Potential impact of diabetes prevention on mortality and future burden of dementia and disability: a modelling study

Association of type 2 diabetes mellitus with dementia-related and non-dementia-related mortality among postmenopausal women: A secondary competing risks analysis of the women's health initiative

INTRODUCTION

Alzheimer's disease (AD) and AD-related dementias (ADRD) are leading causes of death among older adults in the United States. Efforts to understand risk factors for prevention are needed.

METHODS

Participants (n = 146,166) enrolled in the Women's Health Initiative without AD at baseline were included. Diabetes status was ascertained from self-reported questionnaires and deaths attributed to AD/ADRD from hospital, autopsy, and death records. Competing risk regression models were used to estimate the cause-specific hazard ratios (HRs) and 95% confidence intervals (CIs) for the prospective association of type 2 diabetes mellitus (T2DM) with AD/ADRD and non-AD/ADRD mortality.

RESULTS

There were 29,393 treated T2DM cases and 8628 AD/ADRD deaths during 21.6 (14.0-23.5) median (IQR) years of follow-up. Fully adjusted HRs (95% CIs) of the association with T2DM were 2.94 (2.76-3.12) for AD/ADRD and 2.65 (2.60-2.71) for the competing risk of non-AD/ADRD mortality.

DISCUSSION

T2DM is associated with AD/ADRD and non-AD/ADRD mortality.

HIGHLIGHTS

Type 2 diabetes mellitus is more strongly associated with Alzheimer's disease (AD)/AD and related dementias (ADRD) mortality compared to the competing risk of non-AD/ADRD mortality among postmenopausal women. This relationship was consistent for AD and ADRD, respectively. This association is strongest among participants without obesity or hypertension and with younger age at baseline, higher diet quality, higher physical activity, higher alcohol consumption, and older age at the time of diagnosis of type 2 diabetes mellitus.

Dementia incidence trend in England and Wales, 2002-19, and projection for dementia burden to 2040: analysis of data from the English Longitudinal Study of Ageing

BACKGROUND

Dementia incidence declined in many high-income countries in the 2000s, but evidence on the post-2010 trend is scarce. We aimed to analyse the temporal trend in England and Wales between 2002 and 2019, considering bias and non-linearity.

METHODS

Population-based panel data representing adults aged 50 years and older from the English Longitudinal Study of Ageing were linked to the mortality register across wave 1 (2002-03) to wave 9 (2018-19) (90 073 person observations). Standard criteria based on cognitive and functional impairment were used to ascertain incident dementia. Crude incidence rates were determined in seven overlapping initially dementia-free subcohorts each followed up for 4 years (ie, 2002-06, 2004-08, 2006-10, 2008-12, 2010-14, 2012-16, and 2014-18). We examined the temporal trend of dementia incidence according to age, sex, and educational attainment. We estimated the trend of dementia incidence adjusted by age and sex with Cox proportional hazards and multistate models. Restricted cubic splines allowed for potential non-linearity in the time trend. A Markov model was used to project future dementia burden considering the estimated incidence trend.

FINDINGS

Incidence rate standardised by age and sex declined from 2002 to 2010 (from 10·7 to 8·6 per 1000 person-years), then increased from 2010 to 2019 (from 8·6 to 11·3 per 1000 person-years). Adjusting for age and sex, and accounting for missing dementia cases due to death, estimated dementia incidence declined by 28·8% from 2002 to 2008 (incidence rate ratio 0·71, 95% CI 0·58-0·88), and increased by 25·2% from 2008 to 2016 (1·25, 1·03-1·54). The group with lower educational attainment had a smaller decline in dementia incidence from 2002 to 2008 and a greater increase after 2008. If the upward incidence trend continued, there would be 1·7 million (1·62-1·75) dementia cases in England and Wales by 2040, 70% more than previously forecast.

INTERPRETATION

Dementia incidence might no longer be declining in England and Wales. If the upward trend since 2008 continues, along with population ageing, the burden on health and social care will be large.

FUNDING

UK Economic and Social Research Council.

Urolithin A Protects Neuronal Cells against Stress Damage and Apoptosis by Atp2a3 Inhibition

SCOPE

This study aims to investigate the effect and mechanism of Urolithin A (UA) on neuronal stress damage on cognitive impairment in type 2 diabetes mellitus (T2DM) mouse model induced by high-fat diet (HFD) and streptozotocin (STZ).

METHODS AND RESULTS

T2DM mice fed with UA display an attenuated cognitive impairment along with suppressed endoplasmic reticulum (ER) stress and Tau hyperphosphorylation in brain. Similar restraint effect of UA on Tau hyperphosphorylation and ER stress is also observed in high glucose-treated primary hippocampal neurons. Moreover, UA ameliorates oxidative stress, ER stress, aberrant energy metabolism, and apoptosis in 2,3-dimethoxy-1,4-naphthoquinone (DMNQ) induced HT22 cells. Atp2a3 is identified as a potential target gene of UA which is closely related to intracellular calcium homeostasis, ER stress, and apoptosis, so that UA significantly down-regulated Atp2a3 expression in DMNQ-induced cells. Furthermore, the protection effect of UA against ER stress and apoptosis is abolished by Atp2a3 over-expression in HT22 cells. Taken together, these data suggest that UA performs anti-stress effect by suppressing the expression of Atp2a3 in damaged neuronal cells and thus attenuates diabetes-associated cognitive impairment in T2DM mice.

CONCLUSION

The study implies UA as a potential novel pharmaceutic target for neurodegeneration and stress damage through regulating the expression of Atp2a3.

Sildenafil Enhances the Therapeutic Effect of Islet Transplantation for Diabetic Peripheral Neuropathy via mTOR/S6K1 Pathway

Purpose

This study aimed to investigate the potential mechanism underlying the therapeutic effect of sildenafil in combination with islet transplantation for diabetic peripheral neuropathy.

Methods

A streptozotocin-induced diabetic mouse model was established to evaluate the effects of islet transplantation and sildenafil intervention. The mice were subjected to different interventions for 6 weeks, and histopathological staining and immunohistochemistry techniques were employed to examine the pathological changes and protein expressions of BDNF, MBP, and cleaved caspase-3 in the sciatic nerve tissue. Moreover, RSC96 cells were cocultured with islet cells and sildenafil under high glucose conditions to investigate the potential involvement of the mTOR/S6K1 pathway, BDNF, and MBP proteins. Western blotting was used to detect protein expression in each group.

Results

The results showed that islet transplantation can restore sciatic nerve injury in diabetic mice, and sildenafil can enhance the therapeutic effect of islet transplantation. In addition, the combination of sildenafil and islet cells significantly upregulated the expression levels of mTOR/S6K1, BDNF, and MBP in RSC96 cells under high glucose conditions.

Conclusions

Islet transplantation can reverse sciatic nerve injury in diabetic mice, and islet cells exhibit a protective effect on RSC96 cells under high glucose conditions via the activation of the mTOR/S6K1 pathway. Sildenafil enhances the therapeutic effect of islet transplantation, which may represent a potential treatment strategy for diabetic peripheral neuropathy.

High fat diet induces brain injury and neuronal apoptosis via down-regulating 3-β hydroxycholesterol 24 reductase (DHCR24)

Hyperlipidemia (HLP) is one of the risk factors for memory impairment and cognitive impairment. However, its pathological molecular mechanism remained unclear. 3β-hydroxysterol Δ24- reductase (DHCR24) is a key enzyme in cholesterol synthesis and has been reported to decrease in the affected areas in the brain of neurodegenerative disorders. In this study, hyperlipidemic mouse model was established to study the effect of high blood lipid on brain. The data obtained from HPLC analysis demonstrated that the cholesterol level in the brain of mice with hyperlipidemia was significantly elevated compared to the control group. While the pathological damages were observed in both cerebral cortex and hippocampus in the brain of hyperlipidemic mice. Furthermore, the protein level of DHCR24 was downregulated accompanied by elevated ubiquitination level in the hyperlipidemic mice brain. The mouse neuroblastoma cells N2a were exposed to the excess cholesterol loading, the cells underwent apoptosis and the mRNA and protein of DHCR24 in cholesterol-loaded N2a cells were significantly reduced. In addition, the expression level of endoplasmic reticulum stress marker protein (Bip and Chop) was markedly increased in response to the cholesterol loading. More importantly, overexpression of DHCR24 in N2a reversed neuronal apoptosis induced by the cholesterol loading. Conclusively, these findings suggested that hyperlipidemia could cause brain tissue injuries via down-regulating DHCR24, and overexpression of DHCR24 may alleviate hyperlipidemia-induced neuronal cells damage by reversing the endoplasmic reticulum stress-mediated apoptosis.

Impact of hypertension prevalence trend on mortality and burdens of dementia and disability in England and Wales to 2060: a simulation modelling study

BACKGROUND

Previous estimates of the impact of public health interventions targeting hypertension usually focus on one health outcome. This study aims to consider the effects of change in future hypertension prevalence on mortality, dementia, and disability simultaneously.

METHODS

We modelled three plausible scenarios based on observed trends of hypertension prevalence from 2003 to 2017 in England: observed trends continue (baseline scenario); 2017 prevalence remains unchanged; and 2017 prevalence decreases by 50% by 2060. We used a probabilistic Markov model to integrate calendar trends in incidence of cardiovascular disease, dementia, disability, and mortality to forecast their future occurrence in the population of England and Wales. Assuming the hypertension prevalence trend modifies health transition probabilities, we compared mortality outcomes and the burden of dementia and disability to 2060 for the scenarios.

FINDINGS

If the decline in hypertension prevalence stops, there would be a slight increase in the number of additional deaths to 2060 (22·9 [95% uncertainty interval 19·0-26·6] more deaths per 100 000 population), although the burdens of disability and dementia in absolute terms would change little. Alternatively, if the downward hypertension prevalence trend accelerates (with prevalence falling by 50% between 2017 and 2060), there would be a modest additional reduction in deaths (57·0 [50·4-63·5] fewer deaths per 100 000 population), a small increase in dementia burden (9·0 [5·1-13·2] more cases per 100 000 population), no significant effect on disability burden, and an 8% gain in healthy life expectancy at age 65 years from 2020 to 2060 (5·3 years vs 4·9 years) compared with the baseline scenario.

INTERPRETATION

The major future impact of alternative hypertension prevention strategies appears to be on future life expectancy. The salutary effect of lower population blood pressure distribution on incidence of dementia and disability might not offset expansion of the susceptible population due to reduced mortality.

FUNDING

British Heart Foundation and UK Economic and Social Research Council.

Projections of future burden of pharmacologically treated type 2 diabetes and associated life expectancies by income in Finland: a multi-state modeling study

The burden of type 2 diabetes (T2D) differs between socioeconomic groups. The present study combines ongoing and plausible trends in T2D incidence and survival by income to forecast future trends in cases of T2D and life expectancy with and without T2D up to year 2040. Using Finnish total population data for those aged 30 years on T2D medication and mortality in 1995-2018, we developed and validated a multi-state life table model using age-, gender-, income- and calendar year-specific transition probabilities. We present scenarios based on constant and declining T2D incidence and on the effect of increasing and decreasing obesity on T2D incidence and mortality states up to 2040. With constant T2D incidence at 2019-level, the number of people living with T2D would increase by about 26% between 2020 and 2040. The lowest income group could expect more rapid increases in the number with T2D compared to the highest income group (30% vs. 23% respectively). If the incidence of T2D continues the recent declining trend, we predict about 14% fewer cases. However, if obesity increases two-fold, we predict 15% additional T2D cases. Unless, we reduce the obesity-related excess risk, the number of years lived without T2D could decrease up to 6 years for men in the lowest income group. Under all plausible scenarios, the burden of T2D is set to increase and it will be unequally distributed among socioeconomic groups. An increasing proportion of life expectancy will be spent with T2D.

Long term high fat diet induces metabolic disorders and aggravates behavioral disorders and cognitive deficits in MAPT P301L transgenic mice

Most Alzheimer disease (AD) patients present as sporadic late onset AD, with metabolic factors playing an important role in the occurrence and development of AD. Given the link between peripheral insulin resistance and tau pathology in streptozotocin-injected and db/db mouse models of diabetes, we fed high fat diet (HFD) to pR5 mice expressing P301L mutant human tau, with the aim of developing a new model with characteristics of obesity, T2DM and AD to mimic AD patients exacerbated by obesity and T2DM, an increasing trend in modern society. In our study, pR5 and C57BL/6 (WT) mice were randomly allocated to a standard diet (STD) or HFD for 30 weeks starting at 8 weeks of age. Food intake was measured weekly, body weight and fasting glucose levels were measured fortnightly, and a comprehensive behavioral test battery was performed to assess anxiety, depression and cognitive dysfunction. Glucose and insulin tolerance tests were performed after 30 weeks of HFD. We also investigated the effect of long term HFD on tau pathology in the brains of WT and P301L mice by performing western blotting of whole brain homogenates for total tau, phosphorylated tau at Ser396 and Thr231. Our results show that pR5 mice fed with HFD are more vulnerable to diet induced obesity compared to WT, especially with increasing age. In addition, pR5 mice on HFD developed glucose intolerance and insulin resistance. It was identified that long term HFD significantly aggravates depression like behavior and impairs cognitive function in pR5 mice, and also induces anxiety like behavior in both pR5 and WT mice. Long term HFD was also shown to aggravate tau hyperphosphorylation in pR5 transgenic mice, and increase total and hyperphosphorylated tau in WT mice. These results indicate that diet induced obesity of pR5 transgenic mice expressing P301L mutant human tau generates T2DM, and aggravates tau phosphorylation, and is therefore a model useful for investigations that seek to understand the relationships between AD, T2DM and obesity, and the underlying biochemical changes and mechanisms associated with metabolic disorders and AD tauopathy.

What will the cardiovascular disease slowdown cost? Modelling the impact of CVD trends on dementia, disability, and economic costs in England and Wales from 2020–2029

Background

There is uncertainty around the health impact and economic costs of the recent slowing of the historical decline in cardiovascular disease (CVD) incidence and the future impact on dementia and disability.

Methods

Previously validated IMPACT Better Ageing Markov model for England and Wales, integrating English Longitudinal Study of Ageing (ELSA) data for 17,906 ELSA participants followed from 1998 to 2012, linked to NHS Hospital Episode Statistics. Counterfactual design comparing two scenarios: Scenario 1. CVD Plateau—age-specific CVD incidence remains at 2011 levels, thus continuing recent trends. Scenario 2. CVD Fall—age-specific CVD incidence goes on declining, following longer-term trends. The main outcome measures were age-related healthcare costs, social care costs, opportunity costs of informal care, and quality adjusted life years (valued at £60,000 per QALY).

Findings

The total 10 year cumulative incremental net monetary cost associated with a persistent plateauing of CVD would be approximately £54 billion (95% uncertainty interval £14.3-£96.2 billion), made up of some £13 billion (£8.8-£16.7 billion) healthcare costs, £1.5 billion (-£0.9-£4.0 billion) social care costs, £8 billion (£3.4-£12.8 billion) informal care and £32 billion (£0.3-£67.6 billion) value of lost QALYs.

Interpretation

After previous, dramatic falls, CVD incidence has recently plateaued. That slowdown could substantially increase health and social care costs over the next ten years. Healthcare costs are likely to increase more than social care costs in absolute terms, but social care costs will increase more in relative terms. Given the links between COVID-19 and cardiovascular health, effective cardiovascular prevention policies need to be revitalised urgently.

Brain oxidative stress and cognitive function in older adults with diabetes and pre-diabetes who are at risk for dementia

AIMS

Diabetes is an established risk factor for dementia. This study aimed to examine the relationship between various cognitive domains, brain oxidative stress and markers of diabetes in older adults at risk for dementia.

METHODS

Older adults at risk for dementia underwent comprehensive neuropsychological and medical assessment. At risk was defined as those with subjective and/or objective cognitive impairment. Pre-diabetes and type 2 diabetes were defined using American Diabetes Association definitions for fasting blood glucose and HbA1c. Brain oxidative stress as indicated by glutathione (GSH) was assessed via magnetic resonance spectroscopy in the anterior cingulate cortex.

RESULTS

One-hundred and forty-seven older adults completed a neuropsychological assessment and fasting blood sample with 63 also undergoing magnetic resonance spectroscopy. Those with pre-diabetes/diabetes according to FBG had impaired memory retention, set-shifting and response inhibition, compared to those with normal blood glucose. In contrast, there were no significant differences in any cognitive outcome using the HbA1c definition. Increasing glucose and HbA1c levels were associated with reduced GSH concentration in the anterior cingulate.

CONCLUSIONS

This study demonstrates that in older adults at risk for dementia, having pre-diabetes or diabetes is associated with impaired memory and executive dysfunction. It also highlights the potential role of oxidative stress as a pathophysiological mechanism that may underpin the link between diabetes and cognitive dysfunction.

Dementia risk reduction: why haven't the pharmacological risk reduction trials worked? An in-depth exploration of seven established risk factors

Identifying the leading health and lifestyle factors for the risk of incident dementia and Alzheimer's disease has yet to translate to risk reduction. To understand why, we examined the discrepancies between observational and clinical trial evidence for seven modifiable risk factors: type 2 diabetes, dyslipidemia, hypertension, estrogens, inflammation, omega-3 fatty acids, and hyperhomocysteinemia. Sample heterogeneity and paucity of intervention details (dose, timing, formulation) were common themes. Epidemiological evidence is more mature for some interventions (eg, non-steroidal anti-inflammatory drugs [NSAIDs]) than others. Trial data are promising for anti-hypertensives and B vitamin supplementation. Taken together, these risk factors highlight a future need for more targeted sample selection in clinical trials, a better understanding of interventions, and deeper analysis of existing data.

Modelling tool to support decision-making in the NHS Health Check programme: workshops, systematic review and co-production with users

BACKGROUND

Local authorities in England commission the NHS Health Check programme to invite everyone aged 40-74 years without pre-existing conditions for risk assessment and eventual intervention, if needed. However, the programme's effectiveness, cost-effectiveness and equity impact remain uncertain.

AIM

To develop a validated open-access flexible web-based model that enables local commissioners to quantify the cost-effectiveness and potential for equitable population health gain of the NHS Health Check programme.

OBJECTIVES

The objectives were as follows: (1) co-produce with stakeholders the desirable features of the user-friendly model; (2) update the evidence base to support model and scenario development; (3) further develop our computational model to allow for developments and changes to the NHS Health Check programme and the diseases it addresses; (4) assess the effectiveness, cost-effectiveness and equity of alternative strategies for implementation to illustrate the use of the tool; and (5) propose a sustainability and implementation plan to deploy our user-friendly computational model at the local level.

DESIGN

Co-production workshops surveying the best-performing local authorities and a systematic literature review of strategies to increase uptake of screening programmes informed model use and development. We then co-produced the workHORSE (working Health Outcomes Research Simulation Environment) model to estimate the health, economic and equity impact of different NHS Health Check programme implementations, using illustrative-use cases.

SETTING

Local authorities in England.

PARTICIPANTS

Stakeholders from local authorities, Public Health England, the NHS, the British Heart Foundation, academia and other organisations participated in the workshops. For the local authorities survey, we invited 16 of the best-performing local authorities in England.

INTERVENTIONS

The user interface allows users to vary key parameters that represent programme activities (i.e. invitation, uptake, prescriptions and referrals). Scenarios can be compared with each other.

MAIN OUTCOME MEASURES

Disease cases and case-years prevented or postponed, incremental cost-effectiveness ratios, net monetary benefit and change in slope index of inequality.

RESULTS

The survey of best-performing local authorities revealed a diversity of effective approaches to maximise the coverage and uptake of NHS Health Check programme, with no distinct 'best buy'. The umbrella literature review identified a range of effective single interventions. However, these generally need to be combined to maximally improve uptake and health gains. A validated dynamic, stochastic microsimulation model, built on robust epidemiology, enabled service options analysis. Analyses of three contrasting illustrative cases estimated the health, economic and equity impact of optimising the Health Checks, and the added value of obtaining detailed local data. Optimising the programme in Liverpool can become cost-effective and equitable, but simply changing the invitation method will require other programme changes to improve its performance. Detailed data inputs can benefit local analysis.

LIMITATIONS

Although the approach is extremely flexible, it is complex and requires substantial amounts of data, alongside expertise to both maintain and run.

CONCLUSIONS

Our project showed that the workHORSE model could be used to estimate the health, economic and equity impact comprehensively at local authority level. It has the potential for further development as a commissioning tool and to stimulate broader discussions on the role of these tools in real-world decision-making.

FUTURE WORK

Future work should focus on improving user interactions with the model, modelling simulation standards, and adapting workHORSE for evaluation, design and implementation support.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42019132087.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 35. See the NIHR Journals Library website for further project information.

Indicators of dementia disease progression in primary care: An electronic health record cohort study

BACKGROUND AND PURPOSE

The objectives were to assess the feasibility and validity of using markers of dementia-related health as indicators of dementia progression in primary care, by assessing the frequency with which they are recorded and by testing the hypothesis that they are associated with recognised outcomes of dementia. The markers, in 13 domains, were derived previously through literature review, expert consensus, and analysis of regional primary care records.

METHODS

The study population consisted of patients with a recorded dementia diagnosis in the Clinical Practice Research Datalink, a UK primary care database linked to secondary care records. Incidence of recorded domains in the 36 months after diagnosis was determined. Associations of recording of domains with future hospital admission, palliative care, and mortality were derived.

RESULTS

There were 30,463 people with diagnosed dementia. Incidence of domains ranged from 469/1000 person-years (Increased Multimorbidity) to 11/1000 (Home Pressures). An increasing number of domains in which a new marker was recorded in the first year after diagnosis was associated with hospital admission (hazard ratio for ≥4 domains vs. no domains = 1.24; 95% confidence interval = 1.15-1.33), palliative care (1.87; 1.62-2.15), and mortality (1.57; 1.47-1.67). Individual domains were associated with outcomes with varying strengths of association.

CONCLUSIONS

Feasibility and validity of potential indicators of progression of dementia derived from primary care records are supported by their frequency of recording and associations with recognised outcomes. Further research should assess whether these markers can help identify patients with poorer prognosis to improve outcomes through stratified care and targeted support.

Type 2 diabetes and cognitive dysfunction-towards effective management of both comorbidities

Type 2 diabetes and cognitive dysfunction are highly prevalent disorders worldwide. Although type 2 diabetes is associated with an increased risk of dementia, awareness of the link between the two conditions is poor, and few recommendations are available to guide clinicians about how to approach cognitive dysfunction in people with diabetes. Clinical guidelines in diabetes have only recently begun to emphasise the importance of cognitive impairment in diabetes and its management. This Series paper aims to synthesise knowledge about the link between diabetes and cognitive dysfunction, issues pertaining to screening and diagnosis of cognitive impairment and dementia in those with type 2 diabetes, management of diabetes in people with cognitive dysfunction (accounting for age and frailty), and emerging therapies for prevention. A conceptual framework for approaching screening and diagnosis is included, and future research directions to guide the field forward are suggested.

Brain Metabolism Alterations in Type 2 Diabetes: What Did We Learn From Diet-Induced Diabetes Models?

Type 2 diabetes (T2D) is a metabolic disease with impact on brain function through mechanisms that include glucose toxicity, vascular damage and blood–brain barrier (BBB) impairments, mitochondrial dysfunction, oxidative stress, brain insulin resistance, synaptic failure, neuroinflammation, and gliosis. Rodent models have been developed for investigating T2D, and have contributed to our understanding of mechanisms involved in T2D-induced brain dysfunction. Namely, mice or rats exposed to diabetogenic diets that are rich in fat and/or sugar have been widely used since they develop memory impairment, especially in tasks that depend on hippocampal processing. Here we summarize main findings on brain energy metabolism alterations underlying dysfunction of neuronal and glial cells promoted by diet-induced metabolic syndrome that progresses to a T2D phenotype.