Memory Decline Research Articles

Using machine learning model for predicting risk of memory decline: A cross sectional study

BackgroundMemory decline is the earliest symptom of various neurodegenerative disease, such as Alzheimer's disease (AD). However, accurately the prediction and identification of risk factors leading up to memory decline has remained limited. ObjectiveThe objective of this study is to create and verify a machine learning model that can accurately predict risk factors for memory decline among US adults. MethodsA total of 9971 individuals were enrolled from the National Health and Nutrition Examination Survey (NHANES) 2015–2016 database. The least absolute shrinkage and selection operator (LASSO) was used to screen for characteristic predictors. Five machine learning (ML) algorithms: including Logistic Regression, ExtraTrees classifier, Bagging classifier, eXtreme Gradient Boosting (XGBoost), and Random Forest (RF) were employed. The performance of each model was evaluated by confusion matrix, area under curve (AUC), accuracy, precision, specificity, Recall and F1 scores. ResultsThe ultimate sample comprised 4525 subjects, of whom 7.7 % (N = 347) exhibited memory deterioration. The ExtraTrees classifier model and the XGBoost model demonstrated superior prediction performance and clinical value compared to other independent machine learning models, based on the AUC value of 0.915 and 0.911. Additionally, they consistently demonstrated accurate predicting ability for memory decline in the external datasets, with an AUC of 0.851 and 0.843, respectively. ConclusionThe ExtraTrees classifier and the XGBoost models were the two outperformed models in predicting memory decline. Nevertheless, it is necessary to conduct future investigations to confirm the accuracy of our findings.

Longitudinal relationships between Aβ and tau to executive function and memory in cognitively normal older adults

The early accumulation of AD pathology such as Aβ and tau in cognitively normal older people is predictive of cognitive decline, but it has been difficult to dissociate the cognitive effects of these two proteins. Early Aβ and tau target distinct brain regions that have different functional roles. Here, we assessed specific longitudinal pathology-cognition associations in seventy-six cognitively normal older adults from the Berkeley Aging Cohort Study who underwent longitudinal PiB PET, FTP PET, and cognitive assessments. Using linear mixed-effects models to estimate longitudinal changes and residual approach to characterizing cognitive domain-specific associations, we found that Aβ accumulation, especially in frontal/parietal regions, was associated with faster decline in executive function, not memory, whereas tau accumulation, especially in left entorhinal/parahippocampal regions, was associated with faster decline in memory, not executive function, supporting an “Aβ-executive function, tau-memory” double-dissociation in cognitively normal older people. These specific relationships between accumulating pathology and domain-specific cognitive decline may be due to the particular vulnerabilities of the frontal-parietal executive network to Aβ and temporal memory network to tau.

Parietal memory network and memory encoding versus retrieval impairments in PD-MCI patients: A hippocampal volume and cortical thickness study.

The pathophysiology behind memory impairment in Parkinson's Disease Mild Cognitive Impairment (PD-MCI) is unclear. This study aims to investigate the hippocampal and cortical atrophy patterns in PD-MCI patients with different types of memory impairments, categorized as Retrieval Failure (RF) and Encoding Failure (EF). The study included 16 healthy controls (HC) and 34 PD-MCI patients, divided into RF (N = 18) and EF (N = 16) groups based on their Verbal Memory Processes Test (VMPT) scores, including spontaneous recall, recognition, and Index of Sensitivity to Cueing (ISC). Hippocampal subfields and cortical thicknesses were measured using the FreeSurfer software for automatic segmentation. Compared to the HC group, the EF group exhibited significant atrophy in the left lateral occipital region and the right caudal middle frontal, superior temporal, and inferior temporal regions (p⟨0.05). The RF group displayed significant atrophy in the left lateral occipital, middle temporal, and precentral regions, as well as the right pars orbitalis and superior frontal regions (p⟨0.05). Hippocampal subfield analysis revealed distinct volume differences between HC-EF and RF-EF groups, with significant reductions in the CA1, CA3, and CA4 subregions in the EF group, but no differences between HC and RF groups (p > 0.05). Gray matter atrophy patterns differ in PD-MCI patients with encoding and retrieval memory impairments. The significant hippocampal atrophy in the EF group, particularly in the CA subregions, highlights its potential role in disease progression and memory decline. Additionally, the convergence of atrophy in the lateral occipital cortex across both RF and EF groups suggests the involvement of the Parietal Memory Network (PMN) in PD-related memory impairment.

Neurotoxicity of Aluminium Chloride and Okadaic Acid in Zebrafish: Unravelling Alzheimer's Disease Model via Learning and Memory Function Evaluation.

Introduction/ objectivesAlzheimer's disease (AD) is characterised by a progressive decline in cognitive abilities, especially learning and memory. To validate the zebrafish as a suitable model organism for AD, the study examined the effects of two neurotoxin agents, aluminium chloride (AlCl3) and okadaic acid (OKA). In the full experimental design, both neurotoxins were administered intraperitoneally at three distinct doses (low, medium, and high) twice weekly for 21 days. At three time points, behavioural tasks were conducted on day 7 (short duration), day 14 (moderate duration), and day 21 (long duration). The behavioural tasks consisted of a novel tank test lasting six minutes, followed by a T-maze tank test lasting five minutes. MethodsIn this article, the T-maze tank test was discussed in detail to evaluate which neurotoxins and their optimal dosages are impactful in developing a zebrafish AD model towards learning and memory functions. This evaluation measured four parameters: the amount of time spent in the wrong arm, the total distance travelled in the deeper chamber, and the 3-h and 24-h inflexion ratios. ResultsIn summary, a 100 nM dosage of OKA with a maximum of 21 days of evaluation resulted in significant (p < 0.05) outcomes in all parameters evaluated. The longest duration was spent in the wrong arm, accompanied by a reduction in the total distance travelled in the deeper chamber and a decreasing pattern in the 3-h and 24-h inflexion ratios. ConclusionThese observations suggest that OKA is the optimal choice of neurotoxin for a validated and optimised zebrafish AD model.

Recent Advances in Medicinal Chemistry of Memantine Against Alzheimer's Disease.

Alzheimer's disease (AD) is a chronic progressive, age-related neurodegenerative brain disorder characterized by the irreversible decline of memory and other cognitive functions. It is one of the major health threat of the 21st century, which affects around 60% of the population over the age of 60 years. The problem of this disease is even more major because the existing pharmacotherapies only provide symptomatic relief without addressing the basic factors of the disease. It is characterized by the extracellular deposition of amyloid β (Aβ) to form senile plaques, and the intracellular hyperphosphorylation of tau to form neurofibrillary tangles (NFTs). Due to the complex pathophysiology of this disease, various hypotheseshave been proposed, including the cholinergic, Aβ, tau, oxidative stress, and the metal-ion hypothesis. Among these, the cholinergic and Aβ hypotheses are the primary targets for addressing AD. Therefore, continuous advances have been made in developing potential cholinesterase inhibitors and N-methyl-D-aspartate (NMDA) receptor antagonists to delay disease progression and restore cholinergic neurotransmission. In this review article, we tried to comprehensively summarize the recent advancement in NMDA receptor antagonist (memantine) and their hybrid analogs as potential disease-modifying agents for the treatment of AD. Furthermore, we also depicted the design, rationale, and SAR analysis of the memantine-based hybrids used in the last decade for the treatment of AD.

Exercise, memory, and the hippocampus: Uncovering modifiable lifestyle reserve factors in refractory epilepsy

Physical exercise is an emerging target for improving cognition in aging and neurological disease. Due to the beneficial impact of exercise on hippocampal health and the vulnerability of the hippocampus in medication-resistant temporal lobe epilepsy (TLE), exercise could present a promising intervention in TLE. We investigated whether exercise engagement is associated with verbal memory function and hippocampal integrity in 29 young to middle-aged adults with refractory TLE and 21 demographically matched controls. Participants completed a self-reported questionnaire of weekly exercise, three tests of verbal memory, and a subset (n = 44) underwent structural MRI. Individuals with TLE self-reported lower exercise scores than controls across all levels of exercise intensity (p < 0.001). In TLE, greater exercise engagement was associated with better verbal memory (word-list recall and associative learning; rho = 0.46–0.47; ps FDR < 0.05), and with larger contralateral hippocampal volumes (rho = 0.61; p < 0.01). These effects remained significant when controlling for several clinical and demographic factors. These findings suggest that exercise may be a cognitive reserve factor in TLE, potentially mitigating memory decline by enhancing contralateral hippocampal integrity. With future replication and longitudinal investigation, exercise holds promise as a low-cost and accessible modifiable lifestyle target for improving cognitive health in individuals with refractory TLE

MEF2C Alleviates Postoperative Cognitive Dysfunction by Repressing Ferroptosis.

Ferroptosis, a form of programmed cell death featured by lipid peroxidation, has been proposed as a potential etiology for postoperative cognitive dysfunction (POCD). Myocyte-specific enhancer factor 2C (MEF2C), a transcription factor expressed in various brain cell types, has been implicated in cognitive disorders. This study sought to ascertain whether MEF2C governs postoperative cognitive capacity by affecting ferroptosis. Transcriptomic analysis of public data was used to identify MEF2C as a candidate differentially expressed gene in the hippocampus of POCD mice. The POCD mouse model was established via aseptic laparotomy under isoflurane anesthesia after treatment with recombinant adeno-associated virus 9 (AAV9)-mediated overexpression of MEF2C and/or the glutathione peroxidase 4 (GPX4) inhibitor RSL3. Cognitive performance, Nissl staining, and ferroptosis-related parameters were assessed. Dual-luciferase reporter gene assays and chromatin immunoprecipitation assays were implemented to elucidate the mechanism by which MEF2C transcriptionally activates GPX4. MEF2C mRNA and protein levels decreased in the mouse hippocampus following anesthesia and surgery. MEF2C overexpression ameliorated postoperative memory decline, hindered lipid peroxidation and iron accumulation, and enhanced antioxidant capacity, which were reversed by RSL3. Additionally, MEF2C was found to directly bind to the Gpx4 promoter and activate its transcription. Our findings suggest that MEF2C may be a promising therapeutic target for POCD through its negative modulation of ferroptosis.

Suspected Pseudobulbar Affect in Neurodegenerative Disease.

To investigate the association between suspected pseudobulbar affect (PBA), clinical diagnosis, cognitive testing, and self-reported mood in older adults presenting for evaluation of dementia. Patients presenting to an outpatient memory disorders clinic (N=311). We used traditional and novel network modeling approaches to examine associations between neuropsychological (NP) tests, patient and clinician rating scales, and the Center for Neurological Study-Lability Scale (CNS-LS) among patients with suspected AD (n=133) and other neurocognitive diagnosis (n=178). We then examined differences in test performance between patients with and without suspected PBA (CNS-LS cut-off of ≥ 13), while accounting for demographic and psychiatric covariates with propensity score matching. Group differences were assessed with Bayesian models. Prevalence of suspected PBA in AD was slightly less than half (44.4%) and at a similar rate in other dementias (e.g., 46.9% in CVD and 45.5% in LBD). In network models, the CNS-LS was associated with higher anxiety and better word list recall. After accounting for covariates, AD patients with suspected PBA performed better on word list recall βM=0.40, 95% CI [0.15, 0.66], and committed fewer false positive errors on recognition βM=-1.51, 95% CI [-2.34, -0.59] than AD patients without suspected PBA. There were no differences in patients with any other diagnostic impression, nor group differences on other NP measures. Patients with suspected PBA and AD diagnosis had better memory recall and recognition than those without suspected PBA, suggesting that impaired emotional regulation may be an early sign of AD in patients with less prominent memory decline. Better understanding PBA in neurodegenerative diseases, including prevalence and comorbidity with psychiatric conditions, could help with early identification, education, and initiation of treatment.

Kaixinsan regulates neuronal mitochondrial homeostasis to improve the cognitive function of Alzheimer's disease by activating CaMKKβ-AMPK-PGC-1α signaling axis

BackgroundAlzheimer's disease (AD) is a neurodegenerative disease primarily characterized by cognitive impairments. With the intensification of population aging, AD has become a major health issue faced by the elderly. Kaixinsan, a classical traditional Chinese prescription consists of Panax ginseng C. A. Mey., Polygala tenuifolia Willd., Poria cocos (Schw.) Wolf and Acori Tatarinowii rhizoma, is commonly used in clinical for treating memory decline. However, its mechanism remains unclear, which hinders its popularization and application. MethodMorris water maze (MWM) was performed to evaluate the effect of Kaixinsan on improving learning and memory ability in SAMP8 (senescence-accelerated mouse prone 8, an AD model mice) mice. Nissl staining, TdT-mediated dUTP Nick End Labeling (TUNEL) and western blotting (Bax and Bcl-2) were used to confirm the effect of Kaixinsan on the neuronal structure and apoptosis of SAMP8 mice. ultra performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) was performed to identify the distribution components of the brain tissue after receiving Kaixinsan extraction. Based on the identified brain distribution components, the mechanism of Kaixinsan improving the cognitive function was predicted by network pharmacology. Then, using HSP60 as mitochondrial marker and RBFOX3 as neuron marker, immunofluorescence co-localization was used to confirm the effect of Kaixinsan on neuronal mitochondria quantity in SAMP8 mice. Using western blotting to detect the expression of predicted proteins (AMPK, CaMKKβ, PGC-1α and HSP90) affecting mitochondrial homeostasis. To further confirm the mechanism of Kaixinsa. The authors replicated SH-SY5Y cell injury model induced by Amyloid β - protein fragment 25-35 (Aβ25-35) and compared the effects of serum containing Kaixinsan on apoptosis of injured SH-SY5Y cells (detected by flow cytometer) and the expression level of apoptosis-associated protein (Bax and Bcl-2) and mitochondrial homeostasis related proteins (AMPK, CaMKKβ, PGC-1α and HSP90), with or without the addition of CaMKKβ inhibitor (STO-609). ResultsThe results indicate that Kaixinsan can improve the cognitive function of SAMP8 mice, alleviate the hippocampal tissue lesions and inhibit neuron apoptosis. Seventeen brain distribution components of Kaixinsan were identified. Based on the brain distribution components of Kaixinsan, the results of network pharmacology suggest that Kaixinsan may regulate mitochondrial homeostasis through the CaMKKβ-AMPK-PGC-1α signaling axis. In vivo experiments, The authors observed that Kaixinsan could reverse neuronal mitochondrial loss in SAMP8 mice by upregulating CaMKKβ, AMPK, HSP90 and PGC-1α to promote mitochondrial biogenesis and increase the number of neuronal mitochondria. Additionally, the in vitro experiments demonstrated that Kaixinsan can inhibit apoptosis of Aβ25-35 injured SH-SY5Y cells and upregulate mitochondrial homeostasis-related proteins CaMKKβ, AMPK and PGC-1α. However, in addition to CaMKKβ inhibitors, the neuroprotective effect disappeared. ConclusionThe results indicate that Kaixinsan can improve the cognitive function of SAMP8 mice by regulating CaMKKβ-AMPK-PGC-1α signaling axis to maintain mitochondrial homeostasis and inhibit neuronal apoptosis.

Emerging signs of Alzheimer-like tau hyperphosphorylation and neuroinflammation in the brain post recovery from COVID-19.

Coronavirus disease 2019 (COVID-19) has been suggested to increase the risk of memory decline and Alzheimer's disease (AD), the main cause of dementia in the elderly. However, direct evidence about whether COVID-19 induces AD-like neuropathological changes in the brain, especially post recovery from acute infection, is still lacking. Here, using postmortem human brain samples, we found abnormal accumulation of hyperphosphorylated tau protein in the hippocampus and medial entorhinal cortex within 4-13 months post clinically recovery from acute COVID-19, together with prolonged activation of glia cells and increases in inflammatory factors, even though no SARS-COV-2 invasion was detected in these regions. By contrast, COVID-19 did not change beta-amyloid deposition and hippocampal neuron number, and had limited effects on AD-related pathological phenotypes in olfactory circuits including olfactory bulb, anterior olfactory nucleus, olfactory tubercle, piriform cortex and lateral entorhinal cortex. These results provide neuropathological evidences linking COVID-19 with prognostic increase of risk for AD.

Neuroprotective Properties of Rutin Hydrate against Scopolamine-Induced Deficits in BDNF/TrkB/ERK/CREB/Bcl2 Pathways.

Background/Objectives: Alzheimer's disease (AD) is an age-related degenerative brain disorder characterized by a progressive decline in cognitive function and memory. This study aimed to evaluate whether rutin hydrate (RH) has neuroprotective effects in an AD-like learning and memory impairment rat model induced by scopolamine (SCO). Methods: The rats were administered with RH (100 mg/kg) and SCO (1.5 mg/kg) and underwent behavioral tests, including the Morris water maze test, Y-maze test, and passive avoidance test, to evaluate their learning and memory abilities. Additionally, long-term potentiation (LTP) was induced to observe changes in the field excitatory postsynaptic potential (fEPSP) activity. Results: RH treatment attenuated the SCO-induced shortening of step-through latency in the passive avoidance (PA) test, increased the percentage of alternation in the Y-maze, and increased the time spent in the target zone in the Morris water maze (MWM). Moreover, RH increased the total activity of fEPSP following theta burst stimulation and attenuated the SCO-induced blockade of fEPSP. RH also ameliorated the SCO-induced decrease in the expression levels of the BDNF, TrkB, ERK, CREB, and Bcl-2 proteins and the increase in the Bax protein level in the rat hippocampus. This demonstrates that RH has beneficial neuroprotective effects in the brain, improving learning, memory, and synaptic plasticity in rats. Conclusions: Our results highlight the molecular and cellular mechanisms through which RH exerts its neuroprotective effects in the prevention and treatment of learning and memory deficit disorders. RH could potentially be used as a therapeutic strategy for the restoration of learning and memory function and the prevention of the progression of AD.

Age-related decline in source and associative memory.

This review explores the multifaceted nature of age-related decline in source memory and associative memory. The review highlights the potential effects of age-related decline in these types of memory. By integrating insights from behavioral, cognitive, and neuroscientific research, it examines how encoding, retrieval, and neural mechanisms influence this decline. Understanding these processes is critical to alleviate memory decline in older adults. Directing attention to source information during encoding, employing unitization techniques to strengthen memory associations, and utilizing metacognitive strategies to focus on relevant details show promise in enhancing memory retrieval for older adults. However, the review acknowledges limitations in processing resources and executive function, necessitating a nuanced approach to the complexities of age-related decline. In conclusion, this review underscores the importance of understanding the complexities of age-related source and associative memory decline and the potential benefits of specific cognitive strategies. It emphasizes the need for continued research on age-related memory function to improve the quality of life for aging populations.

A Peptide-Drug Conjugate-Based Nanoplatform for Immunometabolic Activation and In Situ Nerve Regeneration in Advanced-Stage Alzheimer's Disease.

The formidable protection of physiological barriers and unclear pathogenic mechanisms impede drug development for Alzheimer's disease (AD). As defenders of the central nervous system, immune-metabolism function, and stemness of glial cells remain dormant during degeneration, representing a significant challenge for simultaneously targeting and modulating. Here, a modular nanoplatform is presented composed of peptide-drug conjugates and an inflammation-responsive core. The nanoplatform is transported through the blood-brain barrier via transcytosis and disassembles in the oxidative stress microenvironment upon intravenous administration. The released drug-conjugated modules can specifically target and deliver hydroxychloroquine (HCQ) and all-trans retinoic acid (ATRA) to microglia and astrocytes, respectively. The immune function of chronic tolerant microglia is activated by metabolic modulation, and reactive astrocytes trans-differentiate into functional neurons. In a transgenic mouse model, nanoplatform reduces levels of toxic proteins and inflammation while increasing neuronal density. This results in the amelioration of learning and memory decline. The modular nanoplatform provides design principles for multi-cellular targeting and combination nano-therapy for inflammation-related diseases.

Peripherally-restricted recurrent infection by engineered E. coli strain modulates hippocampal proteome promoting memory impairments in a rat model

Commensal bacteria that breach endothelial barrier has been reported to induce low grade chronic inflammation producing disease symptoms in major peripheral tissues. In this study, we investigated the role of genetically modified cellular invasive form of commensal E. coli K12 (SK3842) in cognitive impairment. Low-grade systemic infection model was developed using recurring peripheral inoculation of live bacteria in Wistar rats. To examine memory parameters, Novel object recognition test and Radial arm maze test were performed. Differential protein expression profiling of rat hippocampus was carried out using LC-MS/MS and subsequently quantified using SWATH. HBA1/2, NEFH, PFN1 and ATP5d were chosen for validation using quantitative RT-PCR. Results showed drastic decline in Recognition memory of the SK3842 infected rats. Reference and Working Memory of the infected group were also significantly reduced in comparison to control group. Proteome analysis using LC-MS/MS coupled with SWATH revealed differential expression of key proteins that are crucial for the maintenance of various neurological functions. Moreover, expression of NEFH and PFN1transcripts were found to be in line with the proteomics data. Protein interaction network of these validated proteins generated by STRING database converged to RhoA protein. Thus, the present study establishes an association between peripheral infection of a hippocampal protein network dysregulation and overall memory decline.

Stem Cells as a Novel Source for Regenerative Medicinal Applications in Alzheimer's Disease: An Update.

Alzheimer's Disease (AD) is a progressive neurodegenerative disorder characterized by loss of the neurons, excessive accumulation of misfolded Aβ and Tau proteins, and degeneration of neural synapses, primarily occurring in the neocortex and the hippocampus regions of the brain. AD Progression is marked by cognitive deterioration, memory decline, disorientation, and loss of problem-solving skills, as well as language. Due to limited comprehension of the factors contributing to AD and its severity due to neuronal loss, even today, the medications approved by the U.S. Food and Drug Administration (FDA) are not precisely efficient and curative. Stem cells possess great potential in aiding AD due to their self-renewal, proliferation, and differentiation properties. Stem cell therapy can aid by replacing the lost neurons, enhancing neurogenesis, and providing an enriched environment to the pre-existing neural cells. Stem cell therapy has provided us with promising results in regard to the animal AD models, and even pre-clinical studies have shown rather positive results. Cell replacement therapies are potential curative means to treat AD, and there are a number of undergoing human clinical trials to make Stem Cell therapy accessible for AD patients. In this review, we aim to discuss the AD pathophysiology and varied stem cell types and their application.

Progression of hippocampal subfield atrophy and asymmetry in Alzheimer's disease.

Alzheimer's disease (AD) affects the hippocampus during its progression, but the specific observable changes of hippocampal subfields during disease progression remain poorly understood. In this study, we employed an event-based model (EBM) to determine the sequence of occurrence of hippocampal subfield atrophy in mild cognitive impairment (MCI) and AD cohorts. Subjects (207) were included: 86 MCI, 53 AD, and 68 healthy controls from the Alzheimer's Disease Neuroimaging Initiative (ADNI). Participants underwent structural magnetic resonance imaging (MRI) scans to analyse the hippocampal subfields. We assigned each patient to a specific EBM stage, based on the number of their abnormal subfields. A combination of 2-year follow-up MRI scans were applied to demonstrate the longitudinal consistency and utility of the model's staging system. The model estimated that the earliest atrophy occurs in the hippocampal fissure, then spreading to other subregions in both MCI and AD. We identified a marked divergence between the sequences of left and right hippocampal subfields atrophy, so inter-hemispheric asymmetry pattern was further analysed. The sequence of asymmetry index (AI) increases beginning in the molecular and granule cell layers of the dentate gyrus (GC-ML-DG), cornus ammonis (CA) 4, and the molecular layer (ML). Longitudinal analysis confirms the efficacy of the model. In addition, the model stages were significantly correlated with patients' memory scores (p < .05). Collectively, we used a data-driven method to provide new insight into AD hippocampal progression. The present model could aid in understanding of the disease stages, as well as tracking memory decline.

Increased neuronal expression of the early endosomal adaptor APPL1 leads to endosomal and synaptic dysfunction with cholinergic neurodegeneration.

Dysfunction in the endolysosomal system within neurons is a key feature of Alzheimer's disease (AD). Multiple AD risk factors lead to hyperactivity of the early-endosome GTPase rab5, disrupting neuronal pathways including the cholinergic circuits involved early in memory decline. APPL1, a crucial rab5 effector, connects endosomal and neuronal functions through its interaction with a specific amyloid precursor protein (APP) fragment generated within endosomes. To understand APPL1's role, a transgenic mouse model over-expressing human APPL1 in neurons (Thy1-APPL1 mice) was developed. These mice show enlarged early endosomes and increased synaptic endocytosis due to rab5 activation, resulting in impaired hippocampal long-term potentiation and depression, the degeneration of basal forebrain cholinergic neurons, and memory deficits, highlighting a pathological cascade mediated through APPL1 at the early endosome.

Hypoxemia during rapid eye movement sleep mediates memory impairment in older adults at risk for dementia via CA1 hippocampal volume loss

AbstractBackground and PurposeObstructive sleep apnea is associated with increased dementia risk. Nocturnal hypoxemia, which can be more severe during rapid eye movement (REM) sleep, may be a key mechanism. This study examines how REM hypoxemia affects memory and explores whether hippocampal vulnerability to hypoxemia mediates this effect in older adults at risk for dementia.MethodsOlder adults aged ≥50 years (N = 338) with subjective or mild cognitive impairment (i.e., objective impairment) underwent neuropsychological, mood, and medical assessment, magnetic resonance imaging scanning (n = 135), and overnight polysomnography. Verbal learning and memory were assessed with the Rey Auditory Verbal Learning Test. REM sleep hypoxemia was measured using the Oxygen Desaturation Index‐3% (REM‐ODI). Hippocampal subfield (CA1, CA3, subiculum, and dentate gyrus) volumes were derived from T1 and high‐resolution hippocampus T2 scans. We determined whether the relationship between REM‐ODI and learning and memory was mediated by hippocampal subfield volume. Analyses were repeated in non‐REM sleep to determine whether the effects were REM‐specific.ResultsAlthough there was not a direct effect of REM‐ODI on verbal learning (p &gt; 0.05) or memory (p &gt; 0.05), mediation analyses showed a significant indirect effect of high REM‐ODI on poorer verbal learning (β = −0.09, 95% confidence interval [CI] = −0.238 to −0.005) and memory (β = −0.100, 95% CI = −0.255 to −0.005), which was mediated by CA1 volume. These associations were absent in non‐REM sleep (p &gt; 0.05).ConclusionsHypoxemia during REM sleep may impair memory in people at risk for dementia by reducing CA1 hippocampal volume. Research is needed to explore whether interventions targeting REM sleep hypoxemia are protective against memory decline.

Effect of a cash transfer intervention on memory decline and dementia probability in older adults in rural South Africa

Evidence on cash transfers as a population-level intervention to support healthy cognitive aging in low-income settings is sparse. We assessed the effect of a cash transfer intervention on cognitive aging outcomes in older South African adults. We leveraged the overlap in the sampling frames of a Phase 3 randomized cash transfer trial [HIV Prevention Trial Network (HPTN) 068, 2011-2015] and an aging cohort [Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community (HAALSI), 2014-2022] in rural Mpumalanga Province, South Africa. In 2011/12, young women and their primary caregivers were randomly assigned 1:1 to receive a monthly cash transfer or control. In 2014/2015, 862 adults aged 40+ y living in trial households were enrolled in the HAALSI cohort, with cognitive data collected in three waves over 7 y. We estimated the impact of the intervention on rate of memory decline and dementia probability scores. Memory decline in the cash transfer arm was 0.03 SD units (95% CI: 0.002, 0.05) slower per year than in the control arm. Dementia probability scores were three percentage points lower in the cash transfer arm than the control arm (β = -0.03; 95% CI: -0.05, -0.001). Effects were consistent across subgroups. A modestly sized household cash transfer delivered over a short period in mid- to later-life led to a meaningful slowing of memory decline and reduction in dementia probability 7 y later. Cash transfer programs could help stem the tide of new dementia cases in economically vulnerable populations in the coming decades.

A Novel Tetrahydroacridine Derivative with Potent Acetylcholinesterase Inhibitory Properties and Dissociative Capability against Aβ42 Fibrils Confirmed by In Vitro Studies.

Alzheimer's disease (AD) is one of the most common causes of dementia, accounting for more than 60% of all cases. It is a neurodegenerative disease in which symptoms such as a decline in memory, thinking, learning, and organizing skills develop gradually over many years and eventually become more severe. To date, there is no effective treatment for the cause of Alzheimer's disease, and the existing pharmacological options primarily help manage symptoms. Treatment is mainly based on acetylcholinesterase (AChE) inhibitors such as donepezil, rivastigmine, and galantamine, which exhibit numerous adverse cardiovascular and gastrointestinal effects due to excessive stimulation of peripheral cholinergic activity involving muscarinic receptors. Therefore, in addition to the obvious drugs that act on the cause of the disease, new drugs based on AChE inhibition that show the fewest side effects are needed. One potential drug could be a new compound under study, tetrahydroacridine derivative (CHDA), which showed significant potential to inhibit the AChE enzyme in previous in vitro studies. The present study shows that while having very potent AChE inhibitory properties, CHDA is a compound with low toxicity to nerve cell culture and living organisms. In addition, it exhibits dissociative activity against amyloid β fibrils, which is extremely important for applications in Alzheimer's disease therapy.