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Common bacterial infections and risk of incident cognitive decline or dementia: a systematic review protocol.

ABSTRACT: INTRODUCTION:The global burden of dementia is rising, emphasising the urgent need to develop effective approaches to risk reduction. Recent evidence suggests that common bacterial infections may increase the risk of dementia, however the magnitude and timing of the association as well as the patient groups affected remains unclear. We will review existing evidence of the association between common bacterial infections and incident cognitive decline or dementia. METHODS AND ANALYSIS:We will conduct a comprehensive search of published and grey literature from inception to 18 March 2019. The following electronic databases will be searched; MEDLINE, EMBASE, Global health, PsycINFO, Web of Science, Scopus, Cochrane Library, the Cumulative Index to Nursing and Allied Health Literature, Open Grey and the British Library of Electronic Theses databases. There will be no restrictions on the date, language or geographical location of the studies. We will include longitudinal studies with a common clinically symptomatic bacterial infection as an exposure and incident cognitive decline or dementia as an outcome. Study selection, data extraction and risk of bias will be performed independently by two researchers. We will assess the risk of bias using the Cochrane collaboration approach. The overall quality of the studies will be assessed using the Grading of Recommendations, Assessment, Development and Evaluations criteria. We will explore the heterogeneity of relevant studies and, if feasible, a meta-analysis will be performed, otherwise we will present a narrative synthesis. We will group the results by exposure and outcome definitions and differences will be described by subgroups and outcomes. ETHICS AND DISSEMINATION:Ethical approval will not be required as this is a systematic review of existing research in the public domain. Results will be disseminated in a peer-reviewed journal and presented at national and international meetings and conferences. PROSPERO REGISTRATION NUMBER:CRD42018119294.

SUBMITTER: Muzambi R

PROVIDER: S-EPMC6747671 | biostudies-other | 2019 Sep

REPOSITORIES: biostudies-other

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Common bacterial infections and risk of incident cognitive decline or dementia: a systematic review protocol.

Muzambi Rutendo R Bhaskaran Krishnan K Brayne Carol C Smeeth Liam L Warren-Gash Charlotte C

BMJ open 20190912 9

<h4>Introduction</h4>The global burden of dementia is rising, emphasising the urgent need to develop effective approaches to risk reduction. Recent evidence suggests that common bacterial infections may increase the risk of dementia, however the magnitude and timing of the association as well as the patient groups affected remains unclear. We will review existing evidence of the association between common bacterial infections and incident cognitive decline or dementia.<h4>Methods and analysis</h ...[more]

PMID: 31515431

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Project description:Background: More people with cognitive dysfunction and dementia also fall into the category of high vascular risk, for which aspirin is one of the most frequently used drugs. However, previous studies reporting that aspirin buffers against mild cognitive decline (MCI) and dementia remain controversial. We thus conducted an updated systematic review and meta-analysis to evaluate the association of aspirin use with the risk of MCI and dementia in older adults. Methods: Data sources from PubMed, Embase, Web of Science, and the Cochrane Database for randomized controlled trails (RCTs) and cohort studies (published between January 1, 2000 and April 11, 2020). Relative risks (RRs) and 95% confidence intervals (95% CIs) were used to pool data on the occurrence of dementia and MCI with random-effects models. Results: Of 3,193 identified articles, 15 studies (12 cohort studies and three RCTs) were eligible and were included in our analysis, which involved a total of 100,909 participants without cognitive dysfunctions or dementia at baseline. In pooled cohort studies, aspirin use did not reduce the incidence of MCI and dementia (the pooled RR = 0.97; 95% CI = 0.85-1.11; Ifor heterogeneity2 = 65%) compared with non-users. However, low-dose aspirin (75-100 mg/day) was associated with a decreased likelihood of developing dementia or MCI (the pooled RR = 0.75; 95% CI = 0.63-0.9; Ifor heterogeneity2 = 50.5%). This association existed in studies including all-cause dementia (the pooled RR = 0.82; 95% CI = 0.71-0.96) and Alzheimer's disease (AD) (the pooled RR = 0.54; 95% CI = 0.33-0.89), but not in MCI (the pooled RR = 0.58; 95% CI = 0.31-1.08). In RCTs, low-dose aspirin use was not significantly associated with less prevalence of dementia or MCI (RR = 0.94; 95% CI = 0.84-1.05; Ifor heterogeneity2 = 0.0%). Conclusions: In cohort studies, we found that low-dose aspirin use had a higher likelihood of reducing the incidence of dementia, which was not supported by RCTs. The evidence was insufficient to fully evaluate the effect of aspirin on cognitive function and dementia. Well-designed studies and innovative approaches are therefore needed to clarify whether the use of aspirin improves cognitive function and reduces the risk of dementia.

Project description:IntroductionRisk factors for cardiovascular disease (CVD) also increase the risk of dementia. However, whether commonly used CVD risk scores are associated with dementia risk in older adults who do not have a history of CVD, and potential gender differences in this association, remains unclear. The aim of this study was to determine whether CVD risk scores are prospectively associated with cognitive decline and dementia in initially healthy older men and women.MethodsA total of19,114 participants from a prospective cohort of individuals aged 65+ years without known CVD or dementia were recruited. The atherosclerotic cardiovascular disease risk score (ASCVDRS), Systematic Coronary Risk Evaluation 2-Older Persons (SCORE2-OP), and the Framingham risk score (FRS) were calculated at baseline. Risk of dementia (according to DSM-IV criteria) and cognitive decline (defined as a >1.5 standard deviation decline in global cognition, episodic memory, psychomotor speed, or verbal fluency from the previous year) were assessed using hazard ratio.ResultsOver a median follow-up of 6.4 years, 850 individuals developed dementia and 4,352 cognitive decline. Men and women in the highest ASCVDRS tertile had a 41% (95% CI 1.08, 1.85) and 45% (1.11, 1.89) increased risk of dementia compared to the lowest tertile, respectively. Likewise, men and women in the highest SCORE2-OP tertile had a 64% (1.24, 2.16) and 60% (1.22, 2.11) increased risk of dementia compared to the lowest tertile, respectively. Findings were similar, but the risk was slightly lesser when examining risk of cognitive decline for both ASCVDRS and SCORE2-OP. However, FRS was only associated with the risk of cognitive decline among women (highest vs. lowest tertiles: 1.13 [1.01-1.26]).ConclusionThese findings suggest the utility of the ASCVDRS and SCORE2-OP in clinical practice, to not only assess future risk of CVD, but also as potential early indicators of cognitive impairment, even in relatively healthy older men and women.

Project description:INTRODUCTION:Persisting neurotropic viruses are proposed to increase the risk of dementia, but evidence of association from robust, adequately powered population studies is lacking. This is essential to inform clinical trials of targeted preventive interventions. METHODS AND ANALYSIS:We will carry out a comprehensive systematic review of published and grey literature of the association between infection with, reactivation of, vaccination against or treatment of any of the eight human herpesviruses and dementia or mild cognitive impairment. We will search the Cochrane Library, Embase, Global Health, Medline, PsycINFO, Scopus, Web of Science, clinical trials registers, the New York Academy of Medicine Grey Literature Report, Electronic Theses Online Service through the British Library and the ISI Conference Proceedings Citation Index for randomised controlled trials, cohort, caseâ€"control, case crossover or self-controlled case series studies reported in any language up to January 2017. Titles, abstracts and full-text screening will be conducted by two researchers independently. Data will be extracted systematically from eligible studies using a piloted template. We will assess risk of bias of individual studies in line with the Cochrane Collaboration tool. We will conduct a narrative synthesis, grouping studies by exposure and outcome definitions, and will describe any differences by population subgroups and dementia subtypes. We will consider performing meta-analyses if there are adequate numbers of sufficiently homogeneous studies. The overall quality of cumulative evidence will be assessed using selected Grading of Recommendations, Assessment, Development and Evaluations criteria. ETHICS AND DISSEMINATION:As this is a review of existing studies, no ethical approval is required. Results will be disseminated through a peer-reviewed publication and at national and international conferences. We anticipate the review will clarify the current extent and quality of evidence for a link between herpesviruses and dementia, identify gaps and inform the direction of future research. PROSPERO REGISTRATION NUMBER:CRD42017054684.

Project description:ImportanceMotoric cognitive risk (MCR) is a novel predementia syndrome; however, whether it can estimate dementia in a nationwide population or has additive estimation validity over cognitive or motoric components alone remains unknown.ObjectiveTo examine whether modified MCR, which incorporates the timed-up-and-go and one-leg-standing tests, improves estimation validity for incident dementia over using cognitive or motoric components alone.Design, setting, and participantsThis nationwide cohort study evaluated data from individuals aged 66 years who participated in the National Screening Program for Transitional Ages in Korea from January 1, 2009, to December 31, 2013, and examined the association between MCR and incident dementia using Cox proportional hazards regression analysis. Data were collected from the index date (the date on which the participant had the screening) until dementia onset, death, or the end of the follow-up period, whichever came first. The 2 subtypes were defined as subjective cognitive declines with timed-up-and-go impairment or one-leg-standing impairment. The data set was generated with permission from the Korean National Health Insurance Service, and data analysis was conducted from August 2, 2021, to January 31, 2022. Individuals diagnosed with dementia or psychotic disorders or those who had a documented history of dementia medication use before the index date were excluded.Main outcomes and measuresThe main outcome was incidence of dementia, defined as an individual receiving their first dementia medication with the relevant International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, codes after the index date.ResultsAmong the 1 137 530 participants (53.7% women), 15 380 (1.4%) met the MCR criteria for the timed-up-and-go subtype, and 32 910 (2.9%) met the criteria for the one-leg-standing subtype. The mean (SD) follow-up period was 7.02 (1.38) years. Participants with MCR demonstrated an approximately 2-fold higher risk of incident dementia than those without MCR (timed-up-and-go subtype, adjusted hazard ratio, 2.03; 95% CI, 1.94-2.13; one-leg-standing subtype, adjusted hazard ratio, 2.05; 95% CI, 1.98-2.12).Conclusions and relevanceIn this cohort study of participants aged 66 years of the National Screening Program for Transitional Ages, modified motoric cognitive risk had higher adjusted hazard ratios of incident dementia than individual cognitive or motoric components. Motoric cognitive risk may be a practical screening tool for estimating dementia among individuals in their mid-60s ; however, further investigation of the clinical and neurobiological aspects is necessary.

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Common bacterial infections and risk of incident cognitive decline or dementia: a systematic review protocol.

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Common bacterial infections and risk of incident cognitive decline or dementia: a systematic review protocol.

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