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Cells Dec 2023The greatest risk factor for neurodegeneration is the aging of the multiple cell types of human CNS, among which microglia are important because they are the "sentinels"... (Review)
Review
The greatest risk factor for neurodegeneration is the aging of the multiple cell types of human CNS, among which microglia are important because they are the "sentinels" of internal and external perturbations and have long lifespans. We aim to emphasize microglial signatures in physiologic brain aging and Alzheimer's disease (AD). A systematic literature search of all published articles about microglial senescence in human healthy aging and AD was performed, searching for PubMed and Scopus online databases. Among 1947 articles screened, a total of 289 articles were assessed for full-text eligibility. Microglial transcriptomic, phenotypic, and neuropathological profiles were analyzed comprising healthy aging and AD. Our review highlights that studies on animal models only partially clarify what happens in humans. Human and mice microglia are hugely heterogeneous. Like a two-sided coin, microglia can be protective or harmful, depending on the context. Brain health depends upon a balance between the actions and reactions of microglia maintaining brain homeostasis in cooperation with other cell types (especially astrocytes and oligodendrocytes). During aging, accumulating oxidative stress and mitochondrial dysfunction weaken microglia leading to dystrophic/senescent, otherwise over-reactive, phenotype-enhancing neurodegenerative phenomena. Microglia are crucial for managing Aβ, pTAU, and damaged synapses, being pivotal in AD pathogenesis.
Topics: Humans; Mice; Animals; Alzheimer Disease; Microglia; Healthy Aging; Aging; Brain
PubMed: 38132144
DOI: 10.3390/cells12242824 -
Neurologia 2024Risk factors for dementia include genetic factors, aging, environmental factors, certain diseases, and unhealthy lifestyle; most types of dementia share a common chronic... (Review)
Review
INTRODUCTION
Risk factors for dementia include genetic factors, aging, environmental factors, certain diseases, and unhealthy lifestyle; most types of dementia share a common chronic systemic inflammatory phenotype. Psoriasis is also considered to be a chronic systemic inflammatory disease. It has been suggested that psoriasis may also contribute to the risk of dementia. The aim of this study was to systematically review the literature on the association between psoriasis and dementia.
DEVELOPMENT
Articles were selected according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We searched the PubMed and Web of Science databases to identify articles published in peer-reviewed journals and studying the association between psoriasis and dementia. Studies meeting the inclusion criteria were reviewed. We used the Newcastle-Ottawa Scale to assess the quality of each study. After applying the inclusion and exclusion criteria, we included 8 studies for review, 3 of which were found to present a higher risk of bias. Six of the 8 studies supported the hypothesis that prior diagnosis of psoriasis increases the risk of dementia; one study including only a few cases reported that psoriasis decreased the risk of dementia, and one study including relatively young patients found no significant association between psoriasis and the risk of dementia.
CONCLUSION
Most studies included in this review supported the hypothesis that psoriasis constitutes a risk factor for dementia. However, well-designed stratified cohort studies assessing both psoriasis severity and treatment status are still required to determine the real effect of psoriasis on the risk of dementia and its subtypes.
Topics: Humans; Chronic Disease; Psoriasis; Risk Factors; Dementia
PubMed: 38161072
DOI: 10.1016/j.nrleng.2023.12.005 -
Healthcare (Basel, Switzerland) Jan 2024Dementia has become one of the leading causes of death across the world. (Review)
Review
BACKGROUND
Dementia has become one of the leading causes of death across the world.
AIMS
The aim of this study was to investigate the incidence, prevalence, and mortality of dementia in China between 2010 and 2020, and to investigate any geographical, age, and sex differences in the prevalence and incidence of dementia.
METHODS
Five databases were searched. The Joanna Briggs Institute (JBI) critical appraisal tool was used to assess the quality of the included studies. A random-effects meta-analysis was performed to estimate the pooled prevalence of dementia. Subgroup analysis was based on the type of dementia. The incidence and mortality of dementia were synthesized qualitatively.
RESULTS
A total of 19 studies were included. The meta-analysis showed that the prevalence of dementia was 6% (95%CI 5%, 8%), the prevalence of Alzheimer's disease (AD) was 5% (95%CI 4%, 6%), and the prevalence of vascular dementia (VaD) was 1% (95%CI 0%, 2%). The subgroup analysis showed that the prevalence rates of dementia in rural (6%, 95%CI 4%, 8%) and urban areas were similar (6%, 95%CI 4%, 8%). Deaths due to dementia increased over time.
CONCLUSION
The prevalence, incidence, and mortality of dementia increased with age and over time. Applying consistent criteria to the diagnosis of cognitive impairment and dementia is necessary to help with disease monitoring. Promoting dementia knowledge and awareness at the community level is necessary.
PubMed: 38338219
DOI: 10.3390/healthcare12030334 -
Frontiers in Aging Neuroscience 2023Despite a large preclinical literature demonstrating neuroprotective effects of estrogen, use of menopausal hormone therapy (HT) for Alzheimer's disease (AD) risk...
INTRODUCTION
Despite a large preclinical literature demonstrating neuroprotective effects of estrogen, use of menopausal hormone therapy (HT) for Alzheimer's disease (AD) risk reduction has been controversial. Herein, we conducted a systematic review and meta-analysis of HT effects on AD and dementia risk.
METHODS
Our systematic search yielded 6 RCT reports (21,065 treated and 20,997 placebo participants) and 45 observational reports (768,866 patient cases and 5.5 million controls). We used fixed and random effect meta-analysis to derive pooled relative risk (RR) and 95% confidence intervals (C.I.) from these studies.
RESULTS
Randomized controlled trials conducted in postmenopausal women ages 65 and older show an increased risk of dementia with HT use compared with placebo [RR = 1.38, 95% C.I. 1.16-1.64, < 0.001], driven by estrogen-plus-progestogen therapy (EPT) [RR = 1.64, 95% C.I. 1.20-2.25, = 0.002] and no significant effects of estrogen-only therapy (ET) [RR = 1.19, 95% C.I. 0.92-1.54, = 0.18]. Conversely, observational studies indicate a reduced risk of AD [RR = 0.78, 95% C.I. 0.64-0.95, = 0.013] and all-cause dementia [RR = .81, 95% C.I. 0.70-0.94, = 0.007] with HT use, with protective effects noted with ET [RR = 0.86, 95% C.I. 0.77-0.95, = 0.002] but not with EPT [RR = 0.910, 95% C.I. 0.775-1.069, = 0.251]. Stratified analysis of pooled estimates indicates a 32% reduced risk of dementia with midlife ET [RR = 0.685, 95% C.I. 0.513-0.915, = 0.010] and non-significant reductions with midlife EPT [RR = 0.775, 95% C.I. 0.474-1.266, = 0.309]. Late-life HT use was associated with increased risk, albeit not significant [EPT: RR = 1.323, 95% C.I. 0.979-1.789, = 0.069; ET: RR = 1.066, 95% C.I. 0.996-1.140, = 0.066].
DISCUSSION
These findings support renewed research interest in evaluating midlife estrogen therapy for AD risk reduction.
PubMed: 37937120
DOI: 10.3389/fnagi.2023.1260427 -
Drugs & Aging Nov 2023The acetylcholinesterase inhibitors (AChEIs) donepezil, galantamine, and rivastigmine are commonly used in the management of various forms of dementia. (Meta-Analysis)
Meta-Analysis
BACKGROUND
The acetylcholinesterase inhibitors (AChEIs) donepezil, galantamine, and rivastigmine are commonly used in the management of various forms of dementia.
OBJECTIVES
While these drugs are known to induce classic cholinergic adverse events such as diarrhea, their potential to cause psychiatric adverse events has yet to be thoroughly examined.
METHODS
We sought to determine the risk of psychiatric adverse events associated with the use of AChEIs through a systematic review and meta-analysis of double-blind randomized controlled trials involving patients with Alzheimer's dementia and Parkinson's dementia.
RESULTS
A total of 48 trials encompassing 22,845 patients were included in our analysis. Anorexia was the most commonly reported psychiatric adverse event, followed by agitation, insomnia, and depression. Individuals exposed to AChEIs had a greater risk of experiencing appetite disorders, insomnia, or depression compared with those who received placebo (anorexia: odds ratio [OR] 2.93, 95% confidence interval [CI] 2.29-3.75; p < 0.00001; decreased appetite: OR 1.93, 95% CI 1.33-2.82; p = 0.0006; insomnia: OR 1.55, 95% CI 1.25-1.93; p < 0.0001; and depression: OR 1.59, 95% CI 1.23-2.06, p = 0.0004). Appetite disorders were also more frequent with high-dose versus low-dose therapy. A subgroup analysis revealed that the risk of insomnia was higher for donepezil than for galantamine.
CONCLUSIONS
Our findings suggest that AChEI therapy may negatively impact psychological health, and careful monitoring of new psychiatric symptoms is warranted. Lowering the dose may resolve some psychiatric adverse events, as may switching to galantamine in the case of insomnia.
CLINICAL TRIAL REGISTRATION
The study was pre-registered on PROSPERO (CRD42021258376).
Topics: Humans; Acetylcholinesterase; Alzheimer Disease; Anorexia; Cholinesterase Inhibitors; Donepezil; Galantamine; Parkinson Disease; Phenylcarbamates; Randomized Controlled Trials as Topic; Rivastigmine; Sleep Initiation and Maintenance Disorders
PubMed: 37682445
DOI: 10.1007/s40266-023-01065-x -
Neurological Sciences : Official... Mar 2024In this systematic review and meta-analysis, we critically evaluate available evidence regarding the association between primary headaches and subsequent decline of... (Meta-Analysis)
Meta-Analysis
OBJECTIVE
In this systematic review and meta-analysis, we critically evaluate available evidence regarding the association between primary headaches and subsequent decline of cognitive function and dementia.
BACKGROUND
Recent studies suggested that headache disorders may increase the risk for dementia. However, available studies are conflicting.
METHODS
To identify qualifying studies, we searched scientific databases, including Pubmed, Scopus, Web of Science, Science Direct and BMC, screening for relevant papers. In order to reduce the heterogeneity between different studies, the analyses were further subdivided according to the clinical diagnoses and the study methodologies.
RESULTS
We identified 23 studies investigating the association between primary headaches and the risk of dementia. Of these, 18 met our inclusion criteria for meta-analysis (covering 924.140 individuals). Overall effect-size shows that primary headaches were associated with a small increase in dementia risk (OR = 1,15; CI 95%: 1,03-1,28; p = 0,02). Analyzing subgroups, we found that migraine was associated with both a moderate increased risk of all-cause dementia (OR = 1,26; p = 0,00; 95% CI: 1,13-1,40) as well as a moderate increased risk of Alzheimer's disease (OR = 2,00; p = 0,00; 95% CI: 1,46-2,75). This association was significant in both case-control and retrospective cohort studies but not in prospective studies.
CONCLUSIONS
Our study supports the presence of a link between primary headaches and dementia. However, in the subgroup analysis, only patients with migraine showed a moderate increase risk for all-cause dementia and for Alzheimer's disease. Additional rigorous studies are needed to elucidate the possible role of primary headaches on the risk of developing cognitive impairment and dementia.
Topics: Humans; Alzheimer Disease; Retrospective Studies; Prospective Studies; Headache; Cognitive Dysfunction; Risk Factors; Migraine Disorders
PubMed: 37721571
DOI: 10.1007/s10072-023-07069-0 -
Systematic Reviews Aug 2023Subjective cognitive impairment (SCI) substantially increases dementia risk and is often conceptualised as the preclinical asymptomatic phase of the cognitive decline...
BACKGROUND
Subjective cognitive impairment (SCI) substantially increases dementia risk and is often conceptualised as the preclinical asymptomatic phase of the cognitive decline continuum. Due to the lack of pharmacological interventions available to treat SCI and reduce dementia risk, and the popularity of herbal and nutritional medicines, the primary aim of this review was to investigate the efficacy on cognitive function and safety of herbal and nutritional medicines (relative to a control) for older adults with and without SCI. The secondary aims were to describe the study characteristics and assess the methodological quality of included studies.
METHOD
Five databases (Cochrane, MEDLINE, CINAHL, PsycInfo, and EMBASE) were searched from database inception with weekly alerts established until review finalisation on 18 September 2022. Articles were eligible if they included the following: study population of older adults with and without SCI, herbal and nutritional medicines as an intervention, evaluated cognitive outcomes and were randomised control trials.
RESULTS
Data were extracted from 21/7666 eligible full-text articles, and the risk of methodological bias was assessed (with SCI = 9/21; without SCI = 12/21). Most studies (20/21) employed parallel, randomised, placebo-controlled designs and were 12 weeks in length. Herbal supplements were widely used (17/21), namely a form of Ginkgo biloba (8/21) or Bacopa monnieri (6/21). Measures of cognition varied across studies, with 14/21 reporting improvements in at least one domain of cognitive functioning over time, in the intervention group (compared to control). A total of 14/21 studies were deemed as having an overall high methodological risk of bias, 6/21 had some concerns, and only one study (using an SCI population) was assessed as having a low risk of methodological bias.
CONCLUSIONS
Overall, this review found that there is a low quality of evidence regarding the efficacy of cognitive function and safety of herbal and nutritional medicines for older adults with and without SCI, due to a high risk of bias across studies. Additionally, further work needs to be done in classifying and understanding SCI and selecting appropriate trial primary outcomes before future studies can more accurately determine the efficacy of interventions for this population.
Topics: Humans; Aged; Cognition; Cognitive Dysfunction; Databases, Factual; MEDLINE; Dementia; Randomized Controlled Trials as Topic
PubMed: 37592293
DOI: 10.1186/s13643-023-02301-6 -
Medicine Oct 2023Herpes Zoster, commonly known as shingles, is a viral infection that affects a significant portion of the adult population; however, its potential role in the onset or... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Herpes Zoster, commonly known as shingles, is a viral infection that affects a significant portion of the adult population; however, its potential role in the onset or progression of neurodegenerative disorders like dementia remains unclear.
METHODS
We searched the following databases: PubMed, Scopus, Cochrane library, and Web of Science. We included any randomized control trials and controlled observational studies as Cross-sectional, prospective, or retrospective cohort and case-control studies that investigated the prevalence of dementia in Herpes Zoster Virus (HZV)-infected patients and HZV-free control group or if the study investigated the prevalence of HZV in demented patients. Also, if the studies measured the levels of dementia biomarkers in patients with HZV compared with a healthy control group.
RESULTS
After the complete screening, 9 studies were included in the meta-analysis. In the outcome of the incidence of HZV, the pooled analysis showed no statistically significant difference between the dementia group and the No dementia group (RR = 1.04% CI = 0.86-1.25, P = .70). In the outcome of incidences of dementia and Alzheimer's disease, the pooled analysis showed no statistically significant difference between the HZV group and the incidence of dementia (RR = 0.99, 95% CI = 0.92-1.08, P = .89), (RR = 3.74, 95% CI = 0.22-62.70, P = .36) respectively. In the outcome of incidences of Herpes Zoster ophthalmicus (HZO), the generic inverse variance showed a statistically significant association between patients who have HZO and increased incidence of dementia (RR = 6.26, 95% CI = 1.30-30.19, P = .02).
CONCLUSION
Our study showed no significant association between HZV and the incidence of dementia or Alzheimer's disease, but it shows a significant association between HZO and the incidence of dementia. More multicenter studies are needed to establish the actual association between the HZV and dementia.
Topics: Adult; Humans; Herpesvirus 3, Human; Retrospective Studies; Alzheimer Disease; Prospective Studies; Cross-Sectional Studies; Herpes Zoster; Chickenpox
PubMed: 37904465
DOI: 10.1097/MD.0000000000034503 -
PloS One 2023Atopic dermatitis (AD) is a common chronic inflammatory skin disease that affects adults worldwide. Recent evidence suggests that AD may be associated with cognitive... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Atopic dermatitis (AD) is a common chronic inflammatory skin disease that affects adults worldwide. Recent evidence suggests that AD may be associated with cognitive dysfunction, but the results of individual studies have been inconsistent. This systematic review and meta-analysis aimed to evaluate the association between AD and cognitive dysfunction in middle-aged and older adults.
METHODS
To find relevant research, a comprehensive search of electronic databases from the beginning to March 2023 was carried out. Data were taken from studies that were eligible, and a meta-analysis was done to determine the pooled hazard ratio (HR) and 95% confidence interval (CI).
RESULTS
We searched three databases and found a total of 15 studied arms included in 5 cohort studies with over 8.5 million participants were included in the analysis. The results showed that individuals with AD had a higher risk of developing dementia of all-cause dementia (pooled hazard ratio (HR) = 1.16; 95% CI, 1.10-1.23,P<0.001) and the Alzheimer type (pooled HR = 1.28; 95% CI, 1.01-1.63,P<0.001) but not vascular dementia (pooled HR = 1.42; 95% CI, 0.99-2.04,P<0.001). Subgroup analyses showed that the association between atopic dermatitis and all-cause dementia was significant in Europe (P = 0.004) but not in Asia (P = 0.173) and was significant in prospective cohort studies (P<0.001) but not in non-prospective cohort studies (P = 0.068). Sensitivity analysis and publication bias detection confirmed the reliability of the overall findings.
CONCLUSIONS
In conclusion, this study demonstrated that AD was associated with increased risk of cognitive dysfunction, particularly dementia of the Alzheimer type and all-cause dementia, in middle-aged and older participants. Further research is needed to understand the mechanisms behind this association and its potential implications for clinical practice.
SYSTEMATIC REVIEW REGISTRATION
PROSPERO, identifier (CRD42023411627).
Topics: Middle Aged; Humans; Aged; Alzheimer Disease; Dermatitis, Atopic; Prospective Studies; Reproducibility of Results; Cognitive Dysfunction
PubMed: 37878635
DOI: 10.1371/journal.pone.0292987 -
International Journal of Molecular... Sep 2023Aging is a complex process influenced by genetics and the environment, leading to physiological decline and increased susceptibility to diseases. Cognitive decline is a... (Review)
Review
Aging is a complex process influenced by genetics and the environment, leading to physiological decline and increased susceptibility to diseases. Cognitive decline is a prominent feature of aging, with implications for different neurodegenerative disorders. The gut microbiome has gained attention for its potential impact on health and disease, including cognitive function. This systematic review and meta-analysis aimed to investigate the relationship between the gut microbiome and cognitive function in the context of aging. Following PRISMA guidelines, a comprehensive search strategy was employed in PubMed, Scopus, and Web of Science databases. Studies exploring the role of the microbiome in cognition and neurodegenerative disorders, published between 2013 and 2023, were included. Data extraction and quality assessment were performed. Quantitative synthesis using statistical analyses was performed to examine microbial diversity and relative abundance in various cognitive conditions. Sixteen studies involving a total of 1303 participants were included in the analysis. The gut microbiota's relative abundance was different in individuals with cognitive impairments such as Alzheimer's disease, Parkinson's disease, and dementia, compared to the healthy controls. The most prevalent phyla affected were Firmicutes, Bacteroidetes, Actinobacteria, and Proteobacteria. Meta-analyses indicated substantial heterogeneity among studies focusing on Alzheimer's disease. The overall quality of evidence related to microbial analysis was moderate. The gut microbiome's role in cognitive decline and neurodegenerative disorders warrants investigation. Altered microbial abundance, particularly in specific phyla, is associated with cognitive impairments. However, variations in study findings and methodologies highlight the complexity of the relationship between the gut microbiome and cognitive function. Further studies are needed to better understand the mechanisms underlying this connection and its potential implications for aging and cognitive health.
PubMed: 37761988
DOI: 10.3390/ijms241813680