scholarly journals SHORT-TERM PRACTICE EFFECTS AND AMYLOID DEPOSITION: PROVIDING INFORMATION ABOVE AND BEYOND BASELINE COGNITION

2017 ◽  
pp. 1-6
Author(s):  
K. Duff ◽  
D.B. Hammers ◽  
B.C.A. Dalley ◽  
K.R. Suhrie ◽  
T.J. Atkinson ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Clinical Trials ◽  
Test Scores ◽  
Amyloid Deposition ◽  
Cognitive Testing ◽  
Practice Effects ◽  
Cognitive Test ◽  
Cognitive Tests ◽  
Short Term

Background: Practice effects, which are improvements in cognitive test scores due to repeated exposure to testing materials, may provide information about Alzheimer’s disease pathology, which could be useful for clinical trials enrichment. Objectives: The current study sought to add to the limited literature on short-term practice effects on cognitive tests and their relationship to amyloid deposition on neuroimaging. Participants: Twenty-seven, non-demented older adults (9 cognitively intact, 18 with mild cognitive impairment) received amyloid imaging with 18F-Flutemetamol, and two cognitive testing sessions across one week to determine practice effects. Results: A composite measure of 18F-Flutemetamol uptake correlated significantly with all seven cognitive tests scores on the baseline battery (r’s = -0.61 – 0.59, all p’s<0.05), with higher uptake indicating poorer cognition. Practice effects significantly added to the relationship (above and beyond the baseline associations) with 18F-Flutemetamol uptake on 4 of the 7 cognitive test scores (partial r’s = -0.45 – 0.44, p’s<0.05), with higher uptake indicating poorer practice effects. The odds ratio of being “amyloid positive” was 13.5 times higher in individuals with low practice effects compared to high practice effects. Conclusions: Short-term practice effects over one week may be predictive of progressive dementia and serve as an affordable screening tool to enrich samples for preventative clinical trials in Alzheimer’s disease.

scholarly journals Cognitive Practice Effects Delay Diagnosis; Implications for Clinical Trials

2020 ◽  
Author(s):  
Mark Sanderson-Cimino ◽  
Jeremy A. Elman ◽  
Xin M. Tu ◽  
Alden L. Gross ◽  
Matthew S. Panizzon ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Clinical Trials ◽  
Practice Effect ◽  
Cognitive Testing ◽  
Practice Effects ◽  
Criterion Validation ◽  
Novel Method ◽  
Adjusted Scores

AbstractObjectivePractice effects on cognitive tests obscure decline, thereby delaying detection of mild cognitive impairment (MCI). This reduces opportunities for slowing Alzheimer’s disease progression and can hinder clinical trials. Using a novel method, we assessed the ability of practice-effect-adjusted diagnoses to detect MCI earlier, and tested the validity of these diagnoses based on AD biomarkers.MethodsOf 889 Alzheimer’s Disease Neuroimaging Initiative participants who were cognitively normal (CN) at baseline, 722 returned at 1-year-follow-up (mean age=74.9±6.8). Practice effects were calculated by comparing returnee scores at follow-up to demographically-matched individuals who had only taken the tests once, with an additional adjustment for attrition effects. Practice effects for each test were subtracted from follow-up scores. The lower scores put additional individuals below the impairment threshold for MCI. CSF amyloid-beta, phosphorylated tau, and total tau were measured at baseline and used for criterion validation.ResultsPractice-effect-adjusted scores increased MCI incidence by 26% (p<.001). Adjustment increased proportions of amyloid-positive MCI cases (+20%) and reduced proportions of amyloid-positive CNs (−6%) (ps<.007). With the increased MCI base rate, adjustment for practice effects would reduce the sample size needed for detecting significant drug treatment effects by an average of 21%, which we demonstrate would result in multi-million-dollar savings in a clinical trial.InterpretationAdjusting for practice effects on cognitive testing leads to earlier detection of MCI. When MCI is an outcome, this reduces recruitment needed for clinical trials, study duration, staff and participant burden, and can dramatically lower costs. Importantly, biomarker evidence also indicates improved diagnostic accuracy.

Tacrine in Alzheimer's Disease

1992 ◽  
Vol 160 (1) ◽  
pp. 36-40 ◽  
Author(s):  
Sarah Eagger ◽  
Nicola Morant ◽  
Raymond Levy ◽  
Barbara Sahakian
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Treatment Period ◽  
Practice Effects ◽  
Cognitive Tests ◽  
Rebound Effects ◽  
Short Intervals ◽  
Positive Effects ◽  
Cognitive Improvement ◽  
Practical Management

This paper concerns certain questions which arose during the analysis of a trial showing positive effects of tacrine in Alzheimer's disease. Cognitive improvement occurred during the first two weeks, reached a maximum at one month and was maintained during the rest of the three-month treatment period. Rebound effects were not detected in any of the key outcome variables, but were suggested by one of the supporting cognitive tests and other measures. Practice effects occurred on tests which were repeated at short intervals or too frequently. The paper discusses the significance of these findings for the interpretation of other trials and for practical management.

scholarly journals Monthly At-Home Computerized Cognitive Testing to Detect Diminished Practice Effects in Preclinical Alzheimer's Disease

2022 ◽  
Vol 13 ◽  
Author(s):  
Roos J. Jutten ◽  
Dorene M. Rentz ◽  
Jessie F. Fu ◽  
Danielle V. Mayblyum ◽  
Rebecca E. Amariglio ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Decline ◽  
Pet Imaging ◽  
Cognitive Testing ◽  
Practice Effects ◽  
Aging Brain ◽  
Amyloid Burden ◽  
Preclinical Ad ◽  
At Home

Introduction: We investigated whether monthly assessments of a computerized cognitive composite (C3) could aid in the detection of differences in practice effects (PE) in clinically unimpaired (CU) older adults, and whether diminished PE were associated with Alzheimer's disease (AD) biomarkers and annual cognitive decline.Materials and Methods:N = 114 CU participants (age 77.6 ± 5.0, 61% female, MMSE 29 ± 1.2) from the Harvard Aging Brain Study completed the self-administered C3 monthly, at-home, on an iPad for one year. At baseline, participants underwent in-clinic Preclinical Alzheimer's Cognitive Composite-5 (PACC5) testing, and a subsample (n = 72, age = 77.8 ± 4.9, 59% female, MMSE 29 ± 1.3) had 1-year follow-up in-clinic PACC5 testing available. Participants had undergone PIB-PET imaging (0.99 ± 1.6 years before at-home baseline) and Flortaucipir PET imaging (n = 105, 0.62 ± 1.1 years before at-home baseline). Linear mixed models were used to investigate change over months on the C3 adjusting for age, sex, and years of education, and to extract individual covariate-adjusted slopes over the first 3 months. We investigated the association of 3-month C3 slopes with global amyloid burden and tau deposition in eight predefined regions of interest, and conducted Receiver Operating Characteristic analyses to examine how accurately 3-month C3 slopes could identify individuals that showed &gt;0.10 SD annual decline on the PACC-5.Results: Overall, individuals improved on all C3 measures over 12 months (β = 0.23, 95% CI [0.21–0.25], p &lt; 0.001), but improvement over the first 3 months was greatest (β = 0.68, 95% CI [0.59–0.77], p &lt; 0.001), suggesting stronger PE over initial repeated exposures. However, lower PE over 3 months were associated with more global amyloid burden (r = −0.20, 95% CI [−0.38 – −0.01], p = 0.049) and tau deposition in the entorhinal cortex (r = −0.38, 95% CI [−0.54 – −0.19], p &lt; 0.001) and inferior-temporal lobe (r = −0.23, 95% CI [−0.41 – −0.02], p = 0.03). 3-month C3 slopes exhibited good discriminative ability to identify PACC-5 decliners (AUC 0.91, 95% CI [0.84–0.98]), which was better than baseline C3 (p &lt; 0.001) and baseline PACC-5 scores (p = 0.02).Conclusion: While PE are commonly observed among CU adults, diminished PE over monthly cognitive testing are associated with greater AD biomarker burden and cognitive decline. Our findings imply that unsupervised computerized testing using monthly retest paradigms can provide rapid detection of diminished PE indicative of future cognitive decline in preclinical AD.

scholarly journals Automatic Prediction of Cognitive and Functional Decline Can Significantly Decrease the Number of Subjects Required for Clinical Trials in Early Alzheimer’s Disease

2021 ◽  
pp. 1-8
Author(s):  
Neda Shafiee ◽  
Mahsa Dadar ◽  
Simon Ducharme ◽  
D. Louis Collins ◽  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Clinical Trials ◽  
Cognitive Decline ◽  
Functional Decline ◽  
Amyloid Β ◽  
Cognitive Test ◽  
Disease Heterogeneity ◽  
Early Alzheimer’S Disease

Background: While both cognitive and magnetic resonance imaging (MRI) data has been used to predict progression in Alzheimer’s disease, heterogeneity between patients makes it challenging to predict the rate of cognitive and functional decline for individual subjects. Objective: To investigate prognostic power of MRI-based biomarkers of medial temporal lobe atrophy and macroscopic tissue change to predict cognitive decline in individual patients in clinical trials of early Alzheimer’s disease. Methods: Data used in this study included 312 patients with mild cognitive impairment from the ADNI dataset with baseline MRI, cerebrospinal fluid amyloid-β, cognitive test scores, and a minimum of two-year follow-up information available. We built a prognostic model using baseline cognitive scores and MRI-based features to determine which subjects remain stable and which functionally decline over 2 and 3-year follow-up periods. Results: Combining both sets of features yields 77%accuracy (81%sensitivity and 75%specificity) to predict cognitive decline at 2 years (74%accuracy at 3 years with 75%sensitivity and 73%specificity). When used to select trial participants, this tool yields a 3.8-fold decrease in the required sample size for a 2-year study (2.8-fold decrease for a 3-year study) for a hypothesized 25%treatment effect to reduce cognitive decline. Conclusion: When used in clinical trials for cohort enrichment, this tool could accelerate development of new treatments by significantly increasing statistical power to detect differences in cognitive decline between arms. In addition, detection of future decline can help clinicians improve patient management strategies that will slow or delay symptom progression.

scholarly journals Neuroprotective and Anti-Inflammatory Effects of Low–Moderate Dose Ionizing Radiation in Models of Alzheimer’s Disease

2020 ◽  
Vol 21 (10) ◽  
pp. 3678 ◽  
Author(s):  
Sujin Kim ◽  
Yunkwon Nam ◽  
Chanyang Kim ◽  
Hyewon Lee ◽  
Seojin Hong ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Clinical Trials ◽  
Ionizing Radiation ◽  
Pharmacological Intervention ◽  
Therapeutic Effects ◽  
Moderate Dose ◽  
Short Term ◽  
Anti Inflammatory ◽  
5Xfad Mice

Alzheimer’s disease (AD) is the most common cause of dementia. The neuropathological features of AD include amyloid-β (Aβ) deposition and hyperphosphorylated tau accumulation. Although several clinical trials have been conducted to identify a cure for AD, no effective drug or treatment has been identified thus far. Recently, the potential use of non-pharmacological interventions to prevent or treat AD has gained attention. Low-dose ionizing radiation (LDIR) is a non-pharmacological intervention which is currently being evaluated in clinical trials for AD patients. However, the mechanisms underlying the therapeutic effects of LDIR therapy have not yet been established. In this study, we examined the effect of LDIR on Aβ accumulation and Aβ-mediated pathology. To investigate the short-term effects of low–moderate dose ionizing radiation (LMDIR), a total of 9 Gy (1.8 Gy per fraction for five times) were radiated to 4-month-old 5XFAD mice, an Aβ-overexpressing transgenic mouse model of AD, and then sacrificed at 4 days after last exposure to LMDIR. Comparing sham-exposed and LMDIR-exposed 5XFAD mice indicated that short-term exposure to LMDIR did not affect Aβ accumulation in the brain, but significantly ameliorated synaptic degeneration, neuronal loss, and neuroinflammation in the hippocampal formation and cerebral cortex. In addition, a direct neuroprotective effect was confirmed in SH-SY5Y neuronal cells treated with Aβ1–42 (2 μM) after single irradiation (1 Gy). In BV-2 microglial cells exposed to Aβ and/or LMDIR, LMDIR therapy significantly inhibited the production of pro-inflammatory molecules and activation of the nuclear factor-kappa B (NF-κB) pathway. These results indicate that LMDIR directly ameliorated neurodegeneration and neuroinflammation in vivo and in vitro. Collectively, our findings suggest that the therapeutic benefits of LMDIR in AD may be mediated by its neuroprotective and anti-inflammatory effects.

scholarly journals Predicting Progression & Cognitive Decline in Amyloid-Positive Patients with Alzheimer's Disease

2021 ◽  
Author(s):  
Hákon Valur Dansson ◽  
Lena Stempfle ◽  
Hildur Egilsdóttir ◽  
Alexander Schliep ◽  
Erik Portelius ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Decline ◽  
Disease Progression ◽  
Test Scores ◽  
Amyloid Β ◽  
Cognitive Test ◽  
Progression Rate ◽  
Specific Level ◽  
Clinical Variables

Abstract BackgroundIn Alzheimer’s disease (AD), amyloid- β (Aβ) peptides aggregate in the brain forming amyloid plaques, which are a key pathological hallmark of the disease. However, plaques may also be present in cognitively unimpaired elderly individuals. Therefore, it is of great value to explain the variance in disease progression among patients with Aβ pathology. MethodsA cohort of n= 2293 participants from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database was selected to study heterogeneity in disease progression for individuals with Aβ plaque pathology. The analysis used baseline clinical variables including demographics, genetic markers and neuropsychological data to predict how the cognitive ability and AD diagnosis of subjects progressed using statistical models and machine learning. Due to the limited prevalence of Aβ pathology, models fit only to Aβ-positive subjects were compared to models fit to an extended cohort including subjects without established Aβ pathology, adjusting for covariate differences between the cohorts. ResultsAβ pathology status was determined based the Aβ 42 /Aβ 40 ratio. The best predictive model of change in cognitive test scores for Aβ-positive subjects at the two-year follow-up achieved an R 2 score of 0.388 while the best model predicting adverse changes in diagnosis achieved a weighted F1 score of 0.791. Conforming to expectations, Aβ-positive subjects declined faster on average than those without Aβ pathology, but the specific level of Aβ plaques was not predictive of progression rate. For the four-year prediction task of cognitive score change, the best model achieved an R 2 score of 0.325 and it was found that fitting models to the extended cohort substantially improved performance. Moreover, using all clinical variables outperformed the best model based only on baseline cognitive test scores which achieved an R 2 score of 0.228. ConclusionOur analysis shows that levels of Aβ plaques are not strong predictors of the rate of cognitive decline in Aβ-positive subjects. Baseline assessments of cognitive function accounts for the majority of variance explained in the prediction of two-year decline but is insufficient for achieving optimal results in longer-term predictions. Predicting changes both in cognitive test scores and in diagnosis provides multiple perspectives of the progression of potential AD subjects.

scholarly journals Empirically derived composite cognitive test scores to predict preclinical and clinical stages of Alzheimer’s disease

2021 ◽  
Vol 17 (S5) ◽  
Author(s):  
Rosita Shishegar ◽  
Tze Young Chai ◽  
Timothy Cox ◽  
Fiona Lamb ◽  
Joanne S. Robertson ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Test Scores ◽  
Cognitive Test ◽  
Clinical Stages

Deficits in short-term memory binding are detectable in individuals with brain amyloid deposition in the absence of overt neurodegeneration in the Alzheimer’s disease continuum

2021 ◽  
Vol 152 ◽  
pp. 105749
Author(s):  
Mario Amore Cecchini ◽  
Mônica Sanches Yassuda ◽  
Paula Squarzoni ◽  
Artur Martins Coutinho ◽  
Daniele de Paula Faria ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Short Term Memory ◽  
Amyloid Deposition ◽  
Short Term ◽  
Term Memory ◽  
Memory Binding ◽  
Brain Amyloid Deposition

scholarly journals Intermittent Hypoxia-Hyperoxia Training Improves Cognitive Function and Decreases Circulating Biomarkers of Alzheimer’s Disease in Patients with Mild Cognitive Impairment: A Pilot Study

2019 ◽  
Vol 20 (21) ◽  
pp. 5405 ◽  
Author(s):  
Zoya O. Serebrovska ◽  
Tetiana V. Serebrovska ◽  
Viktor A. Kholin ◽  
Lesya V. Tumanovska ◽  
Angela M. Shysh ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Cognitive Function ◽  
Pilot Study ◽  
Peripheral Blood ◽  
Test Scores ◽  
Cognitive Test ◽  
Circulating Biomarkers

Alzheimer’s disease (AD) affects not only the central nervous system, but also peripheral blood cells including neutrophils and platelets, which actively participate in pathogenesis of AD through a vicious cycle between platelets aggregation and production of excessive amyloid beta (Aβ). Platelets adhesion on amyloid plaques also increases the risk of cerebral microcirculation disorders. Moreover, activated platelets release soluble adhesion molecules that cause migration, adhesion/activation of neutrophils and formation of neutrophil extracellular traps (NETs), which may damage blood brain barrier and destroy brain parenchyma. The present study examined the effects of intermittent hypoxic-hyperoxic training (IHHT) on elderly patients with mild cognitive impairment (MCI), a precursor of AD. Twenty-one participants (age 51–74 years) were divided into three groups: Healthy Control (n = 7), MCI+Sham (n = 6), and MCI+IHHT (n = 8). IHHT was carried out five times per week for three weeks (total 15 sessions). Each IHHT session consisted of four cycles of 5-min hypoxia (12% FIO2) and 3-min hyperoxia (33% FIO2). Cognitive parameters, Aβ and amyloid precursor protein (APP) expression, microRNA 29, and long non-coding RNA in isolated platelets as well as NETs in peripheral blood were investigated. We found an initial decline in cognitive function indices in both MCI+Sham and MCI+IHHT groups and significant correlations between cognitive test scores and the levels of circulating biomarkers of AD. Whereas sham training led to no change in these parameters, IHHT resulted in the improvement in cognitive test scores, along with significant increase in APP ratio and decrease in Aβ expression and NETs formation one day after the end of three-week IHHT. Such effects on Aβ expression and NETs formation remained more pronounced one month after IHHT. In conclusion, our results from this pilot study suggested a potential utility of IHHT as a new non-pharmacological therapy to improve cognitive function in pre-AD patients and slow down the development of AD.

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