Dataset Information

Applicability of in vivo staging of regional amyloid burden in a cognitively normal cohort with subjective memory complaints: the INSIGHT-preAD study.

ABSTRACT: BACKGROUND:Current methods of amyloid PET interpretation based on the binary classification of global amyloid signal fail to identify early phases of amyloid deposition. A recent analysis of 18F-florbetapir PET data from the Alzheimer's disease Neuroimaging Initiative cohort suggested a hierarchical four-stage model of regional amyloid deposition that resembles neuropathologic estimates and can be used to stage an individual's amyloid burden in vivo. Here, we evaluated the validity of this in vivo amyloid staging model in an independent cohort of older people with subjective memory complaints (SMC). We further examined its potential association with subtle cognitive impairments in this population at elevated risk for Alzheimer's disease (AD). METHODS:The monocentric INSIGHT-preAD cohort includes 318 cognitively intact older individuals with SMC. All individuals underwent 18F-florbetapir PET scanning and extensive neuropsychological testing. We projected the regional amyloid uptake signal into the previously proposed hierarchical staging model of in vivo amyloid progression. We determined the adherence to this model across all cases and tested the association between increasing in vivo amyloid stage and cognitive performance using ANCOVA models. RESULTS:In total, 156 participants (49%) showed evidence of regional amyloid deposition, and all but 2 of these (99%) adhered to the hierarchical regional pattern implied by the in vivo amyloid progression model. According to a conventional binary classification based on global signal (SUVRCereb =?1.10), individuals in stages III and IV were classified as amyloid-positive (except one in stage III), but 99% of individuals in stage I and even 28% of individuals in stage II were classified as amyloid-negative. Neither in vivo amyloid stage nor conventional binary amyloid status was significantly associated with cognitive performance in this preclinical cohort. CONCLUSIONS:The proposed hierarchical staging scheme of PET-evidenced amyloid deposition generalizes well to data from an independent cohort of older people at elevated risk for AD. Future studies will determine the prognostic value of the staging approach for predicting longitudinal cognitive decline in older individuals at increased risk for AD.

SUBMITTER: Sakr FA

PROVIDER: S-EPMC6357385 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

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Applicability of in vivo staging of regional amyloid burden in a cognitively normal cohort with subjective memory complaints: the INSIGHT-preAD study.

Sakr Fatemah A FA Grothe Michel J MJ Cavedo Enrica E Jelistratova Irina I Habert Marie-Odile MO Dyrba Martin M Gonzalez-Escamilla Gabriel G Bertin Hugo H Locatelli Maxime M Lehericy Stephane S Teipel Stefan S Dubois Bruno B Hampel Harald H

Alzheimer's research & therapy 20190131 1

<h4>Background</h4>Current methods of amyloid PET interpretation based on the binary classification of global amyloid signal fail to identify early phases of amyloid deposition. A recent analysis of 18F-florbetapir PET data from the Alzheimer's disease Neuroimaging Initiative cohort suggested a hierarchical four-stage model of regional amyloid deposition that resembles neuropathologic estimates and can be used to stage an individual's amyloid burden in vivo. Here, we evaluated the validity of th ...[more]

PMID: 30704537

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Project description:There is substantial experimental evidence for dysregulation of several microRNA (miRNA) expression levels in Alzheimer's disease (AD). MiRNAs modulate critical brain intracellular signaling pathways and are associated with AD core pathophysiological mechanisms. First, we conducted a real-time quantitative PCR-based pilot study to identify a set of brain-enriched miRNAs in a monocentric cohort of cognitively normal individuals with subjective memory complaints, a condition associated with increased risk of AD. Second, we investigated the impact of age, sex, and the Apolipoprotein E ε4 (APOE ε4) allele, on the identified miRNA plasma concentrations. In addition, we explored the cross-sectional and longitudinal association of the miRNAs plasma concentrations with regional brain metabolic uptake using amyloid-β (Aβ)-positron emission tomography (Aβ-PET) and 18F-fluorodeoxyglucose-PET (18F-FDG-PET). We identified a set of six brain-enriched miRNAs-miRNA-125b, miRNA-146a, miRNA-15b, miRNA-148a, miRNA-26b, and miRNA-100. Age, sex, and APOE ε4 allele were not associated with individual miRNA abundance. MiRNA-15b concentrations were significantly lower in the Aβ-PET-positive compared to Aβ-PET-negative individuals. Furthermore, we found a positive effect of the miRNA-15b*time interaction on regional metabolic 18F-FDG-PET uptake in the left hippocampus. Plasma miRNA-125b concentrations, as well as the miRNA-125b*time interaction (over a 2-year follow-up), were negatively associated with regional Aβ-PET standard uptake value ratio in the right anterior cingulate cortex. At baseline, we found a significantly negative association between plasma miRNA-125b concentrations and 18F-FDG-PET uptake in specific brain regions. In an asymptomatic at-risk population for AD, we show significant associations between plasma concentrations of miRNA-125b and miRNA-15b with core neuroimaging biomarkers of AD pathophysiology. Our results, coupled with existing experimental evidence, suggest a potential protective anti-Aβ effect of miRNA-15b and a biological link between miRNA-125b and Aβ-independent neurotoxic pathways.

Project description:ImportanceEmotional and behavioral symptoms in cognitively normal older people may be direct manifestations of Alzheimer disease (AD) pathophysiology at the preclinical stage, prior to the onset of mild cognitive impairment. Loneliness is a perceived state of social and emotional isolation that has been associated with cognitive and functional decline and an increased risk of incident AD dementia. We hypothesized that loneliness might occur in association with elevated cortical amyloid burden, an in vivo research biomarker of AD.ObjectiveTo determine whether cortical amyloid burden is associated with greater loneliness in cognitively normal older adults.Design, setting, and participantsCross-sectional analyses using data from the Harvard Aging Brain Study of 79 cognitively normal, community-dwelling participants. A continuous, aggregate measure of cortical amyloid burden, determined by Pittsburgh Compound B-positron emission tomography (PiB-PET), was examined in association with loneliness in linear regression models adjusting for age, sex, apolipoprotein E ε4 (APOEε4), socioeconomic status, depression, anxiety, and social network (without and with the interaction of amyloid and APOEε4). We also quantified the association of high amyloid burden (amyloid-positive group) to loneliness (lonely group) using logistic regression, controlling for the same covariates, with the amyloid-positive group and the lonely group, each composing 32% of the sample (n = 25).Main outcomes and measuresLoneliness, as determined by the 3-item UCLA Loneliness Scale (possible range, 3-12, with higher score indicating greater loneliness).ResultsThe 79 participants included 43 women and 36 men with a mean (SD) age of 76.4 (6.2) years. Mean (SD) cortical amyloid burden via PiB-PET was 1.230 (0.209), and the mean (SD) UCLA-3 loneliness score was 5.3 (1.8). Twenty-two (28%) had positive APOEε4 carrier status, and 25 (32%) were in the amyloid-positive group with cortical PiB distribution volume ratio greater than 1.2. Controlling for age, sex, APOEε4, socioeconomic status, depression, anxiety, and social network, we found that higher amyloid burden was significantly associated with greater loneliness: compared with individuals in the amyloid-negative group, those in the amyloid-positive group were 7.5-fold (95% CI, 1.7-fold to 34.0-fold) more likely to be classified as lonely than nonlonely (β = 3.3, partial r = 0.4, P = .002). Furthermore, the association of high amyloid burden and loneliness was stronger in APOEε4 carriers than in noncarriers.Conclusions and relevanceWe report a novel association of loneliness with cortical amyloid burden in cognitively normal older adults, suggesting that loneliness is a neuropsychiatric symptom relevant to preclinical AD. This work will inform new research into the neural underpinnings and disease mechanisms involved in loneliness and may enhance early detection and intervention research in AD.

Dataset Information

Applicability of in vivo staging of regional amyloid burden in a cognitively normal cohort with subjective memory complaints: the INSIGHT-preAD study.

Publications

Applicability of in vivo staging of regional amyloid burden in a cognitively normal cohort with subjective memory complaints: the INSIGHT-preAD study.

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