| 1. |
- Byman, Elin, et al.
(författare)
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Alpha-amylase 1A copy number variants and the association with memory performance and Alzheimer's dementia
- 2020
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Ingår i: Alzheimers Research & Therapy. - : Springer Science and Business Media LLC. - 1758-9193. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Background Previous studies have shown that copy number variation (CNV) in the alpha (alpha)-amylase gene (AMY1A) is associated with body mass index, insulin resistance, and blood glucose levels, factors also shown to increase the risk of Alzheimer's dementia (AD). We have previously demonstrated the presence of alpha-amylase in healthy neuronal dendritic spines and a reduction of the same in AD patients. In the current study, we investigate the relationship between AMY1A copy number and AD, memory performance, and brain alpha-amylase activity. Methods and materials The association between AMY1A copy number and development of AD was analyzed in 5422 individuals (mean age at baseline 57.5 +/- 5.9, females 58.2%) from the Malmo diet and cancer study genotyped for AMY1A copy number, whereof 247 where diagnosed with AD during a mean follow-up of 20 years. Associations between AMY1A copy number and cognitive performance where analyzed in 791 individuals (mean age at baseline 54.7 +/- 6.3, females 63%), who performed Montreal Cognitive Assessment (MoCA) test. Correlation analysis between alpha-amylase activity or alpha-amylase gene expression and AMY1A copy number in post-mortem hippocampal tissue from on demented controls (n = 8) and AD patients (n = 10) was also performed. Results Individuals with very high ( >= 10) AMY1A copy number had a significantly lower hazard ratio of AD (HR = 0.62, 95% CI 0.41-0.94) and performed significantly better on MoCA delayed word recall test, compared to the reference group with AMY1A copy number 6. A trend to lower hazard ratio of AD was also found among individuals with low AMY1A copy number (1-5) (HR = 0.74, 95% CI 0.53-1.02). A tendency towards a positive correlation between brain alpha-amylase activity and AMY1A copy number was found, and females showed higher brain alpha-amylase activity compared to males. Conclusion Our study suggests that the degree of alpha-amylase activity in the brain is affected by AMY1A copy number and gender, in addition to AD pathology. The study further suggests that very high AMY1A copy number is associated with a decreased hazard ratio of AD and we speculate that this effect is mediated via a beneficial impact of AMY1A copy number on episodic memory performance.
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| 2. |
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| 3. |
- Hansson, Oskar, et al.
(författare)
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Midlife physical activity is associated with lower incidence of vascular dementia but not Alzheimer's disease
- 2019
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Ingår i: Alzheimer's Research & Therapy. - : BMC. - 1758-9193. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Background: Physical activity might reduce the risk of developing dementia. However, it is still unclear whether the protective effect differs depending on the subtype of dementia. We aimed to investigate if midlife physical activity affects the development of vascular dementia (VaD) and Alzheimer's disease (AD) differently in two large study populations with different designs.Methods: Using a prospective observational design, we studied whether long-distance skiers of the Swedish Vasaloppet (n = 197,685) exhibited reduced incidence of VaD or AD compared to matched individuals from the general population (n = 197,684) during 21 years of follow-up (median 10, interquartile range (IQR) 5-15 years). Next, we studied the association between self-reported physical activity, stated twice 5 years apart, and incident VaD and AD in 20,639 participants in the Swedish population-based Malmo Diet and Cancer Study during 18 years of follow-up (median 15, IQR 14-17 years). Finally, we used a mouse model of AD and studied brain levels of amyloid-beta, synaptic proteins, and cognitive function following 6 months of voluntary wheel running.Results Vasaloppet skiers (median age 36.0 years [IQR 29.0-46.0], 38% women) had lower incidence of all-cause dementia (adjusted hazard ratio (HR) 0.63, 95% CI 0.52-0.75) and VaD (adjusted HR 0.49, 95% CI 0.33-0.73), but not AD, compared to non-skiers. Further, faster skiers exhibited a reduced incidence of VaD (adjusted HR 0.38, 95% CI 0.16-0.95), but not AD or all-cause dementia compared to slower skiers. In the Malmo Diet and Cancer Study (median age 57.5 years [IQR 51.0-63.8], 60% women), higher physical activity was associated with reduced incidence of VaD (adjusted HR 0.65, 95% CI 0.49-0.87), but not AD nor all-cause dementia. These findings were also independent of APOE-epsilon 4 genotype. In AD mice, voluntary running did not improve memory, amyloid-beta, or synaptic proteins.Conclusions: Our results indicate that physical activity in midlife is associated with lower incidence of VaD. Using three different study designs, we found no significant association between physical activity and subsequent development of AD.
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| 4. |
- Kim, Woojin Scott, et al.
(författare)
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Alpha-synuclein biology in Lewy body diseases.
- 2014
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Ingår i: Alzheimer's research & therapy. - : BioMed Central. - 1758-9193. ; 6:5
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Tidskriftsartikel (refereegranskat)abstract
- α-Synuclein is an abundantly expressed neuronal protein that is at the center of focus in understanding a group of neurodegenerative disorders called α-synucleinopathies, which are characterized by the presence of aggregated α-synuclein intracellularly. Primary α-synucleinopathies include Parkinson's disease (PD), dementia with Lewy bodies and multiple system atrophy, with α-synuclein also found secondarily in a number of other diseases, including Alzheimer's disease. Understanding how α-synuclein aggregates form in these different disorders is important for the understanding of its pathogenesis in Lewy body diseases. PD is the most prevalent of the α-synucleinopathies and much of the initial research on α-synuclein Lewy body pathology was based on PD but is also relevant to Lewy bodies in other diseases (dementia with Lewy bodies and Alzheimer's disease). Polymorphism and mutation studies of SNCA, the gene that encodes α-synuclein, provide much evidence for a causal link between α-synuclein and PD. Among the primary α-synucleinopathies, multiple system atrophy is unique in that α-synuclein deposition occurs in oligodendrocytes rather than neurons. It is unclear whether α-synuclein originates from oligodendrocytes or whether it is transmitted somehow from neurons. α-Synuclein exists as a natively unfolded monomer in the cytosol, but in the presence of lipid membranes it is thought to undergo a conformational change to a folded α-helical secondary structure that is prone to forming dimers and oligomers. Posttranslational modification of α-synuclein, such as phosphorylation, ubiquitination and nitration, has been widely implicated in α-synuclein aggregation process and neurotoxicity. Recent studies using animal and cell models, as well as autopsy studies of patients with neuron transplants, provided compelling evidence for prion-like propagation of α-synuclein. This observation has implications for therapeutic strategies, and much recent effort is focused on developing antibodies that target extracellular α-synuclein.
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| 5. |
- Nuñez-Diaz, Cristina, et al.
(författare)
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The fluorescent ligand bTVBT2 reveals increased p-tau uptake by retinal microglia in Alzheimer’s disease patients and App NL−F/NL−F mice
- 2024
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Ingår i: Alzheimer's Research and Therapy. - : BMC. - 1758-9193. ; 16:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Amyloid beta (Aβ) deposits and hyperphosphorylated tau (p-tau) accumulation have been identified in the retina of Alzheimer’s disease (AD) patients and transgenic AD mice. Previous studies have shown that retinal microglia engulf Aβ, but this property decreases in AD patients. Whether retinal microglia also take up p-tau and if this event is affected in AD is yet not described. In the current study, we use the p-tau-specific thiophene-based ligand bTVBT2 to investigate the relationship between disease progression and p-tau uptake by microglia in the retina of AD patients and App NL−F/NL−F knock-in mice, an AD mouse model known to demonstrate extracellular Aβ plaques and dystrophic neurites in the brain from 6 months of age. Methods: Evaluation of bTVBT2 specificity and its presence within microglia was assessed by immunofluorescent staining of hippocampal sections and flat-mount retina samples from non-demented controls, AD patients, 3-, 9-, and 12-month-old App NL−F/NL−F knock-in mice and 12- and 18-month-old wild type (WT) mice. We used ImageJ to analyze the amount of bTVBT2 inside Iba1-positive microglia. Co-localization between the ligand and p-tau variant Ser396/Ser404 (PHF-1), Aβ, phosphorylated TAR DNA binding protein 43 (pTDP-43), and islet amyloid polypeptide (IAPP) in the brain and retina was analyzed using confocal imaging. Results: Confocal imaging analysis showed that bTVBT2 binds to PHF-1- and AT8-positive aggregates inside retinal microglia, and not to Aβ, pTDP-43, or IAPP. The density of bTVBT2-positive microglia was higher in cases with a high Aβ load compared to those with a low Aβ load. This density correlated with the neurofibrillary tangle load in the brain, but not with retinal levels of high molecular weight (aggregated) Aβ40 or Aβ42. Analysis of App NL−F/NL−F knock-in mouse retina further showed that 50% of microglia in 3-month-old App NL−F/NL−F knock-in mice contained bTVBT2. The percentage significantly increased in 9- and 12-month-old mice. Conclusion: Our study suggests that the microglial capability to uptake p-tau in the retina persists and intensifies with AD progression. These results also highlight bTVBT2 as a ligand of interest in future monitoring of retinal AD pathology.
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| 6. |
- Nägga, Katarina, et al.
(författare)
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Cerebral inflammation is an underlying mechanism of early death in Alzheimer's disease : a 13-year cause-specific multivariate mortality study
- 2014
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Ingår i: Alzheimer's Research & Therapy. - : BioMed Central. - 1758-9193. ; 6:4
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Although Alzheimer's disease (AD) is associated with early death, its life expectancy differs greatly between patients. A better understanding of this heterogeneity may reveal important disease mechanisms underlying the malignancy of AD. The aim of this study was to examine the relation between AD pathologies and early death in AD caused by dementia.METHODS: At a memory clinic, 247 referred consecutive patients with AD were monitored during 12.6 ± 1.6 years. Multivariate Cox regression analyses were performed with baseline measures of amyloid beta (Aβ) pathology (APOE genotype, cerebrospinal fluid (CSF) Aβ42) tau pathology (CSF phosphorylated tau and total tau), cerebrovascular pathology (white-matter lesions and CSF/serum albumin ratio), neuroinflammatory pathology (CSF soluble vascular cell adhesion molecule-1, sVCAM-1), frontal, temporal, and central brain atrophies, global cognition, sex, and age. Comorbidities and medications also were analyzed. All continuous variables were transformed to z scores to compare hazard ratios (HRs) and 95% confidence intervals (CIs).RESULTS: At follow-up, 89% of the patients had died. The mean survival time was 6.4 ± 3.0 years. The AD pathology that independently predicted an early death caused by dementia was cerebral inflammation (sVCAM-1; HR, 1.32; 95% CI, 1.07-1.64). Other independent predictors were lower global cognition (HR, 0.51; 95% CI, 0.43-0.61), frontal atrophy (HR, 1.38; 95% CI, 1.12-1.70), and medial temporal atrophy (HR, 1.23; 95% CI, 1.02-1.49). When examining death caused by dementia and related causes (vascular diseases and infections), age (HR, 1.23; 95% CI, 1.04-1.46) and cerebrovascular pathology (white-matter lesions: HR, 1.17; 95% CI, 1.01-1.36; and CSF/serum albumin ratio: HR, 1.16; 95% CI, 1.001-1.34) were also significant risk factors in addition to the previous variables. No comorbidity or medication was significant in the specific-cause models.CONCLUSIONS: This is the first study to link neuroinflammation independently to early death in AD and, hence, a rapidly progressing disease. Frontal and medial temporal atrophies and low cognition were also significant predictors. These are probably downstream biomarkers that reflect neuronal degeneration and late-stage disease. Our results suggest that inflammation, and not amyloid or tau pathology, is an independent underlying mechanism in the malignancy of AD.
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| 7. |
- Wennström, Malin, et al.
(författare)
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Cerebrospinal fluid levels of IL-6 are decreased and correlate with cognitive status in DLB patients
- 2015
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Ingår i: Alzheimer's Research & Therapy. - : BioMed Central (BMC). - 1758-9193. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Inflammatory processes have previously been shown to influence cognition and progression of dementia. An involvement of interleukin (IL)-6 has in particular been suggested as altered levels of IL-6 in cerebrospinal fluid (CSF) have been found in patients with Alzheimer's disease (AD). Also, an association between cognitive decline and levels of IL-6 in CSF have been reported. The aim of the present study was to investigate whether patients clinically diagnosed with dementia with Lewy bodies (DLB) display altered CSF IL-6 levels in comparison with patients with AD and control subjects without dementia and whether the IL-6 levels are correlated with cognitive status and biomarkers for AD and synucleinopathy.METHODS: To analyse CSF of patients with AD (n = 45), patients with DLB (n = 29) and control subjects without dementia (n = 36), we used immunoassays to measure levels of IL-6 (multiplex electrochemiluminescence); AD markers phosphorylated tau, total tau and amyloid-β1-42 (enzyme-linked immunosorbent assay [ELISA]); and α-synuclein (ELISA). Cognitive status was evaluated using the Mini Mental State Examination (MMSE).RESULTS: Our analysis showed significantly lower levels of IL-6 in CSF from patients with DLB than in CSF from patients with AD and control subjects without dementia. The IL-6 levels were also negatively correlated with MMSE and positively correlated with α-synuclein CSF levels.CONCLUSIONS: Our findings support previous studies by demonstrating a link between inflammatory processes and dementia progression and further strengthen the hypothesis that IL-6 is involved in dementia pathology and cognitive decline.
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