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

Association between depressive duration and cognitive decline in middle-aged and older adults: Evidence from the Health and Retirement Study 2010-2018

BACKGROUND

Depression has been found to be associated with cognitive decline, but whether longer depressive durations lead to more severe cognitive declines has not been investigated. We aimed to estimate the association between depressive duration and cognitive decline in middle-aged and older Americans based on a large-scale representative population study.

METHODS

We included 27,886 participants from the Health and Retirement Study (HRS) in 2010-2018. Four datasets with 2-, 4-, 6-, and 8-year consecutive interviews were further derived which involving persistent depressed and persistent depression-free individuals. Multiple linear regressions were constructed to estimate the effects of each depressive duration on the decline in global cognition, memory and mental status. Meta-regressions were performed to test the linear trends and to explore the heterogeneity between sex, age and baseline cognitive function along with subgroup analyses.

RESULTS

Depressive durations of 2, 4, 6, and 8 years were associated with reductions in global cognitive scores of 0.62 points (95% CI: 0.51-0.73), 0.77 points (95% CI: 0.60-0.94), 0.83 points (95% CI: 0.55-1.10), and 1.09 points (95% CI: 0.63-1.55), respectively, indicating a linear trend (P = 0.016). More pronounced associations were observed in middle-aged adults and females. Similar patterns were found in the associations between depressive duration and two subdomains, i.e., memory and mental health.

LIMITATIONS

This study is essentially a cross-sectional study and therefore cannot provide causal associations.

CONCLUSIONS

Longer depressive durations were linearly related to more severe cognitive declines. Timely intervention for depression targeted middle-aged adults can more effectively alleviate cognition-related burdens.

Repurposing antidiabetic drugs for Alzheimer's disease: A review of preclinical and clinical evidence and overcoming challenges

Repurposing antidiabetic drugs for the treatment of Alzheimer's disease (AD) has emerged as a promising therapeutic strategy. This review examines the potential of repurposing antidiabetic drugs for AD treatment, focusing on preclinical evidence, clinical trials, and observational studies. In addition, the review aims to explore challenges and opportunities in repurposing antidiabetic drugs for AD, emphasizing the importance of well-designed clinical trials that consider patient selection criteria, refined outcome measures, adverse effects, and combination therapies to enhance therapeutic efficacy. Preclinical evidence suggests that glucagon-like peptide-1 (GLP-1) analogs, dipeptidyl peptidase-4 (DPP4) inhibitors, metformin, thiazolidinediones, and sodium-glucose co-transporter-2 (SGLT2) inhibitors exhibit neuroprotective effects in AD preclinical models. In preclinical studies, antidiabetic drugs have demonstrated neuroprotective effects by reducing amyloid beta (Aβ) plaques, tau hyperphosphorylation, neuroinflammation, and cognitive impairment. Antidiabetic drug classes, notably GLP-1 analogs and SGLT2 inhibitors, and a reduced risk of dementia in patients with diabetes mellitus. While the evidence for DPP4 inhibitors is mixed, some studies suggest a potential protective effect. On the other hand, alpha-glucosidase inhibitors (AGIs) and sulfonylureas may potentially increase the risk, especially in those experiencing recurrent hypoglycemic events. Repurposing antidiabetic drugs for AD is a promising therapeutic strategy, but challenges such as disease heterogeneity, limited biomarkers, and benefits versus risk evaluation need to be addressed. Ongoing clinical trials in mild cognitive impairment (MCI) and early AD patients without diabetes will be crucial in determining the clinical efficacy and safety of the antidiabetic drugs, paving the way for potential treatments for AD.

Neuroprotective effects of Gypenosides: A review on preclinical studies in neuropsychiatric disorders

Gynostemma pentaphyllum (Thunb.) Makino is a perennial creeping herb belonging to the Cucurbitaceae family that has a long history of usage in traditional oriental medicine. Gypenosides are the primary bioactive compounds in Gynostemma pentaphyllum. Because of the medicinal value of gypenosides, functional food and supplements containing gypenosides have been promoted and consumed with popularity, especially among Asian communities. This review presented the progress made in the research of pharmacological properties of gypenosides on diseases of the nervous system and their possible mechanism of action. To date, preclinical studies have demonstrated the therapeutic effects of gypenosides in alleviating neuropsychiatric disorders like depression, Parkinson's disease, Alzheimer's disease, secondary dementia, stroke, optic neuritis, etc. Pharmacological studies have discovered that gypenosides can modulate various major signaling pathways like NF-κB, Nrf2, AKT, ERK1/2, contributing to the neuroprotective properties. However, there is a dearth of clinical research on gypenosides, with current investigations on the compounds being mainly conducted in vitro and on animals. Future studies focusing on isolating and purifying novel gypenosides and investigations on exploring the potential molecular mechanism underlying their biological activities are warranted, which may serve as a foundation for further clinical trials for the betterment of human health.

GLT-1 downregulation in hippocampal astrocytes induced by type 2 diabetes contributes to postoperative cognitive dysfunction in adult mice

AIMS

Type 2 diabetes mellitus (T2DM) is related to an increased risk of postoperative cognitive dysfunction (POCD), which may be caused by neuronal hyperexcitability. Astrocyte glutamate transporter 1 (GLT-1) plays a crucial role in regulating neuron excitability. We investigated if T2DM would magnify the increased neuronal excitability induced by anesthesia/surgery (A/S) and lead to POCD in young adult mice, and if so, determined whether these effects were associated with GLT-1 expression.

METHODS

T2DM model was induced by high fat diet (HFD) and injecting STZ. Then, we evaluated the spatial learning and memory of T2DM mice after A/S with the novel object recognition test (NORT) and object location test (OLT). Western blotting and immunofluorescence were used to analyze the expression levels of GLT-1 and neuronal excitability. Oxidative stress reaction and neuronal apoptosis were detected with SOD2 expression, MMP level, and Tunel staining. Hippocampal functional synaptic plasticity was assessed with long-term potentiation (LTP). In the intervention study, we overexpressed hippocampal astrocyte GLT-1 in GFAP-Cre mice. Besides, AAV-Camkllα-hM4Di-mCherry was injected to inhibit neuronal hyperexcitability in CA1 region.

RESULTS

Our study found T2DM but not A/S reduced GLT-1 expression in hippocampal astrocytes. Interestingly, GLT-1 deficiency alone couldn't lead to cognitive decline, but the downregulation of GLT-1 in T2DM mice obviously enhanced increased hippocampal glutamatergic neuron excitability induced by A/S. The hyperexcitability caused neuronal apoptosis and cognitive impairment. Overexpression of GLT-1 rescued postoperative cognitive dysfunction, glutamatergic neuron hyperexcitability, oxidative stress reaction, and apoptosis in hippocampus. Moreover, chemogenetic inhibition of hippocampal glutamatergic neurons reduced oxidative stress and apoptosis and alleviated postoperative cognitive dysfunction.

CONCLUSIONS

These findings suggest that the adult mice with type 2 diabetes are at an increased risk of developing POCD, perhaps due to the downregulation of GLT-1 in hippocampal astrocytes, which enhances increased glutamatergic neuron excitability induced by A/S and leads to oxidative stress reaction, and neuronal apoptosis.

Association between new-onset atrial fibrillation and dementia among individuals with type 2 diabetes

AIM

To assess the association between new-onset atrial fibrillation and dementia among patients with type 2 diabetes, a group with a high prevalence of atrial fibrillation.

MATERIALS AND METHODS

This cohort study included 22 989 patients with type 2 diabetes from the UK Biobank. New-onset atrial fibrillation was ascertained from hospital admission records. We used an algorithm officially released by the UK Biobank to identify all-cause dementia, Alzheimer's disease and vascular dementia. The algorithm was developed using multiple sources, including hospital admissions and the death registry. Time-varying Cox regression analyses were performed to investigate the association between new-onset atrial fibrillation and dementia.

RESULTS

A total of 2843 participants developed atrial fibrillation, whereas the remaining 20 146 did not. During the median of 12.3 years of follow-up, 844 all-cause dementia, 342 Alzheimer's disease and 246 vascular dementia cases occurred. Compared with participants without atrial fibrillation, those with atrial fibrillation had higher risks of all-cause dementia (hazard ratio [HR] 2.15, 95% confidence interval [CI] 1.80-2.57), Alzheimer's disease (HR 1.44, 95% CI 1.06-1.96) and vascular dementia (HR 3.11, 95% CI 2.32-4.17).

CONCLUSIONS

New-onset atrial fibrillation was associated with a substantially higher risk of all-cause dementia, Alzheimer's disease and vascular dementia in patients with type 2 diabetes. Our findings highlight the significance of atrial fibrillation management in mitigating the risk of dementia in this demographic.

Hyperglycemia and cognitive impairments anticipate the onset of an overt type 2 diabetes-like phenotype in TALLYHO/JngJ mice

Type 2 Diabetes mellitus (T2DM) is a metabolic disorder characterized by chronic hyperglycemia, resulting from deficits in insulin secretion, insulin action, or both. Whilst the role of insulin in the peripheral nervous system has been ascertained in countless studies, its role in the central nervous system (CNS) is emerging only recently. Brain insulin has been lately associated with brain disorders like Alzheimer's disease, obsessive compulsive disorder, and attention deficit hyperactivity disorder. Thus, understanding the role of insulin as a common risk factor for mental and somatic comorbidities may disclose novel preventative and therapeutic approaches. We evaluated general metabolism (glucose tolerance, insulin sensitivity, energy expenditure, lipid metabolism, and polydipsia) and cognitive capabilities (attention, cognitive flexibility, and memory), in adolescent, young adult, and adult male and female TALLYHO/JngJ mice (TH, previously reported to constitute a valid experimental model of T2DM due to impaired insulin signaling). Adult TH mice have also been studied for alterations in gut microbiota diversity and composition. While TH mice exhibited profound deficits in cognitive flexibility and altered glucose metabolism, we observed that these alterations emerged either much earlier (males) or independent of (females) a comprehensive constellation of symptoms, isomorphic to an overt T2DM-like phenotype (insulin resistance, polydipsia, higher energy expenditure, and altered lipid metabolism). We also observed significant sex-dependent alterations in gut microbiota alpha diversity and taxonomy in adult TH mice. Deficits in insulin signaling may represent a common risk factor for both T2DM and CNS-related deficits, which may stem from (partly) independent mechanisms.

The GLCCI1/STAT3 pathway: a novel pathway involved in diabetic cognitive dysfunction and the therapeutic effect of salidroside

Diabetic cognitive dysfunction (DCD) is a complication of diabetes that seriously affects quality of life. Glucocorticoid-induced transcript 1 (GLCCI1) has been found to be involved in inflammation, apoptosis and autophagy in various diseases. However, the distribution of GLCCI1 in the brain and its role in DCD have not yet been revealed. In addition, the potential therapeutics effects of salidroside (SAL), a phenyl propyl glycoside compound known for its neuroprotective effects in treating DCD are unknow. In the present study, we found that GLCCI1 was localized in hippocampal neurons. C57BL/6 J mice with DCD presented downregulation of GLCCI1 and Bcl-2 and upregulation of p-STAT3/STAT3, Bax, Cleaved Caspase-3/Caspase-3. Overexpression of GLCCI1 or SAL administration relieved DCD, reversed the changes in the expression of these cytokines, and alleviated morphological alterations in hippocampal neurons. Interestingly, SAL alleviated DCD and attenuated the expression of GLCCI1 and p-STAT3, showing similar effects as GLCCI1 overexpression. These findings suggest that the GLCCI1/STAT3 axis plays a crucial role in DCD and is involved in SAL-mediated attenuation of DCD.

Risk of dementia after initiation of sodium-glucose cotransporter-2 inhibitors versus dipeptidyl peptidase-4 inhibitors in adults aged 40-69 years with type 2 diabetes: population based cohort study

OBJECTIVE

To compare the risk of dementia associated with sodium-glucose cotransporter-2 (SGLT-2) inhibitors versus dipeptidyl peptidase-4 (DPP-4) inhibitors in adults aged 40-69 years with type 2 diabetes.

DESIGN

Population based cohort study.

SETTING

Korean National Health Insurance Service data, 2013-21.

PARTICIPANTS

110 885 propensity score matched pairs of adults with type 2 diabetes aged 40-69 years who were initiators of either an SGLT-2 inhibitor or a DPP-4 inhibitor.

MAIN OUTCOME MEASURES

The primary outcome was new onset dementia. Secondary outcomes were dementia requiring drug treatment and individual types of dementia, including Alzheimer's disease and vascular dementia. Control outcomes were genital infections (positive), and osteoarthritis related clinical encounters and cataract surgery (negative). Hazard ratios and 95% confidence intervals (CIs) were estimated using Cox models. Follow-up time stratified analyses (>2 years and ≤2 years) and subgroup analyses by age, sex, concomitant use of metformin, and baseline cardiovascular risk were performed.

RESULTS

110 885 propensity score matched pairs of initiators of an SGLT-2 inhibitor or a DPP-4 inhibitor were followed-up for a mean 670 (standard deviation 650) days, generating 1172 people with newly diagnosed dementia: incidence rate 0.22 per 100 person years in initiators of SGLT-2 inhibitors and 0.35 per 100 person years in initiators of DPP-4 inhibitors, with hazard ratios of 0.65 (95% CI 0.58 to 0.73) for dementia, 0.54 (0.46 to 0.63) for dementia requiring drugs, 0.61 (0.53 to 0.69) for Alzheimer's disease, and 0.48 (0.33 to 0.70) for vascular dementia. The hazard ratios for the control outcomes were 2.67 (2.57 to 2.77) for genital infections, 0.97 (0.95 to 0.98) for osteoarthritis related encounters, and 0.92 (0.89 to 0.96) for cataract surgery. When calibrated for residual confounding measured by cataract surgery, the hazard ratio for dementia was 0.70 (0.62 to 0.80). The association was greater for more than two years of treatment (hazard ratio of dementia 0.57, 95% CI 0.46 to 0.70) than for two years or less (0.52, 0.41 to 0.66) and persisted across subgroups.

CONCLUSION

SGLT-2 inhibitors might prevent dementia, providing greater benefits with longer treatment. As this study was observational and therefore prone to residual confounding and informative censoring, the effect size could have been overestimated. Randomised controlled trials are needed to confirm these findings.

The Possible Associations between Tauopathies and Atherosclerosis, Diabetes Mellitus, Dyslipidemias, Metabolic Syndrome and Niemann-Pick Disease

Clinical evaluation and treatment of tauopathic syndromes remain a challenge. There is a growing interest in theories concerning their possible associations with metabolic diseases. The possible connection between those diseases might be linked with cerebrovascular dysfunction. The endothelial cell damage and impairment of the blood-brain barrier observed in atherosclerosis or diabetes may play a role in contributing to tauopathic syndrome development. Additionally, the inflammation evoked by pathological metabolic changes may also be involved in this process. Multiple cases indicate the coexistence of metabolic disorders and tauopathic syndromes. These findings suggest that modifying the evolution of metabolic and cerebrovascular diseases may impact the course of neurodegenerative diseases. Obtained data could indicate the possible benefits of introducing routine carotid artery sonography, revascularization operation or antihypertensive medications among patients at high risk for tauopathies. This review has identified this understudied area, which is currently associated with several diseases for which there is no treatment. Due to the pathomechanisms linking metabolic diseases and tauopathies, further investigation of this area of research, including cohort studies, is recommended and may provide new pharmacological perspectives for treatment.

The association between cognitive decline and exposure to secondhand smoke at work in economically active older adults

OBJECTIVES

Secondhand smoking may contribute to cognitive decline, but evidence on this subject is limited in the working economically active older adults. This study aimed to investigate the association between cognitive decline and exposure to secondhand smoke at work in economically active adults aged 65 years or above.

STUDY DESIGN

Cross-sectional study using nationwide data.

METHODS

Data were from the 2022 Korea Community Health Survey. Chi-squared test was used to perform descriptive statistics. The association between cognitive decline and exposure to secondhand smoke at work was analysed using multivariable logistic regression analysis. Subgroup analysis was performed based on to exposure status to secondhand smoke at home and diabetes mellitus.

RESULTS

Of a total of 28,197 adults, 8767 (28.5%) individuals reported cognitive decline. Compared to individuals without exposure to passive smoking at work, those with such exposure were more likely to report cognitive decline (odds ratio: 1.30, 95% confidence interval: 1.14-1.47). This association was particularly strong in individuals with exposure to passive smoking at both work and home and in those diagnosed with diabetes mellitus.

CONCLUSIONS

Exposure to secondhand smoking at work is associated with a higher likelihood of cognitive decline in older-aged economically active individuals. The findings infer the importance of monitoring passive smoking and implementing public health measures to reduce workplace secondhand smoke exposure.

Loss of Cldn5 -and increase in Irf7-in the hippocampus and cerebral cortex of diabetic mice at the early symptomatic stage

Analyzing changes in gene expression within specific brain regions of individuals with Type 2 Diabetes (T2DM) who do not exhibit significant cognitive deficits can yield valuable insights into the mechanisms underlying the progression towards a more severe phenotype. In this study, transcriptomic analysis of the cortex and hippocampus of mice with long-term T2DM revealed alterations in the expression of 28 genes in the cerebral cortex and 15 genes in the hippocampus. Among these genes, six displayed consistent changes in both the cortex and hippocampus: Interferon regulatory factor 7 (Irf7), Hypoxia-inducible factor 3 alpha (Hif-3α), period circadian clock 2 (Per2), xanthine dehydrogenase (Xdh), and Transforming growth factor β-stimulated clone 22/TSC22 (Tsc22d3) were upregulated, while Claudin-5 (Cldn5) was downregulated. Confirmation of these changes was achieved through RT-qPCR. At the protein level, CLDN5 and IRF7 exhibited similar alterations, with CLDN5 being downregulated and IRF7 being upregulated. In addition, the hippocampus and cortex of the T2DM mice showed decreased levels of IκBα, implying the involvement of NF-κB pathways as well. Taken together, these results suggest that the weakening of the blood-brain barrier and an abnormal inflammatory response via the Interferon 1 and NF-κB pathways underlie cognitive impairment in individuals with long-standing T2DM.

Jiao-tai-wan and its effective component-coptisine alleviate cognitive impairment in db/db mice through the JAK2/STAT3 signaling pathway

BACKGROUND

Cognitive impairment (CI) is now well-accepted as a complication and comorbidity of diabetes mellitus (DM), becoming a serious medical and social problem. Jiao-tai-wan (JTW), one of noted traditional Chinese medicine (TCM), showed dual therapeutic effects on DM and CI. Nevertheless, the potential mechanism is unclear.

PURPOSE

This study sought to investigate the mechanism how JTW protected against DM and CI and screen the active component in JTW.

METHODS

Db/db mice were used as mouse models. Mice were treated by gavage with 0.9 % saline (0.1 mL/10g/d), low dose of JTW (2.4 g/kg/d) or high dose of JTW (4.8 g/kg/d) for 8 weeks separately. To access the effects of JTW, the levels of OGTT, HOMA-IR, blood lipids, inflammatory cytokines in serum and hippocampus were measured, behavioral tests were conducted, and histopathological changes were observed. The mechanism exploration was performed via network pharmacology, RT-qPCR, western blot, and immunofluorescence staining (IF). The impact and mechanism of coptisine in vitro were investigated using BV2 cells induced by LPS as cellular models. In vitro experiments were conducted in two parts. The first part comprised four groups: Control group, LPS group, LPS+LCOP group and LPS+HCOP group. The second part consisted of four groups: Control group, LPS group, LPS+HCOP group, and LPS+ Fed group. The western blot and RT-qPCR methods were used to examine the changes in biomarkers of the JAK2/STAT3 signaling pathways in BV2 cells.

RESULTS

The results demonstrated that JTW could improve OGTT and HOMA-IR, reduce the serum levels of LDL-C, HDL-C, TG, and TC, restore neuronal dysfunction and synaptic plasticity, and decrease the deposition of Aβ in the hippocampus. The findings from ELISA, IF, and RT-qPCR revealed that JTW could alleviate microglial activation and inflammatory status in vivo and coptisine could play the same role in vitro. Moreover, the changes of the JAK2/STAT3 signaling pathway in LPS-induced BV2 cells or hippocampus of db/db mice were distinctly reversed by coptisine or JTW, respectively.

CONCLUSION

Our study suggested that JTW and its effective component coptisine could alleviate diabetes mellitus-related cognitive impairment, closely linked to the JAK2/STAT3 signaling pathway.

Association Between Plasma LRG1 and Lower Cognitive Function in Asians With Type 2 Diabetes Mellitus

CONTEXT

Leucine-rich α-2-glycoprotein 1 (LRG1) has been implicated in the pathogenesis of diabetic complications, but its association with cognitive function remains unclear.

OBJECTIVE

Our primary objective is to investigate the longitudinal association between LRG1 and cognitive function in patients with type 2 diabetes mellitus (T2DM). Secondarily, we determine the causal relationship using Mendelian randomization (MR) and the role of arterial stiffness as a potential mediator.

METHODS

T2DM patients (n = 1039; age = 64.1 ± 6.4 years) were followed-up for 5.3 ± 1.2 years. Plasma LRG1 was measured at baseline using enzyme-linked immunosorbent assay. Baseline and follow-up cognitive function was assessed using Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). One-sample MR was performed with rs4806985 as plasma LRG1-associated single-nucleotide polymorphism. Mediation analysis was performed to examine if pulse wave velocity (PWV), an arterial stiffness index, mediated the association between plasma LRG1 and follow-up cognitive function.

RESULTS

Elevated baseline natural log (Ln)-transformed LRG1 was inversely associated with baseline and follow-up RBANS total score with adjusted coefficients -1.38 (95% CI -2.55 to -.21; P = .021) and -1.38 (95% CI -2.70 to -.07; P = .039), respectively. Genetically predicted higher levels of plasma LRG1 was associated with lower follow-up RBANS total score with coefficient -7.44 (95% CI -14.14 to -.74; P = .030) per unit increase in LnLRG1. Higher PWV accounted for 27.7% of the association between LnLRG1 and follow-up RBANS total score.

CONCLUSION

Baseline plasma LRG1 was associated with lower cognitive function at follow-up in patients with T2DM, mediated by PWV. MR analysis provided evidence of an association between genetically influenced plasma LRG1 and lower cognitive function at follow-up.

Effect of hypoglycemic events on cognitive function in individuals with type 2 diabetes mellitus: a dose-response meta-analysis

Background

Type 2 diabetes mellitus (T2DM) is widely acknowledged as a vital warning sign contributing to cognitive dysfunction. However, there is still a lack of consensus on whether hypoglycemic events resulting from poor glycemic control increase the risk of cognitive dysfunction in people with diabetes, and the potential dose-response correlation between hypoglycemic events and cognitive dysfunction remains unexplored. The primary objective of the current study was to assess the contribution of hypoglycemic events to cognitive dysfunction in T2DM patients and the dose-response correlation between the two.

Methods

A comprehensive search of nine major databases was executed from inception to May 2023. We screened all observational studies examining the connection between hypoglycemia and cognitive dysfunction. The DerSimonian-Laird method was used to compute the combined risk ratio (RR) and its 95% confidence interval (CI). Additionally, dose-response analysis was employed to investigate the correlation between the frequency of hypoglycemia and the likelihood of cognitive dysfunction.

Results

A total of 30 studies of different levels in 17 articles with 3,961,352 participants were included in this review. The pooled RR for the connection of hypoglycemia and the likelihood of cognitive dysfunction was 1.47 (95% CI: 1.35-1.60). Subgroup analyses showed that the pooled RR for the likelihood of cognitive dysfunction was 1.20 (95% CI: 1.11-1.31) for one episode of hypoglycemia, 1.41 (95% CI: 1.05-1.88) for two episodes of hypoglycemia, and 1.62 (95% CI: 1.20-2.91) for three or more episodes of hypoglycemia. Dose-response analysis showed a linear dose-response relationship between hypoglycemia and the likelihood of cognitive dysfunction (exp (b) = 1.178694, z = 7.12, p < 0.001).

Conclusion

Our investigations demonstrated a 47% heightened likelihood of cognitive dysfunction in individuals with hypoglycemia compared to those without. Furthermore, the likelihood of cognitive dysfunction climbed by 17.87% for every subsequent episode of hypoglycemia. Therefore, long-term monitoring of blood glucose, periodic screening of cognitive function, and moderate health education should be encouraged, which will be beneficial for people with diabetes to prevent hypoglycemic events and cognitive dysfunction.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, CRD42023432352.

Microglial activation and polarization in type 2 diabetes-related cognitive impairment: A focused review of pathogenesis

Microglia, as immune cells in the central nervous system, are closely related to cognitive impairment associated with type 2 diabetes (T2D). Preliminary explorations have investigated the relationship between T2D-related cognitive impairment and the activation and polarization of microglia. This review summarizes the potential mechanisms of microglial activation and polarization in the context of T2D. It discusses central inflammatory responses, neuronal apoptosis, amyloid-β deposition, and abnormal phosphorylation of Tau protein mediated by microglial activation and polarization, exploring the connections between microglial activation and polarization and T2D-related cognitive impairment from multiple perspectives. Additionally, this review provides references for future treatment targeting microglia in T2D-related cognitive impairment and for clinical translation.

Association between physical activity level and diabetes incidence among Chinese middle-aged and older adults: a cross-sectional study from the China health and retirement longitudinal study

Background

It has been shown that diabetes is associated with insufficient physical activity among middle-aged and older adults, but the association between different physical activity levels (PAL) and diabetes incidence needs to be further explored.

Objective

This study aims to explore the correlation and dose-response relationship between different PAL and the diabetes incidence in middle-aged and older adults.

Methods

Utilizing data from the 2018 China Health and Retirement Longitudinal Study (CHARLS), this cross-sectional analysis included 17,226 middle-aged and older adults aged 45 and above. Binary logistic regression models and restricted cubic spline (RCS) were used to explore the correlation and dose-response relationship between different PAL and the incidence of diabetes in the total middle-aged and older adults population as well as in subgroups. Sensitivity analyses were also performed to verify the robustness of the findings.

Results

In the entire study population, compared with the lowest PAL, participants in the third and fourth quartiles PAL saw diabetes incidence significantly reduced by 16% (p = 0.005) and 33% (p < 0.001), respectively (p for trend < 0.001). In subgroup analyses, the fourth quartile PAL significantly reduced the diabetes incidence among females, individuals aged 60-69, and rural residents by 25% (p = 0.011), 38% (p < 0.001) and 28% (p < 0.001), respectively. For males, middle-aged (45-59 years), and urban residents, the third quartile PAL reduced diabetes incidence by 22% (p = 0.004), 24% (p = 0.012), 21% (p = 0.013), respectively. When the fourth quartile PAL was reached, the diabetes incidence was significantly reduced in these populations by 41% (p < 0.001), 39% (p < 0.001), and 41% (p < 0.001), respectively. There was a negative dose-response relationship between physical activity and diabetes incidence in specific Chinese middle-aged and older adults population. In addition, sensitivity analyses indicated the robustness of the findings.

Conclusion

Higher PAL was associated with lower diabetes incidence in specific Chinese middle-aged and older adults population. It is feasible to use physical activity to predict diabetes incidence in this demographic, and high PAL may be an effective means of preventing and controlling diabetes.

Increased thyroid hormone action alleviates hippocampal damage by down-regulating neuronal type-Ⅰ interferon signaling/necroptosis in diabetes-associated cognitive dysfunction

BACKGROUND

Thyroid dysfunction plays an important role in the pathology of diabetes-associated cognitive dysfunction (DACD). However, thyroid hormone (TH) signaling and action changes in DACD brains remain unknown. This study evaluated the alternations in TH signaling and action in the brains of DACD mice, and explored the beneficial effects of levothyroxine (L-T4) treatment.

METHODS

KK-Ay mice, serving as a spontaneous type-2 diabetes mellitus model, underwent intragastric administration of 10 ng/g and 20 ng/g of L-T4 solution or normal saline for 8 weeks. Age-matched C57BL/6J mice were used as normal controls. Cognitive and memory functions were examined through the open field and Morris water maze tests. Hippocampal TH signaling and pathogenic status were evaluated. The potential signaling pathways involved in the neuroprotective action of L-T4 were investigated through RNA sequencing and further verified through quantitative real-time PCR (qPCR), Western blotting (WB), immunofluorescence (IF), and fluorescent multiplex immunohistochemistry (mIHC) in vivo and vitro.

RESULTS

The expressions of hippocampal TH transporters (Mct8 and Oatp1c1), Dio2, and TH receptor were up-regulated, while Dio3 as well as the TH positive-regulated genes MBP, Enpp2 and Klf9 were down-regulated in DACD mice. Exogenous L-T4 partially alleviated cognitive and memory dysfunction and restored hippocampal neuronal activity by optimizing TH signaling. RNA sequencing provided insights into the role of type-I interferon (IFN-I) signaling and necroptosis on the amelioration of hippocampal damage following L-T4 treatment. WB and qPCR further confirmed that the levels of key proteins for IFN-I signaling and necroptosis (p-STAT1, p-STAT2, IRF9, ZBP1, p-RIP3, and p-MLKL) were increased, but largely returned following L-T4 administration in vivo and T3 treatment in vitro. IF and mIHC revealed that IRF9 and p-MLKL co-localized in neurons, but not in astrocytes or microglia, of the hippocampus in DACD mice. The diabetes mellitus group had an increased number of IRF9+p-MLKL+NeuN+ cells, which decreased after L-T4 treatment. The elevated IFN-I signaling-mediated necroptosis in HT22 cells was also decreased by T3.

CONCLUSION

We demonstrated abnormal hippocampal TH signaling and action in DACD. Promoting TH action with exogenous L-T4 ameliorated hippocampal impairment through inhibiting IFN-I signaling-induced necroptosis.

Impact of Sodium Glucose Cotransporter 2 Inhibitors (SGLT2i) Therapy on Dementia and Cognitive Decline

Dementia is an age-related syndrome characterized by the progressive deterioration of cognition and capacity for independent living. Diabetes is often associated with cognitive decline and shares similar pathophysiological mechanisms with dementia, such as systemic inflammation, oxidative stress, insulin resistance, and advanced glycation end-products formation. Therefore, adequate diabetes management may reduce the risk of cognitive decline, especially in patients with other comorbidities and risk factors. The sodium glucose cotransporter inhibitors (SGLT2i) regulate renal glucose reabsorption by blocking the SGLT2 cotransporters located in the proximal tubules, causing glycosuria and intraglomerular pressure reduction. Their use helps to lower blood pressure by modifying sodium and water homeostasis; these drugs are also commonly used in the treatment of heart failure and chronic kidney disease, while recently, a potential neuroprotective role in the central nervous system has been suggested. The aim of our scoping review is to analyze current evidence about the potential neuroprotective effects of SGLT2i in adult patients. We performed a scoping literature review to evaluate the effect of SGLT2i on dementia, mild cognitive impairment (MCI) and Alzheimer's disease incidence and progression. The screening process was performed through different searches on PubMed and EMBASE, evaluating original works published up to January 2024. In conclusion, the use of SGLT2i could be associated with a neuroprotective effect in patients with diabetes, reducing the incidence or the progression of MCI and dementia. Further prospective studies are needed to validate this hypothesis and to evaluate the effectiveness of this class of drugs in normal glycemic profile patients.

Beneficial Effects of Echinacoside on Cognitive Impairment and Diabetes in Type 2 Diabetic db/db Mice

INTRODUCTION

Cognitive dysfunction is an important comorbidity of diabetes. Insulin resistance may play a critical role in diabetes-related cognitive impairment. Echinacoside (ECH), a natural phenylethanoid glycoside, is the active component of anti-diabetes prescriptions in traditional Chinese medicine. Its effect on modulating insulin resistance has been confirmed but modulating neurodegenerative disease remains unclear.

METHODS

Db/db mice, a spontaneous type 2 diabetes mode, were intragastrically administered ECH by 300 mg/kg or an equivalent volume of saline. Weight, blood glucose, and insulin resistance index were measured. Morris water maze test was performed to observe the compound effects on cognition. Hippocampal lesions were observed by histochemical analysis.

RESULTS

In db/db mice, ECH alleviated diabetes symptoms, memory loss, and hippocampal neuronal damage. Next, the expression of CD44 and phosphorylated tau was upregulated in diabetic mice. In addition, the insulin receptor substrate-1/phosphatidylinositol 3-kinase /protein kinase B signaling pathway was dysregulated in diabetic mice. All these dysregulations could be reversed by ECH.

DISCUSSION

This study provides theoretical support and experimental evidence for the future application of ECH in diabetic cognition dysfunction treatment, promoting the development of traditional medicines.

Prediction model for mild cognitive impairment in patients with type 2 diabetes using the autonomic function test

OBJECTIVE

Type 2 diabetes mellitus (T2DM) is a risk factor for cognitive impairment, and reduced heart rate variability (HRV) has been correlated with cognitive impairment in elderly individuals. This study investigated risk factors and validated a predictive model for mild cognitive impairment (MCI) in patients with T2DM using an autonomic function test.

METHODS

Patients with T2DM, 50-85 years of age, who attended the diabetes clinic at Gyeongsang National University Hospital between March 2018 and December 2019, were included. A total of 201 patients had been screened; we enrolled 124 patients according to the inclusion and exclusion criteria in this study. Cognitive function was assessed using the Montreal Cognitive Assessment-Korean version (MOCA-K); MCI was defined as a total MOCA-K score ≤ 23. Risk factors for MCI in patients with T2DM, including demographic- and diabetes-related factors, and autonomic function test results, were analyzed. Based on multivariate logistic regression, a nomogram was developed as a prediction model for MCI.

RESULTS

Thirty-nine of 124 patients were diagnosed with MCI. Age, education, and decreased cardiovagal function were associated with a high risk for MCI, with cardiovagal function exerting the greatest influence. However, diabetes-related factors, such as glycemic control, duration of diabetes, or medications, were not associated with the risk for MCI. The nomogram demonstrated excellent discrimination (area under the curve, 0.832) and was well calibrated.

CONCLUSION

Approximately one-third of patients had MCI; as such, carefully evaluating cognitive function in elderly T2DM patients with reduced HRV is important to prevent progression to dementia.

Gender differences in the associations of psychosocial trauma and acute medical stressors with immune system activation and dementia risk

Objective: The purpose of this article is to provide a narrative review synthesizing the literature on differences between women and men in relationships among certain stressors associated with immune system activation and their relationship to cognitive dysfunction and dementia. Method: We review the cycle of stress leading to neuroinflammation via cortisol and neurochemical alterations, cell-mediated immune system activation, and pro-inflammatory cytokines, and how this is implicated in the development of dementia. We follow this by discussing sex differences in stress physiology and immune function. We then review the work on early life adversity (ELA) and adverse childhood experiences (ACEs), post-traumatic stress disorder, acute medical stressors, and their associations with cognitive dysfunction and dementia. Throughout, we emphasize women's presentations and issues unique to women (e.g. trauma disorder prevalence). Conclusions: There is a need for more mechanistic and longitudinal studies that consider trauma accumulation, both physical and emotional, as well as a greater focus on traumas more likely to occur in women (e.g. sexual abuse), and their relationship to early cognitive decline and dementia.

The brain's "dark energy" puzzle: How strongly is glucose metabolism linked to resting-state brain activity?

Brain glucose metabolism, which can be investigated at the macroscale level with [18F]FDG PET, displays significant regional variability for reasons that remain unclear. Some of the functional drivers behind this heterogeneity may be captured by resting-state functional magnetic resonance imaging (rs-fMRI). However, the full extent to which an fMRI-based description of the brain's spontaneous activity can describe local metabolism is unknown. Here, using two multimodal datasets of healthy participants, we built a multivariable multilevel model of functional-metabolic associations, assessing multiple functional features, describing the 1) rs-fMRI signal, 2) hemodynamic response, 3) static and 4) time-varying functional connectivity, as predictors of the human brain's metabolic architecture. The full model was trained on one dataset and tested on the other to assess its reproducibility. We found that functional-metabolic spatial coupling is nonlinear and heterogeneous across the brain, and that local measures of rs-fMRI activity and synchrony are more tightly coupled to local metabolism. In the testing dataset, the degree of functional-metabolic spatial coupling was also related to peripheral metabolism. Overall, although a significant proportion of regional metabolic variability can be described by measures of spontaneous activity, additional efforts are needed to explain the remaining variance in the brain's 'dark energy'.

HECTD3 promotes NLRP3 inflammasome and pyroptosis to exacerbate diabetes-related cognitive impairment by stabilising MALT1 to regulate JNK pathway

BACKGROUND

HECTD3 (HECT domain E3 ubiquitin protein ligase 3) exerts biological activities in neuroinflammation of distinct diseases, such as autoimmune encephalomyelitis and donations after heart death. However, the effect of HECTD3 on diabetes-associated cognitive decline (DACD) remains unclear.

METHODS

Wild-type or HECTD3-knockout rats were administered with streptozotocin to establish diabetic model. Pathological changes in the hippocampus were assessed by NISSL and haematoxylin and eosin staining. Morris water maze test was used to assess cognitive function. Neuronal survival and inflammation were investigated by immunofluorescence staining and ELISA assay. NLRP3 inflammasome and pyroptosis were assessed by western blot, immunofluorescence and flow cytometry assays.

RESULTS

HECTD3 was up-regulated in hippocampus of streptozotocin-induced diabetic rats and high glucose-induced PC12 cells. Knockout of HECTD3 increased the number of neurons and improved the learning and memory function. Moreover, knockout of HECTD3 promoted in vivo neuronal survival, and reduced levels of IL-1β, TNF-α, and IL-6 in the hippocampus. Silencing of HECTD3 increased cell viability, and reduced IL-1β, TNF-α, and IL-6 in high glucose-induced PC12 cells. Fluorescence intensities of NLRP3, GSDMD-N and caspase-1 were reduced in HECTD3-knockout diabetic rats, and knockdown of HECTD3 down-regulated protein expression of NLRP3, GSDMD-N, caspase-1, IL-1β, and IL-18 in high glucose-induced PC12 cells to suppress the pyroptosis. HECTD3 promoted the stability of mucosa-associated lymphoid tissue 1 (MALT1) through up-regulation of c-JUN and phospho (p)-JNK in high glucose-induced PC12 cells. Over-expression of MALT1 attenuated neuroprotective effects of HECTD3 silencing on high glucose-induced PC12 cells.

CONCLUSION

HECTD3 silencing exerted neuroprotective effect against DACD through MALT1-mediated JNK signalling.HighlightsHECTD3 was up-regulated in hippocampus of streptozotocin-induced diabetic rats and high glucose-induced PC12.Knockout of HECTD3 promoted in vivo neuronal survival, reduced inflammation and pyroptosis, and improved the learning and memory function in diabetic rats.Knockout of HECTD3 suppressed the activation of NLRP3 inflammasome in diabetic rats.Silencing of HECTD3 exerted neuroprotective effects through MALT1-mediated JNK signalling.

Metformin-induced changes in the gut microbiome and plasma metabolome are associated with cognition in men

BACKGROUND

An altered gut microbiome characterized by reduced abundance of butyrate producing bacteria and reduced gene richness is associated with type 2 diabetes (T2D). An important complication of T2D is increased risk of cognitive impairment and dementia. The biguanide metformin is a commonly prescribed medication for the control of T2D and metformin treatment has been associated with a significant reduction in the risk of dementia and improved cognition, particularly in people with T2D.

AIM

To investigate the associations of metformin use with cognition exploring potential mechanisms by analyzing the gut microbiome and plasma metabolome using shotgun metagenomics and HPLC-ESI-MS/MS, respectively.

METHODS

We explored two independent cohorts: an observational study (Aging Imageomics) and a phase IV, randomized, double-blind, parallel-group, randomized pilot study (MEIFLO). From the two studies, we analyzed four study groups: (1) individuals with no documented medical history or medical treatment (n = 172); (2) people with long-term T2D on metformin monotherapy (n = 134); (3) people with long-term T2D treated with oral hypoglycemic agents other than metformin (n = 45); (4) a newly diagnosed T2D subjects on metformin monotherapy (n = 22). Analyses were also performed stratifying by sex.

RESULTS

Several bacterial species belonging to the Proteobacteria (Escherichia coli) and Verrucomicrobia (Akkermansia muciniphila) phyla were positively associated with metformin treatment, while bacterial species belonging to the Firmicutes phylum (Romboutsia timonensis, Romboutsia ilealis) were negatively associated. Due to the consistent increase in A. muciniphila and decrease in R.ilealis in people with T2D subjects treated with metformin, we investigated the association between this ratio and cognition. In the entire cohort of metformin-treated T2D subjects, the A.muciniphila/R.ilealis ratio was not significantly associated with cognitive test scores. However, after stratifying by sex, the A.muciniphila/R. ilealis ratio was significantly and positively associated with higher memory scores and improved memory in men. Metformin treatment was associated with an enrichment of microbial pathways involved in the TCA cycle, and butanoate, arginine, and proline metabolism in both cohorts. The bacterial genes involved in arginine metabolism, especially in production of glutamate (astA, astB, astC, astD, astE, putA), were enriched following metformin intake. In agreement, in the metabolomics analysis, metformin treatment was strongly associated with the amino acid proline, a metabolite involved in the metabolism of glutamate.

CONCLUSIONS

The beneficial effects of metformin may be mediated by changes in the composition of the gut microbiota and microbial-host-derived co-metabolites.

Cerebral arteriolosclerosis, lacunar infarcts, and cognition in older Black adults

INTRODUCTION

Older Black adults are at risk of cerebral small vessel disease (CSVD), which contributes to dementia risk. Two subtypes of CSVD, arteriolosclerosis and ischemic lacunar infarcts, have been independently linked to lower cognition and higher dementia risk, but their combined effects on cognition in older Black adults are unclear.

METHODS

Mixed models were used to examine the associations of in vivo measures of arteriolosclerosis (ARTS) and ischemic lacunar infarcts to cognitive level and change in 370 older Black adults without dementia.  RESULTS: Modeled together, higher ARTS load accounted for lower levels of global cognition, episodic memory, semantic memory, and perceptual speed, whereas higher infarct load accounted for lower levels of working memory. There were no associations with rate of cognitive change.

DISCUSSION

Both arteriolosclerosis and ischemic infarcts impact the cognitive health of older Black adults, but arteriolosclerosis affects cognition more broadly and offers promise as an in vivo biomarker of dementia risk.

HIGHLIGHTS

Older Black adults are at risk of cerebral small vessel disease (CSVD) and dementia. Examined magnetic resonance imaging-derived measure of arteriolosclerosis (ARTS), infarcts, and cognition. ARTS load was widely associated with lower cognition after adjusting for infarct load. Infarct load was specifically associated with lower complex attention. More within-Black in vivo studies of CSVD subtypes and cognition are needed.

Impairment of synaptic plasticity in the primary somatosensory cortex in a model of diabetic mice

Type 1 and type 2 diabetic patients experience alterations in the Central Nervous System, leading to cognitive deficits. Cognitive deficits have been also observed in animal models of diabetes such as impaired sensory perception, as well as deficits in working and spatial memory functions. It has been suggested that a reduction of insulin-like growth factor-I (IGF-I) and/or insulin levels may induce these neurological disorders. We have studied synaptic plasticity in the primary somatosensory cortex of young streptozotocin (STZ)-diabetic mice. We focused on the influence of reduced IGF-I brain levels on cortical synaptic plasticity. Unit recordings were conducted in layer 2/3 neurons of the primary somatosensory (S1) cortex in both control and STZ-diabetic mice under isoflurane anesthesia. Synaptic plasticity was induced by repetitive whisker stimulation. Results showed that repetitive stimulation of whiskers (8 Hz induction train) elicited a long-term potentiation (LTP) in layer 2/3 neurons of the S1 cortex of control mice. In contrast, the same induction train elicited a long-term depression (LTD) in STZ-diabetic mice that was dependent on NMDA and metabotropic glutamatergic receptors. The reduction of IGF-I brain levels in diabetes could be responsible of synaptic plasticity impairment, as evidenced by improved response facilitation in STZ-diabetic mice following the application of IGF-I. This hypothesis was further supported by immunochemical techniques, which revealed a reduction in IGF-I receptors in the layer 2/3 of the S1 cortex in STZ-diabetic animals. The observed synaptic plasticity impairments in STZ-diabetic animals were accompanied by decreased performance in a whisker discrimination task, along with reductions in IGF-I, GluR1, and NMDA receptors observed in immunochemical studies. In conclusion, impaired synaptic plasticity in the S1 cortex may stem from reduced IGF-I signaling, leading to decreased intracellular signal pathways and thus, glutamatergic receptor numbers in the cellular membrane.

Interaction between the Neuroprotective and Hyperglycemia Mitigation Effects of Walnut-Derived Peptide LVRL via the Wnt3a/β-Catenin/GSK-3β Pathway in a Type 2 Diabetes Mellitus Model

The term type 3 diabetes mellitus (T3DM) has been considered for Alzheimer's disease (AD) due to the common molecular and cellular characteristics found between type 2 diabetes mellitus (T2DM) and cognitive deficits. However, the specific mechanism of T3DM remains elusive, especially the neuroprotective effects of dietary components in hyperglycemic individuals. In this study, a peptide, Leu-Val-Arg-Leu (LVRL), found in walnuts significantly improved memory decline in streptozotocin (STZ)- and high-fat-diet (HFD)-stimulated T2DM mouse models (p < 0.05). The LVRL peptide also mitigated hyperglycemia, enhanced synaptic plasticity, and ameliorated mitochondrial dysfunction, as demonstrated by Morris water maze tests, immunoblotting, immunofluorescence, immunohistochemistry, transmission electron microscopy, and cellular staining. A Wnt3a inhibitor, DKK1, was subsequently used to verify the possible role of the Wnt3a/β-Catenin/GSK-3β pathway in glucose-induced insulin resistance in PC12 cells. In vitro LVRL treatment dramatically modulated the protein expression of p-Tau (Ser404), Synapsin-1, and PSD95, elevated the insulin level, increased glucose consumption, and relieved the mitochondrial membrane potential, and MitoSOX (p < 0.05). These data suggested that peptides like LVRL could modulate the relationship between brain insulin and altered cognition status via the Wnt3a/β-Catenin/GSK-3β pathway.

Associations of sugar intake, high-sugar dietary pattern, and the risk of dementia: a prospective cohort study of 210,832 participants

BACKGROUND

Limited evidence demonstrated the potential relationship between dietary sugar intake and dementia. This association demands further clarification in a large-scale population.

METHODS

A total of 210,832 participants from the UK Biobank cohort were included in this prospective cohort study. Absolute and relative sugar intake and high-sugar dietary scores were utilized to reflect dietary sugar intake. Absolute sugar intake was identified by the Oxford WebQ in the UK Biobank. Relative sugar intake was calculated by dividing the absolute sugar intake by total diet energy. High-sugar dietary pattern was identified using the method of reduced rank regression. Cox proportional hazards regression analyses and restricted cubic splines were performed to examine the longitudinal associations between dietary sugar intake and all-cause dementia and its main subtype, Alzheimer's disease. Explorative mediation analyses were conducted to explore underlying mechanisms.

RESULTS

Increased absolute sugar intake (g/day) was significantly associated with a higher risk of all-cause dementia (HR = 1.003, [95%CI: 1.002-1.004], p < 0.001) and Alzheimer's disease (1.002, [1.001-1.004], 0.005). Relative sugar intake (%g/kJ/day) also demonstrated significant associations with all-cause dementia (1.317, [1.173-1.480], p < 0.001) and Alzheimer's disease (1.249, [1.041-1.500], 0.017), while the high-sugar dietary score was only significantly associated with a higher risk of all-cause dementia (1.090, [1.045-1.136], p < 0.001). In addition, both sugar intake and high-sugar dietary score demonstrated significant non-linear relationships with all-cause dementia and Alzheimer's disease (all p values for non-linearity < 0.05).

CONCLUSIONS

Our study provided evidence that excessive sugar intake was associated with dementia. Controlling the excess consumption of dietary sugar may be of great public health implications for preventing dementia.

Dysglycemia, gender, and cognitive performance in older persons living with mild cognitive impairment: findings from a cross-sectional, population-based study

OBJECTIVE

This study aims to examine the relationship between dysglycemia - also known as pre-diabetes or impaired glucose tolerance- and cognitive abilities in an older population living Mild Cognitive Impairment (MCI) and stratified by gender.

STUDY DESIGN

This is a retrospective study with data gathered from a large Italian clinical-based database.

MAIN OUTCOME MEASURES

The evaluation of cognitive performances by the Mini-Mental State Examination and the Addenbrooke's Cognitive Examination Revised rating scale as tests of screening and a comprehensive neuropsychological evaluation of several cognitive areas.

RESULTS

The study comprised 682 subjects (445 F/237 M) with a mean age of 76.08 ± 9.03 (range: 66-93) years. In all population, subjects with dysglycemia 193 (28.3%) had significantly poorer performance in memory (p = 0.006) and logic reasoning (p = 0.007) when compared with subjects without dysglycemia. The linear regression analyses revealed significant differences in the correlates of cognitive domains between gender groups. Independent of multiple covariates, women with dysglycemia showed worse performances in attention and short-term memory domains as compared with men. Even in the absence of dysglycemia women were more likely to show lower score in screening test of general cognition and attention.

CONCLUSIONS

Our findings suggest that dysglycemia in older individuals with MCI is associated with declines in specific cognitive domains, potentially influenced by gender. Implementing a comprehensive approach involving risk stratification and preventive strategies may be more effective in averting further cognitive decline in this high-risk population.

Effects of Cognitive Intervention and Rehabilitation Training on the Expression of miR-134-5p in Elderly Patients with Diabetes Mellitus and Cognitive Impairment

OBJECTIVE

This study aimed to analyze the effect and potential mechanism of cognitive intervention and rehabilitation training in elderly patients with diabetes mellitus complicated with mild cognitive impairment.

METHODS

In this study, 128 elderly patients with diabetes mellitus complicated with mild cognitive impairment were randomly divided into the control group and the training group. The effects of the two groups were compared before and after the cognitive intervention. The expression of miR-134-5p was assessed by qRT-PCR. The relationships between miR-134-5p and Mini-Mental State Examination Scale and Montreal Cognitive Assessment Scale were evaluated.

RESULTS

After 3-month management, the Mini-Mental State Examination Scale, Montreal Cognitive Assessment Scale, the Chinese version of the diabetes self-efficacy rating scale, and WHO quality of life brief were improved in both control group and training group, and the training group showed better improvement. Cognitive intervention and rehabilitation training restricted the expression of miR-134-5p. The levels of miR-134-5p were pertinent to cognitive function.

CONCLUSION

Cognitive intervention and rehabilitation training might prevent the development of diabetes mellitus complicated with mild cognitive impairment by inhibiting miR-134-5p.

The reactive pyruvate metabolite dimethylglyoxal mediates neurological consequences of diabetes

Complications of diabetes are often attributed to glucose and reactive dicarbonyl metabolites derived from glycolysis or gluconeogenesis, such as methylglyoxal. However, in the CNS, neurons and endothelial cells use lactate as energy source in addition to glucose, which does not lead to the formation of methylglyoxal and has previously been considered a safer route of energy consumption than glycolysis. Nevertheless, neurons and endothelial cells are hotspots for the cellular pathology underlying neurological complications in diabetes, suggesting a cause that is distinct from other diabetes complications and independent of methylglyoxal. Here, we show that in clinical and experimental diabetes plasma concentrations of dimethylglyoxal are increased. In a mouse model of diabetes, ilvb acetolactate-synthase-like (ILVBL, HACL2) is the enzyme involved in formation of increased amounts of dimethylglyoxal from lactate-derived pyruvate. Dimethylglyoxal reacts with lysine residues, forms Nε-3-hydroxy-2-butanonelysine (HBL) as an adduct, induces oxidative stress more strongly than other dicarbonyls, causes blood-brain barrier disruption, and can mimic mild cognitive impairment in experimental diabetes. These data suggest dimethylglyoxal formation as a pathway leading to neurological complications in diabetes that is distinct from other complications. Importantly, dimethylglyoxal formation can be reduced using genetic, pharmacological and dietary interventions, offering new strategies for preventing CNS dysfunction in diabetes.

Cerebellar gray matter and white matter damage among older adults with prediabetes

AIMS

To investigate alterations in cerebrum and cerebellum in prediabetes. Cerebellar injury in diabetes is traceable, but it has not been systematically studied, and whether cerebellar injury occurs and the degree of damage in prediabetes are not known.

METHODS

The current study investigated cerebral and cerebellar gray matter volume, white matter volume, white matter microstructure and white matter hyperintensity on T1-weighted, T2-weighted fluid-attenuated inversion recovery and diffusion tensor imaging scans in 78 individuals with normal glucose metabolism, 92 with prediabetes, and 108 with type 2 diabetes.

RESULTS

Participants with prediabetes showed significant gray matter and white matter atrophy, microstructural damage in the cerebellar and cerebral regions. Additionally, widespread structural alterations were observed in the diabetic stage. The function of the damaged brain area was further decoded in Neurosynth, and the damaged cerebellar area with prediabetic lesions was closely related to motor function, while the area affected by diabetes was related to complex cognitive function in addition to motor function.

CONCLUSIONS

Cerebellar injury had already appeared in the prediabetic stage, and cerebellar injury was aggravated in the diabetic stage; therefore, the cerebellum is a key area that is damaged early in the development of diabetes.

Microglial SCAP deficiency protects against diabetes-associated cognitive impairment through inhibiting NLRP3 inflammasome-mediated neuroinflammation

Hyperglycemia-induced pathological microglial responses and subsequent neuronal damage are notable characteristics of diabetes-associated cognitive impairment (DACI). Cholesterol accumulation in the brain is a prevalent consequence of diabetes mellitus (DM), exacerbating pathological microglial responses. Regarding disordered glucose and lipid metabolism, the Sterol Regulatory Element-Binding Protein (SREBP) cleavage-activating protein (SCAP), a cholesterol sensor, exhibits increased expression and abnormal translocation from the endoplasmic reticulum to the Golgi, amplifying the inflammatory response. Therefore, we hypothesized that overexpression of microglia-SCAP and cholesterol accumulation in DM mice could induce pathological microglial responses associated with DACI. Our type 2 DM mice model presented an abnormal increase in microglial SCAP expression. The functional loss of microglia-specific SCAP in DM mice improved cognitive impairment, neuronal synaptic plasticity deficits, and abnormal microglial responses. Mechanistically, the accumulated SCAP directly bound to and enhanced the activation of the microglial-specific inflammatory amplifier, NLRP3 inflammasome, in Golgi, thereby increasing pathological microglial responses and promoting neuronal damage. These findings indicate an important regulatory axis of microglial responses from SCAP to the NLRP3 inflammasome pathway in microglia. These underscore the crosstalk between cholesterol disorders and pathological microglial responses, offering a promising avenue for pharmaceutical interventions in DACI.

Assessment of disparities in timely diagnosis and comprehensive workup of cognitive impairment between English and Spanish speakers

BACKGROUND

Previous studies have examined disparities in dementia care that affect the U.S. Hispanic/Latino population, including clinician bias, lack of cultural responsiveness, and less access to health care. However, there is limited research that specifically investigates the impact of language barriers to health disparities in dementia diagnosis.

METHODS

In this retrospective cross-sectional study, 12,080 English- or Spanish- speaking patients who received an initial diagnosis of mild cognitive impairment (MCI) or dementia between July 2017 and June 2019 were identified in the Yale New Haven Health (YNHH) electronic medical record. To evaluate the timeliness of diagnosis, an initial diagnosis of MCI was classified as "timely", while an initial diagnosis of dementia was considered "delayed." Comprehensiveness of diagnosis was assessed by measuring the presence of laboratory studies, neuroimaging, specialist evaluation, and advanced diagnostics six months before or after diagnosis. Binomial logistic regressions were calculated with and without adjustment for age, legal sex, ethnicity, neighborhood disadvantage, and medical comorbidities.

RESULTS

Spanish speakers were less likely to receive a timely diagnosis when compared with English speakers both before (unadjusted OR, 0.65; 95% CI, 0.53-0.80, p <0.0001) and after adjusting for covariates (adjusted OR, 0.55; 95% CI, 0.40-0.75, p = 0.0001). Diagnostic services were provided equally between groups, except for referrals to geriatrics, which were more frequent among Spanish-speaking patients. A subgroup analysis revealed that Spanish-speaking Hispanic/Latino patients were less likely to receive a timely diagnosis compared to English-speaking Hispanic/Latino patients (adjusted OR, 0.53; 95% CI, 0.38-0.73, p = 0.0001).

CONCLUSIONS

Non-English language preference is likely to be a contributing factor to timely diagnosis of cognitive impairment. In this study, Spanish language preference rather than Hispanic/Latino ethnicity was a significant predictor of a less timely diagnosis of cognitive impairment. Policy changes are needed to reduce barriers in cognitive disorders care for Spanish-speaking patients.

Long-term impact of type 2 diabetes onset on dementia incidence rate among New Zealanders with impaired glucose tolerance: A tapered-matched landmark analysis over 25 years

INTRODUCTION

We aimed to investigate the association between the onset of type 2 diabetes (T2D) and dementia incidence rates (IR) in the population with impaired glucose tolerance (IGT) identified in primary care in New Zealand (NZ) over 25 years.

METHODS

Tapered matching and landmark analysis (accounting for immortal bias) were used to control for potential effects of known confounders. The association between T2D onset and 5- and 10-year IR of dementia was estimated by weighted Cox models.

RESULTS

The onset of T2D was significantly associated with the 10-year IR of dementia, especially in the socioeconomically deprived, those of non-NZ European ethnicity, those currently smoking, and patients with higher metabolic measures.

DISCUSSION

Our findings suggest that the onset of T2D is a significant risk factor for dementia in individuals with IGT. Dementia screening and structured diabetes prevention are vital in the population with IGT, particularly those from deprived or ethnic minority backgrounds.

HIGHLIGHTS

Increased dementia incidence rate links with T2D onset in people with IGT. Significant incidence varied by ethnicity, socioeconomic status, and health factors. Results emphasize the diabetes manage and socioeconomic factors on dementia risk. Secondary analysis highlights the key role of vascular health in dementia prevention.

Neuroinflammation induced by amyloid-forming pancreatic amylin: Rationale for a mechanistic hypothesis

Amylin is a systemic neuroendocrine hormone co-expressed and co-secreted with insulin by pancreatic β-cells. In persons with thype-2 diabetes, amylin forms pancreatic amyloid triggering inflammasome and interleukin-1β signaling and inducing β-cell apoptosis. Here, we summarize recent progress in understanding the potential link between amyloid-forming pancreatic amylin and Alzheimer's disease (AD). Clinical data describing amylin pathology in AD alongside mechanistic studies in animals are reviewed. Data from multiple research teams indicate higher amylin concentrations are associated with increased frequency of cognitive impairment and amylin co-aggregates with β-amyloid in AD-type dementia. Evidence from rodent models further suggests cerebrovascular amylin accumulation as a causative factor underlying neurological deficits. Analysis of relevant literature suggests that modulating the amylin-interleukin-1β pathway may provide an approach for counteracting neuroinflammation in AD.

Type-2 Diabetes, Pancreatic Amylin, and Neuronal Metabolic Remodeling in Alzheimer's Disease

Type-2 diabetes raises the risk for Alzheimer's disease (AD)-type dementia and the conversion from mild cognitive impairment to dementia, yet mechanisms connecting type-2 diabetes to AD remain largely unknown. Amylin, a pancreatic β-cell hormone co-secreted with insulin, participates in the central regulation of satiation, but also forms pancreatic amyloid in persons with type-2 diabetes and synergistically interacts with brain amyloid β (Aβ) pathology, in both sporadic and familial Alzheimer's disease (AD). Growing evidence from studies of tumor growth, together with early observations in skeletal muscle, indicates amylin as a potential trigger of cellular metabolic reprogramming. Because the blood, cerebrospinal fluid, and brain parenchyma in humans with AD have increased concentrations of amylin, amylin-mediated pathological processes in the brain may involve neuronal metabolic remodeling. This review summarizes recent progress in understanding the link between prediabetic hypersecretion of amylin and risk of neuronal metabolic remodeling and AD and suggests nutritional and medical effects of food constituents that might prevent and/or ameliorate amylin-mediated neuronal metabolic remodeling.

Age of type 2 diabetes onset as a risk factor for dementia: A 13-year retrospective cohort study

AIMS

To examine whether age at type 2 diabetes onset is an independent predictor of dementia risk.

METHODS

Retrospective cohort drawn from healthcare administrative records of all inhabitants within Romagna's catchment area, Italy, with an estimated onset of type 2 diabetes in 2008-2017 and aged ≥ 55, with follow-up until 2020. Time to dementia or censoring was estimated with the Kaplan-Meier method, using diabetes onset as the time origin. Age groups were compared with the log-rank test. Multivariable competing-risks analysis was used to assess predictors of dementia.

RESULTS

In patients aged ≥ 75 years, dementia-free survival (DFS) declined to below 90 % within five years and linearly decreased to 68.8 % until the end of follow-up. In contrast, DFS for those aged 55-64 years showed a marginal decrease, reaching 97.4 % after 13 years. Competing-risks regression showed that individuals aged ≥ 75 and 65-74 had a significantly higher risk of dementia compared to those aged 55-64 years. Having more comorbidities at diabetes onset and initial treatment with ≥ 2 antidiabetics were clinical predictors.

CONCLUSIONS

Later age at onset of diabetes is strongly associated with dementia. A better understanding of the diabetes-dementia relationship is needed to inform strategies for promoting specific healthcare pathways.

Cerebral Microbleeds Associate with Brain Endothelial Cell Activation-Dysfunction and Blood-Brain Barrier Dysfunction/Disruption with Increased Risk of Hemorrhagic and Ischemic Stroke

Globally, cerebral microbleeds (CMBs) are increasingly being viewed not only as a marker for cerebral small vessel disease (SVD) but also as having an increased risk for the development of stroke (hemorrhagic/ischemic) and aging-related dementia. Recently, brain endothelial cell activation and dysfunction and blood-brain barrier dysfunction and/or disruption have been shown to be associated with SVD, enlarged perivascular spaces, and the development and evolution of CMBs. CMBs are a known disorder of cerebral microvessels that are visualized as 3-5 mm, smooth, round, or oval, and hypointense (black) lesions seen only on T2*-weighted gradient recall echo or susceptibility-weighted sequences MRI images. CMBs are known to occur with high prevalence in community-dwelling older individuals. Since our current global population is the oldest recorded in history and is only expected to continue to grow, we can expect the healthcare burdens associated with CMBs to also grow. Increased numbers (≥10) of CMBs should raise a red flag regarding the increased risk of large symptomatic neurologic intracerebral hemorrhages. Importantly, CMBs are also currently regarded as markers of diffuse vascular and neurodegenerative brain damage. Herein author highlights that it is essential to learn as much as we can about CMB development, evolution, and their relation to impaired cognition, dementia, and the exacerbation of neurodegeneration.

Bitter yet beneficial: The dual role of dietary alkaloids in managing diabetes and enhancing cognitive function

With the rising prevalence of diabetes and its association with cognitive impairment, interest in the use of dietary alkaloids and other natural products has grown significantly. Understanding how these compounds manage diabetic cognitive dysfunction (DCD) is crucial. This comprehensive review explores the etiology of DCD and the effects of alkaloids in foods and dietary supplements that have been investigated as DCD therapies. Data on how dietary alkaloids like berberine, trigonelline, caffeine, capsaicin, 1-deoxynojirimycin, nuciferine, neferine, aegeline, tetramethylpyrazine, piperine, and others regulate cognition in diabetic disorders were collected from PubMed, Research Gate, Web of Science, Science Direct, and other relevant databases. Dietary alkaloids could improve memory in behavioral models and modulate the mechanisms underlying the cognitive benefits of these compounds, including their effects on glucose metabolism, gut microbiota, vasculopathy, neuroinflammation, and oxidative stress. Evidence suggests that dietary alkaloids hold promise for improving cognition in diabetic patients and could open exciting avenues for future research in diabetes management.

Phytoactive drugs used in the treatment of Alzheimer's disease and dementia

The prevalence of Alzheimer's disease and other forms of dementia is increasing worldwide, and finding effective treatments for these conditions is a major public health challenge. Natural bioactive drugs have been identified as a promising source of potential treatments, due to their ability to target multiple pathways and their low toxicity. This paper reviews the current state of research on natural bioactive drugs used in the treatment of Alzheimer's disease and other dementias. The paper summarizes the findings of studies on various natural compounds, including curcumin, resveratrol, caffeine, genistein, quercetin, GinkoBiloba, Withaniasomnifera, Ginseng Brahmi, Giloy, and huperzine, and their effects on cognitive function, neuroinflammation, and amyloid-beta accumulation. In this review, we discuss the mechanism of action involved in the treatment of Alzheimer's disease. The paper also discusses the challenges associated with developing natural bioactive drugs for dementia treatment, including issues related to bioavailability and standardization. Finally, the paper suggests directions for future research in this area, including the need for more rigorous clinical trials and the development of novel delivery systems to improve the efficacy of natural bioactive drugs. Overall, this review highlights the potential of natural bioactive drugs as a promising avenue for the development of safe and effective treatments for Alzheimer's disease and other dementias.

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.

The association of regional cerebral blood flow and glucose metabolism in normative ageing and insulin resistance

Rising rates of insulin resistance and an ageing population are set to exact an increasing toll on individuals and society. Here we examine the contribution of age and insulin resistance to the association of cerebral blood flow and glucose metabolism; both critical process in the supply of energy for the brain. Thirty-four younger (20-42 years) and 41 older (66-86 years) healthy adults underwent a simultaneous resting state MR/PET scan, including arterial spin labelling. Rates of cerebral blood flow and glucose metabolism were derived using a functional atlas of 100 brain regions. Older adults had lower cerebral blood flow than younger adults in 95 regions, reducing to 36 regions after controlling for cortical atrophy and blood pressure. Lower cerebral blood flow was also associated with worse working memory and slower reaction time in tasks requiring cognitive flexibility and response inhibition. Younger and older insulin sensitive adults showed small, negative correlations between relatively high rates of regional cerebral blood flow and glucose metabolism. This pattern was inverted in insulin resistant older adults, who showed hypoperfusion and hypometabolism across the cortex, and a positive correlation. In insulin resistant younger adults, the association showed inversion to positive correlations, although not to the extent seen in older adults. Our findings suggest that the normal course of ageing and insulin resistance alter the rates of and associations between cerebral blood flow and glucose metabolism. They underscore the criticality of insulin sensitivity to brain health across the adult lifespan.

Research Progress on the Pathogenesis, Diagnosis, and Drug Therapy of Alzheimer's Disease

As the population ages worldwide, Alzheimer's disease (AD), the most prevalent kind of neurodegenerative disorder among older people, has become a significant factor affecting quality of life, public health, and economies. However, the exact pathogenesis of Alzheimer's remains elusive, and existing highly recognized pathogenesis includes the amyloid cascade hypothesis, Tau neurofibrillary tangles hypothesis, and neuroinflammation hypothesis. The major diagnoses of Alzheimer's disease include neuroimaging positron emission computed tomography, magnetic resonance imaging, and cerebrospinal fluid molecular diagnosis. The therapy of Alzheimer's disease primarily relies on drugs, and the approved drugs on the market include acetylcholinesterase drugs, glutamate receptor antagonists, and amyloid-β monoclonal antibodies. Still, the existing drugs can only alleviate the symptoms of the disease and cannot completely reverse it. This review aims to summarize existing research results on Alzheimer's disease pathogenesis, diagnosis, and drug therapy, with the objective of facilitating future research in this area.

Sex-dependent effects of carbohydrate source and quantity on caspase-1 activity in the mouse central nervous system

BACKGROUND

Mounting evidence links glucose intolerance and diabetes as aspects of metabolic dysregulation that are associated with an increased risk of developing dementia. Inflammation and inflammasome activation have emerged as a potential link between these disparate pathologies. As diet is a key factor in both the development of metabolic disorders and inflammation, we hypothesize that long term changes in dietary factors can influence nervous system function by regulating inflammasome activity and that this phenotype would be sex-dependent, as sex hormones are known to regulate metabolism and immune processes.

METHODS

5-week-old male and female transgenic mice expressing a caspase-1 bioluminescent reporter underwent cranial window surgeries and were fed control (65% complex carbohydrates, 15% fat), high glycemic index (65% carbohydrates from sucrose, 15% fat), or ketogenic (1% complex carbohydrates, 79% fat) diet from 6 to 26 weeks of age. Glucose regulation was assessed with a glucose tolerance test following a 4-h morning fast. Bioluminescence in the brain was quantified using IVIS in vivo imaging. Blood cytokine levels were measured using cytokine bead array. 16S ribosomal RNA gene amplicon sequencing of mouse feces was performed to assess alterations in the gut microbiome. Behavior associated with these dietary changes was also evaluated.

RESULTS

The ketogenic diet caused weight gain and glucose intolerance in both male and female mice. In male mice, the high glycemic diet led to increased caspase-1 biosensor activation over the course of the study, while in females the ketogenic diet drove an increase in biosensor activation compared to their respective controls. These changes correlated with an increase in inflammatory cytokines present in the serum of test mice and the emergence of anxiety-like behavior. The microbiome composition differed significantly between diets; however no significant link between diet, glucose tolerance, or caspase-1 signal was established.

CONCLUSIONS

Our findings suggest that diet composition, specifically the source and quantity of carbohydrates, has sex-specific effects on inflammasome activation in the central nervous system and behavior. This phenotype manifested as increased anxiety in male mice, and future studies are needed to determine if this phenotype is linked to alterations in microbiome composition.

Dopamine-mediated autocrine inhibition of insulin secretion

The aim of the present research was to explore the mechanisms underlying the role of dopamine in the regulation of insulin secretion in beta cells. The effect of dopamine on insulin secretion was investigated on INS 832/13 cell line upon glucose and other secretagogues stimulation. Results show that dopamine significantly inhibits insulin secretion stimulated by both glucose and other secretagogues, while it has no effect on the basal secretion. This effect requires the presence of dopamine during incubation with the various secretagogues. Both electron microscopy and immunohistochemistry indicate that in beta cells the D2 dopamine receptor is localized within the insulin granules. Blocking dopamine entry into the insulin granules by inhibiting the VMAT2 transporter with tetrabenazine causes a significant increase in ROS production. Our results confirm that dopamine plays an important role in the regulation of insulin secretion by pancreatic beta cells through a regulated and precise compartmentalization mechanisms.

A spontaneous hyperglycaemic cynomolgus monkey presents cognitive deficits, neurological dysfunction and cataract

Chronic hyperglycaemia is a chief feature of diabetes mellitus and complicates with many systematic anomalies. Non-human primates (NHPs) are excellent for studying hyperglycaemia or diabetes and associated comorbidities, but lack behavioural observation. In the study, behavioural, brain imaging and histological analysis were performed in a case of spontaneously hyperglycaemic (HGM) Macaca fascicularis. The results were shown that the HGM monkey had persistent body weight loss, long-term hyperglycaemia, insulin resistance, dyslipidemia, but normal concentrations of insulin, C-peptide, insulin autoantibody, islet cell antibody and glutamic acid decarboxylase antibody. Importantly, an impaired working memory in a delayed response task and neurological dysfunctions were found in the HGM monkey. The tendency for atrophy in hippocampus was observed by magnetic resonance imaging. Lenticular opacification, lens fibres disruptions and vacuole formation also occurred to the HGM monkey. The data suggested that the spontaneous HGM monkey might present diabetes-like characteristics and associated neurobehavioral anomalies in this case. This study first reported cognitive deficits in a spontaneous hyperglycaemia NHPs, which might provide evidence to use macaque as a promising model for translational research in diabetes and neurological complications.

Trajectories of cognitive function among people aged 45 years and older living with diabetes in China: Results from a nationally representative longitudinal study (2011~2018)

OBJECTIVES

Diabetes is associated with decline of cognitive function. Exploring different trajectories of cognitive function occurring in people with diabetes is important to improved prognosis. This study aimed to investigate differential patterns of trajectories of cognitive function and baseline determinants of trajectory group membership utilizing data from middle-aged and older Chinese adults with diabetes.

METHODS

Participants of the Chinese Health And Retirement Longitudinal Study (CHARLS) aged 45 years and above received biennial assessments between 2011 and 2018. The primary outcome was overall cognitive function score operationalized as sum of mental intactness and episodic memory scores derived from the Telephone Interview of Cognitive Status (TICS). A weighted growth mixture model was used to estimate cognitive function trajectories of CHARLS participants with diabetes, and baseline factors associated with trajectory group membership were investigated with weighted multinomial logistic regression.

RESULTS

Data from 1,463 participants with diabetes aged 45 years and above were analyzed, a three-group trajectory model showed the best fit for overall cognitive scores: low baseline, linear declining (22.1%); moderate baseline, linear declining (37.5%) and high-stable (40.3%). Older participants, females, participants with low education, with nighttime sleep <6 h, without daytime napping habits, and with depressive symptoms were at a higher risk of unfavorable cognitive function trajectories.

CONCLUSIONS

We identified heterogeneous trajectories of cognitive function among middle-aged and older people living with diabetes in China. Socially vulnerable groups including females, rural residents, and those with low education were at a higher risk for unfavorable trajectories. In health programs aimed at preventing and mitigating cognitive decline in individuals with diabetes more attention should be given to vulnerable groups. Reduced nighttime sleep, lack of daytime napping, and depressive symptoms appear to be modifiable risk factors.

Deciphering the dual role of N-methyl-D-Aspartate receptor in postoperative cognitive dysfunction: A comprehensive review

Postoperative cognitive dysfunction (POCD) is a common complication following surgery, adversely impacting patients' recovery, increasing the risk of negative outcomes, prolonged hospitalization, and higher mortality rates. The N-methyl-D-aspartate (NMDA) receptor, crucial for learning, memory, and synaptic plasticity, plays a significant role in the development of POCD. Various perioperative factors, including age and anesthetic use, can reduce NMDA receptor function, while surgical stress, inflammation, and pain may lead to its excessive activation. This review consolidates preclinical and clinical research to explore the intricate relationship between perioperative factors affecting NMDA receptor functionality and the onset of POCD. It discusses the influence of aging, anesthetic administration, perioperative injury, pain, and inflammation on the NMDA receptor-related pathophysiology of POCD. The comprehensive analysis presented aims to identify effective treatment targets for POCD, contributing to the improvement of patient outcomes post-surgery.

Diabetes mellitus in older persons with neurocognitive disorder: overtreatment prevalence and associated structural brain MRI findings

BACKGROUND

Tight diabetes control is often applied in older persons with neurocognitive disorder resulting in increased hypoglycemic episodes but little is known about the pattern of brain injury in these overtreated patients. This study aims to: (a) quantify the prevalence of diabetes overtreatment in cognitively impaired older adults in a clinical population followed in an academic memory clinic (b) identify risk factors contributing to overtreatment; and (c) explore the association between diabetes overtreatment and specific brain region volume changes.

METHODS

Retrospective study of older patients with type 2 diabetes and cognitive impairment who were diagnosed in a memory clinic from 2013 to 2020. Patients were classified into vulnerable and dependent according to their health profile. Overtreatment was defined when glycated hemoglobin was under 7% for vulnerable and 7.6% for dependent patients. Characteristics associated to overtreatment were examined in multivariable analysis. Grey matter volume in defined brain regions was measured from MRI using voxel-based morphometry and compared in patients over- vs. adequately treated.

RESULTS

Among 161 patients included (median age 76.8 years, range 60.8-93.3 years, 32.9% women), 29.8% were considered as adequately treated, 54.0% as overtreated, and 16.2% as undertreated. In multivariable analyses, no association was observed between diabetes overtreatment and age or the severity of cognitive impairment. Among patients with neuroimaging data (N = 71), associations between overtreatment and grey matter loss were observed in several brain regions. Specifically, significant reductions in grey matter were found in the caudate (adj β coeff: -0.217, 95%CI: [-0.416 to -0.018], p = .033), the precentral gyri (adj βcoeff:-0.277, 95%CI: [-0.482 to -0.073], p = .009), the superior frontal gyri (adj βcoeff: -0.244, 95%CI: [-0.458 to -0.030], p = .026), the calcarine cortex (adj βcoeff:-0.193, 95%CI: [-0.386 to -0.001], p = .049), the superior occipital gyri (adj βcoeff: -0.291, 95%CI: [-0.521 to -0.061], p = .014) and the inferior occipital gyri (adj βcoeff: -0.236, 95%CI: [-0.456 to - 0.015], p = .036).

CONCLUSION

A significant proportion of older patients with diabetes and neurocognitive disorder were subjected to excessively intensive treatment. The association identified with volume loss in several specific brain regions highlights the need to further investigate the potential cerebral damages associated with overtreatment and related hypoglycemia in larger sample.