Olfactory Measures as Predictors of Conversion to Mild Cognitive Impairment and Alzheimer’s Disease
Abstract
:1. Introduction
1.1. Alzheimer’s Disease
1.2. Mild Cognitive Impairment (MCI)
1.3. Alzheimer’s Pathology
1.4. Apolipoprotein (ApoE) ε4
1.5. Olfaction in Alzheimer’s Disease
1.6. Odor Threshold
1.7. Odor Identification and Odor Familiarity
1.8. Hypotheses
2. Materials and Methods
2.1. Participants
2.2. Genotyping
2.3. Stimuli and Procedures
2.4. Data Analysis
3. Results
3.1. ROC Analysis Comparing Cognitively Normal Controls to Converters from Control to MCI
3.1.1. MMSE
3.1.2. Odor Measures
3.2. ROC Comparing Cognitively Normal Controls to Converters from Control to AD
3.2.1. MMSE
3.2.2. Odor Measures
3.3. ROC Analysis Comparing MCI and Converters from MCI to AD
3.3.1. MMSE
3.3.2. Odor Measures
3.4. Logistic Regression Analyses
4. Discussion
4.1. Threshold
4.2. Identification
4.3. Odor Familiarity
4.4. Apoe ε4 Carriers
4.5. MMSE
4.6. Limitations
4.7. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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AD Status | n | Age | Familiarity | Identification | Threshold | MMSE | Years of Education |
---|---|---|---|---|---|---|---|
Mean (SE) | Mean (SE) | Mean (SE) | Mean (SE) | Mean (SE) | Mean (SE) | ||
Cognitively Normal | 170 | 72.97 (0.80) | 98.05 (2.65) | 5.01 (0.23) | 5.76 (0.17) | 24.01 (0.92) | 15.17 (0.29) |
Mild Cognitive Impairment | 42 | 73.89 (1.25) | 74.59 (5.02) | 3.35 (0.52) | 5.05 (0.38) | 23.37 (1.22) | 15.00 (0.42) |
Alzheimer’s Disease | 210 | 74.32 (0.57) | 72.75 (2.22) | 2.86 (0.17) | 4.64 (0.16) | 20.80 (0.44) | 14.73 (0.42) |
ApoE4 Non-Carrier | 124 | 72.79 (0.81) | 92.97 (3.09) | 4.21 (0.30) | 5.60 (0.21) | 24.68 (0.71) | 15.30 (0.29) |
ApoE4 Carrier | 132 | 71.66 (0.73) | 83.82 (3.08) | 3.81 (0.21) | 5.30 (0.21) | 22.40 (0.69) | 14.25 (0.27) |
Control to MCI | Control to MCI in Apoe ε 4+ | |
---|---|---|
ID + Familiarity | 0.57 | 0.80 |
Familiarity | 0.57 | 0.70 |
ID | 0.51 | 0.73 |
Threshold | 0.54 | 0.59 |
MMSE | 0.64 | 0.39 |
Control to AD | Control to AD in Apoe ε 4+ | |
---|---|---|
ID + Familiarity | 0.56 | 0.52 |
Familiarity | 0.52 | 0.57 |
ID | 0.63 * | 0.59 |
Threshold | 0.5 | 0.76 * |
MMSE | 0.46 | 0.48 |
MCI to AD | MCI to AD in Apoe ε 4+ | |
---|---|---|
ID + Familiarity | 0.7 | 1.00 * |
Familiarity | 0.61 | 0.81 * |
ID | 0.52 | 0.67 |
Threshold | 0.54 | 0.38 |
MMSE | 0.53 | 0.58 |
Control to MCI | Control to MCI in ApoE4+ | |||||
Wald | SE | Sig | Wald | SE | Sig | |
ID + Familiarity | 0.407 | 0.01 | 0.524 | 2.719 | 0.069 | 0.099 |
Familiarity | 1.276 | 0.008 | 0.259 | 4.499 | 0.054 | 0.034 |
ID | 0.058 | 0.184 | 0.809 | 1.812 | 0.871 | 0.178 |
Threshold | 0.452 | 0.11 | 0.502 | 2.743 | 0.237 | 0.097 |
MMSE | 0.008 | 0.026 | 0.93 | 0.415 | 0.045 | 0.519 |
Control to AD | Control to AD in ApoE4 + | |||||
Wald | SE | Sig | Wald | SE | Sig | |
ID + Familiarity | 0.628 | 0.017 | 0.428 | 0.702 | 0.029 | 0.402 |
Familiarity | 3.076 | 0.005 | 0.079 | 2.496 | 0.02 | 0.114 |
ID | 7.973 | 0.017 | 0.005 | 1.039 | 0.329 | 0.308 |
Threshold | 0.834 | 0.097 | 0.361 | 5.397 | 0.457 | 0.02 |
MMSE | 0.313 | 0.023 | 0.576 | 1.045 | 0.052 | 0.307 |
aMCI to AD | aMCI to AD in ApoE4 + | |||||
Wald | SE | Sig | Wald | SE | Sig | |
ID + Familiarity | 5.755 | 0.032 | 0.016 | 0 | 0 | <0.01 |
Familiarity | 2.811 | 0.008 | 0.094 | 5.207 | 0.019 | 0.022 |
ID | 1.057 | 0.231 | 0.304 | 5.943 | 0.134 | 0.015 |
Threshold | 0.917 | 0.135 | 0.338 | 1.35 | 0.243 | 0.245 |
MMSE | 0.763 | 0.037 | 0.382 | 1.051 | 0.07 | 0.388 |
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Wheeler, P.L.; Murphy, C. Olfactory Measures as Predictors of Conversion to Mild Cognitive Impairment and Alzheimer’s Disease. Brain Sci. 2021, 11, 1391. https://doi.org/10.3390/brainsci11111391
Wheeler PL, Murphy C. Olfactory Measures as Predictors of Conversion to Mild Cognitive Impairment and Alzheimer’s Disease. Brain Sciences. 2021; 11(11):1391. https://doi.org/10.3390/brainsci11111391
Chicago/Turabian StyleWheeler, Paul Loyd, and Claire Murphy. 2021. "Olfactory Measures as Predictors of Conversion to Mild Cognitive Impairment and Alzheimer’s Disease" Brain Sciences 11, no. 11: 1391. https://doi.org/10.3390/brainsci11111391