| 1. |
- Zhou, XP, et al.
(författare)
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Non-coding variability at the APOE locus contributes to the Alzheimer's risk
- 2019
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 10:1, s. 3310-
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer’s disease (AD) is a leading cause of mortality in the elderly. While the coding change of APOE-ε4 is a key risk factor for late-onset AD and has been believed to be the only risk factor in the APOE locus, it does not fully explain the risk effect conferred by the locus. Here, we report the identification of AD causal variants in PVRL2 and APOC1 regions in proximity to APOE and define common risk haplotypes independent of APOE-ε4 coding change. These risk haplotypes are associated with changes of AD-related endophenotypes including cognitive performance, and altered expression of APOE and its nearby genes in the human brain and blood. High-throughput genome-wide chromosome conformation capture analysis further supports the roles of these risk haplotypes in modulating chromatin states and gene expression in the brain. Our findings provide compelling evidence for additional risk factors in the APOE locus that contribute to AD pathogenesis.
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| 2. |
- de Heus, R. A. A., et al.
(författare)
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Blood Pressure Lowering With Nilvadipine in Patients With Mild-to-Moderate Alzheimer Disease Does Not Increase the Prevalence of Orthostatic Hypotension
- 2019
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Ingår i: Journal of the American Heart Association. - : Ovid Technologies (Wolters Kluwer Health). - 2047-9980. ; 8:10
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Tidskriftsartikel (refereegranskat)abstract
- Background-Hypertension is common among patients with Alzheimer disease. Because this group has been excluded from hypertension trials, evidence regarding safety of treatment is lacking. This secondary analysis of a randomized controlled trial assessed whether antihypertensive treatment increases the prevalence of orthostatic hypotension (OH) in patients with Alzheimer disease. Methods and Results-Four hundred seventy-seven patients with mild-to-moderate Alzheimer disease were randomized to the calcium-channel blocker nilvadipine 8 mg/day or placebo for 78 weeks. Presence of OH (blood pressure drop >= 20/>= 10 mm Hg after 1 minute of standing) and OH-related adverse events (dizziness, syncope, falls, and fractures) was determined at 7 follow-up visits. Mean age of the study population was 72.2 +/- 8.2 years and mean Mini-Mental State Examination score was 20.4 +/- 3.8. Baseline blood pressure was 137.8 +/- 14.0/77.0 +/- 8.6 mm Hg. Grade I hypertension was present in 53.4% (n=255). After 13 weeks, blood pressure had fallen by -7.8/-3.9 mm Hg for nilvadipine and by -0.4/-0.8 mm Hg for placebo (P<0.001). Across the 78-week intervention period, there was no difference between groups in the proportion of patients with OH at a study visit (odds ratio [95% CI] 1.1 [0.8-1.5], P 0.62), nor in the proportion of visits where a patient met criteria for OH, corrected for number of visits (7.7 +/- 13.8% versus 7.3 +/- 11.6%). OH-related adverse events were not more often reported in the intervention group compared with placebo. Results were similar for those with baseline hypertension. Conclusions-This study suggests that initiation of a low dose of antihypertensive treatment does not significantly increase the risk of OH in patients with mild-to-moderate Alzheimer disease.
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| 4. |
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| 5. |
- Insel, P. S., et al.
(författare)
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Biomarkers and cognitive endpoints to optimize trials in Alzheimer's disease
- 2015
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Ingår i: Annals of Clinical and Translational Neurology. - : Wiley. - 2328-9503. ; 2:5, s. 534-547
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To find the combination of candidate biomarkers and cognitive endpoints to maximize statistical power and minimize cost of clinical trials of healthy elders at risk for cognitive decline due to Alzheimer's disease. Methods: Four-hundred and twelve cognitively normal participants were followed over 7 years. Nonlinear methods were used to estimate the longitudinal trajectories of several cognitive outcomes including delayed memory recall, executive function, processing speed, and several cognitive composites by subgroups selected on the basis of biomarkers, including APOE-epsilon 4 allele carriers, cerebrospinal fluid biomarkers (A beta(42), total tau, and phosphorylated tau), and those with small hippocampi. Results: Derived cognitive composites combining Alzheimer's Disease Assessment Scale (ADAS)-cog scores with additional delayed memory recall and executive function components captured decline more robustly across biomarker groups than any measure of a single cognitive domain or ADAS-cog alone. Substantial increases in power resulted when including only participants positive for three or more biomarkers in simulations of clinical trials. Interpretation: Clinical trial power may be improved by selecting participants on the basis of amyloid and neurodegeneration biomarkers and carefully tailoring primary cognitive endpoints to reflect the expected decline specific to these individuals.
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| 6. |
- Insel, P. S., et al.
(författare)
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The transitional association between beta-amyloid pathology and regional brain atrophy
- 2015
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Ingår i: Alzheimers & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 11:10, s. 1171-1179
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Alzheimer's disease (AD) is characterized by the accumulation of beta-amyloid (A beta) associated with brain atrophy and cognitive decline. The functional form to model the association between A beta and regional brain atrophy has not been well defined. To determine the relationship between Ab and atrophy, we compared the performance of the usual dichotomization of cerebrospinal fluid (CSF) A beta to identify subjects as A beta+ and A beta- with a trilinear spline model of CSF A beta. Methods: One hundred and eighty-three subjects with mild cognitive impairment and 108 cognitively normal controls with baseline CSFA beta and up to 4 years of longitudinal magnetic resonance imaging data from the Alzheimer's Disease Neuroimaging Initiative were analyzed using mixed-effects regression. Piecewise-linear splines were used to evaluate the nonlinear nature of the association between CSF A beta and regional atrophy and to identify points of acceleration of atrophy with respect to A beta. Several parameterizations of CSFA beta were compared using likelihood ratio tests and the Akaike information criterion. Periods of acceleration of atrophy in which subjects transition from CSF A beta negativity to CSFA beta positivity were estimated from the spline models and tested for significance. Results: Spline models resulted in better fits for many temporal and parietal regions compared with the dichotomous models. The trilinear model showed that periods of acceleration of atrophy varied greatly by region with early changes seen in the insula, amygdala, precuneus, hippocampus, and other temporal regions, occurring before the clinical threshold for CSF A beta positivity. Discussion: The use of piecewise-linear splines provides an improved model of the nonlinear association between CSF A beta and regional atrophy in regions implicated in the progression of AD. The important biological finding of this work is that some brain regions show periods of accelerated volume loss well before the CSFA beta(42) threshold. This implies that signs of brain atrophy develop before the current conventional definition of "preclinical AD". (C) 2015 The Alzheimer's Association. Published by Elsevier Inc. All rights reserved.
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| 7. |
- Lista, S., et al.
(författare)
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Evolving Evidence for the Value of Neuroimaging Methods and Biological Markers in Subjects Categorized with Subjective Cognitive Decline
- 2015
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Ingår i: Journal of Alzheimers Disease. - : IOS Press. - 1387-2877 .- 1875-8908. ; 48
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Tidskriftsartikel (refereegranskat)abstract
- There is evolving evidence that individuals categorized with subjective cognitive decline (SCD) are potentially at higher risk for developing objective and progressive cognitive impairment compared to cognitively healthy individuals without apparent subjective complaints. Interestingly, SCD, during advancing preclinical Alzheimer's disease (AD), may denote very early, subtle cognitive decline that cannot be identified using established standardized tests of cognitive performance. The substantial heterogeneity of existing SCD-related research data has led the Subjective Cognitive Decline Initiative (SCD-I) to accomplish an international consensus on the definition of a conceptual research framework on SCD in preclinical AD. In the area of biological markers, the cerebrospinal fluid signature of AD has been reported to be more prevalent in subjects with SCD compared to healthy controls; moreover, there is a pronounced atrophy, as demonstrated by magnetic resonance imaging, and an increased hypometabolism, as revealed by positron emission tomography, in characteristic brain regions affected by AD. In addition, SCD individuals carrying an apolipoprotein epsilon 4 allele are more likely to display AD-phenotypic alterations. The urgent requirement to detect and diagnose AD as early as possible has led to the critical examination of the diagnostic power of biological markers, neurophysiology, and neuroimaging methods for AD-related risk and clinical progression in individuals defined with SCD. Observational studies on the predictive value of SCD for developing AD may potentially be of practical value, and an evidence-based, validated, qualified, and fully operationalized concept may inform clinical diagnostic practice and guide earlier designs in future therapy trials.
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| 8. |
- Mattsson, Niklas, 1979, et al.
(författare)
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Brain structure and function as mediators of the effects of amyloid on memory
- 2015
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Ingår i: Neurology. - : Ovid Technologies (Wolters Kluwer Health). - 0028-3878 .- 1526-632X. ; 84:11, s. 1136-1144
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Tidskriftsartikel (refereegranskat)abstract
- Objective:The objective of this study was to test whether effects of -amyloid (A) pathology on episodic memory were mediated by metabolism and gray matter volume in the early stages of Alzheimer disease.Methods:This was a prospective cohort study. We measured baseline A (using florbetapir-PET), brain function (using fluorodeoxyglucose-PET), and brain structure (using MRI). A mediation analysis was performed to test whether statistical effects of A positivity on cross-sectional and longitudinal episodic memory were mediated by hypometabolism or regional gray matter volume in cognitively healthy controls (CN, n = 280) and mild cognitive impairment (MCI, n = 463).Results:Lower memory scores were associated with A positivity (CN, mildly; MCI, strongly), smaller gray matter volumes (CN, few regions, including hippocampus; MCI, widespread), and hypometabolism. Smaller volumes and hypometabolism mediated effects of A in MCI but not in CN. The strongest individual regions mediated up to approximately 25%. A combination of brain structure and function mediated up to approximately 40%. In several regions, gray matter atrophy and hypometabolism predicted episodic memory without being associated (at p < 0.05) with A positivity.Conclusions:Changes in brain structure and function appear to be, in part, downstream events from A pathology, ultimately resulting in episodic memory deficits. However, A pathology is also strongly related to memory deficits through mechanisms that are not quantified by these imaging measurements, and episodic memory decline is partly caused by Alzheimer disease-like brain changes independently of A pathology.
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| 9. |
- Mattsson, Niklas, 1979, et al.
(författare)
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Predicting Reduction of Cerebrospinal Fluid beta-Amyloid 42 in Cognitively Healthy Controls
- 2015
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Ingår i: Jama Neurology. - : American Medical Association (AMA). - 2168-6149. ; 72:5, s. 554-560
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Tidskriftsartikel (refereegranskat)abstract
- IMPORTANCE Alzheimer disease has a long preclinical stage characterized by beta-amyloid (A beta) accumulation without symptoms. Several trials focus on this stage and use biomarkers to include A beta-positive participants, but an even earlier prevention of A beta accumulation may be an effective treatment strategy. OBJECTIVE To determine whether people who appear to be A beta negative but are at high risk for A beta positivity within the near future can be identified. DESIGN, SETTING, AND PARTICIPANTS Longitudinal biomarker cohort study involving 35 cognitively healthy individuals who underwent cerebrospinal fluid (CSF) sampling for up to 3 years during the study (October 24, 2005, to September 1, 2014). All participants had normal CSF A beta 42 levels at baseline. MAIN OUTCOMES AND MEASURES Predictors of future A beta positivity (levels of CSF A beta 42 declining below a previously validated cutoff level of 192 ng/L) tested by random forest models. Tested predictors included levels of protein in the CSF, hippocampal volume, genetics, demographics, and cognitive scores. RESULTS The CSF A beta 42 levels declined in 11 participants, and the CSF became A beta positive. The baseline CSF A beta 42 level was a strong predictor of future positivity (accuracy, 79% [95% CI, 70%-87%]). Ten of 11 decliners had baseline CSF A beta 42 levels in the lower tertile of the reference range (<225 ng/L), and 22 of 24 nondecliners had baseline CSF A beta 42 levels in the upper 2 tertiles (similar to 225 ng/L). A high CSF P-tau level was associated with decline (accuracy, 68%; 95% CI, 55%-81%). CONCLUSIONS AND RELEVANCE Baseline CSF A beta 42 levels in the lower part of the reference range are strongly associated with future A beta positivity. This finding can be used in trials on very early prevention of Alzheimer disease to identify people at high risk for Ab accumulation as defined by low CSF A beta 42 levels.
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| 10. |
- Sacuiu, Simona, 1971, et al.
(författare)
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Chronic Depressive Symptomatology in Mild Cognitive Impairment Is Associated with Frontal Atrophy Rate which Hastens Conversion to Alzheimer Dementia
- 2016
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Ingår i: American Journal of Geriatric Psychiatry. - : Elsevier BV. - 1064-7481. ; 24:2, s. 126-135
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Investigate the association of chronic depressive symptomatology (chrDS) with cortical atrophy rates and conversion to Alzheimer dementia (AD) over 3 years in mild cognitive impairment (MCI). Methods: In a multicenter, clinic-based study, MCI elderly participants were selected from the Alzheimer's Disease Neuroimaging Initiative repository, based on availability of both serial structural magnetic resonance imaging and chrDS endorsed on three depression-related items from the Neuropsychiatric Inventory Questionnaire (chrDS N = 32 or no depressive symptoms N = 62) throughout follow-up. Clinical and laboratory investigations were performed every 6 months during the first 2 years and yearly thereafter (median follow-up: 3 years; interquartile range: 1.5-4.0 years). Cortical atrophy rates in 16 predefined frontotemporoparietal regions affected in major depression and AD and the rate of incident AD at follow-up. Results: ChrDS in a single domain amnestic MCI sample were associated with accelerated cortical atrophy in the frontal lobe and anterior cingulate but not with atrophy rates in temporomedial or other AD-affected regions. During follow-up, 38 participants (42.7%) developed AD. Participants with chrDS had 60% shorter conversion time to AD than those without depressive symptoms. This association remained significant in survival models adjusted for temporomedial atrophy rates and showed the same trend in models adjusted for frontal cortical atrophy rate, which all increased the risk of AD. Conclusion: Our results suggest that chrDS associated with progressive atrophy of frontal regions may represent an additional risk factor for conversion to dementia in MCI as opposite to representing typical prodromal AD symptomatology.
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