Effects of dipeptidyl peptidase-4 inhibitors and sulphonylureas on cognitive and physical function in nursing home residents

A Bayesian method for adverse effects estimation in observational studies with truncation by death

Death among subjects is common in observational studies evaluating the causal effects of interventions among geriatric or severely ill patients. High mortality rates complicate the comparison of the prevalence of adverse events between interventions. This problem is often referred to as outcome "truncation" by death. A possible solution is to estimate the survivor average causal effect, an estimand that evaluates the effects of interventions among those who would have survived under both treatment assignments. However, because the survivor average causal effect does not include subjects who would have died under one or both arms, it does not consider the relationship between adverse events and death. We propose a Bayesian method which imputes the unobserved mortality and adverse event outcomes for each participant under the intervention they did not receive. Using the imputed outcomes we define a composite ordinal outcome for each patient, combining the occurrence of death and the adverse event in an increasing scale of severity. This allows for the comparison of the effects of the interventions on death and the adverse event simultaneously among the entire sample. We implement the procedure to analyze the incidence of heart failure among geriatric patients being treated for Type II diabetes with sulfonylureas or dipeptidyl peptidase-4 inhibitors.

Exploring the Therapeutic Potential of DPP4 Inhibitors in Alzheimer's Disease: Molecular Insight and Clinical Outcome

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by amyloid-beta (Aβ) plaques, neurofibrillary tangles, and cognitive decline. Given the shared neuropathophysiological traits between AD and type 2 diabetes mellitus (T2DM), repurposing antidiabetic medications, such as dipeptidyl peptidase 4 inhibitors (DPP4i), has emerged as a promising therapeutic strategy. This review comprehensively evaluates the preclinical and clinical evidence supporting the potential of DPP4i in preventing or treating AD by modulating Aβ and tau pathology, improving cognitive function, reducing neuroinflammation and oxidative stress, and promoting neuronal survival. The beneficial effects of DPP4i are likely mediated through the modulation of insulin signaling, anti-inflammatory and antioxidant properties, glucagon-like peptide-1 (GLP-1) upregulation, and modulation of the amyloidogenic pathway. While further research is needed to establish their clinical efficacy in AD patients, DPP4i offers a promising avenue for therapeutic intervention for this devastating neurodegenerative disease.

Identifying predictors of cognitive decline in long-term care: a scoping review

BACKGROUND

Cognitive impairment can cause social, emotional, and financial burdens on individuals, caregivers, and healthcare providers. This is especially important in settings such as long-term care (LTC) homes which largely consist of vulnerable older adults. Thus, the objective of this study is to review and summarize current research examining risk factors of cognitive decline in older adults within LTC.

METHODS

This scoping review includes primary observational research studies assessing within-person change in cognition over time in LTC or equivalent settings in high resource countries. A mean participant age of ≥ 65 years was required. Searches were conducted in Medline, Embase, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and PyscInfo on June 27th, 2022 and included articles published during or after the year 2000. Title, abstract, and full-text screening was performed by two independent reviewers using Covidence. Specific predictors along with their associated relation with cognitive decline were extracted by a team of reviewers into a spreadsheet.

RESULTS

Thirty-eight studies were included in this review. The mean sample size was 14 620. Eighty-seven unique predictors were examined in relation to cognitive decline. Dementia was the most studied predictor (examined by 9 of 38 studies), and the most conclusive, with eight of those studies identifying it as a risk factor for cognitive decline. Other predictors that were identified as risk factors included arterial stiffness (identified by 2 of 2 studies), physical frailty (2 of 2 studies), sub-syndromal delirium (2 of 2 studies), and undergoing the first wave of COVID-19 lockdowns (2 of 2 studies). ADL independence was the most conclusive protective factor (3 of 4 studies), followed by social engagement (2 of 3 studies). Many remaining predictors showed no association and/or conflicting results.

CONCLUSIONS

Dementia was the most common risk factor, while ADL independence was the most common protective factor associated with cognitive decline in LTC residents. This information can be used to stratify residents by risk severity and provide better personalized care for older adults through the targeted management of cognitive decline.

Cognitive protection of incretin-based therapies in patients with type 2 diabetes mellitus: A systematic review and meta-analysis based on clinical studies

AIMS/INTRODUCTION

Cognitive dysfunction, including mild cognitive impairment and dementia, is increasingly recognized as an important complication of type 2 diabetes mellitus. The aims of the preset study was to investigate the cognitive protection of incretin-based therapies, including glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors, in patients with type 2 diabetes mellitus.

MATERIALS AND METHODS

PubMed, EMBASE, Cochrane library, Web of Science and PsycINFO were searched from the inception through 17 January 2023 for randomized controlled trials and cohort studies on the association between incretin-based therapies and cognitive function. A total of 15 studies were finally included in our systematic review, and eight of which were incorporated into our meta-analysis.

RESULTS

Pooled results showed that the Mini-Mental State Examination score in incretin-based therapy groups was increased by 1.20 compared with the control group (weighted mean difference 1.20, 95% confidence interval 0.39-2.01). The results of eight studies assessed by the Newcastle Ottawa Quality Assessment Scale and the Cochrane Collaboration's tool, and the quality of the eight studies were at a relatively high level. Egger's regression did not show significant publication bias.

CONCLUSIONS

Current evidence shows that incretin-based therapies might be more effective, when compared with the other hypoglycemic drugs, for cognitive improvement in patients with type 2 diabetes mellitus.

Comparative safety of sulfonylureas among U.S. nursing home residents

BACKGROUND

The comparative safety of sulfonylureas (SUs) in nursing home (NH) residents remains understudied despite widespread use. We compared the effects of three SU medications and initial SU doses on adverse glycemic and cardiovascular events among NH residents.

METHODS

This national retrospective cohort study linked Medicare claims with Minimum Data Set 2.0 assessments for long-stay NH residents aged ≥65 years between January 2008 and September 2010. Exposures were the SU medication initiated (glimepiride, glipizide, or glyburide) and doses (standard or reduced). One-year outcomes were hospitalizations or emergency department visits for severe hypoglycemia, heart failure (HF), stroke, and acute myocardial infarction (AMI). After the inverse probability of treatment and inverse probability of censoring by death weighting, we estimated hazard ratios (HR) using Cox regression models with robust 95% confidence intervals (CI).

RESULTS

The cohort (N = 6821) included 3698 new glipizide, 1754 glimepiride, and 1369 glyburide users. Overall, the mean (standard deviation) age was 81.4 (8.2) years, 4816 (70.6%) were female, and 5164 (75.7%) were White non-Hispanic residents. The rates of severe hypoglycemia were 30.3 (95% CI 22.3-40.1), 49.0 (95% CI 34.5-67.5), and 35.9 (95% CI 22.2-54.9) events per 1000 person-years among new glipizide, glimepiride, and glyburide users, respectively (glimepiride versus glipizide HR 1.6, 95% CI 1.0-2.4, p = 0.04; glyburide versus glipizide HR 1.2, 95% CI 0.7-1.9, p = 0.59). The rates of severe hypoglycemia were 27.1 (95% CI 18.6-38.0) and 42.8 (95% CI 33.6-53.8) events per 1000 person-years among new users of reduced and standard SU doses, respectively (HR 2.2, 95% CI 1.4-3.5, p < 0.01). Rates of HF, stroke, and AMI were similar between medications and doses.

CONCLUSIONS

Among long-stay NH residents, new use of glimepiride and standard SU doses resulted in higher rates of severe hypoglycemic events. Cardiovascular outcomes may not be affected by the choice of SU medication or dose.

Plasma sDPP4 (Soluble Dipeptidyl Peptidase-4) and Cognitive Impairment After Noncardioembolic Acute Ischemic Stroke

BACKGROUND

DPP4 (dipeptidyl peptidase-4) inhibitors have been proven to promote neuronal regeneration, reverse the development of cognitive deficits. However, the association of circulating soluble form (sDPP4 [soluble DPP4]) with poststroke cognitive impairment (PSCI) is unclear. We aimed to investigate the association between plasma sDPP4 levels and PSCI in patients with ischemic stroke.

METHODS

A total of 600 noncardioembolic stroke patients were included based on a preplanned ancillary study from the CATIS (China Antihypertensive Trial in Acute Ischemic Stroke). We used the Montreal Cognitive Assessment to evaluate cognitive function at 3 months follow-up after ischemic stroke. Binary logistic regression analyses were performed to investigate the association of plasma sDPP4 levels with subsequent PSCI. We further calculated integrated discrimination improvement and category-free net reclassification improvement to investigate the incremental prognostic effect of plasma sDPP4 beyond the basic model with conventional risk factors.

RESULTS

Plasma sDPP4 was inversely associated with PSCI after ischemic stroke, and the adjusted odds ratio (95% CI) for the highest versus lowest quartile of sDPP4 was 0.49 (0.29-0.81; P for trend=0.011). Each 1-SD increase of logarithm-transformed plasma sDPP4 concentration was associated with 17% (odds ratio, 0.83 [95% CI, 0.70-0.99]) lower risk of PSCI. Adding plasma sDPP4 to the basic model notably improved risk reclassification for PSCI, as shown by a category-free net reclassification improvement of 19.10% (95% CI, 2.52%-35.68%; P=0.03) and integrated discrimination improvement of 0.79% (95% CI, 0.13%-1.46%; P=0.02).

CONCLUSIONS

Higher plasma sDPP4 levels were associated with decreased risk of cognitive impairment after noncardioembolic ischemic stroke.

Association between diabetes mellitus and post-stroke cognitive impairment

Stroke survivors suffer from various physical, emotional, and cognitive impairments. These changes are dynamic and depend on multiple factors, including underlying diseases, baseline brain function and pathology, the site of the stroke and the post-stroke inflammation, neurogenesis as well as the subsequent remodeling of the neuro-network. First we review the structural and pathological changes of the brain in stroke survivors with diabetes mellitus, which may lead to post-stroke cognitive dysfunction. Second, we provide evidence of hyperglycemia, diabetes mellitus, hypoglycemia, and their relationship with post-stroke cognitive impairment (PSCI) and post-stroke dementia (PSD). In addition to conventional biomarkers, such as HbA1c, we also provide other novel tools to predict PSCI/PSD, such as glycemic variability, receptor for advanced glycation end products, and gut microbiota. Finally, we attempt to provide some modifying methods for glycemic control, focusing on the prevention of PSCI/PSD.