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

A Cdk5 inhibitor restores cognitive function and alleviates type 2 diabetes in mice

Type 2 diabetes (T2D) is a metabolic disorder commonly linked with cognitive decline, increasing patients' susceptibility to dementia. Alzheimer's disease (AD) has a strong connection with hyperglycemia and insulin dysregulation. Interestingly, certain anti-diabetic drugs have shown potential in reducing T2D-induced cognitive impairment. Previous studies, including ours, have highlighted the dysregulation of cyclin-dependent kinase 5 (Cdk5) activity in both T2D and AD, which may contribute to pathological changes in these conditions. Thus, targeting the Cdk5 kinase could offer a therapeutic approach for T2D and cognitive deterioration. Our research identifies Cdk5 as a key link between T2D and cognitive decline. By screening the KINACore library, we discovered two new brain-penetrant Cdk5 inhibitors, BLINK11 and BLINK15. In a high-fat diet-induced T2D model, these inhibitors improved blood glucose levels, obesity, and cognitive function. BLINK11, in particular, shows promise as a therapeutic candidate for treating cognitive impairment associated with T2D.

The Diabetic Cognitive Impairment Score for Early Screening of Cognitive Impairment in Type 2 Diabetes Patients

Purpose: Diabetes has been associated with an excess risk of cognitive impairment. The hyperphosphorylation of tau protein leads to neurodegeneration and is closely related to Type 2 diabetes (T2D). This study aimed to characterize the association between P-tau181 and diabetic cognitive impairment and to develop a nomogram-based score to screen cognitive impairment in T2D patients. Methods: We used a cohort of 379 patients diagnosed with T2D as a training dataset to develop a predictive model. Risk factors associated with cognitive impairment were identified using stepwise multivariate logistic regressive analysis. A nomogram was established by incorporating these risk factors, and the diabetic cognitive impairment score (DCIS) was built and externally validated in another cohort. Results: In the training cohort, patients with cognitive impairment had higher levels of P-tau181 (13.3 [10.5-18.7] vs. 10.0 [8.0-13.0], p < 0.001). P-tau181 was negatively correlated with MOCA (r = -0.308, p < 0.001) and MMSE (r = -0.289, p < 0.001), and it was independently associated with cognitive impairment in T2D patients (OR, 1.137 [95% CI, 1.080-1.198]; p < 0.001). Other independent risk factors of diabetic cognitive impairment included age, education level, and diabetic retinopathy. The DCIS was built by nomogram based on the four risk factors, which had an area under the receiver operating characteristic curve (AUC) of 0.795 (95% CI, 0.751-0.840). The optimal cut-off of DCIS for the diagnosis of cognitive impairment in T2D patients was 139.5, with a sensitivity of 72.9% and a specificity of 75.3%. In the validation cohort, the AUC of DCIS for screening diabetic cognitive impairment was 0.770 (95% CI, 0.716-0.824). Conclusions: P-tau181 was independently associated with diabetic cognitive impairment. The DCIS, based on P-tau181, age, education level, and diabetic retinopathy, is effective to identify cognitive impairment in T2D patients.

A Narrative Review on Cognitive Impairment in Type 2 Diabetes: Global Trends and Diagnostic Approaches

Diabetes is a chronic disease that affects many people, with both its incidence and prevalence rising globally. Diabetes can lead to various complications, among which cognitive impairment in diabetic patients significantly impacts their daily life and blood glucose management, complicating treatment and worsening prognosis. Therefore, the early diagnosis and treatment of cognitive impairment are essential to ensure the health of diabetic patients. However, there is currently no widely accepted and effective method for the early diagnosis of diabetes-related cognitive impairment. This review aims to summarize potential screening and diagnostic methods, as well as biomarkers, for cognitive impairment in diabetes, including retinal structure and function examination, brain imaging, and peripheral blood biomarkers, providing valuable information and support for clinical decision making and future research.

Association between glycated hemoglobin A1c levels, control status, and cognitive function in type 2 diabetes: a prospective cohort study

Cognitive impairment (CI) is a common complication in patients with type 2 diabetes mellitus (T2DM), but its relationship with long-term glycemic control remains unclear. This study aimed to investigate the associations between mean hemoglobin A1c (HbA1c) levels, HbA1c control status, HbA1c fluctuations, and CI in Chinese adults aged 45 years and older with T2DM using data from the China Health and Retirement Longitudinal Study (CHARLS). A total of 797 participants with HbA1c measurements from 2011 to 2015 and cognitive function assessments in 2018 were included. Logistic regression models and restricted cubic spline (RCS) analysis were applied, adjusting for potential confounders. Higher mean HbA1c levels (≥ 9%) were significantly associated with an increased risk of CI, particularly in global cognition and episodic memory (OR 4.03 (1.45-11.20) for global cognition; OR 2.92 (1.02-8.38) for episodic memory). RCS analysis revealed a U-shaped relationship between mean HbA1c and CI, indicating that both excessively low and high HbA1c levels elevate CI risk. Uncontrolled HbA1c levels (≥ 8%) were also linked to higher CI risk compared to stable HbA1c levels. Maintaining HbA1c levels below 8% may significantly reduce CI risk in T2DM patients, highlighting the importance of personalized glycemic management.

Retinal Microperimetry as a Novel Tool for Early Detection of Subclinical Cognitive Dysfunction and Brain Damage in Type 1 Diabetes: A Pilot Study

CONTEXT

Retinal microperimetry (MPR) is a non-invasive method that measures retinal light sensitivity (RS) and gaze fixation stability (GFS). MPR has been described as a marker of cognitive impairment in people with Type 2 diabetes, but it has never been assessed in people with Type 1 diabetes (T1D). Our group described subclinical cognitive alterations, structural brain differences, and increased levels of light chain neurofilament (NfL) in people with T1D and impaired awareness of hypoglycaemia.

OBJECTIVE

To measure RS and GFS using MPR in individuals with T1D and evaluate its correlation with neuropsychological assessment, plasma NfL levels and CGM-derived glucometric parameters.

SECONDARY OBJECTIVES

to evaluate the possible differences of RS and GFS in people with T1D depending on hypoglycaemia awareness.

DESIGN, SETTING AND PARTICIPANTS

Pilot observational study, people with T1D without clinical cognitive impairment, moderate-severe retinopathy or glaucoma. MPR was performed with MAIA3.

RESULTS

A total of 30 subjects were studied: 40% women, age 58 ± 11 years; T1D duration 31 ± 9 years, mild retinopathy 33%. RS was 27.5 dB (26.1-28.3) and GFS(%) 97.6% (93.5%-99.5%). We found a correlation between RS and memory alteration tests (p = 0.016) and between GFS(%) and a composite of attention and executive neuropsychological tests (p = 0.025). An inverse correlation between GFS and time below range was found. No correlation was found with NfL.

CONCLUSION

This first exploratory study in people with T1D supports the potential utility of MPR as a screening tool for subclinical neurocognitive alterations in this population.

Associations between sociodemographic and clinical characteristics and adherence to self-management behaviours among community-dwelling older adults with mild cognitive impairment

BACKGROUND

Self-management is vital for individuals with mild cognitive impairment (MCI) to enhance cognitive health and mitigate the risk of dementia. However, maintaining consistent engagement in self-management strategies can be challenging for older adults with MCI. This study aimed to explore the associations between sociodemographic and clinical characteristics and adherence to self-management behaviours among community-dwelling older adults with MCI.

METHODS

A cross-sectional study involving 467 community-dwelling older adults with MCI was conducted from July to November 2022 across Nanjing, Xuzhou, and Lianyungang in Jiangsu Province, China. Data on sociodemographic and clinical characteristics, as well as self-management behaviours for MCI, were collected. Multiple linear and binary logistic regressions were employed to identify factors influencing self-management behaviours.

RESULTS

Among the four recommended self-management behaviours for MCI, participants adopted an average of 1.37 ± 1.202 behaviours. Physical exercise (n = 239; 51.2%) was the most prevalent behaviour, followed by modifiable risk factors management (n = 156; 33.4%), cognitive training (n = 144; 30.8%), and cognitive function monitoring (n = 103; 22.1%). Higher education level (B = 0.286, P < 0.001), urban employee medical insurance (B = 0.621, P < 0.001), and non-smoking status (B = 0.389, P = 0.002) positively correlated with aggregate MCI self-management behaviours, while older age (B = -0.295, P < 0.001) had a negative association. Marital status, monthly income, employment status, gender, residence, and family history of cognitive disorders were also found to be associated with specific self-management behaviours for MCI.

CONCLUSIONS

Enhancing adherence to self-management among community-dwelling older adults with MCI is critical. Sociodemographic and clinical factors should be considered to pinpoint at-risk populations and accordingly tailor support strategies.

The Mediating Effect of Physical Performance on Physical Activity and Mild Cognitive Impairment Among Older Adults With Type 2 Diabetes in Rural China

OBJECTIVES

To investigate the intermediary role of physical performance in the association between physical activity and mild cognitive impairment (MCI) in older adults with type 2 diabetes mellitus (T2DM), residing in rural areas.

METHODS

This study employed a random sampling method to select 316 patients aged 65 years and older, all diagnosed with T2DM, from 24 different rural areas in China. The relationships between physical activity, physical performance, and MCI were analyzed using a logistic regression model, and the proposed mediation model was validated through bootstrap test.

RESULTS

In this study, the prevalence of MCI in the rural-based older adults with T2DM was 53.48%. A significant correlation was observed between the levels of physical activity and physical performance. Moreover, diminished physical performance was positively correlated with an increased propensity for MCI, even after adjusting for relevant covariates. Physical performance was discerned to exert a partial mediating influence on the relationship between physical activity and MCI.

CONCLUSIONS

The empirical evidence generated by this study posits that the impact of physical activity on MCI is partially mediated through physical performance in an aging population with T2DM residing in rural environments. Consequently, interventional strategies aimed at ameliorating physical performance may serve as a viable approach to mitigate the progression of cognitive decline.

Prevalence of mild cognitive impairment and modifiable risk factors: A cross-sectional study in rural older adults with diabetes

To determine the prevalence and modifiable risk factors for MCI in older adults with T2DM in rural China. This cross-sectional study encompassed 96 villages, employing a cluster sampling approach to recruit eligible older adults with T2DM as study participants. Logistic regression analysis was utilized to identify modifiable risk factors associated with MCI. Average marginal effects were calculated. The discriminatory performance of these risk factors in identifying MCI was evaluated by plotting the receiver operating curve and calculating the value of the area under the curve. A total of 898 older adults with T2DM in our study. The overall prevalence of MCI was 50.22 %. Independent associations with MCI were found in poor self-management ability of diabetes (OR = 0.808, 95 % CI: 0.808, 0.766), depressive symptoms (OR = 3.500, 95 % CI: 1.933, 6.337), moderate (OR = 0.936, 95 % CI: 0.017, 0.075) and high (OR = 0.939, 95 % CI: 0.016, 0.100) levels of physical activity, poorer oral health (OR = 2.660, 95 % CI: 2.226, 3.179), and lower grip strength (OR = 0.913, 95 % CI: 0.870, 0.958). The AUC was 0.967 (95 % CI 0.508-0.470). The prevalence of MCI was high among older adults with T2DM in rural areas of China. The self-management ability of diabetes, depressive symptoms, physical activity, oral health and grip strength were modifiable risk factors of MCI. Targeted interventions should be developed and implemented to address these modifiable risk factors, aiming to enhance cognitive function and mitigate the incidence of MCI in older adults with T2DM.

Development and first-stage validation of a digital version of the Digit Symbol Substitution test for use in assessing cognitive function in older people with diabetes

AIMS

To describe the development and report the first-stage validation of a digital version of the digit symbol substitution test (DSST), for assessment of cognitive function in older people with diabetes.

MATERIALS AND METHODS

A multidisciplinary team of experts was convened to conceptualize and build a digital version of the DSST and develop a machine-learning (ML) algorithm to analyse the inputs. One hundred individuals with type 2 diabetes (aged ≥ 60 years) were invited to participate in a one-time meeting in which both the digital and the pencil-and-paper (P&P) versions of the DSST were administered. Information pertaining to demographics, laboratory measurements, and diabetes indices was collected. The correlation between the digital and P&P versions of the test was determined. Additionally, as part of the validation process, the performance of the digital version in people with and without known risk factors for cognitive impairment was analysed.

RESULTS

The ML model yielded an overall accuracy of 89.1%. A strong correlation was found between the P&P and digital versions (r = 0.76, p < 0.001) of the DSST, as well as between the ML model and the manual reading of the digital DSST (r = 0.99, p < 0.001).

CONCLUSIONS

This study describes the development of and provides first-stage validation data for a newly developed digital cognitive assessment tool that may be used for screening and surveillance of cognitive function in older people with diabetes. More studies are needed to further validate this tool, especially when self-administered and in different clinical settings.

Clinical characteristics and healthcare utilisation associated with undiagnosed cognitive impairment in elderly patients with diabetes in a primary care setting: a population-based cohort study

OBJECTIVES

The objective of this study is to report the prevalence, clinical characteristics and healthcare utilisation of patients with type 2 diabetes (T2DM) and previously undiagnosed cognitive impairment who were identified as having a low Montreal Cognitive Assessment (MoCA) score.

DESIGN

A population-based cohort study comparing clinical characteristics, medications, outpatient and inpatient care of patients with a MoCA score <19 to MoCA >26 using descriptive statistics, linear regression and multivariate logistic regression.

SETTING

Electronic medical records of a large health maintenance organisation in Israel.

PARTICIPANTS

350 patients, age >65 with T2DM who participated in a cognitive function screening initiative using MoCA, and had a follow-up visit during the 12 months after screening.

RESULTS

130 (37.1%) had a MoCA score >26 and 68 (19.4%) <19. Patients with MoCA<19 had more diabetes-related complications, poorer glycaemic and lipid control, fewer visits to their main primary care physician (PCP; 3.9±3.2 vs 7.3±4.2 visits/year p=0.008), shorter duration of PCP visits (8.3±4.5 vs 4.0±3.5 min, p=0.007), fewer nutritionist and endocrinologist visits, and lower participation in diabetes or smoking cessation workshops. They were less likely to be treated with glucagon-like peptide-1 (GLP-1) agonists, dipeptidyl peptidase-4 inhibitor (DPP-4), or sodium-glucose transport protein 2 (SGLT-2) inhibitors and more likely to receive insulin or sulfonylurea. Moreover, they had more emergency room visits (ER; 15 (11.5%) vs 16 (23.5%), p=0.019), hospitalisations (8 (6.2%) vs 22 (32.4%), p=0.001), and longer hospital stays (4.3±3.2 vs 14.5±9.8, p=0.001). Using statistical models, MoCA<19 was identified as a risk factor for fewer and shorter PCP visits and more ER visits and hospitalisations.

CONCLUSIONS

This study highlights the high prevalence of undiagnosed severe cognitive impairment in elderly patients with T2DM and its association with poor outpatient care. Appropriate interventions are needed to improve outcomes and prevent hospitalisation in this high-risk population.

Structural and Functional Retinal Changes in Patients with Mild Cognitive Impairment with and without Diabetes

Our objective is to analyze retinal changes using optical coherence tomography angiography (OCT-A) in patients with mild cognitive impairment (MCI) to characterize structural and vascular alterations. This cross-sectional study involved 117 eyes: 39 eyes from patients with MCI plus diabetes (DM-MCI), 39 eyes from patients with MCI but no diabetes (MCI); and 39 healthy control eyes (C). All patients underwent a visual acuity measurement, a structural OCT, an OCT-A, and a neuropsychological examination. Our study showed a thinning of retinal nerve fiber layer thickness (RNFL) and a decrease in macular thickness when comparing the MCI-DM group to the C group (p = 0.008 and p = 0.016, respectively). In addition, an increase in arteriolar thickness (p = 0.016), a reduction in superficial capillary plexus density (p = 0.002), and a decrease in ganglion cell thickness (p = 0.027) were found when comparing the MCI-DM group with the MCI group. Diabetes may exacerbate retinal vascular changes when combined with mild cognitive impairment.