Type 2 Diabetes as a Risk Factor for Dementia in Women Compared With Men: A Pooled Analysis of 2.3 Million People Comprising More Than 100,000 Cases of Dementia

Novel Treatment Opportunities Against Cognitive Impairment in Parkinson's Disease with an Emphasis on Diabetes-Related Pathways

Cognitive impairment is highly prevalent in patients with Parkinson's disease (PD) and causes adverse health outcomes. Novel procognitive therapies are needed to address this unmet need. It is now established that there is an increased risk of dementia in patients with type 2 diabetes mellitus (T2DM) and, moreover, T2DM and PD may have common underlying biological mechanisms. As such, T2DM medications are emerging as potential therapies in the context of PD dementia (PDD). In this review, we provide an update on pathophysiological mechanisms underlying cognitive impairments and PDD, focusing on diabetes-related pathways. Finally, we have conducted a review of ongoing clinical trials in PD patients with dementia, highlighting the multiple pharmacological mechanisms that are targeted to achieve cognitive enhancement.

Contributions of sex to cerebrovascular function and pathology

Sex differences exist in how cerebral blood vessels function under both physiological and pathological conditions, contributing to observed sex differences in risk and outcomes of cerebrovascular diseases (CBVDs), such as vascular contributions to cognitive impairment and dementia (VCID) and stroke. Throughout most of the lifespan, women are protected from CBVDs; however, risk increases following menopause, suggesting sex hormones may play a significant role in this protection. The cerebrovasculature is a target for sex hormones, including estrogens, progestins, and androgens, where they can influence numerous vascular functions and pathologies. While there is a plethora of information on estrogen, the effects of progestins and androgens on the cerebrovasculature are less well-defined. Estrogen decreases cerebral tone and increases cerebral blood flow, while androgens increase tone. Both estrogens and androgens enhance angiogenesis/cerebrovascular remodeling. While both estrogens and androgens attenuate cerebrovascular inflammation, pro-inflammatory effects of androgens under physiological conditions have also been demonstrated. Sex hormones exert additional neuroprotective effects by attenuating oxidative stress and maintaining integrity and function of the blood brain barrier. Most animal studies utilize young, healthy, gonadectomized animals, which do not mimic the clinical conditions of aging individuals likely to get CBVDs. This is also concerning, as sex hormones appear to mediate cerebrovascular function differently based on age and disease state (e.g. metabolic syndrome). Through this review, we hope to inspire others to consider sex as a key biological variable in cerebrovascular research, as greater understanding of sex differences in cerebrovascular function will assist in developing personalized approaches to prevent and treat CBVDs.

Exercise and the Aging Brain: Considerations for Sex Differences

Engaging in targeted exercise interventions is a promising, non-pharmacological strategy to mitigate the deleterious effects of aging and disease on brain health. However, despite its therapeutic potential, a large amount of variation exists in exercise efficacy in older adults aged 55 and older. In this review, we present the argument that biological sex may be an important moderator of the relationship between physical activity and cognition. Sex differences exist in dementia as well as in several associated risk factors, including genetics, cardiovascular factors, inflammation, hormones and social and psychological factors. Different exercise interventions, such as aerobic training and resistance training, influence cognition and brain health in older adults and these effects may be sex-dependent. The biological mechanisms underlying the beneficial effects of exercise on the brain may be different in males and females. Specifically, we examine sex differences in neuroplasticity, neurotrophic factors and physiological effects of exercise to highlight the possible mediators of sex differences in exercise efficacy on cognition. Future studies should address the potential sex difference in exercise efficacy if we are to develop effective, evidence-based exercise interventions to promote healthy brain aging for all individuals.

Sex differences in the vascular function and related mechanisms: role of 17β-estradiol

The incidence of cardiovascular disease (CVD) is lower in premenopausal women but increases with age and menopause compared with similarly aged men. Based on the prevalence of CVD in postmenopausal women, sex hormone-dependent mechanisms have been postulated to be the primary factors responsible for the protection from CVD in premenopausal women. Recent Women’s Health Initiative studies, Cochrane Review studies, the Early Versus Late Intervention Trial with Estradiol Study, and the Kronos Early Estrogen Prevention Study have suggested that beneficial effects of hormone replacement therapy (HRT) are seen in women of <60 yr of age and if initiated within <10 yr of menopause. In contrast, the beneficial effects of HRT are not seen in women of >60 yr of age and if commenced after 10 yr of menopause. The higher incidence of CVD and the failure of HRT in postmenopausal aged women could be partly associated with fundamental differences in the vascular structure and function between men and women and in between pre- and postmenopausal women, respectively. In this regard, previous studies from human and animal studies have identified several sex differences in vascular function and associated mechanisms. The female sex hormone 17β-estradiol regulates the majority of these mechanisms. In this review, we summarize the sex differences in vascular structure, myogenic properties, endothelium-dependent and -independent mechanisms, and the role of 17β-estradiol in the regulation of vascular function.

Fasting Glucose Variability in Young Adulthood and Cognitive Function in Middle Age: The Coronary Artery Risk Development in Young Adults (CARDIA) Study

OBJECTIVE

To determine whether intraindividual variability in fasting glucose (FG) below the threshold of diabetes is associated with cognitive function in middle adulthood beyond increasing FG.

RESEARCH DESIGN AND METHODS

We studied 3,307 CARDIA (Coronary Artery Risk Development in Young Adults) Study participants (age range 18-30 years and enrolled in 1985-1986) at baseline and calculated two measures of long-term glucose variability: the coefficient of variation about the mean FG (CV-FG) and the absolute difference between successive FG measurements (average real variability [ARV-FG]) before the onset of diabetes over 25 and 30 years of follow-up. Cognitive function was assessed at years 25 (2010-2011) and 30 (2015-2016) with the Digit Symbol Substitution Test (DSST), Rey-Auditory Verbal Learning Test (RAVLT), Stroop Test, Montreal Cognitive Assessment, and category and letter fluency tests. We estimated the association between glucose variability and cognitive function test score with adjustment for clinical and behavioral risk factors, mean FG level, change in FG level, and diabetes development, medication use, and duration.

RESULTS

After multivariable adjustment, 1-SD increment of CV-FG was associated with worse cognitive scores at year 25: DSST, standardized regression coefficient -0.95 (95% CI -1.54, -0.36); RAVLT, -0.14 (95% CI -0.27, -0.02); and Stroop Test, 0.49 (95% CI 0.04, 0.94). Findings were similar between CV-FG with each cognitive test score at year 30 and when we used an alternative measure of variability (ARV-FG) that captures variability in successive FG values.

CONCLUSIONS

Higher intraindividual FG variability during young adulthood below the threshold of diabetes was associated with worse processing speed, memory, and language fluency in midlife independent of FG levels.

Primary prevention of dementia: from modifiable risk factors to a public brain health agenda?

INTRODUCTION

With large numbers of people affected, no treatment in sight and continuing demographic change, the prevention of dementia is becoming a central public health issue.

METHODS

We conducted a systematic meta-review including systematic reviews and meta-analyses of longitudinal observational studies on modifiable risk and protective factors for dementia published over the last 5 years.

RESULTS

Compelling evidence on a number of modifiable risk factors, mostly lifestyle factors, is available from longitudinal observational studies to inform primary preventive efforts.

DISCUSSION

Evidence stemming from preventive RCTs is limited. However, multi-domain interventions addressing a variety of risk factors at once seem promising with regard to high-risk individuals (selective preventive approach). However, we argue that it is time to move forward and discuss a public brain health agenda as a universal preventive approach. Based on a risk reduction strategy, the public brain health agenda suggests the following ten key actions: (1) increase physical activity, (2) foster social integration, (3) improve education and foster lifelong learning, (4) provide mentally stimulating workplaces, (5) foster a cognitively active lifestyle, (6) propose a healthy Mediterranean-like diet, (7) reduce alcohol consumption, (8) stop smoking, (9) prevent, diagnose and treat chronic conditions, and (10) reduce anticholinergic medication in the elderly.

A potential novel pathological implication of serum soluble triggering receptor expressed on myeloid cell 2 in insulin resistance in a general Japanese population: The Hisayama study

AIMS

No cohort study has examined the pathological significance of triggering receptor expressed on myeloid cell 2 (TREM2), a cell surface receptor expressed on myeloid lineage cells, and its soluble form, sTREM2, in insulin resistance in a general population.

METHODS

A total of 2742 community-dwelling Japanese individuals aged ≥40 years were divided into 4 groups according to the serum sTREM2 concentration quartiles. We examined the cross-sectional association of sTREM2 levels with anthropometric parameters and the homeostasis model assessment of insulin resistance (HOMA-IR).

RESULTS

The median sTREM2 concentrations was 255.6 (interquartile range, 162.5-419.2) pg/mL. In multivariate analyses, waist circumference and fat mass index increased with elevating sTREM2 levels (P for trend: <0.001 and 0.02, respectively), but there was no significant association between sTREM2 levels and body mass index and fat-free mass index. Among the subjects without taking antidiabetic medications (n = 2610), greater sTREM2 levels were associated with higher HOMA-IR (P for trend <0.001) even after adjusting for waist circumference, fat mass index, and high-sensitivity C-reactive protein.

CONCLUSIONS

Our findings suggest that serum sTREM2 had novel pathological roles in insulin resistance, while obesity and inflammation had no substantial effects on the relationship between sTREM2 and insulin resistance in this cohort.

Sex differences in risk factors for vascular contributions to cognitive impairment & dementia

Vascular contributions to cognitive impairment and dementia (VCID) is the second most common cause of dementia. While males overall appear to be at a slightly higher risk for VCID throughout most of the lifespan (up to age 85), some risk factors for VCID more adversely affect women. These include female-specific risk factors associated with pregnancy related disorders (e.g. preeclampsia), menopause, and poorly timed hormone replacement. Further, presence of certain co-morbid risk factors, such as diabetes, obesity and hypertension, also may more adversely affect women than men. In contrast, some risk factors more greatly affect men, such as hyperlipidemia, myocardial infarction, and heart disease. Further, stroke, one of the leading risk factors for VCID, has a higher incidence in men than in women throughout much of the lifespan, though this trend is reversed at advanced ages. This review will highlight the need to take biological sex and common co-morbidities for VCID into account in both preclinical and clinical research. Given that there are currently no treatments available for VCID, it is critical that we understand how to mitigate risk factors for this devastating disease in both sexes.

The Impact of Gender on Atrial Fibrillation Incidence and Progression to Dementia

There are a paucity of data regarding the role of gender and atrial fibrillation (AF) on cognitive decline and incidence of dementia. Such data may provide insight into the disproportionate incidence of dementia in women and may help identify high-risk characteristics to target for prevention. We examined patients who underwent coronary angiography at an Intermountain Healthcare Medical Center and enrolled in a prospective cardiovascular database. To be included, patients could not have a previous diagnosis of AF or dementia and had to have 5years of follow-up. Endpoints included incident AF and dementia. Study cohort consisted of 35,608 patients without a previous history of AF or dementia, with 14,377 (40.4%) being woman. Women had lower rates of hypertension, diabetes, coronary artery disease, and prior myocardial infarction, but higher rates of prior stroke. Men had a higher incidence of 5-year and long-term AF. However, women trended toward a higher incidence of 5-year and long-term dementia and stroke compared with men. In all groups of patients with and without AF, prior stroke predicted cognitive decline. In patients without a history of or development of AF, diabetes significantly increased risk of dementia. Women have higher rates of dementia over time than men, driven by higher baseline stroke rates and nontraditional cardiovascular risk factors. The higher dementia rates were in the setting of lower AF rates. However, in both men and women who develop AF, dementia rates are increased and do not show gender-based differences in risk.

Thinking about brain insulin resistance

INTRODUCTION

Dementia and type 2 diabetes mellitus (T2DM) are two of the epidemics of our time; in which insulin resistance (IR) is playing the central role. Epidemiological studies found that different types of dementia development may be promoted by the presence of T2DM.

OBJECTIVES

We aimed in this review to highlight the role of insulin and the IR in the brain as a pathophysiological factor of dementia development and also to expand our understanding of T2DM as a mediator of IR in the brain and to review the possible mechanisms of action that may explain the association.

METHODOLOGY

A critical review of the relevant published English articles up to 2018, using PubMed, Google Scholar, Science Direct, ADI, and WHO database was carried out. Keywords were included insulin resistance, T3DM, T2DM, dementia, brain insulin resistance were used.

CONCLUSION

The rapidly increased prevalence of dementia concurrently with T2DM and obesity need urgent action to illustrate guidelines for prevention, modifying, and treatment based on mechanistic studies.

Cognitive decline and dementia in diabetes mellitus: mechanisms and clinical implications

Cognitive dysfunction is increasingly recognized as an important comorbidity of diabetes mellitus. Different stages of diabetes-associated cognitive dysfunction exist, each with different cognitive features, affected age groups and prognoses and probably with different underlying mechanisms. Relatively subtle, slowly progressive cognitive decrements occur in all age groups. More severe stages, particularly mild cognitive impairment and dementia, with progressive deficits, occur primarily in older individuals (>65 years of age). Patients in the latter group are the most relevant for patient management and are the focus of this Review. Here, we review the evolving insights from studies on risk factors, brain imaging and neuropathology, which provide important clues on mechanisms of both the subtle cognitive decrements and the more severe stages of cognitive dysfunction. In the majority of patients, the cognitive phenotype is probably defined by multiple aetiologies. Although both the risk of clinically diagnosed Alzheimer disease and that of vascular dementia is increased in association with diabetes, the cerebral burden of the prototypical pathologies of Alzheimer disease (such as neurofibrillary tangles and neuritic plaques) is not. A major challenge for researchers is to pinpoint from the spectrum of diabetes-related disease processes those that affect the brain and contribute to development of dementia beyond the pathologies of Alzheimer disease. Observations from experimental models can help to meet that challenge, but this requires further improving the synergy between experimental and clinical scientists. The development of targeted treatment and preventive strategies will therefore depend on these translational efforts.

Sex differences in the association between diabetes and cancer: a systematic review and meta-analysis of 121 cohorts including 20 million individuals and one million events

AIMS/HYPOTHESIS

Diabetes has been shown to be a risk factor for some cancers. Whether diabetes confers the same excess risk of cancer, overall and by site, in women and men is unknown.

METHODS

A systematic search was performed in PubMed for cohort studies published up to December 2016. Selected studies reported sex-specific relative risk (RR) estimates for the association between diabetes and cancer adjusted at least for age in both sexes. Random-effects meta-analyses with inverse-variance weighting were used to obtain pooled sex-specific RRs and women-to-men ratios of RRs (RRRs) for all-site and site-specific cancers.

RESULTS

Data on all-site cancer events (incident or fatal only) were available from 121 cohorts (19,239,302 individuals; 1,082,592 events). The pooled adjusted RR for all-site cancer associated with diabetes was 1.27 (95% CI 1.21, 1.32) in women and 1.19 (1.13, 1.25) in men. Women with diabetes had ~6% greater risk compared with men with diabetes (the pooled RRR was 1.06, 95% CI 1.03, 1.09). Corresponding pooled RRRs were 1.10 (1.07, 1.13) for all-site cancer incidence and 1.03 (0.99, 1.06) for all-site cancer mortality. Diabetes also conferred a significantly greater RR in women than men for oral, stomach and kidney cancer, and for leukaemia, but a lower RR for liver cancer.

CONCLUSIONS/INTERPRETATION

Diabetes is a risk factor for all-site cancer for both women and men, but the excess risk of cancer associated with diabetes is slightly greater for women than men. The direction and magnitude of sex differences varies by location of the cancer.

Sex-related differences in the prevalence of cognitive impairment among overweight and obese adults with type 2 diabetes

INTRODUCTION

Type 2 diabetes mellitus and obesity may increase risks for cognitive decline as individuals age. It is unknown whether this results in different prevalences of cognitive impairment for women and men.

METHODS

The Action for Health in Diabetes, a randomized controlled clinical trial of a 10-year intensive lifestyle intervention, adjudicated cases of cross-sectional cognitive impairment (mild cognitive impairment or dementia) 10-13 years after enrollment in 3802 individuals (61% women).

RESULTS

The cross-sectional prevalences of cognitive impairment were 8.3% (women) and 14.8% (men): adjusted odds ratio 0.55, 95% confidence interval [0.43, 0.71], P < .001. Demographic, clinical, and lifestyle risk factors varied between women and men but did not account for this difference, which was limited to individuals without apolipoprotein E (APOE)-ε4 alleles (interaction P = .034).

CONCLUSIONS

Among overweight and obese adults with type 2 diabetes mellitus, traditional risk factors did not account for the lower prevalence of cognitive impairment observed in women compared with men.

The relationship between sleep and cognitive function in patients with prediabetes and type 2 diabetes

AIMS

Diabetes is linked to cognitive impairment. Sleep plays a role in memory consolidation. Sleep disturbances, commonly found in patients with diabetes, were shown to be related to cognitive dysfunction. This study explored the role of sleep in cognitive function of patients with abnormal glucose tolerance.

METHODS

A total of 162 patients (81 type 2 diabetes and 81 prediabetes) participated. Sleep duration and sleep efficiency (an indicator of sleep quality) were obtained using 7-day actigraphy recordings. Obstructive sleep apnea (OSA) was screened using an overnight in-home monitor. Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA). Three sub-scores of MoCA, visuoexecutive function, attention and delayed recall, were also analyzed.

RESULTS

Mean age was 54.8 (10.2) years. OSA was diagnosed in 123 participants (76.9%). Mean sleep duration was 6.0 (1.0) h and sleep efficiency was 82.7 (8.1) %. Sleep duration and OSA severity were not related to MoCA scores. Higher sleep efficiency was associated with higher MoCA scores (p = 0.003), and having diabetes (vs. prediabetes) was associated with lower MoCA scores (p = 0.001). After adjusting covariates, both having diabetes (vs. prediabetes) (B = - 1.137, p = 0.002) and sleep efficiency (B = 0.085, p < 0.001) were independently associated with MoCA scores. In addition, diabetes (B = - 0.608, p < 0.001) and sleep efficiency (B = 0.038, p < 0.001) were associated with visuoexecutive function. Sleep parameters were not related to delayed recall or attention scores.

CONCLUSION

Lower sleep efficiency is independently associated with lower cognitive function in patients with abnormal glucose tolerance. Whether sleep optimization may improve cognitive function in these patients should be explored.

Resveratrol Counteracts Insulin Resistance-Potential Role of the Circulation

Pre-clinical data and human trials indicate that resveratrol supplementation may help to counteract diabetes. Several mechanisms of action have been proposed to explain its metabolic benefits, including activation of sirtuins and estrogen receptors (ER) to promote glucose transporter type-4 (GLUT4) translocation and increase glucose uptake. Resveratrol can also enhance vasodilator function, yet the possibility that this action might help to alleviate insulin resistance in type-2 diabetes mellitus has received little attention. In this brief review we propose that, by restoring impaired endothelium-dependent vasodilatation in insulin resistant individuals resveratrol increases blood perfusion of skeletal muscle, thereby facilitating glucose delivery and utilization with resultant improvement of insulin sensitivity. Thus, circulatory improvements by vasoactive nutrients such as resveratrol may play a role in preventing or alleviating insulin resistance.

Selective Impairment of Attentional Networks of Executive Control in Middle-Aged Subjects with Type 2 Diabetes Mellitus

Background

The influence of type 2 diabetes mellitus (T2DM) on attention has been elusive. The Attention Network Test (ANT) was developed to evaluate the functioning of 3 individual attentional networks: orienting, alerting, and executive control. The purpose of this study was to use the ANT to assess attentional function and its sub-components in T2DM patients ages 40–60 years.

Material/Methods

Thirty T2DM patients and 30 healthy controls ages 40–60 years were recruited in this investigation. The ANT was used to statistically compare the efficiency among 3 sub-components of the attention networks between middle-aged T2DM patients (n=30) and gender-, age-, and education-matched healthy controls (n=30).

Results

The ANT demonstrated a significant difference in executive control network between the T2DM patients and healthy controls (t=3.242, P=0.002), whereas no significant difference was observed regarding the domains of alerting (t=0.515, P=0.609) and orienting control (t=0.078, P=0.938) between the T2DM patient group and the healthy control group. Moreover, the mean reaction time in the ANT in the T2DM patients was significantly longer compared with that in the healthy controls (t=3.561, P=0.001).

Conclusions

The ANT reveals significant impairment in the executive control of middle-aged patients diagnosed with T2DM, whereas no significant impairment was observed in the domains of alerting and orienting.

Development of a risk score for the prediction of incident dementia in older adults using a frailty index and health checkup data: The JAGES longitudinal study

In Japan, the prevalence of dementia is expected to reach 4.7 million by 2025. This study aimed to develop a risk score for the prediction of incident dementia in community-dwelling older adults. In this longitudinal observational study, we used data from the Japan Gerontological Evaluation Study (JAGES) conducted in K City. We performed Cox regression analyses to develop three risk score models for the prediction of incident dementia in older adults using a frailty index and health checkup data. Analyses of the area under the receiver operating characteristic curve were conducted to compare the models' predictive abilities. We identified 6656 (9.2%) individuals who developed incident dementia during the observation period. The C-statistics of the risk scores ranged from 0.733 to 0.790. The risk score models were able to predict incident dementia in older adults and may help non-medical professionals detect dementia risk at an early stage.

Ginsenoside Ameliorates Cognitive Dysfunction in Type 2 Diabetic Goto-Kakizaki Rats

Background

Ginsenoside is the major bioactive component of ginseng, which has been proven to be a neuroprotective drug. The aim of this study was to evaluate the therapeutic effect of ginsenoside in a diabetic Goto-Kakizaki (GK) rat model.

Material/Methods

Twenty GK rats were randomly divided into a diabetic model (DM) group (n=10) and a ginsenoside + DM group (n=10); Wistar rats with the same age and body weight were used as the control (CON) group (n=10). Food and water intake, body weight, and blood fasting plasma glucose were measured. The Morris water maze test was used to detect learning and memory functions of the rats. Superoxide dismutase (SOD), malondialdehyde (MDA), and inflammatory cytokines (TNF-α, IL-1β, and IL-6) in the hippocampus were analyzed after ginsenoside treatment.

Results

The blood glucose, body weight, Morris correlation index, SOD, MDA, and other test results were increased in the diabetic rats. Ginsenoside ameliorated diabetic cognitive decline.

Conclusions

The possible mechanism was related to inhibiting brain oxidative/nitrosative damage and affecting the expression of the cytokines IL-1β, IL-6, and TNF-α.

A population-based study of epilepsy incidence in association with type 2 diabetes and severe hypoglycaemia

AIMS

This study was conducted to investigate potential link between type 2 diabetes mellitus (T2DM) and epilepsy, and the role of severe hypoglycaemia (SH) might play in the relationship.

METHODS

This was a cohort study based on Taiwan's National Health insurance claims. Totally 751,792 people with T2DM and 824,253 matched controls were identified in 2002-2003 and followed to incidence of epilepsy or end of 2011. We used Cox proportional hazard model to relate epilepsy incidence to separate and joint effects of T2DM and SH. A possible mediation effect of SH on the association between T2DM and epilepsy was analyzed.

RESULTS

Over a 10-year follow-up, patients with T2DM had a higher incidence rate of epilepsy than controls (35.0 vs 21.9 per 10,000 person-years). After controlling for potential confounders including SH, T2DM increased the hazard of epilepsy by some 50%. The stratified analysis further indicated that T2DM (hazard ratio (HR)=1.44, 95% confidence interval (CI) = 1.40-1.47), and SH (HR = 2.22, 95% CI = 1.76-2.81) were both independent risk factors for epilepsy. SH did not modify but mediated 12% of the association between T2DM and epilepsy.

CONCLUSION

Our findings supported that SH may increase the risk of epilepsy, and that T2DM may increase risk of epilepsy independent of SH.

Sex Differences in the Burden and Complications of Diabetes

PURPOSE OF THE REVIEW

To review the latest evidence on sex differences in the burden and complications of diabetes and discuss the potential explanations for the sex differences described.

RECENT FINDINGS

Diabetes is a strong risk factor for vascular disease, with compelling evidence that the relative risks of vascular diseases conferred by diabetes are considerably greater in women than men. The mechanisms underpinning women's excess relative risk of vascular disease from diabetes are unknown. Sex differences in the health care provided for the prevention, management, and treatment of diabetes and its complications could contribute to women's greater excess relative risks of diabetes complications. However, since the excess risk of vascular disease is not seen for other major vascular risk factors, inherent biological factors may be more likely to be involved. In addition to other cardiometabolic pathways, the sex dimorphism in body composition and fat distribution may be particularly important in explaining women's greater excess risk of the vascular complications of diabetes. There is strong evidence to suggest that diabetes is a stronger risk factor for vascular disease in women than men. Although several mechanisms may be involved, further research is needed to provide new and deeper insights into the mechanisms underpinning sex differences in the association between diabetes and vascular diseases. Such research will inform patients, health care professionals, and policy makers to ensure that women are not disproportionately affected by diabetes, and will help to reduce the burden in both sexes.

Diabetes mellitus and the risk of gastrointestinal cancer in women compared with men: a meta-analysis of cohort studies

Background

The increasing epidemic proportions of diabetes mellitus (DM) are a major cause of premature illness and death. However, whether DM confers the same excess risk of gastrointestinal cancer for women as it does for men remains controversial. The purpose of this study was to estimate the relation between DM and gastrointestinal cancer in women compared with men after accounting for other major risk factors based on cohort studies.

Methods

We performed a meta-analysis of cohort studies published through May 2017 from PubMed, Embase, and the Cochrane Library. Studies with cohort designs were stratified by sex and reported the relation between DM and esophageal cancer (EC), gastric cancer (GC), colorectal cancer (CRC), colon cancer (CC), rectal cancer (RC), hepatocellular carcinoma (HCC), or pancreatic cancer (PC) risk. The ratio of relative risk (RRR) between men and women was employed to measure the sex differences in the relation between DM and gastrointestinal cancer with a random effects model with inverse variance weighting.

Results

We included 38 cohort studies reporting data on 18,060,698 individuals. The pooled RRR indicated DM women was associated with an increased risk of GC (RRR: 1.14; 95%CI: 1.06–1.22; p < 0.001), while the risk of HCC was lower (RRR: 0.88; 95%CI: 0.79–0.99; p = 0.031) as compared with DM men. Further, there was no evidence of sex differences in the RRR between participants who had DM compared with those without DM for EC (p = 0.068), CRC (p = 0.618), and PC (p = 0.976). In addition, the pooled RRR showed a statistically significant association between DM and the risk of CC in women compared with men (RRR: 0.93; 95%CI: 0.86–1.00; p = 0.050), and there was no evidence of sex differences for RC among participants with DM compared to those without DM (p = 0.648). Finally, the sex differences of the comparison between DM and non-DM for gastrointestinal cancer risk at different sites were variable after stratification for different effect estimates.

Conclusions

The findings of this study suggested female-to-male RRR of DM was increased for GC, while reduced for HCC and CC. However, there were no sex differences for the relation between DM and the risk of EC, CRC, PC, and RC.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4351-4) contains supplementary material, which is available to authorized users.

Activation of Macrophages and Microglia by Interferon-γ and Lipopolysaccharide Increases Methylglyoxal Production: A New Mechanism in the Development of Vascular Complications and Cognitive Decline in Type 2 Diabetes Mellitus?

Methylglyoxal (MGO), a dicarbonyl compound derived from glucose, is elevated in diabetes mellitus and contributes to vascular complications by crosslinking collagen and increasing arterial stiffness. It is known that MGO contributes to inflammation as it forms advanced glycation end products (AGEs), which activate macrophages via the receptor RAGE. The aim of study was to investigate whether inflammatory activation can increase MGO levels, thereby completing a vicious cycle. In order to validate this, macrophage (RAW264.7, J774A.1) and microglial (N11) cells were stimulated with IFN-γ and LPS (5 + 5 and 10 + 10 IFN-γ U/ml or μg/ml LPS), and extracellular MGO concentration was determined after derivatization with 5,6-Diamino-2,4-dihydroxypyrimidine sulfate by HPLC. MGO levels in activated macrophage cells (RAW264.7) peaked at 48 h, increasing 2.86-fold (3.14±0.4 μM) at 5 U/ml IFN-γ+5 μg/ml LPS, and 4.74-fold (5.46±0.30 μM) at 10 U/ml IFN-γ+10 μg/ml LPS compared to the non-activated controls (1.15±0.02 μM). The other two cell lines, J774A.1 macrophages and N11 microglia, showed a similar response. We suggest that inflammation increases MGO production, possibly exacerbating arterial stiffness, cardiovascular complications, and diabetes-related cognitive decline.

Diabetes and Alzheimer's Disease: Can Tea Phytochemicals Play a Role in Prevention?

Dementia and diabetes mellitus are prevalent disorders in the elderly population. While recognized as two distinct diseases, diabetes has more recently recognized as a significant contributor to risk for developing dementia, and some studies make reference to type 3 diabetes, a condition resulting from insulin resistance in the brain. Alzheimer's disease, the most common form of dementia, and diabetes, interestingly, share underlying pathological processes, commonality in risk factors, and, importantly, pathways for intervention. Tea has been suggested to possess potent antioxidant properties. It is rich in phytochemicals including, flavonoids, tannins, caffeine, polyphenols, boheic acid, theophylline, theobromine, anthocyanins, gallic acid, and finally epigallocatechin-3-gallate, which is considered to be the most potent active ingredient. Flavonoid phytochemicals, known as catechins, within tea offer potential benefits for reducing the risk of diabetes and Alzheimer's disease by targeting common risk factors, including obesity, hyperlipidemia, hypertension, cardiovascular disease, and stroke. Studies also show that catechins may prevent the formation of amyloid-β plaques and enhance cognitive functions, and thus may be useful in treating patients who have Alzheimer's disease or dementia. Furthermore, other phytochemicals found within tea offer important antioxidant properties along with innate properties capable of modulating intracellular neuronal signal transduction pathways and mitochondrial function.

Comparison of body composition and physical and cognitive function between older Japanese adults with no diabetes, prediabetes and diabetes: A cross-sectional study in community-dwelling Japanese older people

AIM

Diabetes is associated with not only cardiovascular and cerebrovascular disease, but also reductions in physical and cognitive function. The purpose of the present study was to determine whether muscle strength, walking ability and balance declined in Japanese community-dwelling older adults with diabetes or prediabetes.

METHODS

We analyzed data from comprehensive health checkups carried out for 1689 individuals (710 men, 979 women; mean age 71.4 ± 5.6 years) between 2011 and 2016. Participants were divided into three groups: no diabetes (non-history of diabetes and glycated hemoglobin level <5.7%), prediabetes (non-history of diabetes, but glycated hemoglobin level was 5.7-6.4%) and diabetes (history of diabetes or glycated hemoglobin level >6.4%). Physical and cognitive function were compared between groups after adjusting for covariates.

RESULTS

Participants with diabetes showed higher levels of obesity, comorbidity, gonarthrosis, and body fat, and lower levels of physical function relative to those observed in participants with prediabetes or no diabetes. After adjusting covariates, participants with diabetes showed significantly lower grip strength (P < 0.010), slower walking speed (P < 0.005), longer Timed Up and Go test time (P < 0.007) and less time spent standing on one foot (P < 0.001) relative to those with no diabetes, but not those with prediabetes.

CONCLUSIONS

Significant functional decline was observed in community-dwelling older adults with diabetes, but not in those with prediabetes. Prevention of the progression of prediabetes to diabetes is important in avoiding reductions in physical function. Geriatr Gerontol Int 2018; 18: 1031-1037.

Long-term Impact of Weight Loss Intervention on Changes in Cognitive Function: Exploratory Analyses from the Action for Health in Diabetes Randomized Controlled Clinical Trial

Background

Diabetes adversely impacts cognition. Lifestyle change can improve diabetes control and potentially improve cognition. We examined whether weight loss through reduced caloric intake and increased physical activity was associated with slower cognitive aging in older adults with type 2 diabetes mellitus.

Methods

The Look AHEAD randomized controlled clinical trial delivered 10 years of intensive lifestyle intervention (ILI) that yielded long-term weight losses. During 5 years spanning the end of intervention and postintervention follow-up, repeated cognitive assessments were obtained in 1,091 individuals who had been assigned to ILI or a control condition of diabetes support and education (DSE). We compared the means and slopes of scores on cognitive testing over these repeated assessments.

Results

Compared with DSE, assignment to ILI was associated with a -0.082 SD deficit in mean global cognitive function across repeated assessments (p = .010). However, overweight (body mass index [BMI] < 30 kg/m2) ILI participants had 0.099 (95% confidence interval [CI]: -0.006, 0.259) better mean global cognitive function compared with overweight DSE participants, while obese (BMI ≥ 30 kg/m2) ILI participants had -0.117 (-0.185, -0.049) SD worse mean composite cognitive function scores (interaction p = .014) compared to obese DSE participants. For both overweight and obese participants, cognitive decline was marginally (-0.014 SD/y overall) steeper for ILI participants (p = .068), with 95% CI for differences in slopes excluding 0 for measures of attention and memory.

Conclusions

The behavioral weight loss intervention was associated with small relative deficits in cognitive function among individuals who were obese and marginally greater cognitive decline overall compared to control. ClinicalTrials.gov Identifier: NCT00017953.

Lower risk of dementia with pioglitazone, compared with other second-line treatments, in metformin-based dual therapy: a population-based longitudinal study

AIMS/HYPOTHESIS

The effect of pioglitazone was compared with that of other second-line glucose-lowering drugs on the risk of dementia among individuals with type 2 diabetes receiving metformin-based dual therapy.

METHODS

A total of 204,323 individuals with type 2 diabetes aged ≥18 years who were stable metformin users and dementia-free before the initiation of second-line glucose-lowering medication were identified in the period 2000-2011 from Taiwan's National Health Insurance Research Database and followed to the end of 2013. Primary analyses included 51,415 individuals aged ≥65 years without dementia events in the first year of second-line glucose-lowering treatment. Study subjects were classified into mutually exclusive groups according to various second-line glucose-lowering drugs to metformin. Cox proportional hazards models were applied to assess the time-to-event between propensity score-matched glucose-lowering treatment groups.

RESULTS

Individuals aged ≥65 years on metformin + pioglitazone had a significantly lower risk of dementia compared with those on metformin + sulfonylurea (HR 0.56; 95% CI 0.34, 0.93), and a lower, but insignificant, risk of dementia compared with those on other metformin-based dual regimens (i.e. metformin + acarbose, metformin + meglitinide, metformin + insulin or metformin + dipeptidyl peptidase 4 inhibitors). Among individuals aged ≥18 years, there was also a decreased risk of dementia in those taking pioglitazone compared with those taking other second-line glucose-lowering drugs. A lower incidence of dementia was found in users of metformin + pioglitazone compared with users of metformin + rosiglitazone.

CONCLUSIONS/INTERPRETATION

Pioglitazone as a second-line treatment after metformin might provide a protective effect on dementia risk among individuals with type 2 diabetes.

Dietary influences on cognition

Obesity is a world-wide crisis with profound healthcare and socio-economic implications and it is now clear that the central nervous system (CNS) is a target for the complications of metabolic disorders like obesity. In addition to decreases in physical activity and sedentary lifestyles, diet is proposed to be an important contributor to the etiology and progression of obesity. Unfortunately, there are gaps in our knowledge base related to how dietary choices impact the structural and functional integrity of the CNS. For example, while chronic consumption of hypercaloric diets (increased sugars and fat) contribute to increases in body weight and adiposity characteristic of metabolic disorders, the mechanistic basis for neurocognitive deficits in obesity remains to be determined. In addition, studies indicate that acute consumption of hypercaloric diets impairs performance in a wide variety of cognitive domains, even in normal non-obese control subjects. These results from the clinical and basic science literature indicate that diet can have rapid, as well as long lasting effects on cognitive function. This review summarizes our symposium at the 2017 Society for the Study of Ingestive Behavior (SSIB) meeting that discussed these effects of diet on cognition. Collectively, this review highlights the need for integrated and comprehensive approaches to more fully determine how diet impacts behavior and cognition under physiological conditions and in metabolic disorders like type 2 diabetes mellitus (T2DM) and obesity.

SH2B1 is Involved in the Accumulation of Amyloid-β42 in Alzheimer's Disease

Alzheimer's disease (AD) is characterized by deficits in learning and memory abilities, as well as pathological changes of amyloid-β (Aβ) plaque and neurofibrillary tangle formation in the brain. Insulin has been identified as a modulator of the neuronal pathways involved in learning and memory, and is also implicated as a modulator of Aβ and tau metabolism. Disrupted insulin signaling pathways are evident in AD patients and it is understood that type 2 diabetes can increase the risk of developing AD, suggesting a possible link between metabolic disorders and neurodegeneration. SH2B1 is a key protein in the insulin signaling pathway involved in regulating the activity of the insulin receptor. To further identify the role of the insulin signaling pathway in the pathology of AD, SH2B (dSH2B homologue in flies) in neurons was partially knocked out or overexpressed in an AD Drosophila model expressing Aβ42. Partial knockout of neuronal SH2B in the Aβ42-expressing Drosophila had a detrimental effect on mobility and neurotransmission, and increased levels and intraneuronal accumulation of Aβ42, as assessed by ELISA and immunostaining. Alternatively, partial overexpression of neuronal SH2B in the Aβ42-expressing Drosophila improved lifespan, mobility, and neurotransmission, as well as decreased levels and intraneuronal accumulation of Aβ42. Thus, SH2B1 may be an upstream modulator of Aβ metabolism, acting to inhibit Aβ accumulation, and has a role in the pathogenesis of AD. SH2B1 may therefore have potential as a therapeutic target for this common form of dementia.

Challenges for Alzheimer's Disease Therapy: Insights from Novel Mechanisms Beyond Memory Defects

Alzheimer's disease (AD), the most common form of dementia in late life, will become even more prevalent by midcentury, constituting a major global health concern with huge implications for individuals and society. Despite scientific breakthroughs during the past decades that have expanded our knowledge on the cellular and molecular bases of AD, therapies that effectively halt disease progression are still lacking, and focused efforts are needed to address this public health challenge. Because AD is classically recognized as a disease of memory, studies have mainly focused on investigating memory-associated brain defects. However, compelling evidence has indicated that additional brain regions, not classically linked to memory, are also affected in the course of disease. In this review, we outline the current understanding of key pathophysiological mechanisms in AD and their clinical manifestation. We also highlight how considering the complex nature of AD pathogenesis, and exploring repurposed drug approaches can pave the road toward the development of novel therapeutics for AD.

Association of diabetes therapy-related quality of life and physical activity levels in patients with type 2 diabetes receiving medication therapy: the Diabetes Distress and Care Registry at Tenri (DDCRT 17)

AIM

To examine the association between diabetes therapy-related quality of life (DTR-QOL) and physical activity levels, and identify factors associated with high diabetes therapy-related quality of life.

METHODS

Cross-sectional data from 2970 patients with type 2 diabetes in a Japanese diabetes registry were assessed for independent correlations between DTR-QOL (domains 1-4) and high physical activity levels. Data collected by the International Physical Activity Questionnaire were analyzed by logistic regression and adjusted for potential confounders.

RESULTS

The mean patient age, BMI and HbA1c level were 65.8 years, 24.7 kg/m² and 7.6% (58.7 mmol/mol), respectively. Univariate analysis showed that DTR-QOL domain 1, 2 and 4 scores were significantly associated with physical activity levels (p = 0.0046, p = 0.0004 and p < 0.001, respectively, but domain 3 score was not (p = 0.5073). In a multivariable-adjusted logistic regression model, odds ratios (ORs) of DTR-QOL domains 1, 3 and 4 were independently associated with high physical activity (ORs for 2nd to 4th quartile and p for trend; [domain 1] 1.16, 1.56, 1.22, p = 0.032; [domain 3] 1.45, 1.55, 1.38, p = 0.049; [domain 4] 1.09, 1.30, 1.51, p = 0.001, respectively), but domain 2 was not (ORs for 2nd to 4th quartile and p for trend; 1.19, 1.26, 1.23, p = 0.096).

CONCLUSION

High diabetes therapy-related QOL scores were associated with high levels of physical activity in patients with type 2 diabetes. Because this is a cross-sectional study, further study is needed to evaluate the causal association between therapy-related QOL and physical activity.

Population-Based Cohort Study on Dementia Risk in Patients with Type 1 Diabetes Mellitus

BACKGROUND

The risk of dementia increases by 15-28% in patients with type 2 diabetes mellitus (DM). However, studies on dementia risk in type 1 DM have been neither comprehensive nor conclusive.

METHODS

We carried out a cohort study involving 1,077 patients registered to have type 1 DM from 1998 to 2009 and 32,310 matched non-DM controls who were selected from Taiwan National Health Insurance Claims. These participants were followed up from their first clinical appearance for type 1 DM treatment in 1998-2009 to the date of dementia diagnosis or the last day of 2011. The Cox proportional hazard model was employed to estimate the hazard ratio (HR) of dementia incidence.

RESULTS

The incidence rates of dementia reached 42.8 and 13.1 per 104 person-years for the type 1 DM and control groups respectively. The adjusted HR of dementia in patients with type 1 DM was estimated at 3.01 (95% CI 2.18-4.14) after adjustment for demographics, comorbidity, urbanization, monthly income, and annual frequency of ambulatory care visits. No significant difference in sex-specific HR was observed.

CONCLUSIONS

The relative risk of developing dementia (118-314%) in patients with type 1 DM was much higher than the -previously reported relative risk (15-28%) associated with type 2 DM.

Brain insulin resistance in type 2 diabetes and Alzheimer disease: concepts and conundrums

Considerable overlap has been identified in the risk factors, comorbidities and putative pathophysiological mechanisms of Alzheimer disease and related dementias (ADRDs) and type 2 diabetes mellitus (T2DM), two of the most pressing epidemics of our time. Much is known about the biology of each condition, but whether T2DM and ADRDs are parallel phenomena arising from coincidental roots in ageing or synergistic diseases linked by vicious pathophysiological cycles remains unclear. Insulin resistance is a core feature of T2DM and is emerging as a potentially important feature of ADRDs. Here, we review key observations and experimental data on insulin signalling in the brain, highlighting its actions in neurons and glia. In addition, we define the concept of 'brain insulin resistance' and review the growing, although still inconsistent, literature concerning cognitive impairment and neuropathological abnormalities in T2DM, obesity and insulin resistance. Lastly, we review evidence of intrinsic brain insulin resistance in ADRDs. By expanding our understanding of the overlapping mechanisms of these conditions, we hope to accelerate the rational development of preventive, disease-modifying and symptomatic treatments for cognitive dysfunction in T2DM and ADRDs alike.

Social Engagement and Its Change are Associated with Dementia Risk among Chinese Older Adults: A Longitudinal Study

This study aimed to examine the association of social engagement (SE) and changes in SE with the risk of dementia among older adults in China. Data were collected from the 2002, 2005, 2008/2009, and 2011/2012 waves of the Chinese Longitudinal Healthy Longevity Survey (CLHLS). Random-effects logistic regression models were used to examine the association of SE and changes in SE with the risk of dementia. Of the 7511 older Chinese adults aged 65 years and over, 338 developed dementia during the 9-year follow-up. SE was associated with dementia risk after adjusting for sociodemographic characteristics, lifestyles and health status (odds ratio (OR) = 0.71, 95% confidence interval (CI) = 0.63–0.81). Participants with consistently high or increased SE had a lower risk of dementia than those with consistently low SE ((OR = 0.14, 95% CI = 0.06–0.28 and OR = 0.33, 95% CI = 0.23–0.48, respectively). Higher SE can reduce the risk of dementia. Furthermore, consistently high or increasing SE is associated with a lower risk of dementia.

Endoplasmic reticulum stress/autophagy pathway is involved in diabetes-induced neuronal apoptosis and cognitive decline in mice

Diabetes mellitus is a significant global public health problem depicting a rising prevalence worldwide. As a serious complication of diabetes, diabetes-associated cognitive decline is attracting increasing attention. However, the underlying mechanisms are yet to be fully determined. Both endoplasmic reticulum (ER) stress and autophagy have been reported to modulate neuronal survival and death and be associated with several neurodegenerative diseases. Here, a streptozotocin-induced diabetic mouse model and primary cultured mouse hippocampal neurons were employed to investigate the possible role of ER stress and autophagy in diabetes-induced neuronal apoptosis and cognitive impairments, and further explore the potential molecular mechanisms. ER stress markers GRP78 and CHOP were both enhanced in diabetic mice, as was phosphorylation of PERK, IRE1α, and JNK. In addition, the results indicated an elevated level of autophagy in diabetic mice, as demonstrated by up-regulated expressions of autophagy markers LC3-II, beclin 1 and down-regulated level of p62, and increased formation of autophagic vacuoles and LC3-II aggregates. Meanwhile, we found that these effects could be abolished by ER stress inhibitor 4-phenylbutyrate or JNK inhibitor SP600125 in vitro. Furthermore, neuronal apoptosis of diabetic mice was attenuated by pretreatment with 4-phenylbutyrate, while aggravated by application of inhibitor of autophagy bafilomycin A1 in vitro. These results suggest that ER stress pathway may be involved in diabetes-mediated neurotoxicity and promote the following cognitive impairments. More important, autophagy was induced by diabetes possibly through ER stress-mediated JNK pathway, which may protect neurons against ER stress-associated cell damages.

Development, Application, and Results from a Precision-medicine Platform that Personalizes Multi-modal Treatment Plans for Mild Alzheimer's Disease and At-risk Individuals

INTRODUCTION

Alzheimer's Disease (AD) is a progressive neurodegenerative condition in which individuals exhibit memory loss, dementia, and impaired metabolism. Nearly all previous single-treatment studies to treat AD have failed, likely because it is a complex disease with multiple underlying drivers contributing to risk, onset, and progression. Here, we explored the efficacy of a multi-therapy approach based on the disease risk factor status specific to individuals with AD diagnosis or concern.

METHODS

Novel software from uMETHOD Health was designed to execute a precision-medicinebased approach to develop personalized treatment recommendations with the goal of slowing or reversing biologic drivers of AD. AD-associated inputs encompassed genomic data, bio-specimen measurements, imaging data (such as MRIs or PET scans), medical histories, medications, allergies, co-morbidities, relevant lifestyle factors, and results of neuropsychological testing. Algorithms were then employed to prioritize physiologic and lifestyle states with the highest probability of contributing to disease status, and these priorities were incorporated into a personalized care plan, which was delivered to physicians and supported by health coaches to increase adherence. The sample included 40 subjects with Subjective Cognitive Decline patients (SCD), and Mild Cognitive Impairment Patients (MCI).

RESULTS

Software analysis was completed for 40 individuals. They remained on their treatment plan for an average of 8.4 months, equal to 2.8 iterations of care plans. 80% of individuals overall showed improved memory function scores or held steady, as measured by standardized cognitive evaluations. Cognitive assessments showed significant improvement in the SCD group (Composite P value .002, Executive P value .01), and the CNS-VS Executive domain showed significant results in the combined group as well (P value .01). There was also biomarker improvement over time observed from the blood panels. 8 out of 12 selected biomarkers showed slight, though statistically non-significant, improvement overall for symptomatic individuals, and 6 out of 12 for the overall population. Only one biomarker, homocysteine, showed significant improvement, though (P values .03, .04, .002).

CONCLUSIONS

Our analysis of these individuals lead to several interesting observations together suggesting that AD risk factors comprise a network of interlocking feedback loops that may be modifiable. Our findings indicate previously unidentified connectivity between AD risk factors, suggesting that treatment regimens should be tailored to the individual and multi-modal to simultaneously return several risk factors to a normative state. If successfully performed, the possibility to slow progression of AD and possibly reverse aspects of cognitive decline may become achievable.

Association of adiponectin with cognitive function precedes overt diabetes in the Brazilian Longitudinal Study of Adult Health: ELSA

BACKGROUND

Adiponectin is an insulin-sensitizer adipocytokine endowed with neuroprotective actions. Whether adiponectin regulates neuronal functioning toward delaying cognitive decline independently of the glucose metabolism disturbance has been poorly explored. This study evaluated if the performance in cognitive tests was associated with adiponectin levels prior the development of type 2 diabetes in middle-aged individuals.

METHODS

A sample of 938 non-diabetic participants of ELSA had their cognitive function assessed by the CERAD delayed word recall test, the verbal fluency test and the trail making test. Stepwise multiple linear regression using forward selection had the response to cognitive tests as the dependent variable and adiponectin as the independent variable of main interest, adjusted for glucose tolerance status and confounders.

RESULTS

Mean age was 45.7 ± 4.9 years, 54.5% were women, 43.0% had high education level, 59.3% weight excess and 70.0% prediabetes. In crude model, only the delayed recall memory was associated with adiponectin levels. In an initial regression model, delayed recall memory remained independently associated with adiponectin levels and prediabetes. After complete adjustments, adiponectin but not prediabetes maintained independently associated with delayed recall memory (β 0.067; 95% CI 0.006-0.234; p = 0.040). On the other hand, learning memory showed to be associated with prediabetes (β 0.71 95% CI 0.17; 1.24; p = 0.009) but not with adiponectin.

CONCLUSIONS

The association of memory with adiponectin in middle-aged individuals, prior overt diabetes, suggests that this adipocytokine could anticipate cognitive impairmentρ detection, when preventive strategies could be more effectively implemented. The usefulness of adiponectin to identify increased risk for cognitive dysfunction before advanced age needs to be prospectively investigated in ELSA cohort.

Population Neuroscience: Dementia Epidemiology Serving Precision Medicine and Population Health

Over recent decades, epidemiology has made significant contributions to our understanding of dementia, translating scientific discoveries into population health. Here, we propose reframing dementia epidemiology as "population neuroscience," blending techniques and models from contemporary neuroscience with those of epidemiology and biostatistics. On the basis of emerging evidence and newer paradigms and methods, population neuroscience will minimize the bias typical of traditional clinical research, identify the relatively homogenous subgroups that comprise the general population, and investigate broader and denser phenotypes of dementia and cognitive impairment. Long-term follow-up of sufficiently large study cohorts will allow the identification of cohort effects and critical windows of exposure. Molecular epidemiology and omics will allow us to unravel the key distinctions within and among subgroups and better understand individuals' risk profiles. Interventional epidemiology will allow us to identify the different subgroups that respond to different treatment/prevention strategies. These strategies will inform precision medicine. In addition, insights into interactions between disease biology, personal and environmental factors, and social determinants of health will allow us to measure and track disease in communities and improve population health. By placing neuroscience within a real-world context, population neuroscience can fulfill its potential to serve both precision medicine and population health.

Correlation study of Framingham risk score and vascular dementia: An observational study

Vascular dementia (VaD) is one of the most common forms of dementia, and second only to Alzheimer's disease. The purpose of this study was to evaluate the potential diagnostic value of Framingham risk score (FRS) in VaD by investigating the relationship among cardiovascular risks, FRS, and VaD.Data were collected from patients (n = 130) at Tongji Hospital in Wuhan, China. They were divided into 2 groups, including the control group (n = 70) and the VaD group (n = 60). Statistical methods including t-test, logistic regression model, multiple linear regression model, and receiver-operating characteristic (ROC) curve were adopted for the assessment.A significant difference (all P < .05) was observed in systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure, total cholesterol (TC), homosysteine (HCY), glycosylated hemoglobin A1c (HbA1c), FRS, and cerebral white matter lesions (WMLs) between the 2 groups, even after adjusting for age (both P < .05). Age [odds ratio (OR) = 1.20; P = .002], FRS (OR = 1.55; P = .006), and WMLs (OR = 10.17; P = .011) were independent prognostic factors for VaD. The area under the ROC curve (AUC) of FRS for VaD diagnosis prediction was 0.830 (95% confidence interval, 95% CI: 0.730∼ 0.929). There was a significant difference in the AUC between WMLs and WMLs combined with FRS (0.788 (95% CI: 0.667 ∼ 0.880) versus 0.863 (95% CI: 0.754 ∼ 0.936, P = .049). Age, HbA1c, and FRS were negatively correlated with the mini-mental state examination (MMSE) scores (all P < .05) in the VaD group. Moreover, multiple stepwise linear regression analysis showed that the age and FRS were independent predictors of MMSE scores.FRS has a moderate predictive value for the VaD diagnosis, and also increases the risk of cognitive decline.

Interactions between metabolic, reward and cognitive processes in appetite control: Implications for novel weight management therapies

Traditional models of appetite control have emphasised the role of parallel homeostatic and hedonic systems, but more recently the distinction between independent homeostatic and hedonic systems has been abandoned in favour of a framework that emphasises the cross talk between the neurochemical substrates of the two systems. In addition, evidence has emerged more recently, that higher level cognitive functions such as learning, memory and attention play an important role in everyday appetite control and that homeostatic signals also play a role in cognition. Here, we review this evidence and present a comprehensive model of the control of appetite that integrates cognitive, homeostatic and reward mechanisms. We discuss the implications of this model for understanding the factors that may contribute to disordered patterns of eating and suggest opportunities for developing more effective treatment approaches for eating disorders and weight management.

Impact of diabetes mellitus and chronic liver disease on the incidence of dementia and all-cause mortality among patients with dementia

This study investigated the effects of the presence of type 2 diabetes mellitus (T2D) and/or chronic liver disease (CLD) on the incidence and prognosis of dementia during a 10-year period in Korea using a nationwide population-based dataset from the Korea National Health Insurance Service.To assess the impact of T2D and CLD on the incidence of dementia, we included subjects aged ≥60 years without dementia, T2D, and CLD from 2003 to 2005. We created another cohort for evaluating the all-cause mortality in subjects with dementia between 2003 and 2005. The participants were categorized into 4 groups: control (neither CLD nor T2D), CLD-only, T2D-only, and T2D-and-CLD groups, and they were followed up until 2013.The incidence of dementia was higher in the T2D-only group than in the control and CLD-only groups (2.78 vs. 2.04 and 2.00 per 1000 person-years). After adjustment for age, gender, and comorbid conditions, both T2D and CLD increased the risk of any type of dementia; however, the impact of CLD alone was much lower [hazard ratio (HR) 1.07, 95% confidence interval (CI): 1.06-1.08] than that of T2D alone (HR 1.27, 95% CI: 1.27-1.28). The risk of dementia did not significantly change in patients with the co-occurrence of T2D and CLD compared to those with T2D alone. The all-cause mortality rate was the lowest in the control group (2.59 per 1000 person-years) and the highest in the T2D-and-CLD group (3.77 per 1000 person-years). Presence of T2D or CLD alone was associated with higher mortality (HR 1.46 and HR 1.21, respectively) compared with in the absence of both the diseases. Furthermore, the presence of both the diseases further significantly increased the mortality rate compared to the presence of each disease alone (HR 1.67, 95% CI: 1.65-1.69).In conclusion, this study found that the incidence of dementia was much higher in patients with T2D. CLD was associated with a modest increase in risk of dementia; however, there was no additive effect with T2D. In the population with dementia, however, the presence of CLD was associated with high mortality in patients with or without T2D.

Metformin vs sulfonylurea use and risk of dementia in US veterans aged ≥65 years with diabetes

OBJECTIVE

To determine whether metformin is associated with a lower incidence of dementia than sulfonylureas.

METHODS

This was a retrospective cohort study of US veterans ≥65 years of age with type 2 diabetes who were new users of metformin or a sulfonylurea and had no dementia. Follow-up began after 2 years of therapy. To account for confounding by indication, we developed a propensity score (PS) and used inverse probability of treatment weighting (IPTW) methods. Cox proportional hazards models estimated the hazard ratio (HR) of incident dementia.

RESULTS

We identified 17,200 new users of metformin and 11,440 new users of sulfonylureas. Mean age was 73.5 years and mean HbA1c was 6.8%. Over an average follow-up of 5 years, 4,906 cases of dementia were diagnosed. Due to effect modification by age, all analyses were conducted using a piecewise model for age. Crude hazard ratio [HR] for any dementia in metformin vs sulfonylurea users was 0.67 (95% confidence interval [CI] 0.61-0.73) and 0.78 (95% CI 0.72-0.83) for those <75 years of age and ≥75 years of age, respectively. After PS IPTW adjustment, results remained significant in veterans <75 years of age (HR 0.89; 95% CI 0.79-0.99), but not for those ≥75 years of age (HR 0.96; 95% CI 0.87-1.05). A lower risk of dementia was also seen in the subset of younger veterans who had HbA1C values ≥7% (HR 0.76; 95% CI 0.63-0.91), had good renal function (HR 0.86; 95% CI 0.76-0.97), and were white (HR 0.87; 95% CI 0.77-0.99).

CONCLUSIONS

After accounting for confounding by indication, metformin was associated with a lower risk of subsequent dementia than sulfonylurea use in veterans <75 years of age. Further work is needed to identify which patients may benefit from metformin for the prevention of dementia.

Considering sex and gender in Alzheimer disease and other dementias

Suffering related to dementia is multifaceted because cognitive and physical functioning slowly deteriorates. Advanced age and sex, two of the most prominent risk factors for dementia, are not modifiable. Lifestyle factors such as smoking, excessive alcohol use, and poor diet modulate susceptibility to dementia in both males and females. The degree to which the resulting health conditions (eg, obesity, type 2 diabetes, and cardiovascular disease) impact dementia risk varies by sex. Depending on the subtype of dementia, the ratio of male to female prevalence differs. For example, females are at greater risk of developing Alzheimer disease dementia, whereas males are at greater risk of developing vascular dementia. This review examines sex and gender differences in the development of dementia with the goal of highlighting factors that require further investigation. Considering sex as a biological variable in dementia research promises to advance our understanding of the pathophysiology and treatment of these conditions.

Insulin resistance is associated with reductions in specific cognitive domains and increases in CSF tau in cognitively normal adults

Growing evidence supports the hypothesis that type 2 diabetes (T2D) increases the risk of developing dementia. Experimental evidence from mouse models demonstrates that the induction of T2D/insulin resistance (IR) can promote the accumulation of Alzheimer's disease (AD) pathological features. However, the association of T2D with pathological and clinical phenotypes in humans is unclear. Here we investigate the relationship of indices of IR (HOMA-IR) and pancreatic β-cell function (HOMA-B) with cognitive performance across several domains (Verbal/Visual Episodic Memory, Executive Function, Language and a measure of Global cognition) and AD biomarkers (CSF Aβ42, T-tau/P-tau, hippocampal volume and neocortical Aβ-amyloid burden). We reveal that HOMA-IR (p < 0.001) incrementally increases across diagnostic groups, becoming significantly elevated in the AD group compared with cognitively normal (CN) adults. In CN adults, higher HOMA-IR was associated with poorer performance on measures of verbal episodic memory (p = 0.010), executive function (p = 0.046) and global cognition (p = 0.007), as well as with higher CSF T-tau (p = 0.008) and P-tau (p = 0.014) levels. No association was observed with CSF Aβ or imaging modalities. Together our data suggest that IR may contribute to reduced cognitive performance and the accumulation of CSF tau biomarkers in cognitively normal adults.

Observational study of vascular dementia in the Spanish elderly population according to type 2 diabetes status: trends in incidence, characteristics and outcomes (2004-2013)

OBJECTIVES

To examine trends overtime in the incidence and in-hospital outcomes of vascular dementia (VaD) hospitalisations in patients aged 70 years or over suffering and not suffering from type 2 diabetes mellitus (T2DM) between 2004 and 2013 in Spain.

DESIGN

Retrospective study.

SETTING

Spain.

PARTICIPANTS

National hospital discharge data were used; patients aged ≥70, discharged from a hospital with VaD as a primary diagnosis, were selected.

MAIN OUTCOME MEASURES

Overall incidence, therapeutic and diagnostic procedures, comorbidities, infectious complications, duration of hospital stays and in-hospital mortality (IHM).

RESULTS

In total, 170 607 admissions for VaD (34.3% with T2DM) were identified. We found a significant upward linear trend in the incidence of VaD for men and women with and without diabetes between 2004 and 2013. The adjusted incidence was higher among people with T2DM over the study period. We found a higher incidence in men than women in all years under study. A positive association between T2DM and VaD hospitalisation was found among both men (IRR 2.14, 95% CI 2.11 to 2.16) and women (incidence rate ratio (IRR) 2.22; 95% CI 2.19 to 2.25). Pneumonia was significantly associated with a higher mortality (OR 2.59, 95% CI 2.52 to 2.67). We found that percutaneous endoscopic gastrostomy was associated with lower IHM (OR 0.37, 95% CI 0.31 to 0.45), while parenteral nutrition had the opposite effect (OR 1.29, 95% CI 1.18 to 1.41). There was no association between diabetes and higher IHM (OR 0.99, 95% CI 0.93 to 1.06). The time-trend analyses of the entire sample showed a significant reduction in mortality in patients with VaD (OR 0.98, 95% CI 0.97 to 0.99).

CONCLUSIONS

Incidence rates for VaD hospitalisations were twice as high in patients with diabetes compared with those without. Men had significantly higher incidence rates than women, regardless of diabetes status. In both groups studied, pneumonia and parenteral nutrition were associated with mortality while percutaneous endoscopic gastrostomy was associated with survival. Having diabetes was not associated with higher IHM after hospitalisation with VaD.

The diabetic brain and cognition

The prevalence of both Alzheimer's disease (AD) and vascular dementia (VaD) is increasing with the aging of the population. Studies from the last several years have shown that people with diabetes have an increased risk for dementia and cognitive impairment. Therefore, the authors of this consensus review tried to elaborate on the role of diabetes, especially diabetes type 2 (T2DM) in both AD and VaD. Based on the clinical and experimental work of scientists from 18 countries participating in the International Congress on Vascular Disorders and on literature search using PUBMED, it can be concluded that T2DM is a risk factor for both, AD and VaD, based on a pathology of glucose utilization. This pathology is the consequence of a disturbance of insulin-related mechanisms leading to brain insulin resistance. Although the underlying pathological mechanisms for AD and VaD are different in many aspects, the contribution of T2DM and insulin resistant brain state (IRBS) to cerebrovascular disturbances in both disorders cannot be neglected. Therefore, early diagnosis of metabolic parameters including those relevant for T2DM is required. Moreover, it is possible that therapeutic options utilized today for diabetes treatment may also have an effect on the risk for dementia. T2DM/IRBS contribute to pathological processes in AD and VaD.

Correlates of Dementia and Mild Cognitive Impairment in Patients With Atrial Fibrillation: The Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS)

BACKGROUND

Atrial fibrillation (AF) has been associated with faster cognitive decline and increased dementia risk. Factors associated with dementia in patients with AF have been seldom studied.

METHODS AND RESULTS

We studied 6432 individuals from the ARIC-NCS (Atherosclerosis Risk in Communities Neurocognitive Study). In 2011 to 2013, participants underwent a physical exam, echocardiography, detailed cognitive assessments, and a subset, brain magnetic resonance imaging. Dementia and mild cognitive impairment (MCI), as well as etiology of MCI/dementia, Alzheimer's disease-related or vascular, were adjudicated by an expert panel. AF was defined by study ECGs and past hospitalizations. We used logistic regression to estimate odds ratios and 95% CI of MCI/dementia by AF status and to assess cross-sectional correlates of MCI/dementia in patients with AF. Among 6432 participants, 611 (9.5%) had prevalent AF. AF was associated with increased odds of dementia and MCI (odds ratio, 95% CI, 2.25, 1.64-3.10, and 1.28, 1.04-1.56, respectively). Prevalence of Alzheimer's disease-related MCI/dementia and vascular MCI/dementia were higher in participants with AF than without AF (odds ratio, 95% CI, 1.29, 1.04-1.61, and 1.50, 0.99-2.25, respectively). In multivariable analyses, older age, lower body mass index, diabetes mellitus, stroke, and APOE genotype were associated with dementia prevalence in participants with AF. In models evaluating MCI/dementia subtypes, diabetes mellitus was associated with Alzheimer's disease-related MCI/dementia, whereas male sex and stroke were risk factors for vascular MCI/dementia.

CONCLUSIONS

In a large, community-based study, AF was associated with higher prevalence of MCI and dementia. Controlling cardiometabolic risk factors is a potential target for prevention of adverse cognitive outcomes in AF patients.