Serum Soluble Adhesion Molecules and Markers of Systemic Inflammation in Elderly Diabetic Patients with Mild Cognitive Impairment and Depressive Symptoms

Associations Between Neuropsychiatric Symptoms and Inflammation in Neurodegenerative Dementia: A Systematic Review

Background

Neuropsychiatric symptoms are common in dementia and linked to adverse outcomes. Inflammation is increasingly recognized as playing a role as a driver of early disease progression in Alzheimer's disease (AD) and related dementias. Inflammation has also been linked to primary psychiatric disorders, however its association with neuropsychiatric symptoms in neurodegenerative dementias remains uncertain.

Methods

We conducted a systematic literature review investigating associations between inflammation and neuropsychiatric symptoms in neurodegenerative dementias, including AD, Lewy body, Frontotemporal, Parkinson's (PD) and Huntington's disease dementias.

Results

Ninety-nine studies met our inclusion criteria, and the majority (n = 59) investigated AD and/or mild cognitive impairment (MCI). Thirty-five studies included PD, and only 6 investigated non-AD dementias. Inflammation was measured in blood, CSF, by genotype, brain tissue and PET imaging. Overall, studies exhibited considerable heterogeneity and evidence for specific inflammatory markers was inconsistent, with lack of replication and few longitudinal studies with repeat biomarkers. Depression was the most frequently investigated symptom. In AD, some studies reported increases in peripheral IL-6, TNF-a associated with depressive symptoms. Preliminary investigations using PET measures of microglial activation found an association with agitation. In PD, studies reported positive associations between TNF-a, IL-6, CRP, MCP-1, IL-10 and depression.

Conclusion

Central and peripheral inflammation may play a role in neuropsychiatric symptoms in neurodegenerative dementias; however, the evidence is inconsistent. There is a need for multi-site longitudinal studies with detailed assessments of neuropsychiatric symptoms combined with replicable peripheral and central markers of inflammation.

Depression and Eye Disease-A Narrative Review of Common Underlying Pathophysiological Mechanisms and their Potential Applications

Background: Depression has been shown to be associated with eye diseases, including dry eye disease (DED), cataracts, glaucoma, age-related macular degeneration (AMD), and diabetic retinopathy (DR). This narrative review explores potential pathophysiological connections between depression and eye disease, as well as its potential correlations with ocular parameters. Methods: A literature search was conducted in August 2022 in PUBMED, EMBASE, and PsycINFO. Published articles related to the subject were consolidated and classified according to respective eye diseases and pathophysiological mechanisms. Results: The literature reviewed suggests that common pathophysiological states like inflammation and neurodegeneration may contribute to both depression and certain eye diseases, while somatic symptoms and altered physiology, such as disruptions in circadian rhythm due to eye diseases, can also influence patients' mood states. Grounded in the shared embryological, anatomical, and physiological features between the eye and the brain, depression is also correlated to changes observed in non-invasive ophthalmological imaging modalities, such as changes in the retinal nerve fibre layer and retinal microvasculature. Conclusions: There is substantial evidence of a close association between depression and eye diseases. Understanding the underlying concepts can inform further research on treatment options and monitoring of depression based on ocular parameters.

Correlation between inflammatory biomarkers, cognitive function and glycemic and lipid profiles in patients with type 2 diabetes mellitus: A systematic review and meta-analysis

This study aimed to quantitatively estimate the correlation between systemic inflammation with cognitive function, as well as glycemic and lipid profiles in patients with type 2 diabetes mellitus (T2DM). The PubMed, Web of Science, EMBASE, SCOPUS, CNKI, Wanfang, VIP, and CBM databases were searched from its inception until June 2023 (PROSPERO registration: CRD42022356889). We analyzed data extracted from observational studies to quantify the correlations (r) as the pooled effect size and further performed subgroup analyses and sensitivity analyses. A total of 32 studies involving 7,483 patients with T2DM were included. The findings revealed a significant moderate negative correlation between interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and C-reactive protein (CRP) levels with Montreal Cognitive Assessment scores. TNF-α levels also had moderate negative correlation with Mini-Mental State Examination scores. For glycemic and lipid profiles, there was a significant moderate positive correlation between CRP and TNF-α levels and glycated hemoglobin (HbA1c), and TNF-α levels were also found to be lowly positively correlated with fasting blood glucose (FBG). CRP levels were found to have a low positive correlation with total cholesterol (TC), and IL-6 levels were found to be lowly positively correlated with triglycerides. The results indicate that elevated levels of IL-6, CRP, and TNF-α are significantly associated with cognitive impairment in patients with T2DM and may serve as inflammatory markers for T2DM with mild cognitive impairment. The CRP and TNF-α levels were more strongly correlated with HbA1c than with FBG and TC. Further research is needed to determine the clinical value of these inflammatory biomarkers and to investigate potential causal mechanisms underlying this association.

Inflammatory markers in type 2 diabetes with vs. without cognitive impairment; a systematic review and meta-analysis

People with type 2 diabetes mellitus (T2DM) are at increased risk of mild cognitive impairment and dementia. Systemic inflammation has been proposed as a common risk factor. This study aimed to summarize the clinical data pertaining to peripheral blood inflammatory markers. We identified original peer-reviewed articles reporting blood inflammatory marker concentrations in groups of people with a T2DM diagnosis who have cognitive impairment (CI; including mild cognitive impairment, Alzheimer's disease, vascular cognitive impairment) vs. normal cognition (NC). Between-group standardized mean differences (SMD) were summarized in random effects meta-analyses. From 2108 records, data were combined quantitatively from 40 studies. Concentrations of interleukin-6 (IL-6; N_CI/N_NC = 934/3154, SMD 0.74 95% confidence interval [0.07, 1.42], Z₅ = 2.15, p = 0.03; I² = 98.08%), C-reactive protein (CRP; N_CI/N_NC = 1610/4363, SMD 0.80 [0.50, 1.11], Z₁₄ = 5.25, p < 0.01; I² = 94.59%), soluble vascular cell adhesion molecule-1 (sVCAM-1; N_CI/N_NC = 104/1063, SMD 1.64 95% confidence interval [0.21, 3.07], Z₂ = 2.25, p = 0.02; I² = 95.19%), and advanced glycation end products (AGEs; N_CI/N_NC = 227/317, SMD 0.84 95% confidence interval [0.41, 1.27], Z₂ = 3.82, p < 0.01; I² = 81.07%) were higher among CI groups compared to NC. Brain derived neurotropic factor (BDNF) concentrations were significantly lower in CI compared to NC (N_CI/N_NC = 848/2063, SMD -0.67 95% confidence interval [-0.99, -0.35], Z₃ = -4.09, p < 0.01; I² = 89.20%). Cognitive impairment among people with T2DM was associated with systemic inflammation and lower BDNF concentrations. These inflammatory characteristics support an increased inflammatory-vascular interaction associated with cognitive impairment in T2DM. PROSPERO (CRD42020188625).

Vascular and blood-brain barrier-related changes underlie stress responses and resilience in female mice and depression in human tissue

Prevalence, symptoms, and treatment of depression suggest that major depressive disorders (MDD) present sex differences. Social stress-induced neurovascular pathology is associated with depressive symptoms in male mice; however, this association is unclear in females. Here, we report that chronic social and subchronic variable stress promotes blood-brain barrier (BBB) alterations in mood-related brain regions of female mice. Targeted disruption of the BBB in the female prefrontal cortex (PFC) induces anxiety- and depression-like behaviours. By comparing the endothelium cell-specific transcriptomic profiling of the mouse male and female PFC, we identify several pathways and genes involved in maladaptive stress responses and resilience to stress. Furthermore, we confirm that the BBB in the PFC of stressed female mice is leaky. Then, we identify circulating vascular biomarkers of chronic stress, such as soluble E-selectin. Similar changes in circulating soluble E-selectin, BBB gene expression and morphology can be found in blood serum and postmortem brain samples from women diagnosed with MDD. Altogether, we propose that BBB dysfunction plays an important role in modulating stress responses in female mice and possibly MDD.

The montreal cognitive assessment and mini-mental state examination visuoexecutive subtests in acute ischemic stroke patients and their correlations with demographic and clinical factors

Visuoexecutive impairment is common among acute ischemic stroke patients. This study aimed to examine the ability of the Montreal Cognitive Assessment (MoCA) and Mini-Mental State Examination (MMSE) visuoexecutive subtests to detect visuoexecutive abnormality in acute ischemic stroke patients and to identify the predictors for their impairments. 336 patients who completed the MMSE and MoCA were enrolled in this study. We compared the proportion of participants with incorrect MoCA visuoexecutive tasks and MMSE pentagon copying. Multivariate logistic regression analysis was used to evaluate the associations between the visuoexecutive dysfunction and demographic and clinical characteristics in the samples. Among all the participants, the MoCA detected more visuoexecutive dysfunction than the MMSE (88.69% vs. 45.83%, respectively; p < 0.001). The predictors identified by the univariate analysis included the factors of gender, age, educational level, smoking, alcohol consumption, Oxfordshire Community Stroke Project (OCSP), previous strokes, initial NIHSS score and number of old lacunar infarctions, while from the multivariate logistic regression analysis, the factors of age, educational level, NIHSS score, previous strokes and number of old lacunar infarctions served as predictive factors for the visuoexecutive impairment in acute stroke patients. In conclusion, visuoexecutive impairment is associated with the factors of the educational level, stroke severity, stroke history and number of old lacunar infarctions. Our findings may guide the clinicians to intervene the risks for the patients at an early stage after stroke and form the basis for good rehabilitation plans.

Molecular changes associated with spinal cord aging

Age-related muscle weakness and loss of muscle mass (sarcopenia) is a universal problem in the elderly. Our previous studies indicate that alpha motor neurons (α-MNs) play a critical role in this process. The goal of the current study is to uncover changes in the aging spinal cord that contribute to loss of innervation and the downstream degenerative processes that occur in skeletal muscle. The number of α-MNs is decreased in the spinal cord of wildtype mice during aging, beginning in middle age and reaching a 41% loss by 27 months of age. There is evidence for age-related loss of myelin and mild inflammation, including astrocyte and microglia activation and an increase in levels of sICAM-1. We identified changes in metabolites consistent with compromised neuronal viability, such as reduced levels of N-acetyl-aspartate. Cleaved caspase-3 is more abundant in spinal cord from old mice, suggesting that apoptosis contributes to neuronal loss. RNA-seq analysis revealed changes in the expression of a number of genes in spinal cord from old mice, in particular genes encoding extracellular matrix components (ECM) and a 172-fold increase in MMP-12 expression. Furthermore, blood-spinal cord barrier (BSCB) permeability is increased in old mice, which may contribute to alterations in spinal cord homeostasis and exacerbate neuronal distress. Together, these data show for the first time that the spinal cord undergoes significant changes during aging, including progressive α-MNs loss that is associated with low-grade inflammation, apoptosis, changes in ECM, myelination, and vascular permeability.

The activation of immunoglobulin G Fc receptors (FcγRs) with immunoreceptor tyrosine-based activation motifs (ITAMs) promotes cognitive impairment in aged rats with diabetes

AIMS

Although immunoglobulin G Fc receptors with immunoreceptor tyrosine-based activation motifs (ITAM-FcγRs) have been implicated in the mediation of inflammatory responses, the importance of these receptors in the pathogenesis of cognitive impairment in geriatric diabetes remains unclear. The present study investigated the potential role of ITAM-FcγRs in cognitive impairment in geriatric diabetes.

METHODS

Diabetes was induced by streptozotocin (STZ) in aged Wistar rats, and cognitive function and cerebral injury were assessed 8 weeks later using the Morris water maze (MWM), real-time PCR and Western blot. In vitro, the inhibition of ITAM-FcγRs was investigated using rat chromaffin cells cultured with high glucose.

RESULTS

Aged rats with diabetes exhibited marked and persistent learning and memory impairments. Enhanced cerebral inflammation in the diabetic aged rats was associated with the overactivation of the nuclear factor κB (NF-κB) signaling pathway and the upregulation of inflammatory cytokines (interleukin-6 (IL-6) and tumor nuclear factor-α (TNF-α)) in the hippocampus. Compared to no treatment, the knockdown of FcγRIV (the main isoform of ITAM-FcγRs) markedly attenuated cognitive impairment as well as histologic and ultrastructural pathologic changes in the diabetic rats. The increased expression of inflammatory cytokines and the overactivation of the NF-κB signaling pathway were also significantly alleviated. In vitro, high glucose concentrations significantly activated the NF-κB signaling pathway and increased the expression of inflammatory cytokines. The inhibition of FcγR expression by a small interfering RNA and/or a FcγRI- and FcγRIII-neutralizing antibody significantly ameliorated the effects mediated by high glucose.

CONCLUSION

The enhanced activation of the NF-κB signalling pathway may be the mechanism by which ITAM-FcγRs promote cerebral inflammation and cognitive impairment in diabetes. ITAM-FcγRs may be viewed as a potential target for preventative intervention for cognitive impairment in older adults with diabetes.

Evaluating Longitudinal Associations Between Depressive Symptoms, Smoking, and Biomarkers of Cardiovascular Disease in the CARDIA Study

OBJECTIVE

The aim of the study was to evaluate associations between 15-year trajectories of co-occurring depressive symptoms and smoking with biomarkers of cardiovascular disease at year 15.

METHODS

In the Coronary Artery Risk Development in Young Adults study, we modeled trajectories of depressive symptoms (Center for Epidemiologic Studies-Depression scale [CES-D]) and smoking (cigarettes per day [CPD]) among 3614 adults followed from year 0 (ages 18-30 years) through year 15 (ages 33-45 years). Biomarkers of inflammation (high-sensitivity C-reactive protein), oxidative stress (superoxide dismutase, F2-isoprostanes), and endothelial dysfunction (soluble intercellular adhesion molecule 1, soluble P-selectin) were assessed at year 15. We conducted separate linear regression analyses with CES-D trajectory, CPD trajectory, and their interaction with each of the five biomarkers.

RESULTS

The sample was 56% women, 47% black, and 40 years old on average at year 15. The CES-D trajectory by CPD trajectory interaction was not associated with any of the biomarkers (all p's > .01). Removing the interaction term, CES-D trajectory was associated with inflammation: higher levels of high-sensitivity C-reactive protein were observed in the subthreshold (β = 0.57, p = .004) and increasing depressive symptoms (β = 1.36, p < .001) trajectories compared with the no depression trajectory. CPD trajectory was associated with oxidative stress and endothelial dysfunction: compared with never smokers, heavy smokers had significantly higher levels of F2-isoprostanes (β = 6.20, p = .001), soluble intercellular adhesion molecule 1 (β = 24.98, p < .001), and soluble P-selectin (β = 2.91, p < .001).

CONCLUSIONS

Co-occurring depressive symptoms and smoking do not seem to synergistically convey risk for cardiovascular disease via processes of inflammation, oxidative stress, or endothelial dysfunction. Nonetheless, these results advance our understanding of the complex relationships between modifiable risk factors and chronic disease.

Esculin ameliorates cognitive impairment in experimental diabetic nephropathy and induces anti-oxidative stress and anti-inflammatory effects via the MAPK pathway

Esculin is a derivative of coumarin, which is also an active ingredient of ash bark, and has antibacterial, anti-inflammatory, anti‑allergy and skin protective effects. The underlying mechanism and protective effects of esculin on cognitive impairment in experimental diabetic nephropathy (DN) was investigated in the present study. Male C57BL/6J 6‑week‑old mice were injected intravenously with a single dose of streptozotocin (STZ; 30 mg/kg). At 2 weeks after the STZ injection, mice received intravenous injection with 5, 10 or 20 mg/kg esculin for 2 weeks. In the present study, the results of the Morris water maze test demonstrated that esculin significantly improved behavior and recognition memory in STZ‑induced diabetic rats. Furthermore, treatment of STZ‑induced diabetic rats with esculin significantly inhibited tumor necrosis factor‑α, interleukin‑6, malondialdehyde, monocyte chemoattractant protein‑1 and intracellular adhesion molecule‑1 activity levels, and increased the activity of superoxide dismutase, in the kidney, which was determined by ELISA. In addition, esculin treatment significantly suppressed the renal protein expression of activator protein 1, phosphorylated (p)‑p38 mitogen activated protein kinase (MAPK) and p‑c‑Jun N‑terminal kinase, and increased p‑extracellular signal regulated kinase 1/2 protein expression, in STZ‑induced diabetic rats, as determined by western blotting. These results indicate that esculin may ameliorate cognitive impairment in experimental DN, and exert anti‑oxidative stress and anti‑inflammatory effects, via the MAPK signaling pathway. Thus, it may serve as a potential target for cognitive impairment of DN in the future.

Biomarkers for cognitive decline in patients with diabetes mellitus: evidence from clinical studies

Diabetes mellitus is considered as an important factor for cognitive decline and dementia in recent years. However, cognitive impairment in diabetic patients is often underestimated and kept undiagnosed, leading to thousands of diabetic patients suffering from worsening memory. Available reviews in this field were limited and not comprehensive enough. Thus, the present review aimed to summarize all available clinical studies on diabetic patients with cognitive decline, and to find valuable biomarkers that might be applied as diagnostic and therapeutic targets of cognitive impairment in diabetes. The biomarkers or risk factors of cognitive decline in diabetic patients could be classified into the following three aspects: serum molecules or relevant complications, functional or metabolic changes by neuroimaging tools, and genetic variants. Specifically, factors related to poor glucose metabolism, insulin resistance, inflammation, comorbid depression, micro-/macrovascular complications, adipokines, neurotrophic molecules and Tau protein presented significant changes in diabetic patients with cognitive decline. Besides, neuroimaging platform could provide more clues on the structural, functional and metabolic changes during the cognitive decline progression of diabetic patients. Genetic factors related to cognitive decline showed inconsistency based on the limited studies. Future studies might apply above biomarkers as diagnostic and treatment targets in a large population, and regulation of these parameters might shed light on a more valuable, sensitive and specific strategy for the diagnosis and treatment of cognitive decline in diabetic patients.

Seeking a New Paradigm for Alzheimer's Disease: Considering the Roles of Inflammation, Blood-Brain Barrier Dysfunction, and Prion Disease

There is no effective etiologic treatment for Alzheimer's disease, nor is there a prophylactic medication which delays or prevents its onset. The lack of an accurate paradigm is undoubtedly related to the lack of effective means of prophylaxis and treatment. The current paradigm of beta amyloid in Alzheimer's brains causing cognitive dysfunction must be modified. Despite failed clinical trials, research continues into amyloid-oriented treatments. The persistence of the amyloid hypothesis/paradigm is an example of anchoring and representativeness heuristics described by Kahneman and Tversky in their classic 1974 Science paper. Economic factors also contribute to the persistence of this paradigm. Paradigms impact the scientific process by the following: (1) what is studied; (2) the types of questions that are asked; (3) the structure and nature of the questions; (4) the interpretations of research findings. We review the contribution of inflammation, malfunction of the neurovascular unit, and prion disease to Alzheimer's disease manifestations. Any or all of these are candidates for inclusion into a more accurate, inclusive, and useful new paradigm. By incorporating emerging facts and understanding into a new paradigm, we will enhance our ability to move toward effective prophylaxis and therapy for this tragic disease.