Severe diabetic retinal disease and dementia risk in type 2 diabetes

Assessing Risk Factors for Cognitive Decline Using Electronic Health Record Data: A Scoping Review

Background : The data and information contained within electronic health records (EHR) provide a rich, diverse, longitudinal view of real-world patient histories, offering valuable opportunities to study antecedent risk factors for cognitive decline. However, the extent to which such records' data have been utilized to elucidate the risk factors of cognitive decline remains unclear. Methods : A scoping review was conducted following the PRISMA guideline, examining articles published between January 2010 and April 2023, from PubMed, Web of Science, and CINAHL. Inclusion criteria focused on studies using EHR to investigate risk factors for cognitive decline. Each article was screened by at least two reviewers. Data elements were manually extracted based on a predefined schema. The studied risk factors were classified into categories, and a research gap was identified. Results : From 1,593 articles identified, 80 were selected. The majority (87.5%) were retrospective cohort studies, with 66.3% using datasets of over 10,000 patients, predominantly from the US or UK. Analysis showed that 48.8% of studies addressed medical conditions, 31.3% focused on medical interventions, and 17.5% on lifestyle, socioeconomic status, and environmental factors. Most studies on medical conditions were linked to an increased risk of cognitive decline, whereas medical interventions addressing these conditions often reduced the risk. Conclusions : EHR data significantly enhanced our understanding of medical conditions, interventions, lifestyle, socioeconomic status, and environmental factors related to the risk of cognitive decline.

Are Hyperglycemia-Induced Changes in the Retina Associated with Diabetes-Correlated Changes in the Brain? A Review from Zebrafish and Rodent Type 2 Diabetes Models

Diabetes is prevalent worldwide, with >90% of the cases identified as Type 2 diabetes. High blood sugar (hyperglycemia) is the hallmark symptom of diabetes, with prolonged and uncontrolled levels contributing to subsequent complications. Animal models have been used to study these complications, which include retinopathy, nephropathy, and peripheral neuropathy. More recent studies have focused on cognitive behaviors due to the increased risk of dementia/cognitive deficits that are reported to occur in older Type 2 diabetic patients. In this review, we collate the data reported from specific animal models (i.e., mouse, rat, zebrafish) that have been examined for changes in both retina/vision (retinopathy) and brain/cognition, including db/db mice, Goto-Kakizaki rats, Zucker Diabetic Fatty rats, high-fat diet-fed rodents and zebrafish, and hyperglycemic zebrafish induced by glucose immersion. These models were selected because rodents are widely recognized as established models for studying diabetic complications, while zebrafish represent a newer model in this field. Our goal is to (1) summarize the published findings relevant to these models, (2) identify similarities in cellular mechanisms underlying the disease progression that occur in both tissues, and (3) address the hypothesis that hyperglycemic-induced changes in retina precede or predict later complications in brain.

Metformin mitigates dementia risk among individuals with type 2 diabetes

This mini-narrative review explores the relationship between diabetes and dementia, focusing on the potential mitigating role of metformin in reducing cognitive decline among individuals with type 2 diabetes. The interplay of factors such as glycemic control, diabetic complications, and lifestyle influences characterises diabetes-related dementia. This review emphasises the significance of comprehensive diabetes management in addressing the heightened risk of dementia in this population. Methodologically, the review synthesises evidence from 23 studies retrieved through searches on PubMed, Embase, Google Scholar, and Scopus. Current evidence suggests a predominantly positive association between metformin use and a reduced risk of dementia in individuals with diabetes. However, the review shows the complex nature of these outcomes, revealing variations in results in some studies. These discrepancies show the importance of exploring dose-response relationships, long-term effects, and demographic diversity to unravel the complexities of metformin's impact on cognitive health. Limitations in the existing body of research, including methodological disparities and confounding variables, necessitate refined approaches in future studies. Large-scale prospective longitudinal studies and randomised controlled trials focusing specifically on cognitive effects are recommended. Propensity score matching and exploration of molecular mechanisms can enhance the validity of findings in clinical practice. From a clinical perspective, metformin can serve as a potential adjunctive therapy for individuals with diabetes at risk of cognitive decline.

Alzheimer's disease as a causal risk factor for diabetic retinopathy: a Mendelian randomization study

Objectives

This study aims to investigate the causal relationship between Alzheimer's Disease (AD) and Diabetic Retinopathy (DR).

Methods

Employing Mendelian Randomization (MR), Generalized Summary-data-based Mendelian Randomization (GSMR), and the MR-Steiger test, this study scrutinizes the genetic underpinnings of the hypothesized causal association between AD and DR, as well as its Proliferative DR (PDR) and Non-Proliferative DR (NPDR) subtypes. Comprehensive data from Genome-Wide Association Studies (GWAS) were analyzed, specifically AD data from the Psychiatric Genomics Consortium (71,880 cases/383,378 controls), and DR, PDR, and NPDR data from both the FinnGen consortium (FinnGen release R8, DR: 5,988 cases/314,042 controls; PDR: 8,383 cases/329,756 controls; NPDR: 3,446 cases/314,042 controls) and the IEU OpenGWAS (DR: 14,584 cases/176,010 controls; PDR: 8,681 cases/204,208 controls; NPDR: 2,026 cases/204,208 controls). The study also incorporated Functional Mapping and Annotation (FUMA) for an in-depth analysis of the GWAS results.

Results

The MR analyses revealed that genetic susceptibility to AD significantly increases the risk of DR, as evidenced by GWAS data from the FinnGen consortium (OR: 2.5090; 95% confidence interval (CI):1.2102-5.2018, false discovery rate P-value (PFDR)=0.0201; GSMR: bxy=0.8936, bxy_se=0.3759, P=0.0174), NPDR (OR: 2.7455; 95% CI: 1.3178-5.7197, PFDR=0.0166; GSMR: bxy=0.9682, bxy_se=0.3802, P=0.0126), and PDR (OR: 2.3098; 95% CI: 1.2411-4.2986, PFDR=0.0164; GSMR: bxy=0.7962, bxy_se=0.3205, P=0.0129) using DR GWAS from FinnGen consortium. These results were corroborated by DR GWAS datasets from IEU OpenGWAS. The MR-Steiger test confirmed a significant association of all identified instrumental variables (IVs) with AD. While a potential causal effect of DR and its subtypes on AD was identified, the robustness of these results was constrained by a low power value. FUMA analysis identified OARD1, NFYA, TREM1 as shared risk genes between DR and AD, suggesting a potential genetic overlap between these complex diseases.

Discussion

This study underscores the contribution of AD to an increased risk of DR, as well as NPDR and PDR subtypes, underscoring the necessity of a holistic approach in the management of patients affected by these conditions.

The usefulness of the retina for identifying people with type 2 diabetes with prodromal stages of dementia

Type 2 diabetes (T2D) is associated with cognitive impairment and dementia. The detection of cognitive impairment is important because this population is at higher risk of experiencing difficulties in the self-management of diabetes. Mild cognitive impairment (MCI) often remains undiagnosed due to lack of simple tools for screening at large scale. This represents an important gap in the patients' management because subjects with diabetes and MCI are at high risk of progressing to dementia. Due to its developmental origin as a brain-derived tissue, the retina has been proposed as a potential means of non-invasive and readily accessible exploration of brain pathology. Recent evidence showed that retinal imaging and/or functional tests are correlated with the cognitive function and brain changes in T2D. Simple retinal functional tests (i.e. retinal microperimetry) have proven to be useful as reliable tool for the cognitive evaluation and monitoring in patients with T2D>65 years. This review gives an overall update on the usefulness of retinal imaging in identifying patients with T2D at risk of developing dementia.

Retinal microvascular complexity as a putative biomarker of biological age: a pilot study

Physiological changes associated with aging increase the risk for the development of age-related diseases. This increase is non-specific to the type of age-related disease, although each disease develops through a unique pathophysiologic mechanism. People who age at a faster rate develop age-related diseases earlier in their life. They have an older "biological age" compared to their "chronological age". Early detection of individuals with accelerated aging would allow timely intervention to postpone the onset of age-related diseases. This would increase their life expectancy and their length of good quality life. The goal of this study was to investigate whether retinal microvascular complexity could be used as a biomarker of biological age. Retinal images of 68 participants ages ranging from 19 to 82 years were collected in an observational cross-sectional study. Twenty of the old participants had age-related diseases such as hypertension, type 2 diabetes, and/or Alzheimer's dementia. The rest of the participants were healthy. Retinal images were captured by a hand-held, non-mydriatic fundus camera and quantification of the microvascular complexity was performed by using Sholl's, box-counting fractal, and lacunarity analysis. In the healthy subjects, increasing chronological age was associated with lower retinal microvascular complexity measured by Sholl's analysis. Decreased box-counting fractal dimension was present in old patients, and this decrease was 2.1 times faster in participants who had age-related diseases (p = 0.047). Retinal microvascular complexity could be a promising new biomarker of biological age. The data from this study is the first of this kind collected in Montenegro. It is freely available for use.

Potential Retinal Biomarkers in Alzheimer's Disease

Alzheimer's disease (AD) represents a major diagnostic challenge, as early detection is crucial for effective intervention. This review examines the diagnostic challenges facing current AD evaluations and explores the emerging field of retinal alterations as early indicators. Recognizing the potential of the retina as a noninvasive window to the brain, we emphasize the importance of identifying retinal biomarkers in the early stages of AD. However, the examination of AD is not without its challenges, as the similarities shared with other retinal diseases introduce complexity in the search for AD-specific markers. In this review, we address the relevance of using the retina for the early diagnosis of AD and the complex challenges associated with the search for AD-specific retinal biomarkers. We provide a comprehensive overview of the current landscape and highlight avenues for progress in AD diagnosis by retinal examination.

Frequency of coexistent eye diseases and cognitive impairment or dementia: a systematic review and meta-analysis

OBJECTIVE

We aim to quantify the co-existence of age-related macular degeneration (AMD), glaucoma, or diabetic retinopathy (DR) and cognitive impairment or dementia.

METHOD

MEDLINE, EMBASE, PsycINFO and CINAHL were searched (to June 2020). Observational studies reporting incidence or prevalence of AMD, glaucoma, or DR in people with cognitive impairment or dementia, and of cognitive impairment or dementia among people with AMD, glaucoma, or DR were included.

RESULTS

Fifty-six studies (57 reports) were included but marked by heterogeneities in the diagnostic criteria or definitions of the diseases, study design, and case mix. Few studies reported on the incidence. Evidence was sparse but consistent in individuals with mild cognitive impairment where 7.7% glaucoma prevalence was observed. Prevalence of AMD and DR among people with cognitive impairment ranged from 3.9% to 9.4% and from 11.4% to 70.1%, respectively. Prevalence of AMD and glaucoma among people with dementia ranged from 1.4 to 53% and from 0.2% to 25.9%, respectively. Prevalence of DR among people with dementia was 11%. Prevalence of cognitive impairment in people with AMD, glaucoma, and DR ranged from 8.4% to 52.4%, 12.3% to 90.2%, and 3.9% to 77.8%, respectively, and prevalence of dementia in people with AMD, glaucoma and DR ranged from 9.9% to 62.6%, 2.5% to 3.3% and was 12.5%, respectively.

CONCLUSIONS

Frequency of comorbid eye disease and cognitive impairment or dementia varied considerably. While more population-based estimations of the co-existence are needed, interdisciplinary collaboration might be helpful in the management of these conditions to meet healthcare needs of an ageing population.

TRIAL REGISTRATION

PROSPERO registration: CRD42020189484.

Diabetic Retinopathy and Dementia Association, Beyond Diabetes Severity

PURPOSE

To investigate whether associations between diabetic retinopathy (DR) and dementia and Alzheimer's disease (AD) remain significant after controlling for several measures of diabetes severity.

DESIGN

Retrospective cohort study.

METHODS

Adult Changes in Thought (ACT) is a prospective cohort study of adults aged ≥65 years, randomly selected and recruited from the membership rolls of Kaiser Permanente Washington, who are dementia free at enrollment and followed biennially until incident dementia. The ACT participants were included in this study if they had type 2 diabetes mellitus at enrollment or developed it during follow-up, and data were collected through September, 2018 (3516 person-years of follow-up). Diabetes was defined by ≥ 2 diabetes medication fills in 1 year. Diagnosis of DR was based on International Classification of Diseases Ninth and Tenth Revision codes. Estimates of microalbuminuria, long-term glycemia, and renal function from longitudinal laboratory records were used as indicators of diabetes severity. Alzheimer's disease and dementia were diagnosed using research criteria at expert consensus meetings.

RESULTS

A total of 536 participants (median baseline age 75 [interquartile range 71-80], 54% women) met inclusion criteria. Significant associations between DR >5 years duration with dementia (hazard ratio 1.81 [95% CI 1.23, 2.65]) and AD (1.80 [1.15, 2.82]) were not altered by adjustment for estimates of microalbuminuria, long-term glycemia, and renal function (dementia: 1.69 [1.14, 2.50]; AD: 1.73 [1.10, 2.74]).

CONCLUSIONS

Among people with type 2 diabetes, DR itself appears to be an important biomarker of dementia risk in addition to glycemia and renal complications.

Sex-specific associations between diabetes and dementia: the role of age at onset of disease, insulin use and complications

BACKGROUND

Whether the association of type 2 diabetes (T2DM) with dementia was differed by sex remains unclear, and the roles of age at onset of disease, insulin use and diabetes' complications in their association are unknown.

METHODS

This study analyzed data of 447 931 participants from the UK Biobank. We used Cox proportional hazards models to estimate sex-specific hazard ratios (HRs) and 95% confidence intervals (CI), and women-to-men ratio of HRs (RHR) for the association between T2DM and incident dementia [all-cause dementia, Alzheimer's disease (AD), and vascular dementia (VD)]. The roles of age at onset of disease, insulin use and diabetes' complications in their association were also analyzed.

RESULTS

Compared to people with no diabetes at all, people with T2DM had increased risk of all-cause dementia (HR 2.85, 95% CI 2.56-3.17). The HRs between T2DM and AD were higher in women than men, with an RHR (95%CI) of 1.56 (1.20, 2.02). There was a trend that people who experienced T2DM before age 55 had higher risk of VD than those who had T2DM after age 55. In addition, there was a trend that T2DM had higher effect on VD that occurred before age 75 years than events that occurred after age 75. Patients with T2DM using insulin had higher risk of all-cause dementia than those without insulin, with an RHR (95%CI) of 1.54 (1.00-2.37). People with complications had doubled risk of all-cause dementia, AD and VD.

CONCLUSIONS

Adopting a sex-sensitive strategy to address the risk of dementia in patients with T2DM is instrumental for a precision medicine approach. Meanwhile, it is warranted to consider patients' age at onset of T2DM, insulin use status and complications conditions.

Cognitive Performance and Diabetic Retinopathy: What Your Eyes Can Reveal About Your Brain

BACKGROUND

Diabetic retinopathy (DR) is a chronic diabetes complication. People with Type 2 Diabetes Mellitus (T2DM) have two times the risk for dementia, suggesting it is a new chronic diabetes complication.

OBJECTIVE

Evaluate the association of DR with cognitive performance in a T2DM population.

METHODS

Cross-sectional study with 400 T2DM adults from whom socio-demographic, clinical, laboratory data were collected, and screening test for depression symptoms (Patient Health Questionaire- 9 (PHQ-9)), Mini-Mental State Examination (MMSE), Semantic Verbal Fluency Test, Trail Making Test A and B, Word Memory test were performed. All cognitive test scores were converted into Global Cognition z-Score (GCS(z)). The association between GCS(z) < 0 with DR was performed using a multivariate binary logistic regression model adjusted for age ≥ 65 years, school years ≤ 6 years, DM duration ≥ 10 years, depression symptoms score > 9 at PHQ-9, arterial hypertension, physical activity, diabetic retinopathy, macular edema, and cardiovascular disease.

RESULTS

After exclusions, the 251 eligible patients were 56.6% female, with a mean age of 61.1 (±9.8) years, DM duration of 12.6 (±8.9) years, and 7.6 (±4.2) years of school education. DR prevalence was 46.5%. Multivariate Logistic Regression Model showed an association between DR and GCS(z) < 0, with odds ratio (CI95%) of 2.50 (1.18-5.34), adjusted for age, low education level, arterial hypertension and depression symptoms (OD and CI95% respectively: 5.46(2.42-12.34); 12.19 (5.62-26.46); 2.55 (0.88-7.39); 3.53 (1.55-8.07)).

CONCLUSION

In this T2DM population, having DR increased the chance for worse cognitive performance even when adjusted for age, low education level, presence of arterial hypertension, and depression symptoms.

New methods for the diagnosis and monitoring of cognitive function in patients with type 2 diabetes

The presence of type 2 diabetes acts as an accelerator of cognitive impairment (mild cognitive impairment and later dementia), with a significant impact on the management of the disease and its complications. Therefore, it is recommended to perform an annual evaluation of cognitive function in patients with diabetes older than 65 years. Current guidelines still recommend the use of the Minimental State Evaluation Test (MMSE) as screening test, but it has a modest sensitivity and specificity for identifying mild cognitive impairment. This represents an important gap because patients with mild cognitive impairment are at risk of progressing to dementia. The neurocognitive diagnosis is based on complex neuropsychological tests, which require specifically trained personnel and are time consuming, making its routine incorporation into daily clinical practice unfeasible. Therefore, at present there are no reliable biomarkers to identify patients with type 2 diabetes at increased risk of developing cognitive impairment. Since the brain and the retina have a common embryological origin, our Research Group, has worked over the last 10 years evaluating the usefulness of the retina as a "window" to the brain. We provided evidence that retinal microperimetry is a simple, feasible and useful tool for screening and monitoring cognitive function in patients with type 2 diabetes. We propose a review of actual tests recommended for screening of cognitive impairment as well as an update of new emerging methods, such as retinal microperimetry.

Time dependent effects of prolonged hyperglycemia in zebrafish brain and retina

Prolonged hyperglycemia causes long-term vision complications and an increased risk of cognitive deficits. High blood sugar also confers an osmotic load/stress to cells. We assessed behavioral and neurochemical changes in zebrafish brain and retina following prolonged hyperglycemia for 4-weeks or 8-weeks. At each time point, behavior was assessed using 3-chamber choice task and optomotor response; tissue was then collected and levels of inflammatory markers, tight junction proteins, and neurotransmitters determined using Western Blots. After 4-weeks, brain levels of v-rel reticuloendotheliosis viral oncogene homolog A (avian) (RelA; NF-kB subunit), IkB kinase (IKK), and glial fibrillary acidic protein (GFAP) were significantly elevated; differences in zonula occludens-1 (ZO-1), claudin-5, glutamic acid decarboxylase (GAD), and tyrosine hydroxylase (TH) were not significant. In retina, significant differences were observed only for TH (decreased), Rel A (increased), and GFAP (increased) levels. Glucose-specific differences in initial choice latency and discrimination ratios were also observed. After 8-weeks, RelA, GAD, and TH were significantly elevated in both tissues; IKK and GFAP levels were also elevated, though not significantly. ZO-1 and claudin-5 levels osmotically decreased in retina but displayed an increasing trend in glucose-treated brains. Differences in discrimination ratio were driven by osmotic load. OMRs increased in glucose-treated fish at both ages. In vivo analysis of retinal vasculature suggested thicker vessels after 4-weeks, but thinner vessels at 8-weeks. In vitro, glucose treatment reduced formation of nodes and meshes in 3B-11 endothelial cells, suggesting a reduced ability to form a vascular network. Overall, hyperglycemia triggered a strong inflammatory response causing initial trending changes in tight junction and neuronal markers. Most differences after 4-weeks of exposure were observed in glucose-treated fish suggesting effects on glucose metabolism independent of osmotic load. After 8-weeks, the inflammatory response remained and glucose-specific effects on neurotransmitter markers were observed. Osmotic differences impacted cognitive behavior and retinal protein levels; protein levels in brain displayed glucose-driven changes. Thus, we not only observed differential sensitivities of retina and brain to glucose-insult, but also different cellular responses, suggesting hyperglycemia causes complex effects at the cellular level and/or that zebrafish are able to compensate for the continued high blood glucose levels.

Diabetic retinopathy as a predictor of cardiovascular morbidity and mortality in subjects with type 2 diabetes

This study aimed to evaluate the predictive value of diabetic retinopathy (DR) and its stages with the incidence of major cardiovascular events and all-cause mortality in type 2 diabetes mellitus (T2DM) persons in our large primary healthcare database from Catalonia (Spain). A retrospective cohort study with pseudo-anonymized routinely collected health data from SIDIAP was conducted from 2008 to 2016. We calculated incidence rates of major cardiovascular events [coronary heart disease (CHD), stroke, or both—macrovascular events] and all-cause mortality for subjects with and without DR and for different stages of DR. The proportional hazards regression analysis was done to assess the probability of occurrence between DR and the study events. About 22,402 T2DM subjects with DR were identified in the database and 196,983 subjects without DR. During the follow-up period among the subjects with DR, we observed the highest incidence of all-cause mortally. In the second place were the macrovascular events among the subjects with DR. In the multivariable analysis, fully adjusted for DR, sex, age, body mass index (BMI), tobacco, duration of T2DM, an antiplatelet or antihypertensive drug, and HbA1c, we observed that subjects with any stage of DR had higher risks for all of the study events, except for stroke. We observed the highest probability of all-cause death events (adjusted hazard ratios, AHRs: 1.34, 95% CI: 1.28; 1.41). In conclusion, our results show that DR is related to CHD, macrovascular events, and all-cause mortality among persons with T2DM.

Association Between Diabetic Retinopathy, Brain Structural Abnormalities, and Cognitive Impairment for Accumulated Evidence in Observational Studies

PURPOSE

To evaluate the association between diabetic retinopathy (DR) and cerebral disease or cognitive impairment.

DESIGN

Systematic review and meta-analysis.

METHOD

The hypothesis was formulated prior to data collection. Cross-sectional studies and cohort studies that assessed the association between any measure of DR and cerebral small vessel disease or any type of cognitive impairment in diabetic participants were included. The data were independently extracted by two investigators. This systematic review and meta-analysis adhered to the Preferred Reporting Items for Systematic Reviews and Meta-analyses and Meta-analysis of Observational Studies in Epidemiology guidelines RESULTS: A total of 27 studies were included. The combined odds ratio of 5 cross-sectional/cohort studies that reported that the associations between DR and cerebral structural changes was 1.75 (95% confidence interval [CI]: 1.36-2.25). The combined hazard ratio of 4 cohort studies that examined the association between DR and cognitive impairment events was 1.47 (95% CI: 1.22-1.78). The combined odds ratio of 14 cross-sectional/cohort studies that examined the association between DR and different cognitive impairment events was 1.43 (95% CI: 1.06-1.93). The overall coefficient (β) of 4 studies that examined the relationship between DR and specific cognitive performance was 0.09 (95% CI: 0.00-0.18). Considering the quality of the data, we have performed subgroup analysis in studies scored >7 and studies scored ≤7, respectively, according to the Newcastle-Ottawa scale.

CONCLUSION

The present meta-analysis suggests that DR is associated with an increased risk of structural abnormalities in the brain and cognitive impairment. This association remained significant after adjusting for blood glucose, and the presence of hypertension, indicating that DR is an important danger signal for cerebral abnormalities.

Diagnostic, Prognostic, and Mechanistic Biomarkers of Diabetes Mellitus-Associated Cognitive Decline

Cognitive dysfunctions such as mild cognitive impairment (MCI), Alzheimer’s disease (AD), and other forms of dementia are recognized as common comorbidities of type 2 diabetes mellitus (T2DM). Currently, there are no disease-modifying therapies or definitive clinical diagnostic and prognostic tools for dementia, and the mechanisms underpinning the link between T2DM and cognitive dysfunction remain equivocal. Some of the suggested pathophysiological mechanisms underlying cognitive decline in diabetes patients include hyperglycemia, insulin resistance and altered insulin signaling, neuroinflammation, cerebral microvascular injury, and buildup of cerebral amyloid and tau proteins. Given the skyrocketing global rates of diabetes and neurodegenerative disorders, there is an urgent need to discover novel biomarkers relevant to the co-morbidity of both conditions to guide future diagnostic approaches. This review aims to provide a comprehensive background of the potential risk factors, the identified biomarkers of diabetes-related cognitive decrements, and the underlying processes of diabetes-associated cognitive dysfunction. Aging, poor glycemic control, hypoglycemia and hyperglycemic episodes, depression, and vascular complications are associated with increased risk of dementia. Conclusive research studies that have attempted to find specific biomarkers are limited. However, the most frequent considerations in such investigations are related to C reactive protein, tau protein, brain-derived neurotrophic factor, advanced glycation end products, glycosylated hemoglobin, and adipokines.

Expert Consensus on Cognitive Dysfunction in Diabetes

The incidence of diabetes is gradually increasing in China, and diabetes and associated complications, such as cognitive dysfunction have gained much attention in recent time. However, the concepts, clinical treatment, and prevention of cognitive dysfunction in patients with diabetes remain unclear. The Chinese Society of Endocrinology investigated the current national and overseas situation of cognitive dysfunction associated with diabetes. Based on research both in China and other countries worldwide, the Expert Consensus on Cognitive Dysfunction in Diabetes was established to guide physicians in the comprehensive standardized management of cognitive dysfunction in diabetes and to improve clinical outcomes in Chinese patients. This consensus presents an overview, definition and classification, epidemiology and pathogenesis, risk factors, screening, diagnosis, differential diagnosis, treatment, and prevention of cognitive dysfunction in patients with diabetes.

Diabetic retinopathy and cognitive dysfunction: a systematic review and meta-analysis

BACKGROUND

This study aims to determine the relationship between diabetic retinopathy (DR) and cognitive dysfunction as well as explores the effects of DR on different cognitive domains.

METHODS

A systematic search of PubMed, Embase, Web of Science, Wanfang data, CBM, CNKI, and VIP databases from their inception to October 2021. The pooled odds ratio (ORs), hazard ratio (HRs), and 95% confidence interval (CIs) were calculated.

RESULTS

Twenty-two studies met the inclusion criteria and meta-analysis included 15 studies. The presence of DR reflects a higher risk of cognitive dysfunction (OR = 2.45; 95% CI: 1.76-3.41; HR = 1.34 95% CI: 1.10-1.62). Cohort study combined risk was 2.62 (95% CI: 1.93-3.56), in cross-sectional study was 2.07 (95% CI: 1.11-3.88). The pooled OR was 2.38 (95% CI: 1.83-3.10) and 3.11 (95% CI: 1.15-8.40) in Asia and Oceania. No such association was found in North America (OR = 2.22; 95% CI: 0.77-6.38). The pooled risk was 2.47 (95% CI: 1.76-3.48) in patients with T2DM, while did not identify an association between these two conditions in T1DM. The combined unadjusted and adjusted ORs were 2.72 (95% CI: 1.99-3.73) and 2.06 (95% CI: 1.49-2.85). DR severity and the risk of cognitive impairment showed a positive correlation and mainly impaired the speeds of psychomotor and information processing.

CONCLUSIONS

DR can help to identify people at high risk of cognitive dysfunction. Further studies are indispensable for exploring the relationship between DR and cognitive impairment in the patients for different age, gender and race, as well as to assess the risk of cognitive impairment in different populations.

Diabetic Retinopathy Predicts Risk of Alzheimer’s Disease: A Danish Registry-Based Nationwide Cohort Study

Background:

Retinal neurodegeneration is evident in early diabetic retinopathy (DR) which may be associated with other neurodegenerative diseases like Alzheimer's disease (AD).

Objective:

To investigate diabetes and DR as a risk marker of present and incident AD.

Methods:

A register-based cohort study was performed. We included 134,327 persons with diabetes above 60 years of age, who had attended DR screening, and 651,936 age- and gender-matched persons without diabetes.

Results:

At baseline, the prevalence of AD was 0.7% and 1.3% among patients with and without diabetes, respectively. In a multivariable regression model, patients with diabetes were less likely to have AD at baseline (adjusted OR 0.63, 95% CI 0.59–0.68). During follow-up, incident AD was registered for 1473 (0.35%) and 6,899 (0.34%) persons with and without diabetes, respectively. Compared to persons without diabetes, persons with diabetes and no DR had a lower risk to develop AD (adjusted HR 0.87, 95% CI 0.81–0.93), while persons with diabetes and DR had higher risk of AD (adjusted HR 1.24, 95% CI 1.08–1.43). When persons with diabetes and no DR were used as references, a higher risk of incident AD was observed in persons with DR (adjusted HR 1.34, 95% CI 1.18–1.53).

Conclusion:

Individuals with diabetes without DR were less likely to develop AD compared to persons without diabetes. However, individuals with DR had a 34% higher risk of incident AD, which raise the question whether screening for cognitive impairment should be done among individuals with DR.

Altered Functional Topological Organization in Type-2 Diabetes Mellitus With and Without Microvascular Complications

Microvascular complications can accelerate cognitive impairment in patients with type 2 diabetes mellitus (T2DM) and have a high impact on their quality of life; however, the underlying mechanism is still unclear. The complex network in the human brain is the physiological basis for information processing and cognitive expression. Therefore, this study explored the relationship between the functional network topological properties and cognitive function in T2DM patients with and without microvascular complications (T2DM-C and T2DM-NC, respectively). Sixty-seven T2DM patients and 41 healthy controls (HCs) underwent resting-state functional MRI and neuropsychological assessment. Then, graph theoretical network analysis was performed to explore the global and nodal topological alterations in the functional whole brain networks of T2DM patients. Correlation analyses were performed to investigate the relationship between the altered topological parameters and cognitive/clinical variables. The T2DM-C group exhibited significantly higher local efficiency (Eloc), normalized cluster coefficient (γ), and small-world characteristics (σ) than the HCs. Patients with T2DM at different clinical stages (T2DM-C and T2DM-NC) showed varying degrees of abnormalities in node properties. In addition, compared with T2DM-NC patients, T2DM-C patients showed nodal properties disorders in the occipital visual network, cerebellum and middle temporal gyrus. The Eloc metrics were positively correlated with HbA1c level (P = 0.001, r = 0.515) and the NE values in the right paracentral lobule were negatively related with serum creatinine values (P = 0.001, r = −0.517) in T2DM-C patients. This study found that T2DM-C patients displayed more extensive changes at different network topology scales. The visual network and cerebellar may be the central vulnerable regions of T2DM-C patients.

Ophthalmic conditions associated with dementia risk: The Cardiovascular Health Study

INTRODUCTION

Ophthalmic conditions and dementia appear to overlap and may share common pathways, but research has not differentiated dementia subtypes.

METHODS

Diagnoses of cataracts, age-related macular degeneration (AMD), diabetic retinopathy (DR), and glaucoma were based on medical histories and International Classification of Diseases, Ninth Revision (ICD-9) codes for 3375 participants from the Cardiovascular Health Study. Dementia, including Alzheimer's disease (AD) and vascular dementia (VaD), was classified using standardized research criteria.

RESULTS

Cataracts were associated with AD (hazard ratio [HR] = 1.34; 95% confidence interval [CI] = 1.01-1.80) and VaD/mixed dementia (HR = 1.41; 95% CI = 1.02-1.95). AMD was associated with AD only (HR = 1.87; 95% CI = 1.13-3.09), whereas DR was associated with VaD/mixed dementia only (HR = 2.63; 95% CI = 1.10-6.27).

DISCUSSION

Differential associations between specific ophthalmic conditions and dementia subtypes may elucidate pathophysiologic pathways. Lack of association between glaucoma and dementia was most surprising from these analyses.

Visual Impairment, Eye Diseases, and Dementia Risk: A Systematic Review and Meta-Analysis

BACKGROUND

Visual impairment and eye diseases have been associated with dementia, though with mixed findings and often in cross-sectional studies.

OBJECTIVE

To identify prospective studies investigating associations between visual impairment or common eye diseases and risk of all-cause dementia or key dementia subtypes.

METHODS

We searched Medline, PsycINFO, and Embase from inception to January 2020. We also conducted backward and forward citation searches of included studies and set up alerts to identify studies published after the search date. Random-effects meta-analysis was used to combine adjusted estimates across studies.

RESULTS

Thirty studies met our eligibility criteria. For visual impairment, pooled estimates indicated an increased risk of all-cause dementia (37,705 participants, 3,415 cases, risk ratio [RR] = 1.38, 95%confidence interval [CI]: 1.19-1.59, I2 = 28.6%). Pooled estimates also suggested an increased dementia risk associated with cataract (6,659 participants, 1,312 cases, hazard ratio [HR] = 1.17, 95%CI 1.00-1.38, I2 = 0.0%) and diabetic retinopathy (43,658 participants, 7,060 cases, HR = 1.34, 95%CI 1.11-1.61, I2 = 63.9%), respectively. There was no evidence of an association between glaucoma (175,357 participants, 44,144 cases, HR = 0.97, 95%CI 0.90-1.04, I2 = 51.5%) or age-related macular degeneration (7,800,692 participants, >  2,559 cases, HR = 1.15, 95%CI 0.88-1.50, I2 = 91.0%) and risk of dementia, respectively.

CONCLUSION

As visual impairment, cataract, and diabetic retinopathy are associated with an increased likelihood of developing dementia, early diagnosis may help identify those at risk of dementia. Given most causes of visual impairment are treatable or preventable, the potential for dementia prevention warrants further investigation.

Relationship between Diabetic Retinopathy and Systemic Neurodegenerative Diseases: A Systematic Review and Meta-analysis

TOPIC

To examine the potential role of systemic neurodegeneration, this study aimed to provide an overview of the available evidence on the relationship between diabetic retinopathy (DR) and systemic neurodegeneration.

CLINICAL RELEVANCE

The association between DR and systemic neurodegeneration is inconsistent in the literature. A summary estimate on the measures of association is important to establish whether DR may be used as a risk marker of systemic neurodegeneration.

METHODS

We searched the literature databases PubMed/MEDLINE, EMBASE, and Cochrane Library on October 3, 2020, for all observational studies on humans evaluating the association between DR and systemic neurodegenerative diseases. Two authors conducted the literature search, study selection, and data extraction in an independent fashion. Studies were reviewed qualitatively in text and quantitatively in meta-analyses. Heterogeneity was evaluated with Cochran's Q and I², and Funnel plot was used to investigate for skewed results and possible publication bias.

RESULTS

We identified 27 eligible studies with a total of 1 398 041 patients with diabetes. Diagnosis of DR was made using fundus photography or examination (n = 20), health registries (n = 4), was self-reported (n = 1), or was not disclosed in the remaining studies. Neurodegenerative conditions studied were cognitive impairment (n = 23), Alzheimer's disease (n = 3), and Parkinson's disease (n = 1). In cross-sectional and longitudinal studies, respectively, presence of any DR was associated with present (odds ratio [OR], 1.57; 95% confidence interval [CI], 1.02-2.43, P = 0.043) and incident (OR, 2.36; 95% CI, 1.50-3.71, P = 0.00021) systemic neurodegeneration, but severity of DR was not associated with differences in systemic neurodegeneration (OR, 0.98; 95% CI, 0.45-2.15, P = 0.96).

CONCLUSIONS

In this systematic review, DR appears to be a marker of systemic neurodegeneration. Further studies are warranted to better elucidate the clinical practical implications of this relationship.

Vascular complications of diabetes: natural history and corresponding risks of dementia in a national cohort of adults with diabetes

AIMS

This study aimed to determine the trajectory of diabetic vascular diseases and to investigate the association between vascular diseases and dementia.

METHODS

We included adults aged ≥ 50 years with newly diagnosed type 2 diabetes (n = 173,118) from 2001 to 2005 who were followed-up until December 31, 2013 in the Taiwan's National Health Insurance Research Database. Multivariable Cox regression models were constructed to estimate hazard ratios (HRs) and confidence limits (CLs) for all-cause dementia in relation to the number, types, and occurrence patterns of vascular disease.

RESULTS

Within 1 year of diabetes diagnosis, 26.3% of adults developed their first vascular disease. During the 1,864,279 person-years of follow-up, 17,426 adults had all-cause dementia, corresponding to an incidence of 97.9 cases/10,000 person-years in 127,718 adults with at least one vascular disease and 67.5 cases/10,000 person-years in 45,400 adults without vascular diseases. Across all age groups, adults who subsequently developed a vascular disease in two one-year windows since diabetes diagnosis had the highest incidence of all-cause dementia. In comparison with adults without vascular diseases, HR for all-cause dementia was 1.99 (CL: 1.92-2.07) for those with one vascular disease only; 2.04 (CL: 1.98-2.13) for two or more vascular diseases; 3.56 (CL: 3.44-3.70) for stroke only; and 2.06 (CL: 1.99-2.14) for neuropathy alone. Similar associations were also observed with a smaller magnitude for adults with nephropathy, retinopathy, cardiovascular disease, or peripheral arterial disease.

CONCLUSIONS

Patients with diabetes-related complications, particularly stroke and neuropathy, and those with rapidly developed vascular diseases appeared to have a high risk of dementia.

Association Between Diabetic Retinopathy and Cognitive Impairment: A Systematic Review and Meta-Analysis

Diabetic retinopathy (DR) is one of the most common microvascular complications associated with diabetes mellitus. However, its correlation with another diabetes-related disorder, cognitive impairment, has not been well studied. This systematic review and meta-analysis aimed to explore the association between DR and cognitive impairment. MEDLINE (PubMed), the Cochrane Library, and EMBASE databases were searched for observational studies that reported an association between DR and cognitive impairment. Data from selected studies were extracted, and a meta-analysis was conducted using fixed-effects modeling. Fifteen observational studies were included in the systematic review, and 10 studies were included in the meta-analysis. The odds ratio of the association between DR and cognitive impairment was 2.24 (95% confidence interval [CI], 1.89-2.66; I ² = 0.8%). The hazard ratio of the association between DR and cognitive impairment was significant in four studies, ranging from 1.09-1.32. Minimal or mild DR was not significantly associated with cognitive impairment (odds ratio [OR], 2.04; 95% CI, 0.87-4.77). However, the association between proliferative DR and cognitive impairment (OR, 3.57; 95% CI, 1.79-7.12; I ² = 16.6%) was not stronger than the association between moderate or worse DR and cognitive impairment (OR, 4.26; 95% CI, 2.01-9.07; I ² = 0.0%). DR is associated with cognitive impairment, and screening for DR will be helpful for the early identification of individuals with cognitive impairment. Further studies are needed to confirm the association between proliferative DR and cognitive impairment.

Target attainment in insulin-naive patients at high risk for hypoglycemia: Results from ACHIEVE Control

AIMS

To better understand outcomes in people with type 2 diabetes at high risk of hypoglycemia, we conducted post hoc analyses in subgroups of participants from the real-world ACHIEVE Control study (NCT02451137) with ≥1 hypoglycemia risk factor.

METHODS

Insulin-naive adults with type 2 diabetes and A1c ≥8% were randomized 1:1 to insulin glargine 300 U/mL (Gla-300) or standard-of-care basal insulin (SOC-BI). Participants had documented history of ≥1 risk factors for hypoglycemia: chronic kidney disease, cardiovascular disease, dementia or blindness, age ≥65 years, or history of hypoglycemia. Outcomes included individualized A1c target attainment without documented symptomatic hypoglycemia (blood glucose [BG] ≤3.9 mmol/L or <3.0 mmol/L) or severe hypoglycemia, A1c target attainment, and absence of documented symptomatic or severe hypoglycemia at 6 and 12 months.

RESULTS

Within subgroups, odds ratios generally showed trends favoring Gla-300 versus SOC-BI, particularly for hypoglycemia avoidance in participants ≥65 years of age (BG ≤3.9 mmol/L; odds ratio, 1.52; 95% confidence interval, 1.14-2.03) and those with chronic kidney disease (BG ≤3.9 mmol/L; odds ratio, 2.28; 95% confidence interval, 1.26-4.12). Results were consistent with the overall population.

CONCLUSIONS

These data suggest potential benefit of Gla-300 versus SOC-BI for avoiding hypoglycemia in participants with ≥1 hypoglycemia risk factor.

Altered resting cerebral blood flow specific to patients with diabetic retinopathy revealed by arterial spin labeling perfusion magnetic resonance imaging

BACKGROUND

Previous neuroimaging studies have shown that patients with diabetic retinopathy (DR) were accompanied by abnormalities in cerebral functional and structural architecture, whereas the resting cerebral blood flow (CBF) alterations in patients with DR are not well understood.

PURPOSE

To explore CBF alterations in patients with DR using pseudo-continuous arterial spin labeling (pCASL) imaging.

MATERIAL AND METHODS

Thirty-one individuals with DR (15 men, 16 women; mean age = 53.38 ± 9.12 years) and 33 healthy controls (HC) (12 men, 21 women; mean age = 51.61 ± 9.84 years) closely matched for age, sex, and education, underwent pCASL imaging scans. Two-sample T test was conducted to compare different CBF values between two groups.

RESULTS

Patients with DR exhibited significantly increased CBF values in the left middle temporal gyrus (Brodmann's area, BA 22) and the bilateral supplementary motor area (BA3) and decreased CBF values in the bilateral calcarine (BA17,18) and bilateral caudate relative to HC group (two-tailed, voxel level at P < 0.01, Gaussian random field (GRF), cluster level at P < 0.05). Moreover, the HbA1c (%) level showed a positive correlation with CBF values in the bilateral caudate (r = 0.473, P = 0.007) in patients with DR.

CONCLUSION

Our results highlighted that patients with DR had abnormal CBF values in the visual cortices, caudate, middle temporal gyrus, and supplementary motor area, which might reflect vision and sensorimotor and cognition dysfunction in patients with DR. These findings might help us to understanding the neural mechanism of patients with DR.

Understanding the Brain through Aging Eyes

The eye and brain share common mechanisms of aging and disease, thus the retina is an essential source of accessible information about neurodegenerative processes occurring in the brain. Advances in retinal imaging have led to the discovery of many potential biomarkers of Alzheimer's disease, although further research is needed to validate these associations. Understanding the mechanisms of retinal disease in the context of aging will extend our knowledge of AD and may enable advancements in diagnosis, monitoring, and treatment.

Dynamic Changes of Amplitude of Low-Frequency Fluctuations in Patients With Diabetic Retinopathy

Background: Growing evidence demonstrate that diabetic retinopathy (DR) patients have a high risk of cognitive decline and exhibit abnormal brain activity. However, neuroimaging studies thus far have focused on static cerebral activity changes in DR patients. The characteristics of dynamic cerebral activity in patients with DR are poorly understood.

Purpose: The purpose of the study was to investigate the dynamic cerebral activity changes in patients with DR using the dynamic amplitude of low-frequency fluctuation (dALFF) method.

Materials and methods: Thirty-four DR patients (18 men and 16 women) and 38 healthy controls (HCs) (18 males and 20 females) closely matched in age, sex, and education were enrolled in this study. The dALFF method was used to investigate dynamic intrinsic brain activity differences between the DR and HC groups.

Results: Compared with HCs, DR patients exhibited increased dALFF variability in the right brainstem, left cerebellum_8, left cerebellum_9, and left parahippocampal gyrus. In contrast, DR patients exhibited decreased dALFF variability in the left middle occipital gyrus and right middle occipital gyrus.

Conclusion: Our study highlighted that DR patients showed abnormal variability of dALFF in the visual cortices, cerebellum, and parahippocampal gyrus. These findings suggest impaired visual and motor and memory function in DR individuals. Thus, abnormal dynamic spontaneous brain activity might be involved in the pathophysiology of DR.

The type 2 diabetes-specific dementia risk score (DSDRS) is associated with frailty, cognitive and functional status amongst Mexican community-dwelling older adults

Background

The type 2 diabetes (T2D) specific dementia-risk score (DSDRS) was developed to evaluate dementia risk in older adults with T2D. T2D-related factors have been shown increase the risk of age-related conditions, which might also increase dementia risk. Here, we investigate the associations of DSDRS with frailty, disability, quality of life (QoL) and cognition in community-dwelling older adults with T2D.

Methods

We included 257 community-dwelling older adults with T2D to evaluate the association between DSDRS and Mini-mental state examination (MMSE), Isaac’s set-test (IST), clock drawing test (CDT), quality of life (SF-36), risk of malnutrition (Mini-Nutritional Assessment or MNA), as well as frailty, Katz’ and Lawton-Brody scores. We also assessed the phenotype and correlates of high-estimated dementia risk by assessing individuals with DSDRS >75th age-specific percentiles.

Results

Mean age of participants was 78.0 ± 6.2 years. DSDRS showed a significant correlation with MMSE test, IST, CDT, SF-36, MNA, Lawton-Brody and Katz scores, and an increasing number of frailty components. DSDRS was higher among frail, pre-frail, and subjects with limited ADL and IADL (p < 0.001). Participants with DSDRS >75th age-specific percentiles had lower education, MMSE, IST, SF-36, MNA, Katz, Lawton-Brody, and higher frailty scores. High-estimated 10-year dementia risk was associated with ADL and IADL disability, frailty and risk of malnutrition. When assessing individual components of DSDRS, T2D-related microvascular complications were associated to all outcome measures.

Conclusion

The DSDRS is associated with frailty, disability, malnutrition and lower cognitive performance. These findings support that T2D-related factors have significant burden on functional status, QoL, disability and dementia risk.

Neuropathic damage in the diabetic eye: clinical implications

In recent years, emerging evidence support that the eye is target of diabetes neuropathy. There are two components of the eye that are mainly involved in the neurodegenerative process induced by diabetes: the retina and the cornea. The study of functional and structural changes in these components of the eye will provide useful information to identify subjects with diabetes at risk of diabetic peripheral neuropathy and dementia. In this review the state of the art regarding the evidence and clinical implications of this emerging concept will be provided. In addition, the relationship between retinal and corneal neurodegeneration with peripheral neuropathy and cognitive decline will be analyzed. Finally, the scientific gaps than need to be covered and will be critically examined.

Understanding multifactorial brain changes in type 2 diabetes: a biomarker perspective

People with type 2 diabetes are at an increased risk of cognitive impairment and dementia (including Alzheimer's disease), as well as subtle forms of cognitive dysfunction. Current diabetes guidelines recommend screening for cognitive impairment in groups at high risk and providing guidance for diabetes management in patients with diabetes and cognitive impairment. Yet, no disease-modifying treatment is available and important questions remain about the mechanisms underlying diabetes-associated cognitive dysfunction. These mechanisms are likely to be multifactorial and different for subtle and more severe forms of diabetes-associated cognitive dysfunction. Over the past years, research on dementia, brain ageing, diabetes, and vascular disease has identified novel biomarkers of specific dementia aetiologies, brain parenchymal injury, and cerebral blood flow and metabolism. These markers shed light on the processes underlying diabetes-associated cognitive dysfunction, have clear applications in current research and increasingly in clinical diagnosis, and might ultimately guide targeted treatment.

Cerebral microvascular complications of type 2 diabetes: stroke, cognitive dysfunction, and depression

Adults with type 2 diabetes are at an increased risk of developing certain brain or mental disorders, including stroke, dementia, and depression. Although these disorders are not usually considered classic microvascular complications of diabetes, evidence is growing that microvascular dysfunction is one of the key underlying mechanisms. Microvascular dysfunction is a widespread phenomenon in people with diabetes, including effects on the brain. Cerebral microvascular dysfunction is also apparent in adults with prediabetes, suggesting that cerebral microvascular disease processes start before the onset of diabetes. The microvasculature is involved in the regulation of many cerebral processes that when impaired predispose to lacunar and haemorrhagic stroke, cognitive dysfunction, and depression. Main drivers of diabetes-related cerebral microvascular dysfunction are hyperglycaemia, obesity and insulin resistance, and hypertension. Increasing amounts of data from observational studies suggest that diabetes-related microvascular dysfunction is associated with a higher risk of stroke, cognitive dysfunction, and depression. Cerebral outcomes in diabetes might be improved following treatments targeting the pathways through which diabetes damages the microcirculation. These treatments might include drugs that reduce dicarbonyl compounds, augment cerebral insulin signalling, or improve blood-brain barrier permeability and cerebral vasoreactivity.

Association between the Use of Dipeptidyl Peptidase 4 Inhibitors and the Risk of Dementia among Patients with Type 2 Diabetes in Taiwan

STUDY OBJECTIVES

Diabetes mellitus per se and its related therapy have been frequently associated with an increased risk of developing dementia. However, studies that explored the risk of dementia from the use of the novel oral antidiabetic medication dipeptidyl peptidase 4 inhibitor (DPP-4i) have been limited, especially in Asian populations. The present study aimed to determine the effect of DPP-4i on the subsequent risk of dementia among patients with type 2 diabetes (T2D) in Taiwan.

METHODS

This study utilized data from the Longitudinal Health Insurance Database between 2008 and 2015. We enrolled 2903 patients aged ≥50 years, who were on DPP-4i for a diagnosis of T2D and had no dementia. A total of 11,612 subjects were included and compared with a propensity score-matched control group who did not use DPP-4i (non-DPP-4i group). Survival analysis was performed to estimate and compare the risk of dementia-including Alzheimer's disease, vascular dementia, and other dementia types-between the two groups. Results: Both groups had a mean age of 68 years, had a preponderance of women (61.8%), and were followed up for a mean duration of 7 years. The risk of all-cause dementia was significantly lower in the DPP-4i group than in the non-DPP-4i group (hazard ratio (HR) 0.798; 95% confidence interval (CI) 0.681-0.883; p < 0.001), with a class effect. This trend was particularly observed for vascular dementia (HR 0.575; 95% CI 0.404-0.681; p < 0.001), but not in Alzheimer's disease (HR 0.891; 95% CI 0.712-1.265; p = 0.297). The Kaplan-Meier analysis showed that the preventive effect on dementia was positively correlated with the cumulative dose of DPP-4i. Conclusions: DPP-4i decreased the risk of dementia with a class effect, especially vascular dementia, but not in Alzheimer's disease. Our results provide important information on the drug choice when managing patients with T2D in clinical practice.

Depression in type 1 diabetes and risk of dementia

OBJECTIVE

Depression afflicts 14% of individuals with type 1 diabetes (T1D). Depression is a robust risk factor for dementia but it is unknown if this holds true for individuals with T1D, who recently started living to an age conferring dementia risk. We examined if depression is a dementia risk factor among elderly individuals with T1D.

METHODS

3,742 individuals with T1D age ≥50 were followed for dementia from 1/1/96-9/30/2015. Depression, dementia, and comorbidities were abstracted from electronic medical records. Cox proportional hazard models estimated the association between depression and dementia adjusting for demographics, glycosylated hemoglobin, severe dysglycemic epidsodes, stroke, heart disease, nephropathy, and end stage renal disease. The cumulative incidence of dementia by depression was estimated conditional on survival dementia-free to age 55.

RESULTS

Five percent (N = 182) were diagnosed with dementia and 20% had baseline depression. Depression was associated with a 72% increase in dementia (fully adjusted HR = 1.72; 95% CI:1.12-2.65). The 25-year cumulative incidence of dementia was more than double for those with versus without depression (27% vs. 12%).

CONCLUSIONS

For people with T1D, depression significantly increases dementia risk. Given the pervasiveness of depression in T1D, this has major implications for successful aging in this population recently living to old age.

Fractal characterization of retinal microvascular network morphology during diabetic retinopathy progression

OBJECTIVE

The study aimed to characterize morphological changes of the retinal microvascular network during the progression of diabetic retinopathy.

METHODS

Publicly available retinal images captured by a digital fundus camera from DIARETDB1 and STARE databases were used. The retinal microvessels were segmented using the automatic method, and vascular network morphology was analyzed by fractal parametrization such as box-counting dimension, lacunarity, and multifractals.

RESULTS

The results of the analysis were affected by the ability of the segmentation method to include smaller vessels with more branching generations. In cases where the segmentation was more detailed and included a higher number of vessel branching generations, increased severity of diabetic retinopathy was associated with increased complexity of microvascular network as measured by box-counting and multifractal dimensions, and decreased gappiness of retinal microvascular network as measured by lacunarity parameter. This association was not observed if the segmentation method included only 3-4 vessel branching generations.

CONCLUSIONS

Severe stages of diabetic retinopathy could be detected noninvasively by using high resolution fundus photography and automatic microvascular segmentation to the high number of branching generations, followed by fractal analysis parametrization. This approach could improve risk stratification for the development of microvascular complications, cardiovascular disease, and dementia in diabetes.

Pathophysiological Mechanisms Linking Type 2 Diabetes and Dementia: Review of Evidence from Clinical, Translational and Epidemiological Research

BACKGROUND

Type 2 diabetes represents an increasing health burden world-wide and its prevalence in particularly higher in elderly population. Consistent epidemiological evidence suggests an increased risk of dementia associated to type 2 diabetes; the mechanisms underlying these associations, however, remain unclear.

OBJECTIVE

The study aims to review epidemiological, clinical and pre-clinical data that weigh on pathophysiological links, mechanisms of disease and associations between type 2 diabetes and dementia to identify areas of opportunity for future research.

METHODS

We searched the following electronic bibliographic databases: PUBMED, EMBASE, SCIELO, MEDLINE and OVID for clinical, translational and epidemiological research literature that summarize diabetes-related risk factors for dementia, metabolic and neurological changes associated to T2D, evidence of therapeutic approaches in type 2 diabetes and its pathophysiological implications for dementia.

RESULTS

Type 2 diabetes mellitus increases risk for all-cause dementia, vascular dementia and Alzheimer's disease. The most evaluated mechanisms linking both disorders in pre-clinical studies include an increase in neuronal insulin resistance, impaired insulin signaling, pro-inflammatory state, mitochondrial dysfunction and vascular damage which increase deposition of β-amyloid, tau proteins and GSK3β, leading to an earlier onset of dementia in individuals with impairment in the glucose metabolism. Neuroimaging and neuropathology evidence linking cerebrovascular lesions, neurodegeneration and particularly small-vessel disease in the onset of dementia is consistent with the increased risk of incident dementia in type 2 diabetes, but consistent evidence of AD-related pathology is scarce. Epidemiological data shows increased risk of dementia related to hypoglycemic episodes, glycemic control, metabolic syndrome, insulin resistance and genetic predisposition, but the evidence is not consistent and statistical analysis might be affected by inconsistent covariate controlling. Therapeutic approaches for T2D have shown inconsistent result in relation to dementia prevention and delay of cognitive decline; lifestyle intervention, particularly physical activity, is a promising alternative to ameliorate the impact of disability and frailty on T2D-related dementia.

CONCLUSION

Vascular disease, inflammation and impaired brain insulin signaling might occur in T2D and contribute to dementia risk. Evidence from epidemiological studies has not consistently reported associations that could integrate a unified mechanism of disease in humans. Evaluation of the effect of antidiabetic medications and non-pharmacological interventions in dementia prevention in type 2 diabetes is promising but has thus far offered inconsistent results.

Traumatic brain injury associated with dementia risk among people with type 1 diabetes

OBJECTIVE

To examine the association between traumatic brain injury (TBI) and dementia risk among a cohort of middle-aged and elderly individuals with type 1 diabetes (T1D).

METHODS

We evaluated 4,049 members of an integrated health care system with T1D ≥50 years old between January 1, 1996, and September 30, 2015. Dementia and TBI diagnoses throughout the study period were abstracted from medical records. Cox proportional hazards models estimated associations between time-dependent TBI and dementia adjusting for demographics, HbA1c, nephropathy, neuropathy, stroke, peripheral artery disease, depression, and dysglycemic events. Fine and Gray regression models evaluated the association between baseline TBI and dementia risk accounting for competing risk of death.

RESULTS

A total of 178 individuals (4.4%) experienced a TBI and 212 (5.2%) developed dementia. In fully adjusted models, TBI was associated with 3.6 times the dementia risk (hazard ratio [HR] 3.64; 95% confidence interval [CI] 2.34, 5.68). When accounting for the competing risk of death, TBI was associated with almost 3 times the risk of dementia (HR 2.91; 95% CI 1.29, 5.68).

CONCLUSION

This study demonstrates a marked increase in risk of dementia associated with TBI among middle-aged and elderly people with T1D. Given the complexity of self-care for individuals with T1D, and the comorbidities that predispose them to trauma and falls, future work is needed on interventions protecting brain health in this vulnerable population, which is now living to old age.

Associations between recent and established ophthalmic conditions and risk of Alzheimer's disease

INTRODUCTION

Identifying ophthalmic diseases associated with increased risk of Alzheimer's disease (AD) may enable better screening and understanding of those at risk of AD.

METHODS

Diagnoses of glaucoma, age-related macular degeneration (AMD), and diabetic retinopathy (DR) were based on International Classification of Diseases, 9th revision, codes for 3877 participants from the Adult Changes in Thought study. The adjusted hazard ratio for developing probable or possible AD for recent (within 5 years) and established (>5 years) diagnoses were assessed.

RESULTS

Over 31,142 person-years of follow-up, 792 AD cases occurred. The recent and established hazard ratio were 1.46 (P = .01) and 0.87 (P = .19) for glaucoma, 1.20 (P = .12) and 1.50 (P < .001) for AMD, and 1.50 (P = .045) and 1.50 (P = .03) for DR.

DISCUSSION

Increased AD risk was found for recent glaucoma diagnoses, established AMD diagnoses, and both recent and established DR. People with certain ophthalmic conditions may have increased AD risk.

Diabetic Retinopathy and Dementia in Type 1 Diabetes

OBJECTIVE

Retinopathy impacts over one-third of those with diabetes mellitus and is associated with impaired cognitive performance and cerebrovascular lesions in middle-aged adults with type 1 diabetes. However, the association between diabetic retinopathy (DR) and risk of dementia in type 1 diabetes is unknown. We investigated the association between DR and incident dementia in a large, elderly population with type 1 diabetes.

METHODS

A cohort of 3742 patients with type 1 diabetes aged 50 years and above was followed from January 1, 1996 to September 30, 2015 for incident dementia. DR diagnoses were identified from electronic medical records. Age as timescale Cox proportional hazard models evaluated associations between time-updated DR and dementia risk. Models were adjusted for demographics, severe glycemic events, glycosylated hemoglobin, and vascular comorbidities.

RESULTS

Among 3742 patients with type 1 diabetes (47% female, 21% nonwhite), 182 (5%) were diagnosed with dementia during a mean follow-up of 6.2 years. No significant association was found between DR and incident dementia in the main analyses [adjusted Hazard Ratio=1.12; 95% confidence interval, 0.82-1.54), nor among subgroup restricted to those aged 60 years and above or 70 years and above.

CONCLUSIONS

DR was not associated with risk of dementia, suggesting that pathophysiological processes underlying dementia may be different in type 1 versus type 2 diabetes.

An Update on Type 2 Diabetes Mellitus as a Risk Factor for Dementia

With the rapidly expanding evidence on brain structural and functional changes in type 2 diabetes mellitus (T2DM) patients, there is an increasing need to update our understanding on how T2DM associates with dementia as well as the underlying pathophysiological mechanisms. A literature search of T2DM and dementia or cognition impairments was carried out in electronic databases Medline, EMBASE, and Google Scholar. In this review, the chosen evidence was limited to human subject studies only, and data on either type 1 diabetes mellitus (T1DM) or non-classified diabetes were excluded. T2DM is a risk factor for both vascular dementia (VaD) and Alzheimer's disease (AD), although AD pathological marker studies have not provided sufficient evidence. T2DM interacts additively or synergistically with many factors, including old age, hypertension, total cholesterol, and APOEɛ4 carrier status for impaired cognition functions seen in patients with T2DM. In addition, comorbid T2DM can worsen the clinical presentations of patients with either AD or VaD. In summary, T2DM increases the risk for AD through different mechanisms for VaD although some mechanisms may overlap. Tau-related neurofibrillary tangles instead of amyloid-β plaques are more likely to be the pathological biomarkers for T2DM-related dementia. Degeneration of neurons in the brain, impaired regional blood supply/metabolism, and genetic predisposition are all involved in T2DM-associated dementia or cognitive impairments.

Female sex, early-onset hypertension, and risk of dementia

OBJECTIVE

To evaluate the association of early-adulthood and mid-adulthood hypertension with dementia in men and women.

METHODS

We evaluated 5,646 members of a diverse integrated health care delivery system who had clinical examinations and health survey data from 1964 to 1973 (mean age 32.7 years; early adulthood) and 1978-1985 (mean age 44.3 years; mid-adulthood) and were members as of January 1, 1996 (mean age 59.8 years). Hypertension categories based on measurements of blood pressure (BP) and change in hypertension categories between the 2 examinations (e.g., onset hypertension) were used to predict dementia incidence from January 1, 1996, to September 30, 2015. Cox proportional hazard models were adjusted for demographics, vascular comorbidities, and hypertension treatment; inverse probability weighting accounted for differential attrition between first BP measurement and start of follow-up.

RESULTS

A total of 532 individuals (9.4%) were diagnosed with dementia. Early adulthood hypertension was not associated with dementia, though effect estimates were elevated among women. Mid-adulthood hypertension was associated with 65% (95% confidence interval [CI] 1.25-2.18) increased dementia risk among women but not men. Onset of hypertension in mid-adulthood predicted 73% higher dementia risk in women (95% CI 1.24-2.40) compared to stable normotensive. There was no evidence that hypertension or changes in hypertension increased dementia risk among men.

CONCLUSIONS

Though midlife hypertension was more common in men, it was only associated with dementia risk in women. Sex differences in the timing of dementia risk factors have important implications for brain health and hypertension management.

Association Between Birth in a High Stroke Mortality State, Race, and Risk of Dementia

Importance

Birth in a group of predominantly southern US states is robustly linked to increased stroke risk. Given the role of cerebrovascular disease in dementia risk, geographic patterning may also occur for dementia incidence.

Objective

To determine whether birth in 9 high stroke mortality states (HSMSs) is associated with dementia in a diverse cohort of individuals living in Northern California.

Design, Setting, and Participants

An observational cohort study included 7423 members of Kaiser Permanente Northern California (KPNC), an integrated health care delivery system, with health survey and clinical examination data available. Data were collected between 1964 and 1973 when the individuals were middle-aged and 1996 and 2015 when participants were in later life.

Exposures

Self-reported state of birth in an HSMS (top quintile of states for stroke mortality).

Main Outcomes and Measures

Dementia diagnoses obtained from electronic health records from January 1, 1996, to October 15, 2015. Place of birth, race, educational level, and midlife vascular risk factors data were collected between 1964 and 1973.

Results

Of the 7423 persons included in the analysis, 4049 (54.5%) were women; 1354 (18.2%) were black. The mean (SD) age of study participants at their first visit between 1963 and 1974 was 42.94 (1.73) years and mean (SD) age at the beginning of follow-up for dementia in 1996 was 71.14 (2.72) years. Dementia was diagnosed in 2254 (30.4%) of the participants and was more common among those born in an HSMS than those born outside of one (455 [39.0%] vs 1799 [28.8%]). Birth in an HSMS was 9.6 times more common for black participants (795 [58.7%]) than nonblack participants (371 [6.1%]). Overall, birth in an HSMS was associated with a 28% higher risk of dementia (adjusted hazard ratio [aHR], 1.28; 95% CI, 1.13-1.46) adjusted for age, sex, and race. Compared with nonblack persons born outside of an HSMS, black individuals born in an HSMS had the highest dementia risk (aHR, 1.67; 95% CI, 1.48-1.88), followed by black individuals not born in an HSMS (aHR, 1.48; 95% CI, 1.28-1.72), and nonblack persons born in an HSMS had a 46% increased risk (aHR, 1.46; 95% CI, 1.23-1.74). Cumulative 20-year dementia risks at age 65 years were 30.13% (95% CI, 26.87%-32.93%) and 21.80% (95% CI, 20.51%-22.91%) for individuals born in and outside an HSMS, respectively.

Conclusions and Relevance

To our knowledge, this is the first study to date of place of birth and incident dementia and shows increased risk for individuals born in an HSMS, even though all participants subsequently resided in California. Birth in an HSMS was common among black participants. Place of birth has enduring consequences for dementia risk and may be a major contributor to racial disparities in dementia.

Effects of Chimonanthus nitens Oliv. Leaf Extract on Glycolipid Metabolism and Antioxidant Capacity in Diabetic Model Mice

The paper investigated the antihyperglycemic and antihyperlipidemic efficacy and antioxidant capacity of Chimonanthus nitens Oliv. leaf extract (COE) in combination of high-glucose-fat diet-fed and streptozotocin-induced diabetic model mice. Various physiological indexes in diabetic model mice were well improved especially by oral administration of high dose of COE; the results were listed as follows. Fast blood glucose (FBG) level and serum triglyceride (TC), total cholesterol (TG), low-density lipoprotein cholesterol (LDLC), and malondialdehyde (MDA) as well as MDA in liver were significantly reduced; fasting serum insulin (FINS) and insulin sensitivity index (ISI) were both increased; high-density lipoprotein cholesterol (HDLC) in serum was significantly increased; total antioxidant capacity (T-AOC), activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) in serum and liver were apparently enhanced; liver coefficient (LC), liver transaminase, and alkaline phosphatase (ALP) were decreased. Furthermore, pancreas islets and liver in diabetic model mice showed some extend of improvement in morphology and function after 4 weeks of COE treatment. In consequence, COE was advantageous to regulate glycolipid metabolism and elevate antioxidant capacity in diabetic model mice. Thus, the present study will provide a scientific evidence for the use of COE in the management of diabetes and its related complications.

Type 2 diabetes is an independent risk factor for dementia conversion in patients with mild cognitive impairment

AIMS

To explore whether type 2 diabetes (T2D) is a risk factor for dementia conversion in patients with mild cognitive impairment (MCI).

METHODS

A longitudinal nested case-control study in which 101 T2D patients and 101 non-diabetic patients with MCI matched by age and gender were included.

RESULTS

The dementia conversion rate was 57.4% in T2D patients vs. 42.6% in non-diabetic subjects (p=0.02). T2D and APOE ε4 allele were independent risk factors for developing dementia.

CONCLUSION

T2D is an independent risk factor for dementia conversion in MCI patients. This finding has significant clinical implications.

Effect of the treatment of Type 2 diabetes mellitus on the development of cognitive impairment and dementia

BACKGROUND

Prevention of cognitive impairment and dementia is an important public health goal. Epidemiological evidence shows a relationship between cognitive impairment and Type 2 diabetes mellitus. The risk of dementia increases with duration of disease. This updated systematic review investigated the effect on cognitive function of the type of treatment and level of metabolic control in people with Type 2 diabetes.

OBJECTIVES

To assess the effects of different strategies for managing Type 2 diabetes mellitus on cognitive function and the incidence of dementia.

SEARCH METHODS

We searched ALOIS (the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group (CDCIG)), the Cochrane Library, MEDLINE, Embase, PsycINFO, CINAHL and LILACS on 15 October 2016. ALOIS contains records from all major health care databases, (CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, LILACS), as well as from many trials' registers and grey literature sources.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) which compared two or more different treatments for Type 2 diabetes mellitus and in which cognitive function was measured at baseline and after treatment.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the quality of the included RCTs. We pooled data for comparable trials and estimated the effects of treatment by using risk ratios (RRs) and mean differences (MDs), according to the nature of the outcome. We assessed the quality of the evidence using GRADE methods.

MAIN RESULTS

We identified seven eligible studies but only four provided data we could include in efficacy analyses. Two of these studies compared intensive versus standard glycaemic control and two compared different pharmacological treatments. All studies were at unclear risk of bias in at least two domains and one large study was at high risk of performance and detection bias.(a) Two studies with 13,934 participants at high cardiovascular risk provided efficacy data on intensive versus standard glycaemic control. A third study with 1791 participants provided additional data on hypoglycaemic episodes and mortality. There is probably no difference between treatment groups in the number of participants who decline by at least 3 points on the Mini-Mental State Examination (MMSE) over five years (RR 0.98, 95% CI 0.88 to 1.08; 1 study; n = 11,140; moderate-quality evidence); and there may also be little or no difference in the incidence of dementia (RR 1.27, 95% CI 0.87 to 1.85; 1 study; n = 11,140; low-quality evidence). From another study, there was probably little or no difference in MMSE score after 40 months (MD -0.01, 95% CI -0.18 to 0.16; 1 study; n = 2794; moderate quality evidence). Participants exposed to the intensive glycaemic control strategy probably experience more episodes of severe hypoglycaemia than those who have standard treatment (RR 2.18, 95% CI 1.52 to 3.14; 2 studies; n = 12,827; moderate-quality evidence). The evidence from these trials suggests that the intensity of glycaemic control may have little or no effect on all-cause mortality (RR 0.99, 95% CI 0.87 to 1.13; 3 studies; n = 15,888; low-quality evidence).(b) One study with 156 participants compared glibenclamide (glyburide) with repaglinide. There may be a small advantage of glibenclamide on global cognitive function measured with the MMSE after 12 months (MD -0.90, 95% CI -1.68 to -0.12; low-quality evidence). No data were reported on the incidence of dementia, hypoglycaemic events or all-cause mortality.(c) One study with 145 participants compared rosiglitazone plus metformin to glibenclamide (glyburide) plus metformin over 24 weeks. It reported only on cognitive subdomains and not on global cognitive function, incidence of MCI or dementia, hypoglycaemic events or all causes of mortality.

AUTHORS' CONCLUSIONS

We found no good evidence that any specific treatment or treatment strategy for Type 2 diabetes can prevent or delay cognitive impairment. The best available evidence related to the comparison of intensive with standard glycaemic control strategies. Here there was moderate-quality evidence that the strategies do not differ in their effect on global cognitive functioning over 40 to 60 months.

Cognitive impairment and dementia: a new emerging complication of type 2 diabetes-The diabetologist's perspective

Type 2 diabetes mellitus (T2D) and Alzheimer's disease (AD) are two of the most common diseases of aging around the world. Given the frequency with which T2D and AD occur, the notion that people with T2D may be at increased risk for AD has large societal consequences, and understanding the mechanistic links between these diseases is imperative for the development of effective AD prevention and treatment strategies. Apart from being an accelerator of AD, T2D is associated with a progressive cognitive decline. Impaired insulin signaling, inflammation, the accumulation of advanced glycation end-products and oxidative stress all play an essential role in the pathogenesis of both AD and diabetic complications. Therefore, it is reasonable to postulate that these pathways are involved in the increased risk of dementia that occurs in the T2D population. The early diagnosis of cognitive impairment and the identification of the subset of patients at a higher risk of developing AD is a challenge for healthcare providers, and meeting it will permit us to implement a personalized medicine, which is an essential issue in diabetes care with significant therapeutic implications. The main gaps that should be filled to achieve this objective are examined.