Delaying the onset of Alzheimer disease: bilingualism as a form of cognitive reserve.
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ABSTRACT:
SUBMITTER: Craik FI
PROVIDER: S-EPMC3033609 | biostudies-other | 2010 Nov
REPOSITORIES: biostudies-other
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Project description:ObjectiveTo examine the effect of education (a surrogate measure of cognitive reserve) on FDG-PET brain metabolism in elderly cognitively healthy (HC) subjects with preclinical Alzheimer disease (AD).MethodsFifty-two HC subjects (mean age 75 years) with FDG-PET and CSF measurement of Aβ1-42 were included from the prospective Alzheimer's Disease Neuroimaging Initiative biomarker study. HC subjects received a research classification of preclinical AD if CSF Aβ1-42 was <192 pg/mL (Aβ1-42 [+]) vs HC with normal Aβ (Aβ1-42 [-]). In regression analyses, we tested the interaction effect between education and CSF Aβ1-42 status (Aβ1-42 [+] vs Aβ1-42 [-]) on FDG-PET metabolism in regions of interest (ROIs) (posterior cingulate, angular gyrus, inferior/middle temporal gyrus) and the whole brain (voxel-based).ResultsAn interaction between education and CSF Aβ1-42 status was observed for FDG-PET in the posterior cingulate (p < 0.001) and angular gyrus ROIs (p = 0.03), but was not significant for the inferior/middle temporal gyrus ROI (p = 0.06), controlled for age, sex, and global cognitive ability (Alzheimer's Disease Assessment Scale-cognitive subscale). The interaction effect was such that higher education was associated with lower FDG-PET in the Aβ1-42 (+) group, but with higher FDG-PET in the Aβ1-42 (-) group. Voxel-based analysis showed that this interaction effect was primarily restricted to temporo-parietal and ventral prefrontal brain areas.ConclusionsHigher education was associated with lower FDG-PET in preclinical AD (Aβ1-42 [+]), suggesting that cognitive reserve had a compensatory function to sustain cognitive ability in presence of early AD pathology that alters FDG-PET metabolism.
| S-EPMC3691784 | biostudies-literature
Project description:OBJECTIVE:To investigate the relationship between cognitive reserve (CR) and clinical progression across the Alzheimer disease (AD) spectrum. METHODS:We selected 839 β-amyloid (Aβ)-positive participants with normal cognition (NC, n = 175), mild cognitive impairment (MCI, n = 437), or AD dementia (n = 227) from the Alzheimer's Disease Neuroimaging Initiative (ADNI). CR was quantified using standardized residuals (W scores) from a (covariate-adjusted) linear regression with global cognition (13-item Alzheimer's Disease Assessment Scale-cognitive subscale) as an independent variable of interest, and either gray matter volumes or white matter hyperintensity volume as dependent variables. These W scores, reflecting whether an individual's degree of cerebral damage is lower or higher than clinically expected, were tested as predictors of diagnostic conversion (i.e., NC to MCI/AD dementia, or MCI to AD dementia) and longitudinal changes in memory (ADNI-MEM) and executive functions (ADNI-EF). RESULTS:The median follow-up period was 24 months (interquartile range 6-42). Corrected for age, sex, APOE4 status, and baseline cerebral damage, higher gray matter volume-based W scores (i.e., greater CR) were associated with a lower diagnostic conversion risk (hazard ratio [HR] 0.22, p < 0.001) and slower decline in memory (β = 0.48, p < 0.001) and executive function (β = 0.67, p < 0.001). Stratified by disease stage, we found similar results for NC (diagnostic conversion: HR 0.30, p = 0.038; ADNI-MEM: β = 0.52, p = 0.028; ADNI-EF: β = 0.42, p = 0.077) and MCI (diagnostic conversion: HR 0.21, p < 0.001; ADNI-MEM: β = 0.43, p = 0.003; ADNI-EF: β = 0.59, p < 0.001), but opposite findings (i.e., more rapid decline) for AD dementia (ADNI-MEM: β = -0.91, p = 0.002; ADNI-EF: β = -0.77, p = 0.081). CONCLUSIONS:Among Aβ-positive individuals, greater CR related to attenuated clinical progression in predementia stages of AD, but accelerated cognitive decline after the onset of dementia.
| S-EPMC6669930 | biostudies-literature
Project description:ObjectiveTo test whether higher global functional connectivity of the left frontal cortex (LFC) in Alzheimer disease (AD) is associated with more years of education (a proxy of cognitive reserve [CR]) and mitigates the association between AD-related fluorodeoxyglucose (FDG)-PET hypometabolism and episodic memory.MethodsForty-four amyloid-PET-positive patients with amnestic mild cognitive impairment (MCI-Aβ+) and 24 amyloid-PET-negative healthy controls (HC) were included. Voxel-based linear regression analyses were used to test the association between years of education and FDG-PET in MCI-Aβ+, controlled for episodic memory performance. Global LFC (gLFC) connectivity was computed through seed-based resting-state fMRI correlations between the LFC (seed) and each voxel in the gray matter. In linear regression analyses, education as a predictor of gLFC connectivity and the interaction of gLFC connectivity × FDG-PET hypometabolism on episodic memory were tested.ResultsFDG-PET metabolism in the precuneus was reduced in MCI-Aβ+ compared to HC (p = 0.028), with stronger reductions observed in MCI-Aβ+ with more years of education (p = 0.006). In MCI-Aβ+, higher gLFC connectivity was associated with more years of education (p = 0.021). At higher levels of gLFC connectivity, the association between precuneus FDG-PET hypometabolism and lower memory performance was attenuated (p = 0.027).ConclusionsHigher gLFC connectivity is a functional substrate of CR that helps to maintain episodic memory relatively well in the face of emerging FDG-PET hypometabolism in early-stage AD.
| S-EPMC5384837 | biostudies-literature
Project description:OBJECTIVE:Bilingual healthy adults have been shown to exhibit an advantage in executive functioning (EF) that is associated with microstructural changes in white matter (WM) networks. Patients with temporal lobe epilepsy (TLE) often show EF deficits that are associated with WM compromise. In this study, we investigate whether bilingualism can increase cognitive reserve and/or brain reserve in bilingual patients with TLE, mitigating EF impairment and WM compromise. METHODS:Diffusion tensor imaging was obtained in 19 bilingual and 26 monolingual patients with TLE, 12 bilingual healthy controls (HC), and 21 monolingual HC. Fractional anisotropy (FA) and mean diffusivity (MD) were calculated for the uncinate fasciculus (Unc) and cingulum (Cing), superior frontostriatal tract (SFS), and inferior frontostriatal tract (IFS). Measures of EF included Trail Making Test-B (TMT-B) and Delis-Kaplan Executive Function System Color-Word Inhibition/Switching. Analyses of covariance were conducted to compare FA and MD of the Unc, Cing, SFS, and IFS and EF performance across groups. RESULTS:In bilingual patients, FA was lower in the ipsilateral Cing and Unc compared to all other groups. For both patient groups, MD of the ipsilateral Unc was higher relative to HC. Despite more pronounced reductions in WM integrity, bilingual patients performed similarly to monolingual TLE and both HC groups on EF measures. By contrast, monolingual patients performed worse than HC on TMT-B. In addition, differences in group means between bilingual and monolingual patients on TMT-B approached significance when controlling for the extent of WM damage (P = .071; d = 0.62), suggesting a tendency toward higher performance for bilingual patients. SIGNIFICANCE:Despite poorer integrity of regional frontal lobe WM, bilingual patients performed similarly to monolingual patients and HC on EF measures. These findings align with studies suggesting that bilingualism may provide a protective factor for individuals with neurological disease, potentially through reorganization of EF networks that promote greater cognitive reserve.
| S-EPMC7315382 | biostudies-literature
Project description:Education, occupation, premorbid intelligence, and brain size are surrogate markers for cognitive reserve. Whether these markers have biological influence on Alzheimer disease (AD) pathology is not known. We thus aimed to investigate the effect of cognitive reserve proxies on longitudinal change of AD biomarkers. A total of 819 participants with normal cognition, mild cognitive impairment, and mild AD were enrolled in the Alzheimer's Disease Neuroimaging Initiative and followed up with repeated measures of cerebrospinal fluid, positron emission tomography, and magnetic resonance imaging biomarkers. Generalized estimating equations were used to assess whether biomarker rates of change were modified by reserve proxies. Cerebrospinal fluid A?42 decline was slower in normal cognition participants with higher cognitive reserve indexed by education, occupation, and American National Adult Reading Test (ANART). The decline of [F] fluorodeoxyglucose positron emission tomography uptake was slower in AD participants with better performance on the ANART. Education, occupation, and ANART did not modify the rates of magnetic resonance imaging hippocampal atrophy in any group. These findings remained unchanged after accounting for APOE 4, longitudinal missing data, and baseline cognitive performance. Higher levels of reserve markers may slow the rate of amyloid deposition before cognitive impairment and preserve glucose metabolism at the dementia stage over the course of AD pathologic progression.
| S-EPMC3745532 | biostudies-literature
Project description:Alzheimer's disease (AD) extracts a heavy societal toll. The value of medical advances that delay onset of AD could be significant. Using data from nationally representative samples from the Health and Retirement Study (1998-2008) and Aging Demographics and Memory Study (2001-2009), we estimate the prevalence and incidence of AD and the formal and informal health care costs associated with it. We use microsimulation to project future prevalence and costs of AD under different treatment scenarios. We find from 2010 to 2050, the number of individuals ages 70+ with AD increases 153%, from 3.6 to 9.1 million, and annual costs increase from $307 billion ($181B formal, $126B informal costs) to $1.5 trillion. 2010 annual per person costs were $71,303 and double by 2050. Medicare and Medicaid are paying 75% of formal costs. Medical advances that delay onset of AD for 5 years result in 41% lower prevalence and 40% lower cost of AD in 2050. For one cohort of older individuals, who would go on to acquire AD, a 5-year delay leads to 2.7 additional life years (about 5 AD-free), slightly higher formal care costs due to longer life but lower informal care costs for a total value of $511,208 per person. We find Medical advances delaying onset of AD generate significant economic and longevity benefits. The findings inform clinicians, policymakers, businesses and the public about the value of prevention, diagnosis, and treatment of AD.
| S-EPMC4851168 | biostudies-literature
Project description:BackgroundThe course of Alzheimer's disease (AD) includes a 10-20-year preclinical period with progressive accumulation of amyloid β (Aβ) plaques and neurofibrillary tangles in the absence of symptomatic cognitive or functional decline. The duration of this preclinical stage in part depends on the rate of pathologic progression, which is offset by compensatory mechanisms, referred to as cognitive reserve (CR). Comorbid medical conditions, psychosocial stressors, and inappropriate medication use may lower CR, hastening the onset of symptomatic AD. Here, we describe a randomized controlled trial (RCT) designed to test the efficacy of a medication therapy management (MTM) intervention to reduce inappropriate medication use, bolster cognitive reserve, and ultimately delay symptomatic AD.Methods/designOur study aims to enroll 90 non-demented community-dwelling adults ≥ 65 years of age. Participants will undergo positron emission tomography (PET) scans, measuring Aβ levels using standardized uptake value ratios (SUVr). Participants will be randomly assigned to MTM intervention or control, stratified by Aβ levels, and followed for 12 months via in-person and telephone visits. Outcomes of interest include: (1) medication appropriateness (measured with the Medication Appropriateness Index (MAI)); (2) scores from Trail Making Test B (TMTB), Montreal Cognitive Assessment (MoCA), and California Verbal Learning Test (CVLT); (3) perceived health status (measured with the SF-36). We will also evaluate pre- to post-intervention change in: (1) use of inappropriate medications as measured by MAI; 2) CR Change Score (CRCS), defined as the difference in scopolamine-challenged vs unchallenged cognitive scores at baseline and follow-up. Baseline Aβ SUVr will be used to examine the relative impact of preclinical AD (pAD) pathology on CRCS, as well as the interplay of amyloid burden with inappropriate medication use.DiscussionThis manuscript describes the protocol of INCREASE ("INtervention for Cognitive Reserve Enhancement in delaying the onset of Alzheimer's Symptomatic Expression"): a randomized controlled trial that investigates the impact of deprescribing inappropriate medications and optimizing medication regimens on potentially delaying the onset of symptomatic AD and AD-related dementias.Trial registrationClinicalTrials.gov, NCT02849639. Registered on 29 July 2016.
| S-EPMC6937673 | biostudies-literature
Project description:ImportanceIndividuals with autosomal dominant mutations for Alzheimer disease are valuable in determining biomarkers present prior to the onset of cognitive decline, improving the ability to diagnose Alzheimer disease as early as possible. Optical coherence tomography (OCT) has surfaced as a potential noninvasive technique capable of analyzing central nervous system tissues for biomarkers of Alzheimer disease.ObjectiveTo evaluate whether OCT can detect early retinal alterations in carriers of the presenilin 1 (PSEN1 [OMIM 104311]) E280A mutation who are cognitively unimpaired.Design, setting, and participantsA cross-sectional imaging study conducted from July 13, 2015, to September 16, 2020, included 10 carriers of the PSEN1 E280A mutation who were cognitively unimpaired and 10 healthy noncarrier family members, all leveraged from a homogenous Colombian kindred. Statistical analysis was conducted from September 9, 2017, to September 16, 2020.Main outcomes and measuresMixed-effects multiple linear regression was performed to compare the thickness values of the whole retina and individual retinal layers on OCT scans between mutation carriers and noncarriers. Simple linear-effects and mixed-effects multiple linear regression models were used to assess whether age was an effect modifier for PSEN1 mutation of amyloid β levels and retinal thickness, respectively. Fundus photographs were used to compare the number of arterial and venous branch points, arterial and venous tortuosity, and fractal dimension.ResultsThis study included 10 carriers of the PSEN1 E280A mutation who were cognitively unimpaired (7 women [70%]; mean [SD] age, 36.3 [8.1] years) and 10 healthy noncarrier family members (7 women [70%]; mean [SD] age, 36.4 [8.2] years). Compared with noncarrier controls, PSEN1 mutation carriers who were cognitively unimpaired had a generalized decrease in thickness of the whole retina as well as individual layers detected on OCT scans, with the inner nuclear layer (outer superior quadrant, β = -3.06; P = .007; outer inferior quadrant, β = -2.60; P = .02), outer plexiform layer (outer superior quadrant, β = -3.44; P = .03), and outer nuclear layer (central quadrant, β = -8.61; P = .03; inner nasal quadrant, β = -8.39; P = .04; inner temporal quadrant, β = -9.39; P = .02) showing the greatest amount of statistically significant thinning. Age was a significant effect modifier for the association between PSEN1 mutation and amyloid β levels in cortical regions (β = 0.03; P = .001) but not for the association between PSEN1 mutation and retinal thickness. No statistical difference was detected in any of the vascular parameters studied.Conclusions and relevanceThese findings suggest that OCT can detect functional and morphologic changes in the retina of carriers of familial Alzheimer disease who are cognitively unimpaired several years before clinical onset, suggesting that OCT findings and retinal vascular parameters may be biomarkers prior to the onset of cognitive decline.
| S-EPMC7662482 | biostudies-literature
Project description:Huntington disease (HD) is associated with decline in cognition and progressive morphological changes in brain structures. Cognitive reserve may represent a mechanism by which disease-related decline may be delayed or slowed. The current study examined the relationship between cognitive reserve and longitudinal change in cognitive functioning and brain volumes among prodromal (gene expansion-positive) HD individuals. Participants were genetically confirmed individuals with prodromal HD enrolled in the PREDICT-HD study. Cognitive reserve was computed as the composite of performance on a lexical task estimating premorbid intellectual level, occupational status, and years of education. Linear mixed effects regression (LMER) was used to examine longitudinal changes on four cognitive measures and three brain volumes over approximately 6 years. Higher cognitive reserve was significantly associated with a slower rate of change on one cognitive measure (Trail Making Test, Part B) and slower rate of volume loss in two brain structures (caudate, putamen) for those estimated to be closest to motor disease onset. This relationship was not observed among those estimated to be further from motor disease onset. Our findings demonstrate a relationship between cognitive reserve and both a measure of executive functioning and integrity of certain brain structures in prodromal HD individuals.
| S-EPMC3720793 | biostudies-literature
Project description:A systematic review was conducted to investigate whether bilingualism has a protective effect against cognitive decline in aging and can protect against dementia. We searched the Medline, ScienceDirect, Scopus, and ERIC databases with a cut-off date of 31 March, 2019, thereby following the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) protocol. Our search resulted in 34 eligible studies. Mixed results were found with respect to the protective effect of bilingualism against cognitive decline. Several studies showed a protective effect whereas other studies failed to find it. Moreover, evidence for a delay of the onset of dementia of between 4 and 5.5 years in bilingual individuals compared to monolinguals was found in several studies, but not in all. Methodological differences in the set-up of the studies seem to explain these mixed results. Lifelong bilingualism is a complex individual process, and many factors seem to influence this and need to be further investigated. This can be best achieved through large longitudinal studies with objective behavioral and neuroimaging measurements. In conclusion, although some evidence was found for a cognitive reserve-enhancing effect of lifelong bilingualism and protection against dementia, to date, no firm conclusions can be drawn.
| S-EPMC6680432 | biostudies-literature