CAP--advancing the evaluation of preclinical Alzheimer disease treatments.
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ABSTRACT:
SUBMITTER: Reiman EM
PROVIDER: S-EPMC4847536 | biostudies-literature | 2016 Jan
REPOSITORIES: biostudies-literature
Publications
CAP--advancing the evaluation of preclinical Alzheimer disease treatments.
Reiman Eric M EM Langbaum Jessica B JB Tariot Pierre N PN Lopera Francisco F Bateman Randall J RJ Morris John C JC Sperling Reisa A RA Aisen Paul S PS Roses Allen D AD Welsh-Bohmer Kathleen A KA Carrillo Maria C MC Weninger Stacie S
Nature reviews. Neurology 20150929 1
If we are to find treatments to postpone, reduce the risk of, or completely prevent the clinical onset of Alzheimer disease (AD), we need faster methods to evaluate promising preclinical AD treatments, new ways to work together in support of common goals, and a determination to expedite the initiation and performance of preclinical AD trials. In this article, we note some of the current challenges, opportunities and emerging strategies in preclinical AD treatment. We describe the Collaboration f ...[more]
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Project description:ObjectiveRecent studies suggest that white matter hyperintensities (WMH) on MRI, which primarily reflect small vessel cerebrovascular disease, may play a role in the evolution of Alzheimer disease (AD). In a longitudinal study, we investigated whether WMH promote the progression of AD pathology, or alter the association between AD pathology and risk of progression from normal cognition to mild cognitive impairment (MCI).MethodsTwo sets of analyses were conducted. The relationship between whole brain WMH load, based on fluid-attenuated inversion recovery MRI, obtained in initially cognitively normal participants (n = 274) and time to onset of symptoms of MCI (n = 60) was examined using Cox regression models. In a subset of the participants with both MRI and CSF data (n = 204), the interaction of WMH load and CSF AD biomarkers was also evaluated.ResultsBaseline WMH load interacted with CSF total tau (t-tau) with respect to symptom onset, but not with CSF β-amyloid 1-42 or phosphorylated tau (p-tau) 181. WMH volume was associated with time to symptom onset of MCI among individuals with low t-tau (hazard ratio [HR] 1.35, confidence interval [CI] 1.06-1.73, p = 0.013), but not those with high t-tau (HR 0.86, CI 0.56-1.32, p = 0.47). The rate of change in the CSF biomarkers over time was not associated with the rate of change in WMH volumes.ConclusionThese results suggest that WMH primarily affect the risk of progression when CSF measures of neurodegeneration or neuronal injury (as reflected by t-tau) are low. However, CSF biomarkers of amyloid and p-tau and WMH appear to have largely independent and nonsynergistic effects on the risk of progression to MCI.
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Project description:Identifying asymptomatic older individuals at elevated risk for developing Alzheimer disease (AD) is of clinical importance. Among 1,081 asymptomatic older adults, a recently validated polygenic hazard score (PHS) significantly predicted time to AD dementia and steeper longitudinal cognitive decline, even after controlling for APOE ɛ4 carrier status. Older individuals in the highest PHS percentiles showed the highest AD incidence rates. PHS predicted longitudinal clinical decline among older individuals with moderate to high Consortium to Establish a Registry for Alzheimer's Disease (amyloid) and Braak (tau) scores at autopsy, even among APOE ɛ4 noncarriers. Beyond APOE, PHS may help identify asymptomatic individuals at highest risk for developing Alzheimer neurodegeneration. Ann Neurol 2017;82:484-488.
| S-EPMC5758043 | biostudies-literature
Project description:ObjectiveThe present work was undertaken to study the genetic contribution to the start of Alzheimer's disease (AD) with amyloid and tau biomarkers in cognitively intact older identical twins.MethodsWe studied in 96 monozygotic twin-pairs relationships between amyloid-beta (Aβ) aggregation as measured by the Aβ1-42/1-40 ratio in cerebrospinal fluid (CSF; n = 126) and positron emission tomography (PET, n = 194), and CSF markers for Aβ production (beta-secretase 1, Aβ1-40, and Aβ1-38) and CSF tau. Associations among markers were tested with generalized estimating equations including a random effect for twin status, adjusted for age, gender, and apolipoprotein E ε4 genotype. We used twin analyses to determine relative contributions of genetic and/or environmental factors to AD pathophysiological processes.ResultsTwenty-seven individuals (14%) had an abnormal amyloid PET, and 14 twin-pairs (15%) showed discordant amyloid PET scans. Within twin-pairs, Aβ production markers and total-tau (t-tau) levels strongly correlated (r range = 0.73-0.86, all p < 0.0001), and Aβ aggregation markers and 181-phosphorylated-tau (p-tau) levels correlated moderately strongly (r range = 0.50-0.64, all p < 0.0001). Cross-twin cross-trait analysis showed that Aβ1-38 in one twin correlated with Aβ1-42/1-40 ratios, and t-tau and p-tau levels in their cotwins (r range = -0.28 to 0.58, all p < .007). Within-pair differences in Aβ production markers related to differences in tau levels (r range = 0.49-0.61, all p < 0.0001). Twin discordance analyses suggest that Aβ production and tau levels show coordinated increases in very early AD.InterpretationOur results suggest a substantial genetic/shared environmental background contributes to both Aβ and tau increases, suggesting that modulation of environmental risk factors may aid in delaying the onset of AD pathophysiological processes. ANN NEUROL 2021;89:987-1000.
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| S-EPMC7050025 | biostudies-literature
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Project description:Clinical trials testing treatments for Alzheimer disease (AD) are increasingly focused on cognitively normal individuals in the preclinical phase of the disease. To optimize observing a treatment effect, such trials need to enroll cognitively normal individuals likely to show cognitive decline over the duration of the trial.To identify which group of cognitively normal individuals shows the greatest cognitive decline over time based on their cerebrospinal fluid biomarker profile.In this cohort study, cognitively normal participants were classified into 1 of the following 4 hypothetical preclinical AD groups using baseline cerebrospinal fluid levels of A? and tau or A? and phosphorylated tau (p-tau): stage 0 (high A? and low tau), stage 1 (low A? and low tau), stage 2 (low A? and high tau), and suspected non-AD pathology (SNAP) (high A? and high tau). The data presented herein were collected between August 1995 and August 2014.An a priori cognitive composite score based on the following 4 tests previously shown to predict progression from normal cognition to symptom onset of mild cognitive impairment or dementia: Paired Associates immediate recall, Logical Memory delayed recall, Boston Naming, and Digit-Symbol Substitution. Linear mixed-effects models were used to compare the cognitive composite scores across the 4 groups over time, adjusting for baseline age, sex, education, and their interactions with time.Two hundred twenty-two cognitively normal participants were included in the analyses (mean follow-up, 11.0 years [range, 0-18.3 years] and mean baseline age, 56.9 years [range, 22.1-85.8 years]). Of these, 102 were stage 0, 46 were stage 1, 28 were stage 2, and 46 were SNAP. Individuals in stage 2 (low A? and high tau [or p-tau]) had lower baseline cognitive scores and a greater decline in the cognitive composite score relative to the other 3 groups (????-0.06 for all and P???.001 for the rate of decline for all). Individuals in stage 0, stage 1, and SNAP did not differ from one another in cognitive performance at baseline or over time (11.0 years) and showed practice-related improvement in performance. The APOE ?4 genotype was not associated with baseline cognitive composite score or the rate of change in the cognitive composite score.These results suggest that, to optimize observing a treatment effect, clinical trials enrolling cognitively normal individuals should selectively recruit participants with abnormal levels of both amyloid and tau (ie, stage 2) because this group would be expected to show the greatest cognitive decline over time if untreated.
| S-EPMC5173327 | biostudies-literature
Project description:ObjectiveTo determine whether a decline in cued recall is observable in the preclinical stage of Alzheimer disease (AD) in clinically normal older adults with elevated ?-amyloid (A?) burden on PET imaging.MethodsClinically normal older adults underwent baseline neuroimaging (PET to assess A?+/- status and MRI) and annual neuropsychological testing. Cox proportional hazards models were used to assess the relative risk of cued memory decline (drop of 1, 2, 3, or 4 points on the total score of the Free and Cued Selective Reminding Test) in relation to neuroimaging measures, functional status, age, sex, and education.ResultsA total of 276 older adults (Clinical Dementia Rating = 0, mean Mini-Mental State Examination score = 29 ± 1.06) were followed up for a mean of 3.6 ± 1.2 years. Despite the infrequency of cued memory decline (only 19% of participants scored ?46/48 in total recall by year 3), A?+ participants were 3.55 times (95% confidence interval = 1.77-7.12) more likely to exhibit decline in total recall (?46/48) compared with their A?- peers. Furthermore, A?+ participants who scored ?46/48 had smaller hippocampal volumes (t = 3.37, p = 0.001) and evidence of early functional decline, i.e., greater risk of progression to global Clinical Dementia Rating of 0.5 (?2 = 14.30, p < 0.001), compared with their A?+ peers with intact total recall.ConclusionsCued memory decline in healthy older adults may be particularly indicative of A?-related decline during the preclinical stage of AD and useful for identifying A?+ clinically normal individuals at greatest risk of short-term clinical progression.
| S-EPMC5386436 | biostudies-literature