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

Defining a vitamin A5/X specific deficiency - vitamin A5/X as a critical dietary factor for mental health

A healthy and balanced diet is an important factor to assure a good functioning of the central and peripheral nervous system. Retinoid X receptor (RXR)-mediated signaling was identified as an important mechanism of transmitting major diet-dependent physiological and nutritional signaling such as the control of myelination and dopamine signalling. Recently, vitamin A5/X, mainly present in vegetables as provitamin A5/X, was identified as a new concept of a vitamin which functions as the nutritional precursor for enabling RXR-mediated signaling. The active form of vitamin A5/X, 9-cis-13,14-dehydroretinoic acid (9CDHRA), induces RXR-activation, thereby acting as the central switch for enabling various heterodimer-RXR-signaling cascades involving various partner heterodimers like the fatty acid and eicosanoid receptors/peroxisome proliferator-activated receptors (PPARs), the cholesterol receptors/liver X receptors (LXRs), the vitamin D receptor (VDR), and the vitamin A(1) receptors/retinoic acid receptors (RARs). Thus, nutritional supply of vitamin A5/X might be a general nutritional-dependent switch for enabling this large cascade of hormonal signaling pathways and thus appears important to guarantee an overall organism homeostasis. RXR-mediated signaling was shown to be dependent on vitamin A5/X with direct effects for beneficial physiological and neuro-protective functions mediated systemically or directly in the brain. In summary, through control of dopamine signaling, amyloid β-clearance, neuro-protection and neuro-inflammation, the vitamin A5/X - RXR - RAR - vitamin A(1)-signaling might be "one of" or even "the" critical factor(s) necessary for good mental health, healthy brain aging, as well as for preventing drug addiction and prevention of a large array of nervous system diseases. Likewise, vitamin A5/X - RXR - non-RAR-dependent signaling relevant for myelination/re-myelination and phagocytosis/brain cleanup will contribute to such regulations too. In this review we discuss the basic scientific background, logical connections and nutritional/pharmacological expert recommendations for the nervous system especially considering the ageing brain.

Effects of antidiabetic agents on platelet characteristics with implications in Alzheimer's disease: Mendelian randomization and colocalization study

Background

Observational studies have found a potential link between the use of thiazolidinediones (TZDs) and a lower risk of Alzheimer's disease (AD) development. Platelets were the great source of amyloid-β (Aβ) and involved in the development of AD. This study aimed to assess the correlation between antidiabetic agents and platelet characteristics, hoping to provide a potential mechanism of TZDs neuroprotection in AD.

Method

Drug-targeted Mendelian randomization (MR) was performed to systematically illustrate the long-term effects of antidiabetic agents on platelet characteristics. Four antidiabetic agent targets were considered. Positive control analysis for type 2 diabetes (T2D) was conducted to validate the selection of instrumental variables (IVs). Colocalization analysis was used to further strengthen the robustness of the results.

Result

Positive control analysis showed an association of four antidiabetic agents with lower risk of T2D, which was consistent with their mechanisms of action and previous evidence from clinical trials. Genetically proxied TZDs were associated with lower platelet count (β[IRNT] = -0.410 [95 % CI -0.533 to -0.288], P = 5.32E-11) and a lower plateletcrit (β[IRNT] = -0.344 [95 % CI -0.481 to -0.206], P = 1.04E-6). Colocalization suggested the posterior probability of hypothesis 4 (PPH4) > 0.8, which further strengthened the MR results.

Conclusion

Genetically proxied TZDs were causally associated with lower platelet characteristics, particularly platelet count and plateletcrit, providing insight into the involvement of platelet-related pathways in the neuroprotection of TZDs against AD. Future studies are warranted to reveal the underlying molecular mechanism of TZDs' neuroprotective effects through platelet pathways.

Diabetes, antidiabetic medications and risk of dementia: A systematic umbrella review and meta-analysis

AIMS

The objective of this umbrella review and meta-analysis was to evaluate the effect of diabetes on risk of dementia, as well as the mitigating effect of antidiabetic treatments.

MATERIALS AND METHODS

We conducted a systematic umbrella review on diabetes and its treatment, and a meta-analysis focusing on treatment. We searched MEDLINE/PubMed, Embase, PsycINFO, CINAHL and the Cochrane Library for systematic reviews and meta-analyses assessing the risk of cognitive decline/dementia in individuals with diabetes until 2 July 2023. We conducted random-effects meta-analyses to obtain risk ratios and 95% confidence intervals estimating the association of metformin, thiazolidinediones, pioglitazone, dipeptidyl peptidase-4 inhibitors, α-glucosidase inhibitors, meglitinides, insulin, sulphonylureas, glucagon-like peptide-1 receptor agonists (GLP1RAs) and sodium-glucose cotransporter-2 inhibitors (SGLT2is) with risk of dementia from cohort/case-control studies. The subgroups analysed included country and world region. Risk of bias was assessed with the AMSTAR tool and Newcastle-Ottawa Scale.

RESULTS

We included 100 reviews and 27 cohort/case-control studies (N = 3 046 661). Metformin, thiazolidinediones, pioglitazone, GLP1RAs and SGLT2is were associated with significant reduction in risk of dementia. When studies examining metformin were divided by country, the only significant effect was for the United States. Moreover, the effect of metformin was significant in Western but not Eastern populations. No significant effect was observed for dipeptidyl peptidase-4 inhibitors, α-glucosidase inhibitors, or insulin, while meglitinides and sulphonylureas were associated with increased risk.

CONCLUSIONS

Metformin, thiazolidinediones, pioglitazone, GLP1RAs and SGLT2is were associated with reduced risk of dementia. More longitudinal studies aimed at determining their relative benefit in different populations should be conducted.

Anti-diabetics and the Prevention of Dementia: A Systematic Review

Type 2 diabetes mellitus (T2DM) is a worldwide epidemic that is only increasing as the years progress, and as of 2019, affecting over 37 million. T2DM is a chronic condition caused by reduced insulin secretion and increased insulin resistance. Due to insulin not operating at optimal conditions, blood glucose rises and remains high, thus disturbing metabolic hemostasis. Many complications can arise from T2DM, such as coronary vascular disease, kidney damage, eye damage, and, quite significantly, dementia. It is theorized that dementia from T2DM stems from the fact that the brain is susceptible to hyperglycemic conditions, which are promoted by the increase in insulin resistance of target cells in the central nervous system. This directly affects cognitive processes and memory, which correlates to decreased temporal and front lobes volume. The risk of diabetic complications can be minimized with therapeutic interventions such as oral-antidiabetic (OAD) agents and insulin. Several OADs are on the market, but the first-line agent is metformin, a biguanide that decreases glucose production and increases insulin sensitivity. This paper aims to determine if currently prescribed OADs can help slow cognitive decline and reduce the risk and incidence of dementia as a complication of T2DM. Studies found that, for the most part, all OADs except sulfonylureas (SU) significantly slowed the decline of cognitive function and reduced the risk and incidence of dementia. SU's were shown to increase the risk of dementia in most studies. Of all the OADs, thiazolidinediones may be the most beneficial drug class for reducing the risk of dementia in T2DM patients. Future research should focus on whether early intervention with specific classes of OADs can not only improve glycemic control, leading to decreased hyperglycemia but also prevent the build-up of damaged brain tissue and help to reduce the risk and incidence of dementia in patients with T2DM.

Sex Differences in the Preventive Effect of Cardiovascular and Metabolic Therapeutics on Dementia

Dementia is a clinical syndrome characterized by progressive impairment of cognitive and functional abilities. As currently applied treatments for dementia can only delay the progression of dementia and cannot fundamentally cure it, much attention is being paid to reducing its incidence by preventing the associated risk factors. Cardiovascular and metabolic diseases are well-known risk factors for dementia, and many studies have attempted to prevent dementia by treating these risk factors. Growing evidence suggests that sex-based factors may play an important role in the pathogenesis of dementia. Therefore, a deeper understanding of the differences in the effects of drugs based on sex may help improve their effectiveness. In this study, we reviewed sex differences in the impact of therapeutics targeting risk factors for dementia, such as cardiovascular and metabolic diseases, to prevent the incidence and/or progression of dementia.

Direct Thrombectomy versus Bridging Thrombectomy within 6 Hours of Stroke Onset: A Prospective Cohort Study on Cognitive and Physical Function Outcomes

PURPOSE

To evaluate the physical and cognitive functions of patients with stroke who underwent either direct or bridging thrombectomy within 6 hours of stroke onset.

MATERIALS AND METHODS

Patients with large vessel occlusion in anterior circulation treated with direct (direct group) or bridging thrombectomy (bridging group) were prospectively analyzed between June 2020 and February 2022. The efficacy outcome was the 3-month modified Rankin Scale (mRS) score, the safety outcome was symptomatic intracranial hemorrhage (sICH), and cognitive function was assessed using the Clinical Dementia Rating (CDR) scale at 6 months after stroke.

RESULTS

A total of 125 patients (direct group, n = 75; bridging group, n = 50) who had completed follow-up at 3 months by telephone call were included. No significant differences were observed between the direct and bridging groups in terms of an mRS score of 0-2 (25.3% vs 22.0%, respectively; P = .83), an mRS score of 0-3 (37.3% vs 44.0%, respectively; P = .58), sICH (17.3% vs 14.0%, respectively; P = .80), or 3-month all-cause mortality (36.3% vs 30.0%, respectively; P = .34). Sixty-nine patients (direct group, n = 38; bridging group, n = 31) completed the CDR assessment at 6 months after stroke. There was no significant difference in poststroke dementia, defined as a CDR score of ≥1 point between the direct group (42.1%) and bridging group (22.6%) (P = .12). Ordinal regression analyses showed that the CDR score at 6 months was not associated with treatment type (direct thrombectomy vs bridging thrombectomy).

CONCLUSIONS

With regard to physical and cognitive functions at 3 and 6 months, direct thrombectomy was comparable with bridging thrombectomy in patients who were treated within 6 hours of stroke onset.

Cognitive disorders in patients with chronic kidney disease: Approaches to prevention and treatment

BACKGROUND

Cognitive impairment is common in patients with chronic kidney disease (CKD), and early intervention may prevent the progression of this condition.

METHODS

Here, we review interventions for the complications of CKD (anemia, secondary hyperparathyroidism, metabolic acidosis, harmful effects of dialysis, the accumulation of uremic toxins) and for prevention of vascular events, interventions that may potentially be protective against cognitive impairment. Furthermore, we discuss nonpharmacological and pharmacological methods to prevent cognitive impairment and/or minimize the latter's impact on CKD patients' daily lives.

RESULTS

A particular attention on kidney function assessment is suggested during work-up for cognitive impairment. Different approaches are promising to reduce cognitive burden in patients with CKD but the availabe dedicated data are scarce.

CONCLUSIONS

There is a need for studies assessing the effect of interventions on the cognitive function of patients with CKD.

Insulin sensitizers in 2023: lessons learned and new avenues for investigation

INTRODUCTION

'Insulin sensitizers' derived discoveries of the Takeda Company in 1970s. Pioglitazone remains the best in class with beneficial pleiotropic pharmacology, although use is limited by tolerability issues. Various attempts to expand out of this class assumed the primary molecular target was the transcription factor, PPARγ. Findings over the last 10 years have identified new targets of thiazolidinediones (TZDs) that should alter the drug discovery paradigm.

AREAS COVERED

We review structural classes of experimental insulin sensitizer drugs, some of which have attained limited approval in some markets. The TZD pioglitazone, originally approved in 1999 as a secondary treatment for type 2 diabetes, has demonstrated benefit in apparently diverse spectrums of disease from cardiovascular to neurological issues. New TZDs modulate a newly identified mitochondrial target (the mitochondrial pyruvate carrier) to reprogram metabolism and produce insulin sensitizing pharmacology devoid of tolerability issues.

EXPERT OPINION

Greater understanding of the mechanism of action of insulin sensitizing drugs can expand the rationale for the fields of treatment and potential for treatment combinations. This understanding can facilitate the registration and broader use of agents with that impact the pathophysiology that underlies chronic metabolic diseases as well as host responses to environmental insults including pathogens, insulin sensitizer, MPC, mitochondrial target, metabolic reprogramming, chronic and infectious disease.

Population-based discovery and Mendelian randomization analysis identify telmisartan as a candidate medicine for Alzheimer's disease in African Americans

INTRODUCTION

African Americans (AAs) and European Americans (EAs) differ in Alzheimer's disease (AD) prevalence, risk factors, and symptomatic presentation and AAs are less likely to enroll in AD clinical trials.

METHODS

We conducted race-conscious pharmacoepidemiologic studies of 5.62 million older individuals (age ≥60) to investigate the association of telmisartan exposure and AD outcome using Cox analysis, Kaplan-Meier analysis, and log-rank test. We performed Mendelian randomization (MR) analysis of large ethnically diverse genetic data to test likely causal relationships between telmisartan's target and AD.

RESULTS

We identified that moderate/high telmisartan exposure was significantly associated with a reduced incidence of AD in the AAs compared to low/no telmisartan exposure (hazard ratio [HR] = 0.77, 95% CI: 0.65-0.91, p-value = 0.0022), but not in the non-Hispanic EAs (HR = 0.97, 95% CI: 0.89-1.05, p-value = 0.4110). Sensitivity and sex-/age-stratified patient subgroup analyses identified that telmisartan's medication possession ratio (MPR) and average hypertension daily dosage were significantly associated with a stronger reduction in the incidence of both AD and dementia in AAs. Using MR analysis from large genome-wide association studies (GWAS) (over 2 million individuals) across AD, hypertension, and diabetes, we further identified AA-specific beneficial effects of telmisartan for AD.

DISCUSSION

Randomized controlled trials with ethnically diverse patient cohorts are warranted to establish causality and therapeutic outcomes of telmisartan and AD.

HIGHLIGHTS

Telmisartan is associated with lower risk of Alzheimer's disease (AD) in African Americans (AAs). Telmisartan is the only angiotensin II receptor blockers having PPAR-γ agonistic properties with beneficial anti-diabetic and renal function effects, which mitigate AD risk in AAs. Mendelian randomization (MR) analysis demonstrates the specificity of telmisartan's protective mechanism to AAs.

Pioglitazone use increases risk of Alzheimer's disease in patients with type 2 diabetes receiving insulin

Pioglitazone is an insulin resistance inhibitor widely used as monotherapy or combined with metformin or insulin in treating type 2 diabetes mellitus (T2DM). This study further investigated the relationship between pioglitazone use and the risk of developing Alzheimer's disease (AD) in patients newly diagnosed with T2DM, and examined the potential impact of insulin use on this association. Data were extracted from the National Health Insurance Research Database (NHIRD) of Taiwan. Our data exhibited that the risk of developing AD in the pioglitazone group was 1.584-fold (aHR = 1.584, 95% CI 1.203-1.967, p < 0.05) higher than that in the non-pioglitazone controls. Compared to patients without both insulin and pioglitazone, higher cumulative risk of developing AD was found in patients receiving both insulin and pioglitazone (aHR = 2.004, 95% CI = 1.702-2.498), pioglitazone alone (aHR = 1.596, 95% CI = 1.398-1.803), and insulin alone (aHR = 1.365, 95% CI = 1.125-1.572), respectively (all p < 0.05). A similar observation also found in the evaluation the use of diabetic drugs with a cumulative defined daily dose (cDDD). No interaction between pioglitazone and major risk factors (comorbidities) of AD was observed. In conclusion, alternative drug therapies may be an effective strategy for reducing risk of developing AD in T2DM patients.

Multi-Target Neuroprotection of Thiazolidinediones on Alzheimer's Disease via Neuroinflammation and Ferroptosis

Alzheimer's disease (AD) is the main cause of dementia in older age. The prevalence of AD is growing worldwide, causing a tremendous burden to societies and families. Due to the complexity of its pathogenesis, the current treatment of AD is not satisfactory, and drugs acting on a single target may not prevent AD progression. This review summarizes the multi-target pharmacological effects of thiazolidinediones (TZDs) on AD. TZDs act as peroxisome proliferator-activated receptor gamma (PPARγ) agonists and long-chain acyl-CoA synthetase family member 4 (ACSL4) inhibitors. TZDs ameliorated neuroinflammation and ferroptosis in preclinical models of AD. Here, we discussed recent findings from clinical trials of pioglitazone in the treatment of AD, ischemic stroke, and atherosclerosis. We also dissected the major limitations in the clinical application of pioglitazone and explained the potential benefit of pioglitazone in AD. We recommend the use of pioglitazone to prevent cognitive decline and lower AD risk in a specific group of patients.

Maillard reaction between oligopeptides and reducing sugar at body temperature: The putative anti-glycation agents

Type 2 Diabetes mellitus (T2DM) is one of the most common chronic multifactorial diseases, which is associated with the increased concentration of glucose in the blood. Therefore, the utilization of blood lowering agents is clearly a promising approach which can lead to a suppression of the evaluated blood glucose, and thus curing T2DM and other complication. In this study, we evaluated the glucose lowering effect of a varieties of amino acids (alanine and histidine), dipeptides (carnosine and α-alanine-L-histidine), and tripeptide (glutathione) by reacting with glucose, fructose, and sucrose under 37°C and pH 7.4 to mimic their reaction in physiological condition. By measuring the reduction of reactants and the formation of Maillard reaction products over the course of 21 days’ storage, we found that the glucose lowering effect of carnosine was better than the counterparts. The histidine residue in carnosine may contribute to its glucose lowing effect while β-amino acid β-alanine residue could facilitate the glucose lowering effect of carnosine by maintaining its chemical stability during the storage. These results may open up new avenues for the applications of bioactive peptide carnosine as a natural blood sugar lowering agent to control T2DM.

Insight into the potential role of ferroptosis in neurodegenerative diseases

Ferroptosis is a newly discovered way of programmed cell death, mainly caused by the accumulation of iron-dependent lipid peroxides in cells, which is morphologically, biochemically and genetically different from the previously reported apoptosis, necrosis and autophagy. Studies have found that ferroptosis plays a key role in the occurrence and development of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease and vascular dementia, which suggest that ferroptosis may be involved in regulating the progression of neurodegenerative diseases. At present, on the underlying mechanism of ferroptosis in neurodegenerative diseases is still unclear, and relevant research is urgently needed to clarify the regulatory mechanism and provide the possibility for the development of agents targeting ferroptosis. This review focused on the regulatory mechanism of ferroptosis and its various effects in neurodegenerative diseases, in order to provide reference for the research on ferroptosis in neurodegenerative diseases.

Use of oral diabetes medications and the risk of incident dementia in US veterans aged ≥60 years with type 2 diabetes

INTRODUCTION

Studies have reported that antidiabetic medications (ADMs) were associated with lower risk of dementia, but current findings are inconsistent. This study compared the risk of dementia onset in patients with type 2 diabetes (T2D) treated with sulfonylurea (SU) or thiazolidinedione (TZD) to patients with T2D treated with metformin (MET).

RESEARCH DESIGN AND METHODS

This is a prospective observational study within a T2D population using electronic medical records from all sites of the Veterans Affairs Healthcare System. Patients with T2D who initiated ADM from January 1, 2001, to December 31, 2017, were aged ≥60 years at the initiation, and were dementia-free were identified. A SU monotherapy group, a TZD monotherapy group, and a control group (MET monotherapy) were assembled based on prescription records. Participants were required to take the assigned treatment for at least 1 year. The primary outcome was all-cause dementia, and the two secondary outcomes were Alzheimer's disease and vascular dementia, defined by International Classification of Diseases (ICD), 9th Revision, or ICD, 10th Revision, codes. The risks of developing outcomes were compared using propensity score weighted Cox proportional hazard models.

RESULTS

Among 559 106 eligible veterans (mean age 65.7 (SD 8.7) years), the all-cause dementia rate was 8.2 cases per 1000 person-years (95% CI 6.0 to 13.7). After at least 1 year of treatment, TZD monotherapy was associated with a 22% lower risk of all-cause dementia onset (HR 0.78, 95% CI 0.75 to 0.81), compared with MET monotherapy, and 11% lower for MET and TZD dual therapy (HR 0.89, 95% CI 0.86 to 0.93), whereas the risk was 12% higher for SU monotherapy (HR 1.12 95% CI 1.09 to 1.15).

CONCLUSIONS

Among patients with T2D, TZD use was associated with a lower risk of dementia, and SU use was associated with a higher risk compared with MET use. Supplementing SU with either MET or TZD may partially offset its prodementia effects. These findings may help inform medication selection for elderly patients with T2D at high risk of dementia.

Glucose-lowering drugs, cognition, and dementia: The clinical evidence

Type 2 diabetes mellitus (T2DM) is an important risk factor for dementia. The possibility to mitigate this risk by controlling T2DM is compelling; however, different glucose-lowering drugs have different effects on the brain by virtue of their different mechanisms of action. The clinical and epidemiological data appear mixed, warranting careful critical evaluation of the human studies. Here we examine the evidence in the context of dementia prevention and treatment, both for people with and without T2DM. We discuss the evidence on this scaffold of research directions, identifying methodological complexities in the extant literature (e.g. comparator discrepancies, changes in the therapeutic landscape), and the implications of different outcome measures (e.g. neuropsychological). We consider possible implications of cerebrovascular protection vs. effects on progression of neurodegenerative proteinopathy, and we present a research roadmap for glucose-lowering drugs in cognitive neurology, including neuroimaging, and fluid biomarkers. We conclude that there is great potential to advance personalized strategies to prevent and treat dementia with glucose-lowering drugs.

Potential Roles of Glucagon-Like Peptide-1 and Its Analogues in Dementia Targeting Impaired Insulin Secretion and Neurodegeneration

Dementia is a chronic, irreversible condition marked by memory loss, cognitive decline, and mental instability. It is clinically related to various progressive neurological diseases, including Parkinson’s disease, Alzheimer’s disease, and Huntington’s. The primary cause of neurological disorders is insulin desensitization, demyelination, oxidative stress, and neuroinflammation accompanied by various aberrant proteins such as amyloid-β deposits, Lewy bodies accumulation, tau formation leading to neurofibrillary tangles. Impaired insulin signaling is directly associated with amyloid-β and α-synuclein deposition, as well as specific signaling cascades involved in neurodegenerative diseases. Insulin dysfunction may initiate various intracellular signaling cascades, including phosphoinositide 3-kinase (PI3K), c-Jun N-terminal kinases (JNK), and mitogen-activated protein kinase (MAPK). Neuronal death, inflammation, neuronal excitation, mitochondrial malfunction, and protein deposition are all influenced by insulin. Recent research has focused on GLP-1 receptor agonists as a potential therapeutic target. They increase glucose-dependent insulin secretion and are beneficial in neurodegenerative diseases by reducing oxidative stress and cytokine production. They reduce the deposition of abnormal proteins by crossing the blood-brain barrier. The purpose of this article is to discuss the role of insulin dysfunction in the pathogenesis of neurological diseases, specifically dementia. Additionally, we reviewed the therapeutic target (GLP-1) and its receptor activators as a possible treatment of dementia.

Three-step matching algorithm to enhance between-group comparability and minimize confounding in comparative effectiveness studies

We developed a three-step matching algorithm to enhance the between-group comparability for comparative drug effect studies involving prevalent new-users of the newer study drug versus older comparator drug(s). The three-step matching scheme is to match on: (1) index date of initiating the newer study drug to align the cohort entry time between study groups, (2) medication possession ratio measures that consider prior exposure to all older comparator drugs, and (3) propensity scores estimated from potential confounders. Our approach is illustrated with a comparative cardiovascular safety study of glucagon-like peptide-1 receptor agonist (GLP-1ra) versus sulfonylurea (SU) in type 2 diabetes patients using Taiwan’s National Health Insurance Research Database 2003–2015. 66% of 3195 GLP-1ra users had previously exposed to SU. The between-group comparability was well-achieved after implementing the matching algorithm (i.e., standardized mean difference < 0.2 for all baseline patient characteristics). Compared to SU, the use of GLP-1ra yielded a significantly reduced risk of the primary composite cardiovascular events (hazard ratio [95% confidence interval]: 0.71 [0.54–0.95], p = 0.022). Our matching scheme can enhance the between-group comparability in prevalent new-user cohort designs to minimize time-related bias, improve confounder adjustment, and ensure the reliability and validity of study findings.

Chronic oral administration of adipoRon reverses cognitive impairments and ameliorates neuropathology in an Alzheimer's disease mouse model

Circulating adiponectin (APN) levels decrease with age and obesity. On the other hand, a reduction in APN levels is associated with neurodegeneration and neuroinflammation. We previously showed that aged adiponectin knockout (APN^-/-) mice developed Alzheimer's like pathologies, cerebral insulin resistance, and cognitive impairments. More recently, we also demonstrated that APN deficiency increased Aβ-induced microglia activation and neuroinflammatory responses in 5xFAD mice. There is compelling evidence that deregulated insulin activities or cerebral insulin resistance contributes to neuroinflammation and Alzheimer's disease (AD) pathogenesis. Here, we demonstrated that APN levels were reduced in the brain of AD patients and 5xFAD mice. We crossbred 5xFAD mice with APN^-/- mice to generate APN-deficient 5xFAD (5xFAD;APN^-/-). APN deficiency in 5xFAD mice accelerated amyloid loading, increased cerebral amyloid angiopathy, and reduced insulin-signaling activities. Pharmacokinetics study demonstrated adipoRon (APN receptor agonist) was a blood-brain barrier penetrant. AdipoRon improved neuronal insulin-signaling activities and insulin sensitivity in vitro and in vivo. Chronic adipoRon treatment improved spatial memory functions and significantly rescued neuronal and synaptic loss in 5xFAD and 5xFAD;APN^-/- mice. AdipoRon lowered plaque and Aβ levels in AD mice. AdipoRon also exerted anti-inflammatory effects by reducing microglial and astrocytes activation as well as suppressing cerebral cytokines levels. The microglial phagocytic activity toward Aβ was restored after adipoRon treatment. Our results indicated that adipoRon exerts multiple beneficial effects providing important therapeutic implications. We propose chronic adipoRon administration as a potential treatment for AD.

Different glycaemia-related risk factors for incident Alzheimer's disease in men and women with type 2 diabetes-A sex-specific analysis of the Hong Kong diabetes database

AIMS

Sexual dimorphism has been reported in the epidemiology, neurobiologic susceptibility and clinical presentation of Alzheimer's disease (AD). As poor glycaemic control is associated with increased risks of AD, we aimed to investigate whether glycaemia-related risk factors also differ between men and women, using a retrospective, sex-specific analysis of a large Chinese cohort with diabetes.

MATERIALS & METHODS

A total of 85,514 Chinese individuals with type 2 diabetes (T2D; 46,783 women and 38,731 men), aged ≥60 years, were identified from electronic health records and observed for incident AD. Multivariable Cox regression analysis was used to evaluate the associations with incident AD of several glycaemia-related risk factors, including severe hypoglycaemia, mean HbA1c and indices of HbA1c variability, in men and women separately.

RESULTS

Over a median follow-up of 6 years, women had a higher incidence of AD than men (2.3% vs. 1.2%, p < 0.001). Both men and women shared the same independent non-glycaemic clinical predictors, which included older age, lower body mass index and longer duration of diabetes. However, for glycaemia-related risk factors, we observed that severe hypoglycaemia and indices of HbA1c variability were independent predictors of incident AD in women but not in men, and the associations were irrespective of their baseline glycaemic control and duration of diabetes.

CONCLUSIONS

Our findings highlighted that glycaemia-related risk factors for incident AD differ between men and women with T2D. Strategies to maintain glycaemic stability and avoid severe hypoglycaemia might be especially important to preserve healthy cognition in older women with diabetes.

Brain Atrophy and White Matter Damage Linked to Peripheral Bioenergetic Deficits in the Neurodegenerative Disease FXTAS

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder affecting subjects (premutation carriers) with a 55-200 CGG-trinucleotide expansion in the 5'UTR of the fragile X mental retardation 1 gene (FMR1) typically after age 50. As both the presence of white matter hyperintensities (WMHs) and atrophied gray matter on magnetic resonance imaging (MRI) are linked to age-dependent decline in cognition, here we tested whether MRI outcomes (WMH volume (WMHV) and brain volume) were correlated with mitochondrial bioenergetics from peripheral blood monocytic cells in 87 carriers with and without FXTAS. As a parameter assessing cumulative damage, WMHV was correlated to both FXTAS stages and age, and brain volume discriminated between carriers and non-carriers. Similarly, mitochondrial mass and ATP production showed an age-dependent decline across all participants, but in contrast to WMHV, only FADH2-linked ATP production was significantly reduced in carriers vs. non-carriers. In carriers, WMHV negatively correlated with ATP production sustained by glucose-glutamine and FADH2-linked substrates, whereas brain volume was positively associated with the latter and mitochondrial mass. The observed correlations between peripheral mitochondrial bioenergetics and MRI findings-and the lack of correlations with FXTAS diagnosis/stages-may stem from early brain bioenergetic deficits even before overt FXTAS symptoms and/or imaging findings.

Targeting Nuclear Receptors in Neurodegeneration and Neuroinflammation

Nuclear receptors, also known as ligand-activated transcription factors, regulate gene expression upon ligand signals and present as attractive therapeutic targets especially in chronic diseases. Despite the therapeutic relevance of some nuclear receptors in various pathologies, their potential in neurodegeneration and neuroinflammation is insufficiently established. This perspective gathers preclinical and clinical data for a potential role of individual nuclear receptors as future targets in Alzheimer's disease, Parkinson's disease, and multiple sclerosis, and concomitantly evaluates the level of medicinal chemistry targeting these proteins. Considerable evidence suggests the high promise of ligand-activated transcription factors to counteract neurodegenerative diseases with a particularly high potential of several orphan nuclear receptors. However, potent tools are lacking for orphan receptors, and limited central nervous system exposure or insufficient selectivity also compromises the suitability of well-studied nuclear receptor ligands for functional studies. Medicinal chemistry efforts are needed to develop dedicated high-quality tool compounds for the therapeutic validation of nuclear receptors in neurodegenerative pathologies.

The Association Between Second-Line Oral Antihyperglycemic Medication on Types of Dementia in Type 2 Diabetes: A Nationwide Real-World Longitudinal Study

BACKGROUND

There are few reports that evaluated the association between various types of dementia and dual oral therapy with antihyperglycemic medication.

OBJECTIVE

The goal of this study was to investigate the association between treatment of dual antihyperglycemic medication and dementia subclass in type 2 diabetes mellitus using the Korean National Health Insurance System.

METHODS

This study included 701,193 individuals with diabetes prescribed dual oral therapy between 2009 and 2012 from the Korean National Health Insurance Service Database, which were tracked until 2017. All-cause, Alzheimer's (AD) and vascular dementia (VaD) were investigated by dual oral therapy. Adjustments were made for age, sex, income, diabetes duration, hypertension, dyslipidemia, smoking, drinking, exercise, body mass index, glucose level, and estimated glomerular filtration rate.

RESULTS

Dual therapy with metformin (Met) + dipeptidyl peptidase-4 inhibitor (DPP-4i), Met + thiazolidinedione (TZD), and sulfonylurea (SU) + thiazolidinediones (TZD) were significantly associated with all-cause dementia (HR = 0.904, 0.804, and 0.962, respectively) and VaD (HR = 0.865, 0.725, and 0.911, respectively), compared with Met + SU. Met + DPP-4i and Met + TZD were associated with significantly lower risk of AD (HR = 0.922 and 0.812), compared with Met + SU. Dual therapy with TZD was associated with a significantly lower risk of all-cause dementia, AD, and VaD than nonusers of TZD (HR = 0.918, 0.925 and 0.859, respectively).

CONCLUSION

Adding TZD or DPP-4i instead of SU as second-line anti-diabetic treatment may be considered for delaying or preventing dementia. Also, TZD users relative to TZD non-users on dual oral therapy were significantly associated with lower risk of various types of dementia.

Diabetes, Albuminuria and the Kidney-Brain Axis

Cognitive decline and kidney disease are significant public health problems that share similar characteristics and risk factors. The pathophysiology of the kidney-brain axis is not completely understood, and studies analysing the relationship between the biomarkers of kidney damage and cognitive impairment show different results. This article focuses on the epidemiological and clinical aspects concerning the association of albuminuria, a marker for endothelial dysfunction and microvascular disease, and cognitive impairment in patients with chronic kidney disease, diabetic kidney disease and end-stage kidney disease. Most studies show a positive relationship between albuminuria and cognitive impairment in all groups, but evidence in type 2 diabetes (T2D) patients is limited. We briefly discuss the mechanisms underlying these associations, such as damage to the microvascular circulation, leading to hypoperfusion and blood pressure fluctuations, as well as increased inflammation and oxidative stress, both in the brain and in the kidneys. Further clinical and epidemiological studies developed to understand the interplay between the kidneys and brain diseases will hopefully lead to a reduction in cognitive impairment in these patients.

Targeting impaired nutrient sensing with repurposed therapeutics to prevent or treat age-related cognitive decline and dementia: A systematic review

BACKGROUND

Dementia is a debilitating syndrome that significantly impacts individuals over the age of 65 years. There are currently no disease-modifying treatments for dementia. Impairment of nutrient sensing pathways has been implicated in the pathogenesis of dementia, and may offer a novel treatment approach for dementia.

AIMS

This systematic review collates all available evidence for Food and Drug Administration (FDA)-approved therapeutics that modify nutrient sensing in the context of preventing cognitive decline or improving cognition in ageing, mild cognitive impairment (MCI), and dementia populations.

METHODS

PubMed, Embase and Web of Science databases were searched using key search terms focusing on available therapeutics such as 'metformin', 'GLP1', 'insulin' and the dementias including 'Alzheimer's disease' and 'Parkinson's disease'. Articles were screened using Covidence systematic review software (Veritas Health Innovation, Melbourne, Australia). The risk of bias was assessed using the Cochrane Risk of Bias tool v 2.0 for human studies and SYRCLE's risk of bias tool for animal studies.

RESULTS

Out of 2619 articles, 114 were included describing 31 different 'modulation of nutrient sensing pathway' therapeutics, 13 of which specifically were utilized in human interventional trials for normal ageing or dementia. Growth hormone secretagogues improved cognitive outcomes in human mild cognitive impairment, and potentially normal ageing populations. In animals, all investigated therapeutic classes exhibited some cognitive benefits in dementia models. While the risk of bias was relatively low in human studies, this risk in animal studies was largely unclear.

CONCLUSIONS

Modulation of nutrient sensing pathway therapeutics, particularly growth hormone secretagogues, have the potential to improve cognitive outcomes. Overall, there is a clear lack of translation from animal models to human populations.

The Diabetes Syndrome - A Collection of Conditions with Common, Interrelated Pathophysiologic Mechanisms

The four basic pathophysiologic mechanisms which damage the β-cell within diabetes (ie, genetic and epigenetic changes, inflammation, an abnormal environment, and insulin resistance [IR]) also contribute to cell and tissue damage and elevate the risk of developing all typical diabetes-related complications. Genetic susceptibility to damage from abnormal external and internal environmental factors has been described including inflammation and IR. All these mechanisms can promote epigenetic changes, and in total, these pathophysiologic mechanisms interact and react with each other to cause damage to cells and tissues ultimately leading to disease. Importantly, these pathophysiologic mechanisms also serve to link other common conditions including cancer, dementia, psoriasis, atherosclerotic cardiovascular disease (ASCVD), nonalcoholic fatty liver disease (NAFLD), and nonalcoholic steatohepatitis (NASH). The “Diabetes Syndrome”, an overarching group of interrelated conditions linked by these overlapping mechanisms, can be viewed as a conceptual framework that can facilitate understanding of the inter-relationships of superficially disparate conditions. Recognizing the association of the conditions within the Diabetes Syndrome due to common pathophysiologies has the potential to provide both benefit to the patient (eg, prevention, early detection, precision medicine) and to the advancement of medicine (eg, driving education, research, and dynamic decision-based medical practice).

Association of ambient air pollution with cardiovascular disease risks in people with type 2 diabetes: a Bayesian spatial survival analysis

BACKGROUND

Evidence is limited on excess risks of cardiovascular diseases (CVDs) associated with ambient air pollution in diabetic populations. Survival analyses without considering the spatial structure and possible spatial correlations in health and environmental data may affect the precision of estimation of adverse environmental pollution effects. We assessed the association between air pollution and CVDs in type 2 diabetes through a Bayesian spatial survival approach.

METHODS

Taiwan's national-level health claims and air pollution databases were utilized. Fine individual-level latitude and longitude were used to determine pollution exposure. The exponential spatial correlation between air pollution and CVDs was analyzed in our Bayesian model compared to traditional Weibull and Cox models.

RESULTS

There were 2072 diabetic patients included in analyses. PM_2.5 and SO₂ were significant CVD risk factors in our Bayesian model, but such associations were attenuated or underestimated in traditional models; adjusted hazard ratio (HR) and 95% credible interval (CrI) or confidence interval (CI) of CVDs for a 1 μg/m³ increase in the monthly PM_2.5 concentration for our model, the Weibull and Cox models was 1.040 (1.004-1.073), 0.994 (0.984-1.004), and 0.994 (0.984-1.004), respectively. With a 1 ppb increase in the monthly SO₂ concentration, adjusted HR (95% CrI or CI) was 1.886 (1.642-2.113), 1.092 (1.022-1.168), and 1.091 (1.021-1.166) for these models, respectively.

CONCLUSIONS

Against traditional non-spatial analyses, our Bayesian spatial survival model enhances the assessment precision for environmental research with spatial survival data to reveal significant adverse cardiovascular effects of air pollution among vulnerable diabetic patients.

Does glitazone treatment have a role on the prevention of Parkinson's disease in adult diabetic population? A systematic review

Lately, focus on the relation between Parkinson's disease (PD) and Diabetes has risen greatly, as neuroprotective properties have been attributed to insulin use. Several studies have assessed the effect of glitazones, an insulin-sensitizing agent, in diabetic population on PD future risk. However, reports on the effect of their use have been heterogeneous. We aimed to synthesize the available scientific evidence which assesses the effect of glitazone use in type 2 diabetes patients on PD incidence. A systematic review was performed on multiple electronic databases. Considered for inclusion were studies that assessed the incidence of PD in type 2 diabetes glitazone users. Two reviewers worked independently and in duplicate to assess all studies, extract information and assess the methodological quality in each included study. Four high quality retrospective cohorts fulfilled inclusion criteria. Comparison groups varied across studies. In each study, incidence of PD was lower in glitazone-exposed patients compared to their respective comparison group. Pooled analysis showed lesser risk of PD in ever versus never glitazone users (RR 0.75 [95% C.I. 0.67-0.85; p < .0001; I² = 0]). Our pooled analysis showed lesser risk of PD in glitazone versus non glitazone users, however, we advise to take results with caution since results are non-adjusted to possible confounding variables, furthermore, different glitazone-exposure time, follow up and comparison groups are aspects that also need to be pointed out. More clinical research focused on glitazone use and its relation with PD is needed, as this could result in new potential treatment modalities.

Impact of antidiabetic agents on dementia risk: A Bayesian network meta-analysis

BACKGROUND

Dementia is more prevalent among people with type 2 diabetes, but little is known regarding the influence of antidiabetic agents on this association.

OBJECTIVE

This study assessed the impact of various antidiabetic agents on the risk of dementia among patients with Type 2 diabetes mellitus.

METHODS

Relevant studies were retrieved from the PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and ClinicalTrials.gov databases. Nine antidiabetic agents were included in the search. Data were pooled via network meta-analysis and meta-analysis.

RESULTS

Nine studies were selected for the network meta-analysis with 530,355 individuals and 17 studies for the meta-analysis with 1,258,879 individuals. The analysis excluded glucagon-like peptide 1 (GLP-1) analogs and sodium-dependent glucose transporter 2 (SGLT-2) inhibitors due to the absence of relevant data. The use of dipeptidyl peptidase-4 (DPP-4) inhibitors, metformin, thiazolidinedione, and sulfonylurea was associated with a decreased risk of dementia in comparison to no treatment with antidiabetic agents (hazard ratio [HR] for DPP-4 inhibitors, 0.54; 95% confidence interval [CI], 0.38-0.74, HR for metformin, 0.75; 95% CI, 0.63-0.86; HR for sulfonylurea, 0.85; 95%CI, 0.73-0.98 and HR for thiazolidinedione, 0.70; 95% CI, 0.55-0.89, respectively). However, the node-splitting analysis showed the inconsistency of direct and indirect estimates in sulfonylurea (P = 0.042). DPP-4 inhibitors, metformin, thiazolidinedione, and sulfonylurea exhibited a significant impact on the risk of dementia in diabetics compared with insulin (HR, 0.35; 95%CI, 0.20-0.59, HR, 0.48; 95% CI, 0.30-0.77, HR, 0.45; 95% CI, 0.29-0.73 and HR, 0.55; 95% CI, 0.34-0.88, respectively). DPP-4 inhibitors also exhibited a protective effect on the risk of Alzheimer's dementia compared with the no treatment with antidiabetic agents (HR, 0.48; 95% CI, 0.25-0.92). The meta-analysis demonstrated a protective effect of using metformin and DPP-4 inhibitors on the risk of dementia (HR, 0.86; 95% CI, 0.74-1.00 and HR, 0.65; 95% CI, 0.55-0.76, respectively). Further analysis showed insulin was associated with an increased risk of Alzheimer's dementia (HR, 1.60; 95% CI, 1.13-2.26). Only two case-control studies mentioned GLP-1 analogs and SGLT-2 inhibitors, and the pooled ORs showed no evidence of an association with dementia (GLP-1 analogs: 0.71; 95% CI, 0.46-1.10 and SGLT-2 inhibitors: 0.74; 95% CI, 0.47-1.15).

CONCLUSION

This analysis indicated that patients with type 2 diabetes under treatment with DPP-4 inhibitors presented with the lowest risk of dementia, followed by those treated with metformin and thiazolidinedione, while treatment with insulin was associated with the highest risk. For the increasing focus on the protective effect on dementia, further specific clinical studies are needed to evaluate the impact of GLP-1 analogs and SGLT-2 inhibitors on the risk of dementia.

Health Care Costs Associated With Macrovascular, Microvascular, and Metabolic Complications of Type 2 Diabetes Across Time: Estimates From a Population-Based Cohort of More Than 0.8 Million Individuals With Up to 15 Years of Follow-up

OBJECTIVE

Developing country-specific unit-cost catalogs is a key area for advancing economic research to improve medical and policy decisions. However, little is known about how health care costs vary by type 2 diabetes (T2D) complications across time in Asian countries. We sought to quantify the economic burden of various T2D complications in Taiwan.

RESEARCH DESIGN AND METHODS

A nationwide, population-based, longitudinal study was conducted to analyze 802,429 adults with newly diagnosed T2D identified during 1999-2010 and followed up until death or 31 December 2013. Annual health care costs associated with T2D complications were estimated, with multivariable generalized estimating equation models adjusted for individual characteristics.

RESULTS

The mean annual health care cost was $281 and $298 (2017 U.S. dollars) for a male and female, respectively, diagnosed with T2D at age <50 years, with diabetes duration of <5 years, and without comorbidities, antidiabetic treatments, and complications. Depression was the costliest comorbidity, increasing costs by 64-82%. Antidiabetic treatments increased costs by 72-126%. For nonfatal complications, costs increased from 36% (retinopathy) to 202% (stroke) in the event year and from 13% (retinopathy or neuropathy) to 49% (heart failure) in subsequent years. Costs for the five leading costly nonfatal subtype complications increased by 201-599% (end-stage renal disease with dialysis), 37-376% (hemorrhagic/ischemic stroke), and 13-279% (upper-/lower-extremity amputation). For fatal complications, costs increased by 1,784-2,001% and 1,285-1,584% for cardiovascular and other-cause deaths, respectively.

CONCLUSIONS

The cost estimates from this study are crucial for parameterizing diabetes economic simulation models to quantify the economic impact of clinical outcomes and determine cost-effective interventions.

Diabetes and dementia - the two faces of Janus

Patients with type 2 diabetes are at high risk for cognitive decline and dementia. Despite the limited data on the possible pathogenetic mechanisms, evidence suggests that cognitive decline, and thus dementia and Alzheimer’s disease, might arise from a complex interplay between type 2 diabetes and the aging brain, including decreased insulin signalling and glucose metabolism, mitochondrial dysfunction, neuroinflammation, and vascular disease. Furthermore, there is increasing interest on the effects of antidiabetic agents on cognitive decline. There are many studies showing that antidiabetic agents might have beneficial effects on the brain, mainly through inhibition of oxidative stress, inflammation, and apoptosis. In addition, experimental studies on patients with diabetes and Alzheimer’s disease have shown beneficial effects on synaptic plasticity, metabolism of amyloid-β, and microtubule-associated protein tau. Therefore, in the present review, we discuss the effects of antidiabetic agents in relation to cognitive decline, and in particular dementia and Alzheimer’s disease, in patients with type 2 diabetes.

Comparative cardiovascular safety of GLP-1 receptor agonists versus other glucose-lowering agents in real-world patients with type 2 diabetes: a nationwide population-based cohort study

Background

Current evidence about the cardiovascular safety of glucagon-like peptide-1 receptor agonist (GLP-1ra) possesses limited generalizability to real-world patients with type 2 diabetes (T2D) in usual practice. This study aimed to investigate the comparative cardiovascular safety of GLP-1ra in comparisons with dipeptidyl peptidase-4 inhibitor (DPP-4i), sulfonylurea (SU), and insulin in a real-world population with T2D.

Methods

Adults with newly-diagnosed T2D were identified from Taiwan’s National Health Insurance Research Database in 2003–2014. A prevalent new-user cohort design was adopted to include a broad representation of real-world T2D patients being treated with GLP-1ra. The between-group comparability of baseline patient characteristics was achieved by matching on (1) initiation time of study drugs, (2) prior exposure to glucose-lowering agents, and (3) diabetes severity and complications, comorbidities, and concomitant cardiovascular medications using propensity scores. The primary outcome was a composite of cardiovascular disease (CVD) events and assessed up to the end of 2015. Cox modeling was employed to assess the association between study drugs and outcomes.

Results

A total of 3195 GLP-1ra stable users was identified in 2011-2014. 1893, 1829, and 1367 GLP-1ra stable users were 1:1 matched to DPP-4i, SU and insulin users, respectively. Compared to DPP-4i, SU and insulin, the use of GLP-1ra was associated with a lower risk of composite CVD events [hazard ratio (95% confidence interval) 0.73 (0.57–0.96), 0.76 (0.57–1.00), and 0.81 (0.62–1.07), respectively]. Subgroup analyses revealed that GLP-1ra versus DPP-4i yielded a greater cardiovascular benefit in those without established CVD versus those with established CVD.

Conclusions

This comparison study extends the supporting evidence for the cardiovascular safety of GLP-1ra to a broad spectrum of real-world T2D patients using GLP-1ra.

Parkinson's disease treatment: past, present, and future

The substantial contributions of Dr. Gerald Stern to past and current treatments for Parkinson's disease patients are reviewed, which form the foundation for an evaluation of future options to control symptoms and halt progression of the disease. These opportunities will depend on a greater understanding of the relative contributions of the environment, genetic and epigenetic influences to disease onset, and promise to emerge as strategies for improving mitochondrial function, halting accumulation of synuclein and neuromelanin, in addition to refinement of stem cell and gene therapies. Such advances will be achieved through deployment of improved models for the disease.

Association Between the Use of Antihyperglycemic Drugs and Dementia Risk: A Case-Control Study

BACKGROUND

There is a conflicting literature on the association between the use of antihyperglycemic drugs and dementia risk.

OBJECTIVE

The goal of this case-control study was to analyze the association between the use of antihyperglycemic drugs and dementia risk in patients followed in general practices in Germany.

METHODS

This study included patients with type 2 diabetes mellitus who had received a first dementia diagnosis in 972 general practices in Germany between January 2013 and December 2017 (index date). Controls without dementia were matched (1:1) to cases by age, gender, index year, and physician. Two multivariate regression models were used to study the association between the use of antihyperglycemic drugs and dementia risk. Model 1 included all antihyperglycemic drugs prescribed to patients regardless of the prescription duration, whereas Model 2 only included the longest therapy prescribed to each patient.

RESULTS

There were 8,276 diabetes patients with dementia and 8,276 diabetes patients without dementia included in this study. In Model 1, glitazones were associated with a decreased dementia risk (odds ratio [OR] = 0.80), whereas insulin was associated with an increased risk of developing the condition (OR = 1.34). In Model 2, metformin, prescribed as monotherapy (OR = 0.71) or as dual therapy with sulfonylureas (OR = 0.90), was associated with a decrease in the likelihood of subsequently being diagnosed with dementia. By contrast, the combination of basal insulin and bolus insulin (OR = 1.47) and premix insulin (OR = 1.33) were risk factors for dementia.

CONCLUSION

Metformin and glitazones were negatively associated with dementia, while insulin was positively associated with dementia.

Investigating the Relationship Between Type 2 Diabetes and Dementia Using Electronic Medical Records in the GoDARTS Bioresource

OBJECTIVE

To investigate the impact of type 2 diabetes on incidence of major dementia subtypes, Alzheimer and vascular dementia, using electronic medical records (EMR) in the GoDARTS bioresource.

RESEARCH DESIGN AND METHODS

GoDARTS (Genetics of Diabetes Audit and Research in Tayside Scotland) comprises a large case-control study of type 2 diabetes with longitudinal follow-up in EMR. Dementia case subjects after recruitment were passively identified in the EMR, and using a combination of case note review, an Alzheimer-specific weighted genetic risk score (wGRS), and APOE4 genotype, we validated major dementia subtypes. We undertook a retrospective matched cohort study to determine the risk of type 2 diabetes status for incident dementia accounting for competing risk of death.

RESULTS

Type 2 diabetes status was associated with a significant risk of any dementia (cause-specific hazard ratio [csHR] 1.46, 95% CI 1.31-1.64), which was attenuated, but still significant, when competing risk of death was accounted for (subdistribution [sd]HR 1.26, 95% CI 1.13-1.41). The accuracy of EMR-defined cases of Alzheimer or vascular dementia was high-positive predictive value (PPV) 86.4% and PPV 72.8%, respectively-and wGRS significantly predicted Alzheimer dementia (HR 1.23, 95% CI 1.12-1.34) but not vascular dementia (HR 1.02, 95% CI 0.91-1.15). Conversely, type 2 diabetes was strongly associated with vascular dementia (csHR 2.47, 95% C 1.92-3.18) but not Alzheimer dementia, particularly after competing risk of death was accounted for (sdHR 1.02, 95% CI 0.87-1.18).

CONCLUSIONS

Our study indicates that type 2 diabetes is associated with an increased risk of vascular dementia but not with an increased risk of Alzheimer dementia and highlights the potential value of bioresources linked to EMR to study dementia.

The effect of mid-life insulin resistance and type 2 diabetes on older-age cognitive state: the explanatory role of early-life advantage

AIMS/HYPOTHESIS

Type 2 diabetes, hyperglycaemia and insulin resistance are associated with cognitive impairment and dementia, but causal inference studies using Mendelian randomisation do not confirm this. We hypothesised that early-life cognition and social/educational advantage may confound the relationship.

METHODS

From the population-based British 1946 birth cohort, a maximum number of 1780 participants had metabolic variables (type 2 diabetes, insulin resistance [HOMA2-IR] and HbA1c) assessed at age 60-64 years, and cognitive state (Addenbrooke's Cognitive Examination III [ACE-III]) and verbal memory assessed at age 69 years. Earlier-life measures included socioeconomic position (SEP), cognition at age 8 years and educational attainment. Polygenic risk scores (PRSs) for type 2 diabetes were calculated. We first used a PRS approach with multivariable linear regression to estimate associations between PRSs and metabolic traits and later-life cognitive state. Second, using a path model approach, we estimated the interrelationships between earlier-life measures, features of mid-life type 2 diabetes and cognitive state at age 69 years. All models were adjusted for sex.

RESULTS

The externally weighted PRS for type 2 diabetes was associated with mid-life metabolic traits (e.g. HOMA2-IR β = 0.08 [95% CI 0.02, 0.16]), but not with ACE-III (β = 0.04 [-0.02, 0.90]) or other cognitive outcomes. While there was an association between HOMA2-IR and subsequent ACE-III (β = -0.09 [-0.15, -0.03]), path modelling showed no direct effect (β = -0.01 [-0.06, 0.03]) after accounting for the association between childhood SEP and education with HOMA2-IR. The same pattern was observed for later-life verbal memory.

CONCLUSIONS/INTERPRETATION

Associations between type 2 diabetes and mid-life metabolic traits with subsequent cognitive state do not appear causal, and instead they may be explained by SEP in early life, childhood cognition and educational attainment. Therefore, glucose-lowering medication may be unlikely to combat cognitive impairment in older age.

Different treatment forms of type II diabetes and the risk of dementia in German health claims data

AIMS

The association between type II diabetes (T2D) and increased all-cause dementia risk is well established. However, to date, there is no definite proof that a specific therapy for diabetes can halt a progress of cognitive decline. Therefore, we analyzed a large longitudinal random sample of German health claims data to focus on associations between T2D and dementia and to elucidate the role of different treatment forms of T2D on the risk for dementia.

METHODS

We used a longitudinal random sample (n = 250,000) of claims data of the largest public sickness fund in Germany, the Allgemeine Ortskrankenkasse (AOK). Dementia was defined as ICD-10 codes G31.0, G31.82, G23.1, F00, F01, F02, F03, and F05, and T2D was defined as E11-E14. We performed Cox proportional hazard models to explore the transition into dementia and to calculate the relative risk of dementia dependent on T2D and different T2D treatment forms.

RESULTS

All models were adjusted for sex, age, and each patient's history of depression, renal insufficiency, and cardiovascular comorbidities. Non-pharmacologic-treated diabetics showed a 23% increased dementia risk (p < 0.001) and oral ADM-treated diabetics showed a 16% increased risk (p < 0.001). Insulin-dependent diabetics is still the highest dementia risk (40%; p < 0.001) and obesity additionally attenuated this risk (75%; p < 0.001) increased risk.

CONCLUSIONS

We found that diabetes is an independent risk factor for all-cause dementia. An increased risk for dementia in insulin-dependent and obese subjects with diabetes was evident. Longitudinal studies on the effect of different forms of therapy and weight reduction are needed to verify the results of this study.

The Emerging Roles of Ferroptosis in Vascular Cognitive Impairment

Vascular cognitive impairment (VCI) is a clinical syndrome that encompasses all forms of cognitive deficits caused by cerebrovascular disease, from mild cognitive impairment to dementia. Vascular dementia, the second most common type of dementia after Alzheimer’s disease (AD), accounts for approximately 20% of dementia patients. Ferroptosis is a recently defined iron-dependent form of cell death, which is distinct from apoptosis, necrosis, autophagy, and other forms of cell death. Emerging evidence suggests that ferroptosis has significant implications in neurological diseases such as stroke, traumatic brain injury, and AD. Additionally, ferroptosis inhibition has an obvious neuroprotective effect and ameliorates cognitive impairment in various animal models. Here, we summarize the underlying mechanisms of ferroptosis and review the close relationship between ferroptosis and VCI.

Diabetes Therapies for Dementia

PURPOSE OF REVIEW

Type 2 diabetes (T2D) is a well-established risk factor for the development of dementia. Dementia and T2D share some underlying pathophysiology that has led to interest in the potential to repurpose drugs used in the management of T2D to benefit brain health. This review describes the scientific data available on the use of T2D medications for the risk reduction or management of dementia, in people with and without T2D.

RECENT FINDINGS

Results from basic laboratory research support the potential for commonly-used medications for T2D, including those with direct glucose-lowering properties, to have a beneficial effect on brain health. However, human studies have been mostly observational in nature and report conflicting results. Preliminary data suggest that intranasal insulin, metformin, and GLP-1 agonists show promise for dementia, but confirmatory evidence for their benefit in dementia is still lacking. Current evidence does not support the repurposing of T2D medications for dementia risk reduction or management. Research in the field of T2D and dementia is active, and further data are required before definitive conclusions can be drawn.

Sweet Mitochondria: A Shortcut to Alzheimer's Disease

A growing body of evidence supports a clear association between Alzheimer's disease and diabetes and several mechanistic links have been revealed. This paper is mainly devoted to the discussion of the role of diabetes-associated mitochondrial defects in the pathogenesis of Alzheimer's disease. The research experience and views of the author on this subject will be highlighted.

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

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

Pioglitazone Reduces Dementia Risk in Patients with Type 2 Diabetes Mellitus: A Retrospective Cohort Analysis

BACKGROUND

The beneficial effect of pioglitazone on dementia requires confirmation.

METHODS

The database of Taiwan's National Health Insurance was used to enroll a propensity score-matched-pair cohort of patients who had ever used pioglitazone and patients who had never used pioglitazone from Taiwanese patients with newly diagnosed diabetes mellitus during 1999⁻2008. The patients were to be alive on 1 January 2009 and were followed up for dementia until 31 December 2011. Hazard ratios were estimated using the Cox proportional hazards model.

RESULTS

There were 11,011 never users and 11,011 ever users of pioglitazone, with respective numbers of incident dementia of 123 and 91. The overall hazard ratio was 0.716 (95% confidence interval: 0.545⁻0.940) for ever users versus never users. The hazard ratios for the first (<11.0 months), second (11.0⁻19.6 months) and third (>19.6 months) tertiles of cumulative duration were 0.806 (0.544⁻1.193), 0.654 (0.430⁻0.994) and 0.694 (0.469⁻1.026), respectively. When cumulative duration was treated as a continuous variable, the hazard ratio was 0.987 (0.976⁻0.998). In subgroup analyses, the beneficial effect was mainly observed in patients who had not been treated with metformin. Among metformin ever users, the hazard ratio for dementia for pioglitazone ever users versus never users was 0.802 (0.580⁻1.109); and was 0.494 (0.284⁻0.857) among never users of metformin. No interaction between pioglitazone and major risk factors of dementia (i.e., stroke, hypoglycemia, head injury and Parkinson's disease) was observed.

CONCLUSIONS

Pioglitazone use is associated with a lower risk of dementia, especially when it is used in never users of metformin and has been used for more than 20 months.