Dietary salt promotes cognition impairment through GLP-1R/mTOR/p70S6K signaling pathway

Dietary salt has been associated with cognitive impairment in mice, possibly related to damaged synapses and tau hyperphosphorylation. However, the mechanism underlying how dietary salt causes cognitive dysfunction remains unclear. In our study, either a high-salt (8%) or normal diet (0.5%) was used to feed C57BL/6 mice for three months, and N2a cells were cultured in normal medium, NaCl medium (80 mM), or NaCl (80 mM) + Liraglutide (200 nM) medium for 48 h. Cognitive function in mice was assessed using the Morris water maze and shuttle box test, while anxiety was evaluated by the open field test (OPT). Western blotting (WB), immunofluorescence, and immunohistochemistry were utilized to assess the level of Glucagon-like Peptide-1 receptor (GLP-1R) and mTOR/p70S6K pathway. Electron microscope and western blotting were used to evaluate synapse function and tau phosphorylation. Our findings revealed that a high salt diet (HSD) reduced the level of synaptophysin (SYP) and postsynaptic density 95 (PSD95), resulting in significant synaptic damage. Additionally, hyperphosphorylation of tau at different sites was detected. The C57BL/6 mice showed significant impairment in learning and memory function compared to the control group, but HSD did not cause anxiety in the mice. In addition, the level of GLP-1R and autophagy flux decreased in the HSD group, while the level of mTOR/p70S6K was upregulated. Furthermore, liraglutide reversed the autophagy inhibition of N2a treated with NaCl. In summary, our study demonstrates that dietary salt inhibits the GLP-1R/mTOR/p70S6K pathway to inhibit autophagy and induces synaptic dysfunction and tau hyperphosphorylation, eventually impairing cognitive dysfunction.

Kallistatin leads to cognition impairment via downregulating glutamine synthetase

In many neurodegenerative disorders, such as Alzheimer's disease (AD), glutamate-mediated neuronal excitotoxicity is considered the basis for cognitive impairment. The mRNA and protein expression of SERPINA4(Kallistatin) are higher in patients with AD. However, whether Kallistatin plays a regulatory role in glutamate-glutamine cycle homeostasis remains unclear. In this study, we identified impaired cognitive function in Kallistatin transgenic (KAL-TG) mice. Baseline glutamate levels were elevated and miniature excitatory postsynaptic current (mEPSC) frequency was increased in the hippocampus, suggesting the impairment of glutamate homeostasis in KAL-TG mice. Mechanistically, we demonstrated that Kallistatin promoted lysine acetylation and ubiquitination of glutamine synthetase (GS) and facilitated its degradation via the proteasome pathway, thereby downregulating GS. Fenofibrate improved cognitive memory in KAL-TG mice by downregulating serum Kallistatin. Collectively, our study findings provide insights the mechanism by which Kallistatin regulates cognitive impairment, and suggest the potential of fenofibrate to prevente and treat of AD patients with high levels of Kallistatin.

Increased serum methylmalonic acid levels were associated with the presence of cognitive dysfunction in older chronic kidney disease patients with albuminuria

BACKGROUND

This study aimed to evaluate the correlation between serum methylmalonic acid (MMA) levels and cognition function in patients with chronic kidney disease (CKD).

METHODS

In this cross-sectional study, we included 537 CKD individuals aged ≥ 60-year-old with albuminuria from the National Health and Nutrition Examination Survey (NHANES) 2011-2014. Four cognitive tests including the Digit Symbol Substitution Test (DSST), the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Delayed Recall and Word Learning tests, and the Animal Fluency test (AF) were performed. Associations between MMA and cognition scores were assessed with linear regression models.

RESULTS

MMA level was negatively associated with residual renal function and nutrition status. After multivariate adjustment, elevated serum MMA levels were independently correlated with decline of cognition in CKD patients with albuminuria.

CONCLUSION

Our study showed that higher serum MMA levels were independently associated with the presence of cognition dysfunction in CKD patients. The exact pathogenesis of MMA and cognition needs further research.

Attenuation of estrogen and its receptors in the post-menopausal stage exacerbates dyslipidemia and leads to cognitive impairment

Cognitive dysfunction increases as menopause progresses. We previously found that estrogen receptors (ERs) contribute to dyslipidemia, but the specific relationship between ERs, dyslipidemia and cognitive dysfunction remains poorly understood. In the present study, we analyzed sequencing data from female hippocampus and normal breast aspirate samples from normal and Alzheimer's disease (AD) women, and the results suggest that abnormal ERs signaling is associated with dyslipidemia and cognitive dysfunction. We replicated a mouse model of dyslipidemia and postmenopausal status in LDLR-/- mice and treated them with β-estradiol or simvastatin, and found that ovariectomy in LDLR-/- mice led to an exacerbation of dyslipidemia and increased hippocampal apoptosis and cognitive impairment, which were associated with reduced estradiol levels and ERα, ERβ and GPER expression. In vitro, a lipid overload model of SH-SY-5Y cells was established and treated with inhibitors of ERs. β-estradiol or simvastatin effectively attenuated dyslipidemia-induced neuronal apoptosis via upregulation of ERs, whereas ERα, ERβ and GPER inhibitors together abolished the protective effect of simvastatin on lipid-induced neuronal apoptosis. We conclude that decreased estrogen and its receptor function in the postmenopausal stage promote neuronal damage and cognitive impairment by exacerbating dyslipidemia, and that estrogen supplementation or lipid lowering is an effective way to ameliorate hippocampal damage and cognitive dysfunction via upregulation of ERs.

Brain morphology and functional connectivity alterations in patients with severe obstructive sleep apnea

BACKGROUND

It has been demonstrated that widespread structural and functional brain alterations influence the development of cognitive impairment in patients with obstructive sleep apnea (OSA). However, the literature has limited evidence regarding the neuropathophysiological mechanisms behind these impairments. This research aimed to investigate brain morphologic and functional connectivity (FC) abnormalities related to neurocognitive function in OSA.

METHODS

Fifty treatment-naïve males, newly diagnosed patients with severe OSA, and 50 well-matched healthy controls (HCs) were enrolled prospectively. All subjects underwent an MRI scan, cognitive psychological and sleep scale assessment. The differences of brain morphological and seed-based FC between the two groups were compared. The correlation analysis and receiver operating characteristic curve were performed for further analysis.

RESULTS

Compared with HCs, the right brainstem, left dorsal-lateral superior frontal gyrus (SFGdor), and superior temporal gyrus (STG) exhibited atrophy in the OSA group. In addition, FC between the left SFGdor and the right postcentral gyrus (PoCG) was increased, which was positively correlated with disease duration (r = 0.312, FDR-corrected P = 0.027). The Jacobian values of the brainstem were negatively correlated with MoCA and recall scores (r = -0.449, FDR-corrected P = 0.0025; r = -0.416, FDR-corrected P = 0.005). Furthermore, the Jacobian values of the left SFGdor demonstrated a relatively high diagnostic performance (sensitivity: 86%, specificity: 56%, AUC: 0.740, 95% CI: 0.643-0.836, P < 0.0001).

CONCLUSIONS

Structural atrophy in brainstem and frontotemporal lobe and altered FC may be the neurobiological hallmark of brain impairment in OSA. Notably, brainstem atrophy has been associated with cognitive impairment, which may provide new insights into understanding the neuropathophysiological mechanisms of cognitive impairment in OSA patients.

Prevalence and incidence of mild cognitive impairment in adults with diabetes in the United States

BACKGROUND

Limited evidence exists about the prevalence and incidence of mild cognitive impairment (MCI) in individuals with diabetes in the U.S. We aimed to address such knowledge gaps using a nationally representative study dataset.

METHOD

We conducted a secondary analysis from the Health and Retirement Study (HRS) (1996-2018). The sample for examining the prevalence of MCI was14,988, with 4192 (28.0%) having diabetes, while the sample for the incidence was 21,824, with 1534 (28.0%) having diabetes.

RESULTS

Participants with diabetes had a higher prevalence of MCI than those without diabetes (19.9 % vs. 14.8 %; odds ratio [95 % confidence interval] (OR[95 %CI]): 1.468 [1.337, 1.611], p <.001). The incidence of MCI in participants with/without newly diagnosed diabetes was 42.9 % vs. 31.6 % after a mean 10-year follow-up, with the incidence rate ratio (IRR) [95 %CI] (1.314 [1.213, 1.424], p <.001). Newly diagnosed diabetes was associated with elevated risks of MCI compared with non-diabetes, with the uncontrolled hazard ratio (HR) [95 %CI] (1.498 [1.405, 1.597], p <.001).

CONCLUSIONS

Using a nationally representative study data in the U.S., participants with diabetes had a higher prevalence and incidence of MCI than those without diabetes. Findings show the importance of developing interventions tailored to the needs of individuals with diabetes and cognitive impairment.

A network pharmacology approach to explore pharmacological mechanisms of Asparagus racemosus for ameliorative effect in epilepsy and comorbid progressive memory dysfunction

Background

Network pharmacology approach has been observed a powerful tool to predict underlying complex pharmacological mechanism of herbs. Asparagus racemosus has been reported to show ameliorative effects in treating epilepsy and comorbid memory dysfunction but mechanism of this amelioration is elusive. Hence a network pharmacology approach was employed to investigate the plausible mechanism of A. recemosus.

Methodology

: Bioactive compounds of A. racemosus were extracted based on the TCMSP, PCIDB, and BATMAN-TCM database. The potential targets of bioactive compounds were collected using target fishing. Epilepsy and comorbid dementia genes were collected from DISGENET. A PPI network among these targets was constructed using the intersecting key targets between herb targets and disease targets. Besides, DAVID bioinformatics resource was utilized for the pathway enrichment analysis on GO and KEGG. Ultimately, phytochemical compound-target genes-Pathways network has been assembled utilizing Cytoscape to decipher the mechanism of the herb.

Results

The network analysis revealed that 5 targets (CASP3, TNF, VEGFA, PTGS2 and CNR1) might be the key therapeutic targets of asparagus on Epilepsy comorbid Alzheimer's disease. Based on high connectivity, four hub compounds with the highest connectivity were noted and it includes Shatavarin V, Sarsasapogenin, Shatavarin IX, and Shatavarin VI. A total of 19 KEGG terms were enriched as the potential pathways of A. racemosus in Epilepsy comorbid Alzheimer's disease.

Conclusion

This study envisaged the pharmacological and molecular mechanism of A. racemosus against epilepsy comorbid Alzheimer's disease and put forward a strategy to uncover the mechanisms of Traditional Indian Medicine based on network pharmacology.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40203-023-00169-x.

Effectiveness of photobiomodulation for people with age-related cognitive impairment: a systematic review and meta-analysis

The increasing incident of age-related cognitive impairment worldwide and the lack of pharmaceutical treatments emphasizes the value of non-pharmaceutical therapy. Emerging evidence suggested photobiomodulation (PBM) is a popular intervention to brain disorder; however, it remains unclear the efficacy of PBM for patients with age-related cognitive impairment. The purpose of this systematic review is to compare the different parameters used in PBM, analyze the beneficial effects of PBM as a potential therapy for age-related cognitive impairment. Five electronic database, PubMed, Web of Science, Cochrane Library, CINAHL, and PsycINFO, were systematically searched from inception to November 2021. Relevant randomized controlled trials (RCTs) were screened and assessed for risk of bias. Eleven RCTs evaluating PBM interventions were included. The systematic review and meta-analysis has been registered in PROSPERO(CRD42022374562). Results showed that PBM had a significant moderated effect on global cognition function (SMD=0.51, 95% CI [0.162, 0.864], p=0.004). We found that multiple wavelength PBM (SMD=0.648, 95% CI [0.220, 1.075], p=0.003) had significant effects while single wavelength PBM was non-significant (SMD=0.385, 95% CI [-0.168, 0.987], p=0.172). Laser effect (SMD=0.682, 95% CI [0.37, 0,994], p<0.001) was larger than LED effect (SMD=0.582, 95% CI [0.269, 0.895], p<0.001). PBM in clinical setting (SMD=0.468, 95% CI [0.050, 0.887], p=0.028) had significant effect, but there was no significant effect of home-used PBM (SMD=0.616, 95% CI [-0.121, 1.354], p=0.101). The pool effect of multi-modality PBM (SMD=0.720, 95% CI [0.027, 1.414], p=0.040) was significantly higher in the studies of transcranial irradiation (SMD=0.616, 95% CI [-0.121, 1.354], p=0.010). Cumulative irradiation time was a moderator between the PBM and cognitive function improvement. Photobiomodulation have the potential to improve cognitive function in aging adults. Cumulative irradiation duration, light source, device type, penetration modality, and intervention site can affect the effectiveness of PBM intervention.

Comprehensive analysis of N6-methyladenosine-related RNA methylation in the mouse hippocampus after acquired hearing loss

BACKGROUND

The mechanism underlying cognitive impairment after hearing loss (HL) remains unclear. N6-methyladenosine (m6A) is involved in many neurodegenerative diseases; however, its role in cognitive impairment after HL has not yet been investigated. Therefore, we aimed to analyze the m6A modification profile of the mouse hippocampus after HL exposure. A mouse model of neomycin-induced HL was established. An auditory brainstem-response test was utilized for detecting hearing threshold. The passive avoidance test was served as the mean for evaluating cognitive function. The m6A-regulated enzyme expression levels were analyzed by using reverse transcription quantitative real-time polymerase chain reaction and western blot analyses. RNA sequencing (RNA-Seq) and methylated RNA immunoprecipitation sequencing (MeRIP-Seq) were performed with the aim of investigating gene expression differences and m6A modification in the mouse hippocampus.

RESULTS

Neomycin administration induced severe HL in mice. At four months of age, the mice in the HL group showed poorer cognitive performance than the mice in the control group. METTL14, WTAP, and YTHDF2 mRNA levels were downregulated in the hippocampi of HL mice, whereas ALKBH5 and FTO mRNA levels were significantly upregulated. At the protein level, METTL3 and FTO were significantly upregulated. Methylated RNA immunoprecipitation sequencing analysis revealed 387 and 361 m6A hypermethylation and hypomethylation peaks, respectively. Moreover, combined analysis of mRNA expression levels and m6A peaks revealed eight mRNAs with significantly changed expression levels and methylation.

CONCLUSIONS

Our findings revealed the m6A transcriptome-wide profile in the hippocampus of HL mice, which may provide a basis for understanding the association between HL and cognitive impairment from the perspective of epigenetic modifications.

Neuronal glutamate transporters are associated with cognitive impairment in obstructive sleep apnea patients without dementia

Increasing evidence supports a link between obstructive sleep apnea (OSA) and cognition, and the mechanism is complex and still not well understood. We analyzed the relationship between the glutamate transporters and cognitive impairment in OSA. For this study 317 subjects without dementia, including 64 healthy controls (HCs), 140 OSA patients with mild cognitive impairment (MCI) and 113 OSA patients without cognitive impairment were assessed. All participants who completed polysomnography, cognition and white matter hyperintensity (WMH) volume were used. Plasma neuron-derived exosomes (NDEs) excitatory amino acid transporter 2 (EAAT2) and vesicular glutamate transporter 1 (VGLUT1) proteins were measured by ELISA kits. After 1 year of continuous positive airway pressure (CPAP) treatment, we analyzed plasma NDEs EAAT2 level and cognition changes. Plasma NDEs EAAT2 level was significantly higher in OSA patients than in HCs. Higher plasma NDEs EAAT2 level were significantly associated with cognitive impairment than normal cognition in OSA patients. Plasma NDEs EAAT2 level was inversely associated with the total Montreal Cognitive Assessment (MoCA) scores, visuo-executive function, naming, attention, language, abstraction, delayed recall and orientation. One year after CPAP treatment, plasma NDEs EAAT2 level (P = 0.019) was significantly lower, while MoCA scores (P = 0.013) were significantly increased compared with baseline. Upregulation of neuronal glutamate transporters at baseline may reflect a self-compensatory mechanism to prevent further neuronal damage, while plasma NDEs EAAT2 level was decreased after one year of CPAP therapy, which may be due to the loss of astrocytes and neurons.

Rodent Model Preclinical Assessment of PEGylated Block Copolymer Targeting Cognition and Oxidative Stress Insults of Alzheimer's Disease

Misfolded peptide amyloid beta (Aβ₄₂), neurofibrillary tangles of hyper-phosphorylated tau, oxidative damage to the brain, and neuroinflammation are distinguished determinants of Alzheimer's disease (AD) responsible for disease progression. This multifaceted neurodegenerative disease is challenging to cure under a single treatment regime until the key disease determinants are traced for their sequential occurrence in disease progression. In an early report, a novel side-chain tripeptide containing PEGylated block copolymer has been tested thoroughly in vitro and in silico for the early inhibition of Aβ₄₂ aggregation as well as degradation of preformed Aβ₄₂ fibril deposits. The present study demonstrates a preclinical assessment of the PEGylated block copolymer in colchicine-induced AD-mimicking rodent model. The colchicine-induced Wistar rats receiving an intranasal delivery of the block copolymer at a daily dosage of 100 µg/kg and 200 µg/kg body weights, respectively, for 14 days manifested a notable attenuation of behavioral deficit pattern, oxidative stress, and neurotransmitters' deficiency as compared to the untreated ones. The current study also reports the ameliorative property of the PEGylated compound for progressive neuroinflammation and decreased mitochondrial bioenergetics in astrocytoma cell line, viz., U87. A closer look into the drug mechanism of action of a compact 3D PEGylated block copolymer confirmed its disintegrative interaction with Aβ₄₂ fibril via in silico simulation. The results obtained from this study signify the potential of the novel PEGylated block copolymer to ameliorate the cognitive decline and progressive oxidative insults in AD and may envision a successful clinical phase trial. The amelioration of disease condition of colchicine-induced AD rat. Initially the rat has given colchicine via stereotaxic surgery which led to a mimicking condition of AD including neuronal death in hippocampal CA1 region. After recovery from the surgery, the rat was treated with the PEGylated block copolymer through intranasal delivery, and this has led to the decrease in neuronal death in hippocampal CA1 region. The mechanism of drug action has shown by the separation of monomer chains of Aβ₄₂.

Childhood absence epilepsy patients with cognitive impairment have decreased sleep spindle density

OBJECTIVE

To explore the differences in sleep spindle (SS) characteristics during stage N2 sleep between children with childhood absence epilepsy and healthy controls, and between children with childhood absence epilepsy with or without cognitive impairment.

METHODS

We recruited 29 children (14 females, 15 males, mean age: 8 (2.5) years) with childhood absence epilepsy who did not undergone antiseizure treatments previously and 30 age-matched controls (14 females, 16 males, mean age: 9 (3.0) years). For all patients, data on medical history were collected. Each child was monitored overnight by long-term video electroencephalography and was evaluated by the Wechsler Intelligence Scale for Children-Fourth Edition. Next, we compared anterior SS characteristics, including density, frequency, cycle length, duration, amplitude, and percentage of sleep stages.

RESULTS

The childhood absence epilepsy group exhibited lower spindle density and duration in the first 37.5 min of stage N2 sleep than the control group (P < 0.01). A decrease in spindle density could be observed in the childhood absence epilepsy group with aggravated cognition impairment. The spindle density was substantially lower in the cognitively impaired group than in the cognitively unimpaired group (P < 0.01). No significant differences were observed in SS amplitude, SS frequency, SS cycle length, and the distribution of sleep stages.

CONCLUSIONS

Reduction in spindle density and duration is associated with the mechanisms underlying childhood absence epilepsy. The deficit in SS density is related with impaired cognition. This deficiency in SSs may be a useful predictive indicator of cognitive impairment in children with absence epilepsy, indicating that SSs may become a useful biomarker and potential adjuvant anti-seizure target for cognitive impairment caused by childhood absence epilepsy.

Proteome-Wide Analysis of the Hippocampus in Adult Mice with Learning and Memory Impairment Caused by Chronic Ethanol Exposure

Alcohol consumption may cause various impairments in the brain. The hippocampus is particularly vulnerable to alcohol exposure, which may cause learning and memory deficits. Recently, proteomics analysis has become a popular approach to explore the pathogenesis of various diseases. The present study was conducted to investigate protein expression alteration in the hippocampus and to identify the molecular mechanisms underlying ethanol-induced learning and memory impairments. Mouse models of chronic ethanol intoxication were established by intragastrical administration for 28 consecutive days, and hippocampal neuronal damage was assessed by Nissl staining. Recognition memory was evaluated by Novel object recognition and Morris water maze tests, and hippocampus tissues were collected for label-free quantitative proteomics and analyzed using bioinformatics methods. Our study showed that chronic ethanol exposure prompted marked changes in protein expression in the hippocampus. We identified 32 differentially expressed proteins, of which 21 were upregulated and 11 downregulated. Gene Ontology analysis suggested that the identified differentially proteins were mainly involved in cytoskeleton and signal transduction mechanisms. Further verification using Western blotting and real-time quantitative PCR revealed that the hippocampal CTSL (cathepsin L), and PVALB (Parvalbumin) showed strongest expression changes, the latter being specifically expressed in GABAergic interneurons. These two proteins might serve as candidate protein biomarkers, providing new prospects for the diagnosis and treatment of ethanol-induced learning and memory disorders.

Enhanced defense against ferroptosis ameliorates cognitive impairment and reduces neurodegeneration in 5xFAD mice

Oxidative damage including lipid peroxidation is widely reported in Alzheimer's disease (AD) with the peroxidation of phospholipids in membranes being the driver of ferroptosis, an iron-dependent oxidative form of cell death. However, the importance of ferroptosis in AD remains unclear. This study tested whether ferroptosis inhibition ameliorates AD. 5xFAD mice, a widely used AD mouse model with cognitive impairment and robust neurodegeneration, exhibit markers of ferroptosis including increased lipid peroxidation, elevated lyso-phospholipids, and reduced level of Gpx4, the master defender against ferroptosis. To determine if enhanced defense against ferroptosis retards disease development, we generated 5xFAD mice that overexpress Gpx4, i.e., 5xFAD/GPX4 mice. Consistent with enhanced defense against ferroptosis, neurons from 5xFAD/GPX4 mice showed an augmented capacity to reduce lipid reactive oxygen species. In addition, compared with control 5xFAD mice, 5xFAD/GPX4 mice showed significantly improved learning and memory abilities and had reduced neurodegeneration. Moreover, 5xFAD/GPX4 mice exhibited attenuated markers of ferroptosis. Our results indicate that enhanced defense against ferroptosis is effective in ameliorating cognitive impairment and decreasing neurodegeneration of 5xFAD mice. The findings support the notion that ferroptosis is a key contributor to AD pathogenesis.

The effect of water source on cognitive functioning in Chinese adults: A cross-sectional and follow-up study

The effect of water source on cognitive functioning is poorly understood. The present study explored the associations between water source and cognition in 9921 participants from the China Health and Retirement Longitudinal Study (CHARLS). Cognitive functioning was measured from three aspects: orientation and attention, episodic memory, and visuo-construction. Water sources included tap and non-tap water. Generalized linear models and multiple logistic regression models were conducted to investigate the associations of cognitive scores with water source among the whole population and different subgroups. Results from cross-sectional analysis reported that participants without access to tap water showed a lower cognitive score (β = - 0.57; 95% CI: - 0.74, - 0.39) than those with tap water as a water source; and this phenomenon was pronounced for both sexes and across all residences. During 4-years' follow-up, a greater decline of cognitive score was associated with no tap water use in the lowest quartile of baseline cognitive scores (β = - 0.67; 95% CI: - 1.26, - 0.08). Additionally, the utilization rate of tap water was lower in rural areas compared to urban areas. The lowest utilization rates were observed in urban areas of the Anhui province (0.38 in 2011 and 0.55 in 2015) and in rural areas of Inner Mongolia (0.09 in 2011 and 0.20 in 2015). These findings suggest that having no tap water may be a risk factor for cognition impairment, particularly for those with a low basic cognition score. Additionally, our results support the need to expand tap water use in China.

Associations between caregiver mastery and anxiety in persons living with dementia: A study of dyads living in community

Anxiety is common in persons living with dementia (PLWD), and particularly burdensome for caregivers. Little is known about how caregiver factors such as caregiver mastery can influence anxiety in PLWD. This study was conducted to examine the relationship between caregiver mastery and anxiety in PLWD. Secondary data analysis was conducted using baseline data from a randomized controlled trial of 170 dyads of community residing PLWD and their caregivers. Logistic regression analyses were used for data analyses. After controlling for covariates (e.g., age, cognitive impairment, sleep impairment, and depression), a higher level of caregiver mastery was related to lower odds of anxiety presentation in PLWD (OR=0.870, 95% CI=0.759-0.998, p=0.046). As caregiver mastery is related to anxiety in PLWD, a comprehensive education program for caregivers that can improve their caregiving skills and mastery is suggested to improve anxiety in PLWD.

Interaction of human IAPP and Aβ1-42 aggravated the AD-related pathology and impaired the cognition in mice

Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM) have a common pathology. Both diseases are characterized by local deposition of amyloid proteins in the brain or islet organ, but their phenotypes and clinical manifestation vary widely. Although the sources of islet amyloid polypeptide (IAPP) and amyloid beta (Aβ) are independent, their fibrillar sequences are highly homologous. The prevalence of AD in T2DM populations is considerably higher than that in the normal population, but a mechanistic linkage remains elusive. Therefore, the present study aimed to explore the effects of Aβ42 deposition in the brain on the persistently expression of human IAPP (hIAPP). Additionally, cognitive ability, synaptic plasticity, the state of neural stem cells and mitochondrial function were evaluated at 2 or 6 months after stereotaxically injected the oligomer Aβ_1-42 into the dentate gyrus of hIAPP ^(-/+) mice or the wild-type littermates. We found that Aβ₄₂ and amylin were co-located in hippocampus and Aβ₄₂ levels increased when Aβ_1-42 was injected in hIAPP transgenic mice compared with that of the wild-type littermates. Furthermore, at 6 months after Aβ_1-42 injection in hIAPP ^(-/+) mice, it exhibits exacerbated AD-related pathologies including Aβ₄₂ deposition, cognitive impairment, synapse reduction, neural stem cells exhaustion and mitochondrial dysfunction. Our present study suggested that hIAPP directly implicated the Aβ₄₂ production and deposition as an important linkage between T2DM and AD.

Characteristics of cognitive impairment in adult asymptomatic moyamoya disease

Background

Cognitive impairment in adult moyamoya disease (MMD) is thought to be the result of ischemic stroke; however, the presence and extent of cognitive decline in asymptomatic patients is unclear.

Methods

After classification using T2-weighted fluid attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI), a total of 19 MMD patients with a history of cerebral infarction, 21 asymptomatic MMD patients, and 20 healthy controls matched for age, sex, and years of education were prospectively included in this study. A detailed neuropsychological evaluation of two moyamoya subgroups and normal controls was conducted.

Results

Asymptomatic patients showed varying degrees of decline in intelligence (Raven’s Standard Progressive Matrices, P = 0.001), spatial imagination (mental rotation, P = 0.014), working memory (verbal working memory-backward digit span, P = 0.011), and computational ability (simple subtraction, P = 0.014; complex subtraction, P < 0.001) compared with normal controls. MMD patients with cerebral infarction had more severe impairment in complex arithmetic (P = 0.027) and word short-term memory (P = 0.01) than those without symptoms.

Conclusion

In asymptomatic MMD patients, a variety of cognitive impairment precedes the onset of clinical symptoms such as cerebral infarction, which may be a long-term complication of conservative treatment.

Risk factors for neurocognitive decline in lung cancer patients treated with prophylactic cranial irradiation: A systematic review

BACKGROUND

Prophylactic cranial irradiation (PCI) reduces brain metastasis incidence in lung cancer, however with risk of neurocognitive decline. Nevertheless, risk factors for neurocognitive decline after PCI remain unclear.

METHODS

We systematically reviewed the PubMed database according to the PRISMA guideline. Inclusion criteria were: randomized clinical trials (RCTs) and observational/single arm trials evaluating PCI, including ≥20 patients, reporting neurocognitive test results for lung cancer. Primary aim: evaluate risk factors associated with neurocognitive decline after PCI.

RESULTS

Twenty records were eligible (8 different RCTs, 8 observational studies), including 3553 patients in total (858 NSCLC, 2695 SCLC) of which 73.6% received PCI. Incidence of mild/moderate cognitive decline after PCI varied from 8 to 89% (grading not always provided); for those without PCI, this was 3.4-42%. Interestingly, 23-95% had baseline cognitive impairment. Risk factors were often not reported. In one trial, both age (>60 years) and higher PCI dose (36 Gy) including twice-daily PCI were associated with a higher risk of cognitive decline. In one trial, white matter abnormalities were more frequent in the concurrent or sandwiched PCI arm, but without significant neuropsychological differences. One trial identified hippocampal sparing PCI to limit the neurocognitive toxicities of PCI and another reported an association between hippocampal dose volume effects and memory decline. As neurocognition was a secondary endpoint in most RCTs, and was assessed by various instruments with often poor/moderate compliance, high-quality data is lacking.

CONCLUSIONS

Age, PCI dose, regimen and timing might be associated with cognitive impairment after PCI in lung cancer patients, but high-quality data is lacking. Future PCI trials should collect and evaluate possible risk factors systematically.

[Risk factors and their interaction on cognitive impairment in the elderly in China: case-control study]

Objective: To investigate the association of apolipoprotein E (ApoE) genotype, sleep problem, olfaction problems, chronic constipation and their interactions on cognitive impairment in the elderly aged 60 and above. Methods: A stratified multi-stage cluster sampling was used in 6 provinces (autonomous administrative regions and municipalities) to select the sample. 1 300 cases with cognitive impairment and 2 600 controls without cognitive impairment were recruited and matched according to their age, gender and resident area in a 1∶2 case-control study. A total of 3 501 people were included after data cleaning. Chi-square test and conditional logistic regression model were used for univariate analysis, multivariate analysis and interaction analysis. Results: ApoE carrying ε4 genotypes, sleep problems, smell disorders, constipation is independent risk factors of cognitive impairment in the elderly (OR=1.44, 1.65, 2.26, 2.13, P<0.001). The additive interaction between ApoE genotype and olfaction change was statistically significant [AP=0.45(95%CI: 0.13- 0.77), S=2.37 (95%CI: 1.08-5.24)]. The interaction between other factors with cognitive impairment was not found to be statistically significant. The above results were adjusted for occupation, tea drinking, neighborhood interaction, social activities, physical exercise, reading books and newspapers, playing cards and mahjong, memory changes and hypertension, diabetes, stroke. Conclusions: ApoE genotype, sleep problems, olfaction problems, and chronic constipation are risk factors for cognitive impairment in people 60 and older. There is a synergistic interaction effect between ApoE genotype and olfaction problems on cognitive impairment in the elderly over 60 years old.

The role of inflammation and endoplasmic reticulum stress in obesity-related cognitive impairment

The epidemiological investigations and animal model experiments have confirmed the impact of obesity on the brain, behavior, and cognition. However, the mechanism by which obesity affects cognitive function is not fully understood. With the development of an aging society, there is an increase in the economic and social burden caused by the decline in cognitive function. This manuscript reviews the effects of inflammation and endoplasmic reticulum stress (ERS) on the hypothalamus, hippocampus, and the possible impact on cognitive impairment. These findings provide new insights into the pathophysiological mechanisms that lead to the development of cognitive impairment in the context of obesity.

Protective role of metformin against methamphetamine induced anxiety, depression, cognition impairment and neurodegeneration in rat: The role of CREB/BDNF and Akt/GSK3 signaling pathways

BACKGROUND

Methamphetamine is a neuro-stimulant with neurodegenerative effects, and ambiguous mechanism of action. Metformin is an antidiabetic agent with neuroprotective properties but not fully understood mechanisms. The present study investigated the molecular basis of metformin neuroprotection against methamphetamine-induced neurodegeneration.

BRIEF METHOD

Sixty adult male rats were randomly divided into six groups: group 1 (received normal saline), group 2 (received 10 mg/kg of methamphetamine) and groups 3, 4, 5 and 6 [received methamphetamine (10 mg/kg) plus metformin (50, 75, 100 and 150 mg/kg) respectively]. Elevated Plus Maze (EPM), Open Field Test (OFT), Forced Swim Test (FST), Tail Suspension Test (TST) and Morris Water Maze (MWM) were used to assess the level of anxiety, depression and cognition in experimental animals. Also animals' hippocampus were isolated and oxidative stress and inflammatory parameters and expression of total and phosphorylated forms of cAMP response element binding (CREB), brain-derived neurotrophic factor (BDNF), protein kinase B (Akt) and glycogen synthase kinase 3 (GSK3) proteins were evaluated by ELISA method.

RESULTS

According to the data obtained, methamphetamine caused significant depression, anxiety, motor activity disturbances and cognition impairment in experimental animals. Metformin, in all used doses, decreased methamphetamine induced behavioral disturbances. Also chronic administration of methamphetamine could increase malondialdehyde (MDA), tumor necrosis factor-Alpha (TNF-α) and interleukine-1 beta (IL-1β) in rats, while caused reduction of superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR) activities. Metformin, especially in high doses, could prevent these malicious effects of methamphetamine. Also Metformin could activate CREB (both forms), BDNF and Akt (both forms) proteins' expression and inhibited GSK3 (both forms) protein expression in methamphetamine treated rats.

SIGNIFICANCE

According to obtained data, metformin could protect the brain against methamphetamine-induced neurodegeneration probably by mediation of CREB/BDNF or Akt/GSK3 signaling pathways. These data suggested that CREB/BDNF or Akt/GSK3 signaling pathways may have a critical role in methamphetamine induced neurotoxicity and/or neuroprotective effects of metformin.

[Case-control study on the influencing factors related to cognitive impairment in the elderly population of China]

Objective: To explore the influencing factors affecting the cognitive impairment of the elderly population in China. Methods: A stratified multi-stage cluster sampling was used in 6 provinces (autonomous administrative regions and municipalities) to select the sample. A total 24 000 urban and rural residents aged 60 years and above received a set of standardized questionnaire interview, physical examinations, laboratory test of lipid and glucose levels of blood and apolipoprotein E (APOE) genotype. The primary screening of cognitive function was assessed by using the Chinese Version of Ascertain Dementia 8, and then suspicious cognitive impairment cases with more than two abnormal results would receive the further cognitive function assessment by using the Mini-Mental State Examination (MMSE). 1 300 cases with cognitive impairment and 2 600 controls without cognitive impairment were recruited and matched according to their age, gender and resident area in a 1∶2 case-control study. The conditional logistic regression model was used to analyze the association between relevant factors and cognitive impairment. Results: Factors negatively associated with cognitive impairment and their OR (95%CI) values were primary or middle school as 0.63 (0.51-0.77), high school and above as 0.59 (0.39-0.88), daily neighborhood communication as 0.61 (0.50-0.75), weekly participating in social activities 0.59 (0.44-0.79), daily tea drinking as 0.71 (0.58-0.88) and doing regular exercise as 0.71 (0.57-0.88), reading newspaper (occasional: 0.50 (0.37-0.67); frequent: 0.40 (0.28-0.57)), playing majiang or cards (occasional: 0.51 (0.34-0.74); frequent: 0.50 (0.36-0.68)) respectively. Factors positively associated with cognitive impairment and their OR (95%CI) values were APOE-ε4 heterozygote as 1.31 (1.08-1.58), homozygote as 2.74 (1.52-5.00), diabetes onset before 50 years of age and after as 9.03 (3.07-33.60) and 4.40 (3.18-6.17), stroke as 1.90 (1.35-2.69), asthma as 1.95 (1.11-3.42) respectively. Conclusion: APOE-ε4 alleles, lower educational level, stroke, asthma, diabetes are risk factors of cognitive impairment in the elderly. Keeping a healthy lifestyle and preventing chronic diseases in the whole life course could significantly reduce the incidence of cognitive impairment in the elderly.

Moderate- and Low-Dose of Atorvastatin Alleviate Cognition Impairment Induced by High-Fat Diet via Sirt1 Activation

Mounting evidences have demonstrated that diet-induced obesity is associated with cognition impairment via increasing oxidative stress and inflammation in the brain. Atorvastatin (Ator, a HMG-CoA reductase inhibitor) is a cholesterol lowering drug. Studies have reported that Ator can ameliorate the development and progression of cognition impairment. Additionally, silent information regulator 1 (SIRT1) has been demonstrated to be beneficial in cognition impairment. However, the interaction between Ator and SIRT1 activation for cognition impairment remains unclear. This study aimed to identify a relationship between the use of Ator and cognition impairment induced by high-fat diet via Sirt1 activation. A total of 60 healthy male C57BL/6J mice were purchased and then divided into 6 groups, including normal diet group (control), a high-fat diet group (40%HFD, 40% energy from fat), a model group (60%HFD, 60% energy from fat), and model group treated with different doses of Ator (high-dose (80 mg), moderate-dose (40 mg), and low-dose (20 mg) groups). All interventions took place for 7 months. Metabolic phenotypes were characterized for body weight and analysis of serum lipid level. The level of cognition development was examined by Morris water maze (MWM) approach and novel object recognition test (NORT); besides, the expression of Creb1, Gap-43, BDNF, CaMKII, and ERKs of frontal cortex and hippocampus was determined by reverse transcription polymerase chain reaction (RT-PCR). Then, the levels of factors related to inflammation (TNF-a, IL-1β, HMGB1 and IL-6) and oxidation stress (SOD, MDA, CAT and GSH-Px) were assessed using commercially available kits. Finally, SIRT1 and its downstream molecules (Ac-FoxO1, Ac-p53, Ac-NF-κB, Bcl-2 and Bax) were evaluated by Western blot analysis. Compared with the 60% HFD group, body weight and serum lipid levels were significantly decreased in the Ator treated groups. The results of MWM and NORT, as well as the levels of Creb1, Gap-43, BDNF, CaMKII, and ERKs were markedly reversed in the moderate- and low-dose of Ator treated groups. Meanwhile, the expression of IL-1β, TNF-a, IL-6, HMGB1, and MDA was notably decreased, whereas the activity of SOD, CAT, and GSH-Px was increased. It was also revealed that the expression of SIRT1 was remarkably unregulated, the level of Bcl-2 was upregulated, and the content of Ac-FoxO1, Ac-p53, Ac-NF-κB, and Bax was downregulated in the moderate- and low-dose of Ator. Furthermore, results showed that the effect of moderate-dose of Ator was significantly greater than the low-dose of Ator. However, these effects were not observed in the high-dose of Ator. Our results showed that moderate- and low-dose of Ator can significantly attenuate cognition impairment induced by HFD through its antioxidant and anti-inflammatory functions related to SIRT1 activation.

Neuroprotective Effects of Forced Exercise and Bupropion on Chronic Methamphetamine-induced Cognitive Impairment via Modulation of cAMP Response Element-binding Protein/Brain-derived Neurotrophic Factor Signaling Pathway, Oxidative Stress, and Inflammatory Biomarkers in Rats

Background

Forced exercise can act as non-pharmacologic neuroprotective agent. In current study, we tried the involved molecular mechanisms of protective effects of forced exercise against methamphetamine induced neurodegeneration.

Materials and Methods

Forty adult male rats were divided to Group 1 and 2 which received normal saline and methamphetamine (10 mg/kg) respectively for 30 days. Groups 3, 4 and 5 were treated with methamphetamine for first 15 days and then were treated by forced exercise, bupropion (20 mg/kg/day) or combination of them for the following 15 days. Between 26^th and 30^th days, Morris Water Maze (MWM) was used to evaluate the cognition. On day 31, hippocampus was isolated from each rat and oxidative, antioxidant and inflammatory factors also the level of total and phosphorylated forms of cAMP response element-binding protein (CREB) and brain derived neurotrophic factor (BDNF) proteins were also evaluated.

Results

Chronic abuse of methamphetamine could decreases cognition and increase malondialdehyde (MDA), Tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β), while caused decreases in superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR) activities all these changes was significant (P < 0.001) in compared to control group while treatment with bupropion, forced exercise and bupropion in combination with forced exercise could prevent all these malicious effects of methamphetamine (P < 0.001). Bupropion, forced exercise and bupropion in combination with forced exercise could activate CREB (both forms) and activates BDNF proteins' expression with P < 0.001 in methamphetamine treated rats.

Conclusions

P-CREB/BDNF signaling pathways might have critical role in forced exercise protective effects against methamphetamine induced neurodegeneration.

Music therapy is a potential intervention for cognition of Alzheimer's Disease: a mini-review

Alzheimer's Disease (AD) is a global health issue given the increasing prevalence rate and the limitations of drug effects. As a consequent, non-pharmacological interventions are of importance. Music therapy (MT) is a non-pharmacological way with a long history of use and a fine usability for dementia patients. In this review, we will summarize different techniques, diverse clinical trials, and the mechanisms of MT as it is helpful to the cognition in AD, providing reference for future research. Many articles have demonstrated that MT can reduce cognitive decline especially in autobiographical and episodic memories, psychomotor speed, executive function domains, and global cognition. MT is a promising intervention for strategy of dementia especially of AD and it must be started as early as possible. However, more evidences with prospective, randomized, blinded, uniform and rigorous methodological investigations are needed. And we should consider to combine MT with other cognitive stimulations such as dance, physical exercise, video game, art and so on.

Relationship between soluble Semaphorin4D and cognitive impairment in patients with obstructive sleep apnea-hypopnea syndrome

To investigate the relationship between plasma soluble semaphorin4D (sSema4D) and obstructive sleep apnea-hypopnea syndrome (OSAHS), and to ascertain the effect of sSema4D on cognitive dysfunction in patients with OSAHS. We prospectively recruited 30 men with moderate-severe OSAHS diagnosed by polysomnography, and 30 healthy controls with matched gender, age and education level. Montreal Cognitive Assessment (MoCA) was administered to determine cognitive impairment. Plasma sSema4D levels were measured. Among the total of 60 study patients, the overall plasma sSema4D level was 7.81 ± 1.91 ng/ml. Plasma sSema4D level in OSAHS group was significantly higher than that in controls (8.92 ± 1.79 vs 6.70 ± 1.28 ng/ml, p < 0.001). In OSAHS subgroup, patients with cognition impairment (CI) had higher plasma sSema4D level (10.50 ± 1.16 vs 8.00 ± 1.41 ng/ml, p < 0.001) and apnea-hypopnea index (AHI) (48.1 ± 14.0 vs 30.3 ± 9.2, p < 0.001) than those in non-CI group. Multiple logistic regression revealed that plasma sSema4D level (AOR 2.824, 95 % CI 1.562-5.103; p = 0.001) and BMI (AOR 2.237, 95 % CI 1.345-3.722; p = 0.002) were significantly associated with OSAHS, and plasma sSema4D was a significant predictor of CI after adjustment for other confounders (AOR 4.956, 95 % CI 1.581-15.538; p = 0.006). OSAHS patients, especially those with cognition impairment, are featured by elevated plasma sSema4D level, and sSema4D is significantly associated with cognition impairment induced by OSAHS.

Aluminum chloride induces neuroinflammation, loss of neuronal dendritic spine and cognition impairment in developing rat

Aluminum (Al) is present in the daily life of humans, and the incidence of Al contamination increased in recent years. Long-term excessive Al intake induces neuroinflammation and cognition impairment. Neuroinflammation alter density of dendritic spine, which, in turn, influence cognition function. However, it is unknown whether increased neuroinflammation is associated with altered density of dendritic spine in Al-treated rats. In the present study, AlCl3 was orally administrated to rat at 50, 150 and 450 mg/kg for 90d. We examined the effects of AlCl3 on the cognition function, density of dendritic spine in hippocampus of CA1 and DG region and the mRNA levels of IL-1β, IL-6, TNF-α, MHC II, CX3CL1 and BNDF in developing rat. These results showed exposure to AlCl3 lead to increased mRNA levels of IL-1β, IL-6, TNF-α and MCH II, decreased mRNA levels of CX3CL1 and BDNF, decreased density of dendritic spine and impaired learning and memory in developing rat. Our results suggest AlCl3 can induce neuroinflammation that may result in loss of spine, and thereby leads to learning and memory deficits.

Cognitive dysfunction in severe chronic obstructive pulmonary disease (COPD) with or without Long-Term Oxygen Therapy (LTOT)

Background

Chronic Obstructive Pulmonary Disease (COPD) is a progressive respiratory condition which can lead to comorbidities of variable severity, cognitive dysfunction included. The role of supplemental oxygen in preventing COPD-induced cognitive deterioration is still debated, but only episodically investigated. The aim of this study was to compare the cognitive pattern of hypoxemic COPD subjects treated with long-term oxygen (LTOT) to that of patients of comparable severity assuming oxygen on irregular basis, and to normal reference values.

Methods

Lung function, arterial blood gases, health status, and cognitive function measured by means of four psychometric tests focusing different domains of cognition (such as: MMSE, Clock test; TMT-A; TMT-B) were assessed in 146 well matched hypoxemic COPD patients (males n = 96, 66%; mean age = 70.5 ± 12.9). Seventy-three patients were assuming long-term oxygen (LTOT), while the remaining seventy-three were only using oxygen as needed (AN). Regarding statistics, t test and ANOVA (Duncan test) were used to analyze data, assuming a p < 0.05 as the lowest limit of significance.

Results

Even though all COPD patients showed a poorer psychometric profile vs corresponding normal reference values, LTOT patients showed a lower prevalence of severe deterioration in cognition. Also the extent of impairment was significantly lower in these patients when assessed by TMT-A and TMT-B (p < 0.012 and 0.001, respectively), but not when measured by MMSE and Clock test (both p = ns). Several domains of cognition are variably affected by persistent hypoxemia in COPD patients. A panel of psychometric tools is needed for identifying the pattern of cognitive dysfunctions in these patients. Memory and attention (functions assessed by MMSE and Clock test) are only mildly-moderately affected, while visual processing, reproduction of numeric sequences, cognition flexibility, and shifting capacity (functions assessed by TMT-A and TMT-B) are much more deteriorated (p < 0.012 and p < 0.001, respectively).

Conclusions

Only LTOT allows to preserve significantly (p < 0.022) cognitive functions from the COPD-induced deterioration. This assumption is of strategic value for COPD patients who are prescribed long-term oxygen because they frequently are not aware of the cognitive risks related to their condition.