Dataset Information

The preclinical Alzheimer cognitive composite: measuring amyloid-related decline.

ABSTRACT: As Alzheimer disease (AD) research moves to intervene in presymptomatic phases of the disease, we must develop outcome measures sensitive to the earliest disease-related changes.To demonstrate the feasibility of a cognitive composite outcome for clinically normal elderly participants with evidence of AD pathology using the ADCS Preclinical Alzheimer Cognitive Composite (ADCS-PACC). The ADCS-PACC combines tests that assess episodic memory, timed executive function, and global cognition. The ADCS-PACC is the primary outcome measure for the first clinical trial in preclinical AD (ie, the Anti-Amyloid Treatment in Asymptomatic Alzheimer's study).With the ADCS-PACC, we derive pilot estimates of amyloid-related decline using data from 2 observational studies conducted in North America and another conducted in Australia. The participants analyzed had normal cognition and mean ages of 75.81, 71.37, and 79.42 years across the 3 studies.For the 2 studies that collected data on A? levels (ADNI and AIBL), we estimate decline in a preclinical AD "A?-positive" placebo group and compare them with an "A?-negative" group. For the study that did not include data on A? levels (the ADCS Prevention Instrument [ADCS-PI] study), we grouped participants by the presence of APOE-?4 and by clinical progression.In ADNI, A?-positive participants showed more decline than did A?-negative participants with regard to the ADCS-PACC score at 24 months (mean [SE] difference, -1.239 [0.522] [95% CI, -2.263 to -0.215]; P?=?.02). In AIBL, the mean (SE) difference is significant at both 18 months (-1.009 [0.406] [95% CI, -1.805 to -0.213]; P?=?.01) and 36 months (-1.404 [0.452] [95% CI, -2.290 to -0.519]; P?=?.002). In the ADCS-PI study, APOE-?4 allele carriers performed significantly worse on the ADCS-PACC at 24 months (mean [SE] score, -0.742 [0.294] [95% CI, -1.318 to -0.165]; P?=?.01) and 36 months (-1.531 [0.469] [95% CI, -2.450 to -0.612]; P?=?.001). In the ADCS-PI study, cognitively normal participants who progress from a global Clinical Dementia Rating score of 0 are significantly worse on the ADCS-PACC than cognitively normal participants who are stable with a global Clinical Dementia Rating score of 0 at months 12, 24, and 36 (mean [SE] ADCS-PACC score, -4.471 [0.702] [95% CI, -5.848 to -3.094]; P?

SUBMITTER: Donohue MC

PROVIDER: S-EPMC4439182 | biostudies-literature | 2014 Aug

REPOSITORIES: biostudies-literature

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The preclinical Alzheimer cognitive composite: measuring amyloid-related decline.

Donohue Michael C MC Sperling Reisa A RA Salmon David P DP Rentz Dorene M DM Raman Rema R Thomas Ronald G RG Weiner Michael M Aisen Paul S PS

JAMA neurology 20140801 8

<h4>Importance</h4>As Alzheimer disease (AD) research moves to intervene in presymptomatic phases of the disease, we must develop outcome measures sensitive to the earliest disease-related changes.<h4>Objective</h4>To demonstrate the feasibility of a cognitive composite outcome for clinically normal elderly participants with evidence of AD pathology using the ADCS Preclinical Alzheimer Cognitive Composite (ADCS-PACC). The ADCS-PACC combines tests that assess episodic memory, timed executive func ...[more]

PMID: 24886908

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Project description:ImportanceAlzheimer disease (AD) pathology starts with a prolonged phase of β-amyloid (Aβ) accumulation without symptoms. The duration of this phase differs greatly among individuals. While this disease phase has high relevance for clinical trial designs, it is currently unclear how to best predict the onset of clinical progression.ObjectiveTo evaluate combinations of different plasma biomarkers for predicting cognitive decline in Aβ-positive cognitively unimpaired (CU) individuals.Design, setting, and participantsThis prospective population-based prognostic study evaluated data from 2 prospective longitudinal cohort studies (the Swedish BioFINDER-1 and the Wisconsin Registry for Alzheimer Prevention [WRAP]), with data collected from February 8, 2010, to October 21, 2020, for the BioFINDER-1 cohort and from August 11, 2011, to June 27, 2021, for the WRAP cohort. Participants were CU individuals recruited from memory clinics who had brain Aβ pathology defined by cerebrospinal fluid (CSF) Aβ42/40 in the BioFINDER-1 study and by Pittsburgh Compound B (PiB) positron emission tomography (PET) in the WRAP study. A total of 564 eligible Aβ-positive and Aβ-negative CU participants with available relevant data from the BioFINDER-1 and WRAP cohorts were included in the study; of those, 171 Aβ-positive participants were included in the main analyses.ExposuresBaseline P-tau181, P-tau217, P-tau231, glial fibrillary filament protein, and neurofilament light measured in plasma; CSF biomarkers in the BioFINDER-1 cohort, and PiB PET uptake in the WRAP cohort.Main outcomes and measuresThe primary outcome was longitudinal measures of cognition (using the Mini-Mental State Examination [MMSE] and the modified Preclinical Alzheimer Cognitive Composite [mPACC]) over a median of 6 years (range, 2-10 years). The secondary outcome was conversion to AD dementia. Baseline biomarkers were used in linear regression models to predict rates of longitudinal cognitive change (calculated separately). Models were adjusted for age, sex, years of education, apolipoprotein E ε4 allele status, and baseline cognition. Multivariable models were compared based on model R2 coefficients and corrected Akaike information criterion.ResultsAmong 171 Aβ-positive CU participants included in the main analyses, 119 (mean [SD] age, 73.0 [5.4] years; 60.5% female) were from the BioFINDER-1 study, and 52 (mean [SD] age, 64.4 [4.6] years; 65.4% female) were from the WRAP study. In the BioFINDER-1 cohort, plasma P-tau217 was the best marker to predict cognitive decline in the mPACC (model R2 = 0.41) and the MMSE (model R2 = 0.34) and was superior to the covariates-only models (mPACC: R2 = 0.23; MMSE: R2 = 0.04; P < .001 for both comparisons). Results were validated in the WRAP cohort; for example, plasma P-tau217 was associated with mPACC slopes (R2 = 0.13 vs 0.01 in the covariates-only model; P = .01) and MMSE slopes (R2 = 0.29 vs 0.24 in the covariates-only model; P = .046). Sparse models were identified with plasma P-tau217 as a predictor of cognitive decline. Power calculations for enrichment in hypothetical clinical trials revealed large relative reductions in sample sizes when using plasma P-tau217 to enrich for CU individuals likely to experience cognitive decline over time.Conclusions and relevanceIn this study, plasma P-tau217 predicted cognitive decline in patients with preclinical AD. These findings suggest that plasma P-tau217 may be used as a complement to CSF or PET for participant selection in clinical trials of novel disease-modifying treatments.

Project description:Importance:Older age, high levels of ?-amyloid (A?), and the presence of the apolipoprotein E (APOE) ?4 allele are risk factors for Alzheimer disease (AD). However, the extent to which increasing age, A?, and ?4 are associated with memory decline remains unclear, and the age at which memory decline begins for A?-positive ?4 carriers and noncarriers has not been determined. Objective:To determine the association of age, A? level, and APOE ?4 with memory decline in a large group of cognitively healthy older adults. Design, Setting, and Participants:This longitudinal observational study included cognitively healthy older adults (age >60 years) enrolled in the Australian Imaging, Biomarkers and Lifestyle (AIBL) study from March 31, 2006, through March 31, 2017; of 1583 individuals enrolled, 1136 refused or were excluded owing to other criteria (eg, having mild cognitive impairment or AD). Participants underwent A? imaging in research clinics in Perth and Melbourne and more than 72 months of follow-up (at 18-month intervals). The association of age with memory was fitted to a quadratic model. Age was treated as a continuous, time-dependent variable. Exposures:?-Amyloid imaging using positron emission tomography, genotyping for APOE ?4, and longitudinal neuropsychological assessments of episodic memory during the 72-month follow-up. Main Outcomes and Measures:Episodic memory composite score. Results:Of the 447 participants, 203 (45.4%) were men and 244 (54.6%) were women; mean (SD) age was 72.5 (6.6) years. Equal proportions of female participants were observed in each A?-?4 group (24 of 51 A?-positive ?4 noncarriers [47.1%] ; 35 of 64 A?-negative ?4 carriers [54.7%]; 40 of 72 A?-positive ?4 carriers [55.6%]; and 145 of 260 A?-negative ?4 noncarriers [55.8%]). Adults with A? findings (mean [SD] age, 74.4 [6.8] years) were approximately 4 years older than those negative for A? (mean [SD] age, 69.8 [6.1] years). Memory decline diverged significantly from A?-negative ?4 noncarriers at an earlier age in A?-positive ?4 carriers (64.5 years) than in A?-positive ?4 noncarriers (76.5 years), such that by 85 years of age, A?-positive ?4 carriers performed approximately 1.5 SD units worse on the episodic memory composite than A?-negative ?4 noncarriers and approximately 0.8 SD units worse than A?-positive ?4 noncarriers. Memory performance of A?-negative ?4 carriers did not differ from that of the A?-negative ?4 noncarriers (estimate [SE], 0.001 [0.001]; t?=?0.526; P?=?.77). Conclusions and Relevance:Prior work has shown that A? and ?4 combine to influence memory decline in nondemented older adults. Results of this study indicate that increasing age may further exacerbate these effects. The estimates provided may be used to determine the risk of memory decline associated with A? and ?4 at each age.

Dataset Information

The preclinical Alzheimer cognitive composite: measuring amyloid-related decline.

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The preclinical Alzheimer cognitive composite: measuring amyloid-related decline.

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