Dataset Information

Late-onset Alzheimer's risk variants in memory decline, incident mild cognitive impairment, and Alzheimer's disease.

ABSTRACT: We tested association of nine late-onset Alzheimer's disease (LOAD) risk variants from genome-wide association studies (GWAS) with memory and progression to mild cognitive impairment (MCI) or LOAD (MCI/LOAD) in older Caucasians, cognitively normal at baseline and longitudinally evaluated at Mayo Clinic Rochester and Jacksonville (n>2000). Each variant was tested both individually and collectively using a weighted risk score. APOE-e4 associated with worse baseline memory and increased decline with highly significant overall effect on memory. CLU-rs11136000-G associated with worse baseline memory and incident MCI/LOAD. MS4A6A-rs610932-C associated with increased incident MCI/LOAD and suggestively with lower baseline memory. ABCA7-rs3764650-C and EPHA1-rs11767557-A associated with increased rates of memory decline in subjects with a final diagnosis of MCI/LOAD. PICALM-rs3851179-G had an unexpected protective effect on incident MCI/LOAD. Only APOE-inclusive risk scores associated with worse memory and incident MCI/LOAD. The collective influence of the nine top LOAD GWAS variants on memory decline and progression to MCI/LOAD appears limited. Discovery of biologically functional variants at these loci may uncover stronger effects on memory and incident disease.

SUBMITTER: Carrasquillo MM

PROVIDER: S-EPMC4268433 | biostudies-literature | 2015 Jan

REPOSITORIES: biostudies-literature

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Late-onset Alzheimer's risk variants in memory decline, incident mild cognitive impairment, and Alzheimer's disease.

Carrasquillo Minerva M MM Crook Julia E JE Pedraza Otto O Thomas Colleen S CS Pankratz V Shane VS Allen Mariet M Nguyen Thuy T Malphrus Kimberly G KG Ma Li L Bisceglio Gina D GD Roberts Rosebud O RO Lucas John A JA Smith Glenn E GE Ivnik Robert J RJ Machulda Mary M MM Graff-Radford Neill R NR Petersen Ronald C RC Younkin Steven G SG Ertekin-Taner Nilüfer N

Neurobiology of aging 20140804 1

We tested association of nine late-onset Alzheimer's disease (LOAD) risk variants from genome-wide association studies (GWAS) with memory and progression to mild cognitive impairment (MCI) or LOAD (MCI/LOAD) in older Caucasians, cognitively normal at baseline and longitudinally evaluated at Mayo Clinic Rochester and Jacksonville (n>2000). Each variant was tested both individually and collectively using a weighted risk score. APOE-e4 associated with worse baseline memory and increased decline wit ...[more]

PMID: 25189118

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Project description:ObjectiveTo estimate the incidence of psychotic symptoms in Alzheimer's disease.MethodsThe study consists of 776 elderly subjects presenting to the Alzheimer Disease Research Center at the University of Pittsburgh (Pittsburgh, Pennsylvania) between May 9, 2000, and August 19, 2014. All participants were diagnosed with mild cognitive impairment (National Institute on Aging-Alzheimer's Association workgroup criteria) or possible or probable Alzheimer's disease (National Institute of Neurologic and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association criteria) and were without psychosis at entry. Psychotic symptoms were evaluated using the Consortium to Establish a Registry for Alzheimer's Disease Behavioral Rating Scale every 6 months. One-, 3- and 5-year cumulative incidences of psychosis were calculated.ResultsThe 1-year psychosis incidence was 10% (95% CI, 8%-12%), and this annual rate remained remarkably consistent at 3 and 5 years. Psychosis incidence was related to cognitive status at all time points. However, the incidence rate reached a plateau during the disease course. Cumulative psychosis incidence at 5 years was 61% (95% CI, 52%-69%) in individuals with moderate to severe Alzheimer's disease, not statistically significantly different from the cumulative incidence at 3 years in this group, which was 48% (95% CI, 40%-55%) or from the 5-year incidence in individuals who entered the study with mild Alzheimer's disease, which was 48% (95% CI, 41%-56%).ConclusionsPsychosis in Alzheimer's disease has been associated with a number of adverse clinical outcomes. We provide estimates of the risk of psychosis onset within clinically defined subgroups of individuals, a tool clinicians can use in treatment planning. Anticipating which subjects are at high risk for psychosis and the poor outcomes associated with it can help with family education and support decisions to implement nonpharmacologic strategies that may reduce or prevent symptoms.

Project description:In this paper, we explore the utility of resting-state EEG measures as potential biomarkers for the detection and assessment of cognitive decline in mild cognitive impairment (MCI) and Alzheimer's disease (AD). Neurophysiological biomarkers of AD derived from EEG and FDG-PET, once characterized and validated, would expand the set of existing diagnostic molecular biomarkers of AD pathology with associated biomarkers of disease progression and neural dysfunction. Since symptoms of AD often begin to appear later in life, successful identification of EEG-based biomarkers must account for age-related neurophysiological changes that occur even in healthy individuals. To this end, we collected EEG data from individuals with AD (n = 26), MCI (n = 53), and cognitively normal healthy controls stratified by age into three groups: 18-40 (n = 129), 40-60 (n = 62) and 60-90 (= 55) years old. For each participant, we computed power spectral density at each channel and spectral coherence between pairs of channels. Compared to age matched controls, in the AD group, we found increases in both spectral power and coherence at the slower frequencies (Delta, Theta). A smaller but significant increase in power of slow frequencies was observed for the MCI group, localized to temporal areas. These effects on slow frequency spectral power opposed that of normal aging observed by a decrease in the power of slow frequencies in our control groups. The AD group showed a significant decrease in the spectral power and coherence in the Alpha band consistent with the same effect in normal aging. However, the MCI group did not show any significant change in the Alpha band. Overall, Theta to Alpha ratio (TAR) provided the largest and most significant differences between the AD group and controls. However, differences in the MCI group remained small and localized. We proposed a novel method to quantify these small differences between Theta and Alpha bands' power using empirically derived distributions of spectral power across the time domain as opposed to averaging power across time. We defined Power Distribution Distance Measure (PDDM) as a distance measure between probability distribution functions (pdf) of Theta and Alpha power. Compared to average TAR, using PDDF enhanced the statistical significance, the effect size, and the spatial distribution of significant effects in the MCI group. We designed classifiers for differentiating individual MCI and AD participants from age-matched controls. The classification performance measured by the area under ROC curve after cross-validation were AUC = 0.85 and AUC = 0.6, for AD and MCI classifiers, respectively. Posterior probability of AD, TAR, and the proposed PDDM measure were all significantly correlated with MMSE score and neuropsychological tests in the AD group.

Project description:BackgroundAlzheimer's disease (AD) biomarkers are emerging as critically important for disease detection and monitoring. Most biomarkers are obtained through invasive, resource-intense procedures. A cognitive marker, intra-individual cognitive variability (IICV) may provide an alternative or adjunct marker of disease risk for individuals unable or disinclined to undergo lumbar puncture.ObjectiveTo contrast risk of incident AD and mild cognitive impairment (MCI) associated with IICV to risk associated with well-established biomarkers: cerebrospinal fluid (CSF) phosphorylated tau protein (p-tau181) and amyloid-β 42 (Aβ42) peptide.MethodsDispersion in cognitive performance, IICV, was estimated with a published algorithm, and included Trail Making Test A and B, Rey Auditory Verbal Learning Test (RAVLT), and the American National Adult Reading Test (ANART). CSF biomarkers were expressed as a ratio: p-tau181/Aβ42, wherein high values signified pathognomonic profiles. Logistic regression models included longitudinal data from 349 Alzheimer's Disease Neuroimaging Initiative (ADNI) participants who completed lumbar puncture. All subjects were cognitively healthy (n = 105) or diagnosed with MCI (n = 244) at baseline. We examined odds of conversion associated with baseline elevations in IICV and/or ratio of CSF p-tau181/Aβ42.ResultsWhen included in models alone or in combination with CSF p-tau181/Aβ42, one standard IICV unit higher was associated with an estimated odds ratio for incident AD or MCI of 2.81 (95% CI: 1.83-4.33) in the most inclusive sample, and an odds ratio of 3.41 (95% CI: 2.03-5.73) when restricted to participants with MCI. Iterative analyses suggested that IICV independently improved model fit even when individual index components were included in comparative models.ConclusionsThese analyses provide preliminary support for IICV as a marker of incident AD and MCI. This easily-disseminated, non-invasive marker compared favorably to well-established CSF biomarkers.

Dataset Information

Late-onset Alzheimer's risk variants in memory decline, incident mild cognitive impairment, and Alzheimer's disease.

Publications

Late-onset Alzheimer's risk variants in memory decline, incident mild cognitive impairment, and Alzheimer's disease.

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