolism, respectively. The association of neuroimaging biomarkers with OI was examined using multinomial logistic regression and simple linear regression models adjusted for potential confounders. Results: Among 829 CN participants (mean age = 79.2 years; 51.5% men), 248 (29.9%) were normosmic and 78 (9.4%) had anosmia (B-SIT score < 6). Abnormal AD signature cortical thickness and reduced HVa were associated with decreased OI as a continuous measure (slope = −0.43, 95% confidence interval [CI] = −0.76 to −0.09, p = 0.01 and slope = −0.72, 95% CI = −1.15 to −0.28, p < 0.01, respectively). Reduced HVa, decreased AD signature cortical thickness, and increased amyloid accumulation were significantly associated with increased odds of anosmia. Interpretation: Our findings suggest that OI may be a noninvasive, inexpensive marker for risk stratification, for identifying participants at the preclinical stage of AD who may be at risk for cognitive impairment and eligible for inclusion in AD prevention clinical trials. These cross-sectional findings remain to be validated prospectively. Ann Neurol 2017;81:871–882.

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