Incidence, age at diagnosis and survival with dementia across ethnic groups in England: A longitudinal study using electronic health records

Racial and ethnic minority representation in dementia risk factor research: a scoping review of cohort studies

BACKGROUND

Despite a potentially greater burden of dementia, racial and ethnic minority populations around the world may be more likely to be excluded from research examining risk factors for incident dementia. We aimed to systematically investigate and quantify racial and ethnic minority representation in dementia risk factor research.

METHODS

We performed a two-stage systematic search of databases-MEDLINE (Ovid SP), Embase (Ovid SP) and Scopus-from inception to March 2021 to identify population-based cohort studies looking at risk factors for dementia incidence. We included cohort studies which were population-based and incorporated a clinical dementia diagnosis.

RESULTS

Out of the 97 identified cohort studies, fewer than half (40 studies; 41%) reported the race or ethnicity of participants and just under one-third (29 studies; 30%) reported the inclusion of racial and ethnic minority groups. We found that inadequate reporting frequently prevented assessment of selection bias and only six studies that included racial and ethnic minority participants were at low risk for measurement bias in dementia diagnosis. In cohort studies including a multiethnic cohort, only 182 out of 337 publications incorporated race or ethnicity in data analysis-predominantly (90%) through adjustment for race or ethnicity as a confounder. Only 14 publications (4.2% of all publications reviewed) provided evidence about drivers of any observed inequalities.

CONCLUSIONS

Racial and ethnic minority representation in dementia risk factor research is inadequate. Comparisons of dementia risk between different racial and ethnic groups are likely hampered by significant selection and measurement bias. Moreover, the focus on 'adjusting out' the effect of race and ethnicity as a confounder prevents understanding of underlying drivers of observed inequalities. There is a pressing need to fundamentally change the way race, ethnicity and the inclusion of racial and ethnic minorities are considered in research if health inequalities are to be adequately addressed.

Understanding engagement in diet and dementia prevention research among British South Asians: a short report of findings from a patient and public involvement group

BACKGROUND

Dementia is a global public health challenge. Evidence suggests that individuals from South Asian communities are an at-risk group for dementia, partly as a result of early and cumulative exposure to known dementia risk factors, such as obesity and type 2 diabetes. There needs to be more culturally appropriate community engagement to increase awareness of dementia and identify better strategies to encourage participation in dementia-related research.

METHODS

We aimed to better understand the barriers and facilitators towards engaging with, and participating in, diet and dementia related research among British South Asians. This was achieved using a public and patient involvement (PPI) approach. A community-based, engagement event involving information sharing from experts and roundtable discussions with South Asian communities (n = 26 contributors) was held in June 2023 in Newcastle-upon-Tyne, UK. Collaboration from preidentified PPI representatives (n = 3) informed the content and structure of PPI activities, as well as recruitment. Data were synthesised using template analysis, a form of codebook thematic analysis. This involved deductively analysing data using relevant a priori themes, which were expanded upon, or modified, via inductive analysis.

RESULTS

The findings highlighted the importance of trust, representation and appreciation of cultural barriers as facilitators to engagement in diet and dementia risk reduction research. Consideration of language barriers, time constraints, social influences and how to embed community outreach activities were reported as driving factors to maximise participation.

CONCLUSIONS

This PPI work will inform the design and co-creation of a culturally adapted dietary intervention for brain health in accordance with the Medical Research Council and National Institute for Health and Care Research guidance for developing complex interventions.

Changes in prevalence and incidence of dementia and risk factors for dementia: an analysis from cohort studies

BACKGROUND

Some cohort studies have reported a decline in dementia prevalence and incidence over time, although these findings have not been consistent across studies. We reviewed evidence on changes in dementia prevalence and incidence over time using published population-based cohort studies that had used consistent methods with each wave and aimed to quantify associated changes in risk factors over time using population attributable fractions (PAFs).

METHODS

We searched for systematic reviews of cohort studies examining changes in dementia prevalence or incidence over time. We searched PubMed for publications from database inception up to Jan 12, 2023, using the search terms "systematic review" AND "dementia" AND ("prevalence" OR "incidence"), with no language restrictions. We repeated this search on March 28, 2024. From eligible systematic reviews, we searched the references and selected peer-reviewed publications about cohort studies where dementia prevalence or incidence was measured in the same geographical location, at a minimum of two timepoints, and that reported age-standardised prevalence or incidence of dementia. Additionally, data had to be from population-based samples, in which participants' cognitive status was assessed and where validated criteria were used to diagnose dementia. We extracted summary-level data from each paper about dementia risk factors, contacting authors when such data were not available in the published paper, and calculated PAFs for each risk factor at all available timepoints. Where possible, we linked changes in dementia prevalence or incidence with changes in the prevalence of risk factors.

FINDINGS

We identified 1925 records in our initial search, of which five eligible systematic reviews were identified. Within these systematic reviews, we identified 71 potentially eligible primary papers, of which 27 were included in our analysis. 13 (48%) of 27 primary papers reported change in prevalence of dementia, ten (37%) reported change in incidence of dementia, and four (15%) reported change in both incidence and prevalence of dementia. Studies reporting change in dementia incidence over time in Europe (n=5) and the USA (n=5) consistently reported a declining incidence in dementia. One study from Japan reported an increase in dementia prevalence and incidence and a stable incidence was reported in one study from Nigeria. Overall, across studies, the PAFs for less education or smoking, or both, generally declined over time, whereas PAFs for obesity, hypertension, and diabetes generally increased. The decrease in PAFs for less education and smoking was associated with a decline in the incidence of dementia in the Framingham study (Framingham, MA, USA, 1997-2013), the only study with sufficient data to allow analysis.

INTERPRETATION

Our findings suggest that lifestyle interventions such as compulsory education and reducing rates of smoking through country-level policy changes could be associated with an observed reduction, and therefore future reduction, in the incidence of dementia. More studies are needed in low-income and middle-income countries, where the burden of dementia is highest, and continues to increase.

FUNDING

National Institute for Health and Care Research Three Schools' Dementia Research Programme.

Understanding the inclusion and participation of adults from Black African Diaspora Communities (BAFDC) in health and care research in the UK: a realist review protocol

INTRODUCTION

People from Black African Diaspora Communities (BAFDC) experience poorer health outcomes, have many long-term conditions and are persistently under-represented in health and care research. There is limited focus on programmes, or interventions that support inclusion and participation of people from BAFDC in research. Through coproduction, this realist review seeks to provide a programme theory explaining what context and mechanisms may be required, to produce outcomes that facilitate inclusion and participation for people from BAFDC in health and care research, in the UK.

METHODS AND ANALYSIS

A group of people from BAFDC with lived and professional experience, representing all levels of the health and care research system, will coproduce a realist review with a team of African-Caribbean, white British and white British of Polish origin health and care researchers. They will follow Pawson's five steps: (1) shaping the scope of the review; (2) searching for evidence; (3) document selection and appraisal; (4) data extraction and (5) data synthesis. The coproduction group will help to map the current landscape, identifying key issues that may inhibit or facilitate inclusion. Data will be extracted, analysed and synthesised following realist logic analysis, identifying and explaining how context and mechanisms are conceptualised in the literature and the types of contextual factors that exist and impact on inclusion and participation. Findings will be reported in accordance with Realist and Meta-narrative Evidence Synthesis Evolving Standards .

ETHICS AND DISSEMINATION

The coproduction group will agree an ethical approach considering accountability, responsibility and power dynamics, by establishing a terms of reference, taking a reflexive approach and coproducing an ethical framework. Findings will be disseminated to BAFDC and the research community through arts-based methods, peer-reviewed publications and conference presentations, agreeing a coproduced strategy for dissemination. Ethical review is not required.

PROSPERO REGISTRATION NUMBER

CRD42024517124.

Phosphodiesterase Type 5 Inhibitors in Men With Erectile Dysfunction and the Risk of Alzheimer Disease: A Cohort Study

BACKGROUND AND OBJECTIVES

Repurposing phosphodiesterase type 5 inhibitors (PDE5Is) as drugs for Alzheimer disease (AD) risk reduction has shown promise based on animal studies. However, evidence in humans remains inconclusive. Therefore, we conducted a cohort study to evaluate the association between PDE5I initiation compared with nonuse and the risk of developing AD in men with erectile dysfunction (ED).

METHODS

Using electronic health records from IQVIA Medical Research Data UK (formerly known as the THIN database), we identified men aged ≥40 years with a new diagnosis of ED between 2000 and 2017. Individuals with a previous diagnosis of dementia, cognitive impairment, confusion, or prescription for dementia symptoms were excluded. The occurrence of incident AD was identified using diagnostic read codes. To minimize immortal-time bias, PDE5I initiation was treated as a time-varying exposure variable. Potential confounders were adjusted using inverse probability of treatment weighting based on propensity scores. Cox proportional hazard models were used to estimate the adjusted hazard ratio (HR) with 95% CIs. A secondary analysis explored the association between AD and the cumulative number of PDE5I prescriptions. Sensitivity analyses included lag (delay) periods of 1 and 3 years after cohort entry to address the prodromal stage of AD.

RESULTS

The study included 269,725 men, with 1,119 newly diagnosed with AD during a median follow-up of 5.1 (interquartile range 2.9-8.9) years. The adjusted HR in PDE5I initiators compared with nonuse was 0.82 (95% CI 0.72-0.93). The associated risk of AD decreased in individuals issued >20 prescriptions: HR 0.56 (95% CI 0.43-0.73) for 21-50 prescriptions and HR 0.65 (95% CI 0.49-0.87) for >50 prescriptions. Sensitivity analysis with a 1-year lag period supported the primary findings (HR 0.82, 95% CI 0.72-0.94), but the results differed with the inclusion of a 3-year lag period (HR 0.93, 95% CI 0.80-1.08).

DISCUSSION

PDE5I initiation in men with ED was associated with a lower risk of AD, particularly in those most frequently issued prescriptions. The differences between primary and sensitivity analyses highlight the need to explore the optimal lag period. To enhance the generalizability of our findings, a randomized controlled trial including both sexes and exploring various PDE5I doses would be beneficial to confirm the association between PDE5I and AD.

Prediction of survival of persons with advanced dementia using the advanced dementia prognostic tool: A 2-year prospective study

BACKGROUND

In this prospective study, we evaluated the usefulness of the advanced dementia prognostic tool (ADEPT) for estimating the 2-year survival of persons with advanced dementia (AD) in China.

METHODS

The study predicted the 2-year mortality of 115 persons with AD using the ADEPT score.

RESULTS

In total, 115 persons with AD were included in the study. Of these persons, 48 died. The mean ADEPT score was 13.0. The AUROC for the prediction of the 2-year mortality rate using the ADEPT score was 0.62. The optimal threshold of the ADEPT score was 11.2, which had an AUROC of 0.63, specificity of 41.8, and sensitivity of 83.3.

CONCLUSIONS

The ADEPT score based on a threshold of 11.2 may serve as a prognostic tool to determine the 2-year survival rate of persons with AD in Chongqing, China. However, further studies are needed to explore the nature of this relationship.

Artificial intelligence for dementia prevention

INTRODUCTION

A wide range of modifiable risk factors for dementia have been identified. Considerable debate remains about these risk factors, possible interactions between them or with genetic risk, and causality, and how they can help in clinical trial recruitment and drug development. Artificial intelligence (AI) and machine learning (ML) may refine understanding.

METHODS

ML approaches are being developed in dementia prevention. We discuss exemplar uses and evaluate the current applications and limitations in the dementia prevention field.

RESULTS

Risk-profiling tools may help identify high-risk populations for clinical trials; however, their performance needs improvement. New risk-profiling and trial-recruitment tools underpinned by ML models may be effective in reducing costs and improving future trials. ML can inform drug-repurposing efforts and prioritization of disease-modifying therapeutics.

DISCUSSION

ML is not yet widely used but has considerable potential to enhance precision in dementia prevention.

HIGHLIGHTS

Artificial intelligence (AI) is not widely used in the dementia prevention field. Risk-profiling tools are not used in clinical practice. Causal insights are needed to understand risk factors over the lifespan. AI will help personalize risk-management tools for dementia prevention. AI could target specific patient groups that will benefit most for clinical trials.

Estimating the prevalence of diagnosed Alzheimer disease in England across deprivation groups using electronic health records: a clinical practice research datalink study

OBJECTIVE

Estimate the prevalence of diagnosed Alzheimer's disease (AD) and early Alzheimer's disease (eAD) overall and stratified by age, sex and deprivation and combinations thereof in England on 1 January 2020.

DESIGN

Cross-sectional.

SETTING

Primary care electronic health record data, the Clinical Practice Research database linked with secondary care data, Hospital Episode Statistics (HES) and patient-level deprivation data, Index of Multiple Deprivation (IMD).

OUTCOME MEASURES

The prevalence per 100 000 of the population and corresponding 95% CIs for both diagnosed AD and eAD overall and stratified by covariates. Sensitivity analyses were conducted to assess the sensitivity of the population definition and look-back period.

RESULTS

There were 448 797 patients identified in the Clinical Practice Research Datalink that satisfied the study inclusion criteria and were eligible for HES and IMD linkage. For the main analysis of AD and eAD, 379 763 patients are eligible for inclusion in the denominator. This resulted in an estimated prevalence of diagnosed AD of 378.39 (95% CI, 359.36 to 398.44) per 100 000 and eAD of 292.81 (95% CI, 276.12 to 310.52) per 100 000. Prevalence estimates across main and sensitivity analyses for the entire AD study population were found to vary widely with estimates ranging from 137.48 (95% CI, 127.05 to 148.76) to 796.55 (95% CI, 768.77 to 825.33). There was significant variation in prevalence of diagnosed eAD when assessing the sensitivity with the look-back periods, as low as 120.54 (95% CI, 110.80 to 131.14) per 100 000, and as high as 519.01 (95% CI, 496.64 to 542.37) per 100 000.

CONCLUSIONS

The study found relatively consistent patterns of prevalence across both AD and eAD populations. Generally, the prevalence of diagnosed AD increased with age and increased with deprivation for each age category. Women had a higher prevalence than men. More granular levels of stratification reduced patient numbers and increased the uncertainty of point prevalence estimates. Despite this, the study found a relationship between deprivation and prevalence of AD.

Potentially modifiable dementia risk factors in all Australians and within population groups: an analysis using cross-sectional survey data

BACKGROUND

Dementia is the second leading cause of disease burden in Australia. We aimed to calculate the population attributable fractions (PAFs) of dementia attributable to 11 of 12 previously identified potentially modifiable health and social risk factors (less education, hearing loss, hypertension, obesity, smoking, depression, social isolation, physical inactivity, diabetes, alcohol excess, air pollution, and traumatic brain injury), for Australians overall and three population groups (First Nations, and those of European and Asian ancestry).

METHODS

We calculated the prevalence of dementia risk factors (excluding traumatic brain injury) and PAFs, adjusted for communality, from the cross-sectional National Aboriginal and Torres Strait Islander Health Survey (2018-19), National Aboriginal and Torres Strait Islander Social Survey (2014-15), National Health Survey (2017-18), and General Social Survey (2014) conducted by the Australian Bureau of Statistics. We conducted sensitivity analyses using proxy estimates for traumatic brain injury (12th known risk factor) for which national data were not available.

FINDINGS

A large proportion (38·2%, 95% CI 37·2-39·2) of dementia in Australia was theoretically attributable to the 11 risk factors; 44·9% (43·1-46·7) for First Nations Australians, 36·4% (34·8-38·1) for European ancestry, and 33·6% (30·1-37·2) for Asian ancestry. Including traumatic brain injury increased the PAF to 40·6% (39·6-41·6) for all Australians. Physical inactivity (8·3%, 7·5-9·2), hearing loss (7·0%, 6·4-7·6), and obesity (6·6%, 6·0-7·3) accounted for approximately half of the total PAF estimates across Australia, and for all three population groups.

INTERPRETATION

Our PAF estimates indicate a substantial proportion of dementia in Australia is potentially preventable, which is broadly consistent with global trends and results from other countries. The highest potential for dementia prevention was among First Nations Australians, reflecting the enduring effect of upstream social, political, environmental, and economic disadvantage, leading to greater life-course exposure to dementia risk factors. Although there were common dementia risk factors across different population groups, prevention strategies should be informed by community consultation and be culturally and linguistically appropriate.

FUNDING

Australian National Health and Medical Research Council and University College London Hospitals' National Institute for Health Research (NIHR) Biomedical Research Centre, and North Thames NIHR Applied Research Collaboration.

Repurposing of Tibolone in Alzheimer's Disease

Alzheimer's disease (AD) is a debilitating neurodegenerative disease characterised by the accumulation of amyloid-beta and tau in the brain, leading to the progressive loss of memory and cognition. The causes of its pathogenesis are still not fully understood, but some risk factors, such as age, genetics, and hormones, may play a crucial role. Studies show that postmenopausal women have a higher risk of developing AD, possibly due to the decrease in hormone levels, especially oestrogen, which may be directly related to a reduction in the activity of oestrogen receptors, especially beta (ERβ), which favours a more hostile cellular environment, leading to mitochondrial dysfunction, mainly affecting key processes related to transport, metabolism, and oxidative phosphorylation. Given the influence of hormones on biological processes at the mitochondrial level, hormone therapies are of clinical interest to reduce the risk or delay the onset of symptoms associated with AD. One drug with such potential is tibolone, which is used in clinics to treat menopause-related symptoms. It can reduce amyloid burden and have benefits on mitochondrial integrity and dynamics. Many of its protective effects are mediated through steroid receptors and may also be related to neuroglobin, whose elevated levels have been shown to protect against neurological diseases. Its importance has increased exponentially due to its implication in the pathogenesis of AD. In this review, we discuss recent advances in tibolone, focusing on its mitochondrial-protective effects, and highlight how valuable this compound could be as a therapeutic alternative to mitigate the molecular pathways characteristic of AD.

Has COVID-19 affected dementia diagnosis rates in England?

BACKGROUND

The COVID-19 pandemic impacted on the provision of care and routine activity of all National Health Service (NHS) services. While General Practitioner referrals to memory services in England have returned to pre-pandemic levels, the estimated dementia diagnosis rate (DDR) fell by 5.4% between March 2020 and February 2023.

METHODS

In this paper we explore whether this reduction is accurate or is an artefact of the way the NHS collects data.

RESULTS

We explore the processes that may have affected national dementia diagnosis rates during and following the COVID-19 pandemic.

CONCLUSIONS

We discuss what action could be taken to improve the DDR in the future.