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Aging Jun 2024Down Syndrome (DS) is a common genetic disorder characterized by an extra copy of chromosome 21, leading to dysregulation of various metabolic pathways. Oxidative stress...
Down Syndrome (DS) is a common genetic disorder characterized by an extra copy of chromosome 21, leading to dysregulation of various metabolic pathways. Oxidative stress in DS is associated with neurodevelopmental defects, neuronal dysfunction, and a dementia onset resembling Alzheimer's disease. Additionally, chronic oxidative stress contributes to cardiovascular diseases and certain cancers prevalent in DS individuals. This study investigates the impact of ageing on oxidative stress and liver fibrosis using a DS murine model (Ts2Cje mice). Our results show that DS mice show increased liver oxidative stress and impaired antioxidant defenses, as evidenced by reduced glutathione levels and increased lipid peroxidation. Therefore, DS liver exhibits an altered inflammatory response and mitochondrial fitness as we showed by assaying the expression of HMOX1, CLPP, and the heat shock proteins Hsp90 and Hsp60. DS liver also displays dysregulated lipid metabolism, indicated by altered expression of PPARα, PPARγ, FATP5, and CTP2. Consistently, these changes might contribute to non-alcoholic fatty liver disease development, a condition characterized by liver fat accumulation. Consistently, histological analysis of DS liver reveals increased fibrosis and steatosis, as showed by Col1a1 increased expression, indicative of potential progression to liver cirrhosis. Therefore, our findings suggest an increased risk of liver pathologies in DS individuals, particularly when combined with the higher prevalence of obesity and metabolic dysfunctions in DS patients. These results shed a light on the liver's role in DS-associated pathologies and suggest potential therapeutic strategies targeting oxidative stress and lipid metabolism to prevent or mitigate liver-related complications in DS individuals.
PubMed: 38942607
DOI: 10.18632/aging.205970 -
NeuroImage. Clinical Jun 2024Advanced age is the most important risk factor for Alzheimer's disease (AD), and carrier-status of the Apolipoprotein E4 (APOE4) allele is the strongest known genetic...
Advanced age is the most important risk factor for Alzheimer's disease (AD), and carrier-status of the Apolipoprotein E4 (APOE4) allele is the strongest known genetic risk factor. Many studies have consistently shown a link between APOE4 and synaptic dysfunction, possibly reflecting pathologically accelerated biological aging in persons at risk for AD. To test the hypothesis that distinct functional connectivity patterns characterize APOE4 carriers across the clinical spectrum of AD, we investigated 128 resting state functional Magnetic Resonance Imaging (fMRI) datasets from the Alzheimer's Disease Neuroimaging Initiative database (ADNI), representing all disease stages from cognitive normal to clinical dementia. Brain region centralities within functional networks, computed as eigenvector centrality, were tested for multivariate associations with chronological age, APOE4 carrier status and clinical stage (as well as their interactions) by partial least square analysis (PLSC). By PLSC analysis two distinct brain activity patterns could be identified, which reflected interactive effects of age, APOE4 and clinical disease stage. A first component including sensorimotor regions and parietal regions correlated with age and AD clinical stage (p < 0.001). A second component focused on medial-frontal regions and was specifically related to the interaction between age and APOE4 (p = 0.032). Our findings are consistent with earlier reports on altered network connectivity in APOE4 carriers. Results of our study highlight promise of graph-theory based network centrality to identify brain connectivity linked to genetic risk, clinical stage and age. Our data suggest the existence of brain network activity patterns that characterize APOE4 carriers across clinical stages of AD.
PubMed: 38941766
DOI: 10.1016/j.nicl.2024.103635 -
Science Advances Jun 2024Declined memory is a hallmark of Alzheimer's disease (AD). Experiments in rodents and human postmortem studies suggest that serotonin (5-hydroxytryptamine, 5-HT) plays a...
Declined memory is a hallmark of Alzheimer's disease (AD). Experiments in rodents and human postmortem studies suggest that serotonin (5-hydroxytryptamine, 5-HT) plays a role in memory, but the underlying mechanisms are unknown. Here, we investigate the role of 5-HT 2C receptor (5-HTR) in regulating memory. Transgenic mice expressing a humanized mutation exhibit impaired plasticity of hippocampal ventral CA1 (vCA1) neurons and reduced memory. Further, 5-HT neurons project to and synapse onto vCA1 neurons. Disruption of 5-HT synthesis in vCA1-projecting neurons or deletion of 5-HTRs in the vCA1 impairs neural plasticity and memory. We show that a selective 5-HTR agonist, lorcaserin, improves synaptic plasticity and memory in an AD mouse model. Cumulatively, we demonstrate that hippocampal 5-HTR signaling regulates memory, which may inform the use of 5-HTR agonists in the treatment of dementia.
Topics: Animals; Humans; Receptor, Serotonin, 5-HT2C; Memory; Mice; Mice, Transgenic; Neuronal Plasticity; Alzheimer Disease; Hippocampus; Serotonin; Disease Models, Animal; CA1 Region, Hippocampal; Neurons; Serotonin 5-HT2 Receptor Agonists
PubMed: 38941473
DOI: 10.1126/sciadv.adl2675 -
Science Advances Jun 2024Bile acids (BAs) metabolism has a significant impact on the pathogenesis of Alzheimer's disease (AD). We found that deoxycholic acid (DCA) increased in brains of AD mice...
Bile acids (BAs) metabolism has a significant impact on the pathogenesis of Alzheimer's disease (AD). We found that deoxycholic acid (DCA) increased in brains of AD mice at an early stage. The enhanced production of DCA induces the up-regulation of the bile acid receptor Takeda G protein-coupled receptor (TGR5), which is also specifically increased in neurons of AD mouse brains at an early stage. The accumulation of exogenous DCA impairs cognitive function in wild-type mice, but not in TGR5 knockout mice. This suggests that TGR5 is the primary receptor mediating these effects of DCA. Furthermore, excitatory neuron-specific knockout of TGR5 ameliorates Aβ pathology and cognition impairments in AD mice. The underlying mechanism linking TGR5 and AD pathology relies on the downstream effectors of TGR5 and the APP production, which is succinctly concluded as a "p-STAT3-APH1-γ-secretase" signaling pathway. Our studies identified the critical role of TGR5 in the pathological development of AD.
Topics: Animals; Receptors, G-Protein-Coupled; Alzheimer Disease; Amyloid beta-Protein Precursor; Neurons; Mice; Mice, Knockout; Humans; Disease Models, Animal; Deoxycholic Acid; Amyloid Precursor Protein Secretases; Signal Transduction; Brain
PubMed: 38941459
DOI: 10.1126/sciadv.ado1855 -
Medicine Jun 2024Taiwan is an aging society, and the number of people with dementia is rapidly increasing. Due to a decline in cognitive and physical function, older adults with dementia...
BACKGROUND
Taiwan is an aging society, and the number of people with dementia is rapidly increasing. Due to a decline in cognitive and physical function, older adults with dementia not only gradually lose the ability to complete daily living tasks on their own, but are also at a higher risk of falls and injurious falls. It is important to develop interventions that combine cognitive and exercise training for older adults with dementia to promote or maintain their cognitive and physical functions and reduce their risk of falls. This study aimed to investigate the feasibility and effect of cognitive-based board games and multi-component exercise interventions on cognitive function, physical fitness, and fall risk in older adults with dementia.
METHODS
This was a quasi-experimental study with a single-group pretest and post-test design. The study participants were 41 community-dwelling older adults with mild to moderate dementia. They received cognitive-based board games and multi-component exercise interventions once a week for 12 weeks. The interventions included 1 hour of exercise training and 1 hour of cognitive training. Scores for the Taiwan version of the Montreal Cognitive Assessment (MoCA-T), physical fitness, and the St. Thomas Risk Assessment Tool for Falling Elderly Inpatients (STRATIFY) were measured as outcome indicators at baseline and after the 12-week period.
RESULTS
The overall MoCA-T score increased significantly (effect size = 0.402), with participants with mild dementia showing a greater increase (effect size = 0.522) than those with moderate dementia (effect size = 0.310). Participants' physical fitness performance improved. Female participants exhibited significant improvements in the 30-second chair stand test (effect size = 0.483) and 8-foot up-and-go test (effect size = 0.437). The fall risk score decreased by 0.05 points, the change was not significant.
CONCLUSION
The cognitive-based board game and multi-component exercise interventions used in this study are beneficial for improving cognitive function and physical fitness in older adults with dementia. These interventions are feasible and suitable for promotion among community-dwelling and institution-dwelling older adults with mild cognitive impairment or dementia to delay the decline in cognitive and physical function.
Topics: Humans; Female; Male; Aged; Dementia; Feasibility Studies; Exercise Therapy; Accidental Falls; Aged, 80 and over; Taiwan; Cognition; Physical Fitness; Games, Recreational; Independent Living
PubMed: 38941425
DOI: 10.1097/MD.0000000000038640 -
Medicine Jun 2024Old age is associated with a higher risk of dementia. Psychosocial characteristics frequently affect cognitive function; however, the exact mechanism underlying the...
Effects of psychosocial characteristics on cognitive function in middle-aged and older adults: Focusing on change by year using the Korean Longitudinal Study of Aging panel data (2014-2018).
Old age is associated with a higher risk of dementia. Psychosocial characteristics frequently affect cognitive function; however, the exact mechanism underlying the effect of psychosocial factors on cognitive function is unclear. Therefore, this study aimed to investigate the effects of psychosocial characteristics on cognitive function. The participants comprised 4809 middle-aged and older (years 50+) adults. The analysis used data from the Korean Longitudinal Study of Aging from 2014 to 2018. The effects of neighborhood interaction, depression, life satisfaction, and economic activity on cognitive function were examined, and a linear mixed model analysis was performed to assess the change in cognitive function by year. A statistically significant association was found between neighborhood interaction and time. Additionally, cognitive function decreased in the presence of depression and with time. In men, significant interactions were found between depression and time and between economic activity and time. In women, significant interactions were found between life satisfaction and time. The findings indicate that since active neighborhood interaction positively affects cognitive function, it is necessary to develop various community-wide social activity programs for middle-aged and older adults. As depression is a risk factor for cognitive impairment, it is crucial to prevent cognitive decline through continuous management of depression. Given the positive effects of economic activity on cognitive function in men, it is essential to expand infrastructure to sustain economic activity by developing educational programs and creating job opportunities for middle-aged and older men.
Topics: Humans; Male; Female; Longitudinal Studies; Middle Aged; Republic of Korea; Aged; Cognition; Depression; Personal Satisfaction; Cognitive Dysfunction; Residence Characteristics; Aging; Risk Factors; Sex Factors; Aged, 80 and over
PubMed: 38941412
DOI: 10.1097/MD.0000000000038637 -
PloS One 2024This study began as a single-blind randomized controlled trial (RCT) to investigate the efficacy and safety of electroconvulsive therapy (ECT) for severe... (Randomized Controlled Trial)
Randomized Controlled Trial
OBJECTIVE
This study began as a single-blind randomized controlled trial (RCT) to investigate the efficacy and safety of electroconvulsive therapy (ECT) for severe treatment-refractory agitation in advanced dementia. The aims are to assess agitation reduction using the Cohen-Mansfield Agitation Inventory (CMAI), evaluate tolerability and safety outcomes, and explore the long-term stability of agitation reduction and global functioning. Due to challenges encountered during implementation, including recruitment obstacles and operational difficulties, the study design was modified to an open-label format and other protocol amendments were implemented.
METHODS
Initially, the RCT randomized participants 1:1 to either ECT plus usual care or simulated ECT plus usual care (S-ECT) groups. As patients were enrolled, data were collected from both ECT and simulated ECT (S-ECT) patients. The study now continues in an open-label study design where all patients receive actual ECT, reducing the targeted sample size from 200 to 50 participants.
RESULTS
Study is ongoing and open to enrollment.
CONCLUSION
The transition of the ECT-AD study design from an RCT to open-label design exemplifies adaptive research methodologies in response to real-world challenges. Data from both the RCT and open-label phases of the study will provide a unique perspective on the role of ECT in managing severe treatment-refractory agitation in dementia, potentially influencing future clinical practices and research approaches.
Topics: Humans; Electroconvulsive Therapy; Psychomotor Agitation; Dementia; Single-Blind Method; Female; Male; Treatment Outcome; Aged; Aberrant Motor Behavior in Dementia
PubMed: 38941338
DOI: 10.1371/journal.pone.0303894 -
JAMA Network Open Jun 2024Although existing research has found daily heat to be associated with dementia-related outcomes, there is still a gap in understanding the differing associations of...
IMPORTANCE
Although existing research has found daily heat to be associated with dementia-related outcomes, there is still a gap in understanding the differing associations of nighttime and daytime heat with dementia-related deaths.
OBJECTIVES
To quantitatively assess the risk and burden of dementia-related deaths associated with short-term nighttime and daytime heat exposure and identify potential effect modifications.
DESIGN, SETTING, AND PARTICIPANTS
This case-crossover study analyzed individual death records for dementia across all mainland China counties from January 1, 2013, to December 31, 2019, using a time-stratified case-crossover approach. Statistical analysis was conducted from January 1, 2013, to December 31, 2019.
EXPOSURES
Two novel heat metrics: hot night excess (HNE) and hot day excess (HDE), representing nighttime and daytime heat intensity, respectively.
MAIN OUTCOMES AND MEASURES
Main outcomes were the relative risk and burden of dementia-related deaths associated with HNE and HDE under different definitions. Analysis was conducted with conditional logistic regression integrated with the distributed lag nonlinear model.
RESULTS
The study involved 132 573 dementia-related deaths (mean [SD] age, 82.5 [22.5] years; 73 086 women [55.1%]). For a 95% threshold, the median hot night threshold was 24.5 °C (IQR, 20.1 °C-26.2 °C) with an HNE of 3.7 °C (IQR, 3.1 °C-4.3 °C), and the median hot day threshold was 33.3 °C (IQR, 29.9 °C-34.7 °C) with an HDE of 0.6 °C (IQR, 0.5 °C-0.8 °C). Both nighttime and daytime heat were associated with increased risk of dementia-related deaths. Hot nights' associations with risk of dementia-related deaths persisted for 6 days, while hot days' associations with risk of dementia-related deaths extended over 10 days. Extreme HDE had a higher relative risk of dementia-related deaths, with a greater burden associated with extreme HNE at more stringent thresholds. At a 97.5% threshold, the odds ratio for dementia-related deaths was 1.38 (95% CI, 1.22-1.55) for extreme HNE and 1.46 (95% CI, 1.27-1.68) for extreme HDE, with an attributable fraction of 1.45% (95% empirical confidence interval [95% eCI], 1.43%-1.47%) for extreme HNE and 1.10% (95% eCI, 1.08%-1.11%) for extreme HDE. Subgroup analyses suggested heightened susceptibility among females, individuals older than 75 years of age, and those with lower educational levels. Regional disparities were observed, with individuals in the south exhibiting greater sensitivity to nighttime heat and those in the north to daytime heat.
CONCLUSIONS AND RELEVANCE
Results of this nationwide case-crossover study suggest that both nighttime and daytime heat are associated with increased risk of dementia-related deaths, with a greater burden associated with nighttime heat. These findings underscore the necessity of time-specific interventions to mitigate extreme heat risk.
Topics: Humans; China; Dementia; Female; Male; Aged; Aged, 80 and over; Hot Temperature; Cross-Over Studies; Risk Factors
PubMed: 38941091
DOI: 10.1001/jamanetworkopen.2024.19250 -
Frontiers in Bioscience (Landmark... Jun 2024
Topics: Humans; Biomarkers; Dementia; Proteostasis Deficiencies; Protein Folding; Alzheimer Disease
PubMed: 38940055
DOI: 10.31083/j.fbl2906227 -
Frontiers in Bioscience (Landmark... Jun 2024Alzheimer's disease is characterized by extracellular beta-amyloid plaques, intraneuronal tau neurofibrillary tangles and excessive neurodegeneration. The mechanisms of...
BACKGROUND
Alzheimer's disease is characterized by extracellular beta-amyloid plaques, intraneuronal tau neurofibrillary tangles and excessive neurodegeneration. The mechanisms of neuron degeneration and the potential of these neurons to form new nerve fibers for compensation remain elusive. The present study aimed to evaluate the impact of beta-amyloid and tau on new formations of nerve fibers from mouse organotypic brain slices connected to collagen-based microcontact prints.
METHODS
Organotypic brain slices of postnatal day 8-10 wild-type mice were connected to established collagen-based microcontact prints loaded with polyornithine to enhance nerve fiber outgrowth. Human beta-amyloid(42) or P301S mutated aggregated tau was co-loaded to the prints. Nerve fibers were immunohistochemically stained with neurofilament antibodies. The physiological activity of outgrown neurites was tested with neurotracer MiniRuby, voltage-sensitive dye FluoVolt, and calcium-sensitive dye Rhod-4.
RESULTS
Immunohistochemical staining revealed newly formed nerve fibers extending along the prints derived from the brain slices. While collagen-only microcontact prints stimulated nerve fiber growth, those loaded with polyornithine significantly enhanced nerve fiber outgrowth. Beta-amyloid(42) significantly increased the neurofilament-positive nerve fibers, while tau had only a weak effect. MiniRuby crystals, retrogradely transported along these newly formed nerve fibers, reached the hippocampus, while FluoVolt and Rhod-4 monitored electrical activity in newly formed nerve fibers.
CONCLUSIONS
Our data provide evidence that intact nerve fibers can form along collagen-based microcontact prints from mouse brain slices. The Alzheimer's peptide beta-amyloid(42) stimulates this growth, hinting at a neuroprotective function when physiologically active. This "brain-on-chip" model may offer a platform for screening bioactive factors or testing drug effects on nerve fiber growth.
Topics: Animals; Amyloid beta-Peptides; Mice; Nerve Fibers; Brain; tau Proteins; Humans; Immunohistochemistry; Peptide Fragments; Alzheimer Disease; Mice, Inbred C57BL
PubMed: 38940051
DOI: 10.31083/j.fbl2906232