Sea Cucumber Peptides Attenuated the Scopolamine-Induced Memory Impairment in Mice and Rats and the Underlying Mechanism

Social stress and unhealthy diets lead to memory impairment, triggering health problems. This study aimed to determine the mitigating effect and regulation mechanism of sea cucumber peptides (SCP) against memory impairment. Here, scopolamine-induced memory impairment in mouse and rat models was used based on behavioral tests, a histological staining technique, Fourier transform infrared microscopy, and gas-chromatographic analysis as well as a Western blotting method. SCP improved the behavioral performance and regulated the disorder of the cholinergic system in mouse models in a dose-dependent manner. Therefore, the underlying mechanism was explored in high-dose SCP using mouse and rat models. SCP repaired damaged neuronal cells, enhanced the Nissl body number, increased the unsaturated lipid level, and activated the long-term potentiation (LTP) pathway (p-CaMKII, p-CREB, and BDNF), both in the mouse and rat hippocampus. The results indicated that SCP upregulated the LTP pathway and unsaturated lipid level to combat scopolamine-induced memory impairment, suggesting that SCP was a potential candidate for neurological recovery.

Refined Analysis of Chronic White Matter Changes after Traumatic Brain Injury and Repeated Sports-Related Concussions: Of Use in Targeted Rehabilitative Approaches?

Traumatic brain injury (TBI) or repeated sport-related concussions (rSRC) may lead to long-term memory impairment. Diffusion tensor imaging (DTI) is helpful to reveal global white matter damage but may underestimate focal abnormalities. We investigated the distribution of post-injury regional white matter changes after TBI and rSRC. Six patients with moderate/severe TBI, and 12 athletes with rSRC were included ≥6 months post-injury, and 10 (age-matched) healthy controls (HC) were analyzed. The Repeatable Battery for the Assessment of Neuropsychological Status was performed at the time of DTI. Major white matter pathways were tracked using q-space diffeomorphic reconstruction and analyzed for global and regional changes with a controlled false discovery rate. TBI patients displayed multiple classic white matter injuries compared with HC (p < 0.01). At the regional white matter analysis, the left frontal aslant tract, anterior thalamic radiation, and the genu of the corpus callosum displayed focal changes in both groups compared with HC but with different trends. Both TBI and rSRC displayed worse memory performance compared with HC (p < 0.05). While global analysis of DTI-based parameters did not reveal common abnormalities in TBI and rSRC, abnormalities to the fronto-thalamic network were observed in both groups using regional analysis of the white matter pathways. These results may be valuable to tailor individualized rehabilitative approaches for post-injury cognitive impairment in both TBI and rSRC patients.

Genistein: A Potential Natural Lead Molecule for New Drug Design and Development for Treating Memory Impairment

Genistein is a naturally occurring polyphenolic molecule in the isoflavones group which is well known for its neuroprotection. In this review, we summarize the efficacy of genistein in attenuating the effects of memory impairment (MI) in animals. Scopus, PubMed, and Web of Science databases were used to find the relevant articles and discuss the effects of genistein in the brain, including its pharmacokinetics, bioavailability, behavioral effects, and some of the potential mechanisms of action on memory in several animal models. The results of the preclinical studies highly suggested that genistein is highly effective in enhancing the cognitive performance of the MI animal models, specifically in the memory domain, including spatial, recognition, retention, and reference memories, through its ability to reduce oxidative stress and attenuate neuroinflammation. This review also highlighted challenges and opportunities to improve the drug delivery of genistein for treating MI. Along with that, the possible structural modifications and derivatives of genistein to improve its physicochemical and drug-likeness properties are also discussed. The outcomes of the review proved that genistein can enhance the cognitive performance and ameliorate MI in different preclinical studies, thus indicating its potential as a natural lead for the design and development of a novel neuroprotective drug.

Research advances on how metformin improves memory impairment in "chemobrain"

Cognitive impairment caused by chemotherapy, referred to as “chemobrain,” is observed in approximately 70% of cancer survivors. However, it is not completely understood how chemotherapy induces cognitive dysfunction, and clinical treatment strategies for this problem are lacking. Metformin, used as a first-line treatment for type 2 diabetes mellitus, is reported to reduce the effects of chemobrain. Recently, several studies have examined the effect of metformin in rescuing chemobrain. This review discusses recent clinical/preclinical studies that addressed some mechanisms of chemobrain and evaluates the effect of metformin in rescuing chemobrain and its potential mechanisms of action.

Effects of ginsenosides on memory impairment in propofol-anesthetized rats

To investigate the effects of ginsenosides on the memory impairment in Sprague–Dawley rats (SD rats) after anesthesia through the administration of propofol SPF, SD rats were randomly divided into four groups: control group (Group I), propofol-treated group (Group II), low dose of ginsenosides-treated group (Group III) and high dose of ginsenosides-treated group (Group IV). These rats were subjected to fear memory test in shuttle box, Y-maze test and Morris water maze test. Immediately after the test, the expression levels of nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF) were further detected by ELISA method. Ginsenosides could ameliorate the impairment on the functions of fear memory, working memory and spatial memory in rats caused by anesthesia via the injection of Propofol. Furthermore, the expression levels of NGF and BDNF on rat hippocampus were significant increased by the treatment of ginsenosides at both two doses compared with the control group (both P < 0.05). Ginsenosides hold potential to be developed as a novel therapeutic agent for those patients suffering from postoperative cognitive dysfunction caused by anesthesia via the treatment of propofol.

L-Carnitine prevents memory impairment induced by post-traumatic stress disorder

BACKGROUND

Post-traumatic stress disorder (PTSD) is a genuine obstructing mental disorder. As indicated by the name, it is related to the patients' stress augmented by life-threatening conditions or accidents. The PTSD has linked to oxidative stress that can result in neurodegeneration. L-carnitine (L-CAR) is known for its antioxidant properties, which can protect against neuronal damage.

OBJECTIVE

In the current study, we investigated the beneficial effects of L-CAR on the memory impairment induced by PTSD using a rat model.

METHODS

A model of single-prolonged stress (a cycle of restraining, forced swimming, rest, and finally diethyl ether exposure for 2 h, 20 min, 15 min, and 1-2 min, respectively) was used to induce PTSD-like behavior. Intraperitoneal L-CAR treatment (300 mg/kg/day) was introduced for four weeks. Both memory and special learning were evaluated utilizing the radial arm water maze (RAWM). Moreover, the levels of glutathione peroxidase (GPx), glutathione reduced (GSH), and glutathione oxidized (GSSG) were assessed as biomarkers oxidative stress in the hippocampus.

RESULTS

The results demonstrated that both the short and long-term memories were impaired by PTSD/SPS model (P <  0.05), while L-CAR treatment prevented this memory impairment in PTSD rats. Besides, L-CAR prevented the reduction in GPx activity and increase in GSSG, which were altered in the hippocampus of the PTSD/SPS rats (P <  0.05). Levels of GSH were not changed in PTSD and/or L-CAR rats.

CONCLUSIONS

L-CAR administration prevented short- and long-term memories' impairments induced in the PTSD/SPS rat model. This is probably related to its antioxidant effects in the hippocampus.

Advancing Smart Home Awareness-A Conceptual Computational Modelling Framework for the Execution of Daily Activities of People with Alzheimer's Disease

Utilizing context-aware tools in smart homes (SH) helps to incorporate higher quality interaction paradigms between the house and specific groups of users such as people with Alzheimer's disease (AD). One method of delivering these interaction paradigms acceptably and efficiently is through context processing the behavior of the residents within the SH. Predicting human behavior and uncertain events is crucial in the prevention of upcoming missteps and confusion when people with AD perform their daily activities. Modelling human behavior and mental states using cognitive architectures produces computational models capable of replicating real use case scenarios. In this way, SHs can reinforce the execution of daily activities effectively once they acquire adequate awareness about the missteps, interruptions, memory problems, and unpredictable events that can arise during the daily life of a person living with cognitive deterioration. This paper presents a conceptual computational framework for the modelling of daily living activities of people with AD and their progression through different stages of AD. Simulations and initial results demonstrate that it is feasible to effectively estimate and predict common errors and behaviors in the execution of daily activities under specific assessment tests.

The Independent and Joint Effects of Different Childhood Abuse Types on Subjective Prospective and Retrospective Memory Impairment During Pregnancy

Background and Objective: Childhood abuse is considered a risk factor in various health outcomes during pregnancy. However, no study has explored the relationship between childhood abuse and memory impairment during pregnancy. This study is the first to explore the relationship between childhood abuse and subjective memory impairment.

Participants, Setting, and Methods: A total of 1,825 pregnant women were recruited from a comprehensive hospital in Shandong province, China, and completed a questionnaire survey. Multivariable linear regression analysis was used to explore the relationship between childhood abuse and subjective prospective and retrospective memory.

Results: Pregnant women with high total childhood abuse scores had high prospective and retrospective memory impairment. Among pregnant women reporting only emotional abuse, only physical abuse, or only sexual abuse, women reporting only emotional abuse were found to have high prospective and retrospective memory impairment. Women with all three childhood abuse types also had high prospective and retrospective memory impairment.

Conclusion: Women who experienced childhood abuse, especially childhood emotional abuse, had high subjective memory impairment during pregnancy. It is important to ask pregnant women about their experiences of childhood abuse, especially emotional abuse, during early prenatal care, as such abuse is likely to have negative effects on memory during pregnancy.

Hesperidin Reduces Memory Impairment Associated with Adult Rat Hippocampal Neurogenesis Triggered by Valproic Acid

Treatment with valproic acid (VPA) deteriorates hippocampal neurogenesis, which leads to memory impairment. Hesperidin (Hsd) is a plant-based bioflavonoid that can augment learning and memory. This study aimed to understand the effect of Hsd on the impairment of hippocampal neurogenesis and memory caused by VPA. The VPA (300 mg/kg) was administered by intraperitoneal injection twice daily for 14 days, and Hsd (100 mg/kg/day) was administered by oral gavage once a day for 21 days. All rats underwent memory evaluation using the novel object location (NOL) and novel object recognition (NOR) tests. Immunofluorescent staining of Ki-67, BrdU/NeuN, and doublecortin (DCX) was applied to determine hippocampal neurogenesis in cell proliferation, neuronal survival, and population of the immature neurons, respectively. VPA-treated rats showed memory impairments in both memory tests. These impairments resulted from VPA-induced decreases in the number of Ki-67-, BrdU/NeuN-, and DCX-positive cells in the hippocampus, leading to memory loss. Nevertheless, the behavioral expression in the co-administration group was improved. After receiving co-administration with VPA and Hsd, the numbers of Ki-67-, BrdU/NeuN-, and DCX-positive cells were improved to the normal levels. These findings suggest that Hsd can reduce the VPA-induced hippocampal neurogenesis down-regulation that results in memory impairments.

A culturally sensitive approach to Indigenous older Sámi living with memory loss- disconnected from their environment and spirituality

The aim of this article is to discuss attitudes to memory loss in old age among older Sámi people in the Arctic region of Norway. What preferences and lived experiences are expressed when older Sámi people need health and social care because of memory loss? According to the Sámi Act (§ 108), the Sámi Indigenous people in Norway have a legal right to receive equitable health and social services adapted to the Sámi language, traditional lifestyle and religious customs. However, standard services are offered that are adapted to the majority of clients in a homogenisation of needs and wishes, and older Sámi clients are treated in the same way regardless of their cultural background. Ethnographic interviews and participant observation illustrated as case studies. Older Sámis' long-term connectedness to nature and spirituality makes them sensitive to the changes in the environment. Healthcare personnel enable older Sámi to feel connected to their environment and spirituality in old age, by facilitating culturally sensitive care. This study explores a need of culturally sensitive approach to health care, aiming to increase the understanding of the preferences and lived experiences of Indigenous older people with cognitive impairment.

OAB-14 Effectively Ameliorates the Dysfunction of the Endosomal-Autophagic-Lysosomal Pathway in APP/PS1 Transgenic Mice

In Alzheimer's disease (AD), damaged Aβ clearance contributes to elevated levels of Aβ that cause a series of cytotoxic cascade reactions. Thus, targeting Aβ clearance has now been considered a valid therapeutic approach for AD. Cellular uptake and degradation are important mechanisms for Aβ clearance, which are mainly performed by the endosomal-autophagic-lysosomal (EAL) pathway. Our previous study showed that OAB-14, a novel small molecule designed with bexarotene as the lead compound, treatment for 3 months significantly alleviated cognitive disorders and remarkably reduced the deposition of Aβ without affecting its production in APP/PS1 transgenic mice. Here, we further revealed that enhancement of the EAL activity is one of the mechanisms that increases Aβ clearance after OAB-14 administration for 3 months. OAB-14 facilitates receptor-mediated endocytosis and restores autophagy flux via the AMPK/mTOR pathway. Meanwhile, OAB-14 enhances the lysosomal activity, and reduced Aβ accumulation in lysosomes was observed in OAB-14-treated AD mice. These results suggest that OAB-14 may promote Aβ clearance in lysosomes by alleviating the EAL dysfunction in AD mice.

Depressed mood and frailty among older people in Tokyo during the COVID-19 pandemic

BACKGROUND

The study aim was to identify depressed mood and frailty and its related factors in older people during the coronavirus disease 19 pandemic.

METHODS

Since 2010, we have conducted questionnaire surveys on all older residents, who are not certified in the long-term care insurance, living in one district of Tokyo municipality. These residents are divided into two groups by birth month, that is those born between April and September and those born between October and March, and each group completes the survey every 2 years (in April and May). Study participants were older residents who were born between April and September and who completed the survey in spring 2018 and in spring 2020, the pandemic period. Depressed mood and frailty were assessed using the Kihon Checklist, which is widely used by local governments in Japan. We had no control group in this study.

RESULTS

A total of 1736 residents responded to both surveys. From 2018 to 2020, the depressed mood rate increased from 29% to 38%, and frailty increased from 10% to 16%. The incidence of depressed mood and frailty was 25% and 11%, respectively. Incidence of depressed mood was related to subjective memory impairment and difficulty in device usage, and incidence of frailty was related to being older, subjective memory impairment, lack of emotional social support, poor subjective health, and social participation difficulties.

CONCLUSIONS

Older people with subjective memory impairment may be a high-risk group during the coronavirus pandemic. Telephone outreach for frail older people could be an effective solution. We recommend extending the scope of the 'reasonable accommodation' concept beyond disability and including older people to build an age-friendly and crisis-resistant community.

Electroacupuncture promotes the survival and synaptic plasticity of hippocampal neurons and improvement of sleep deprivation-induced spatial memory impairment

Aims

This study aimed to investigate whether electroacupuncture (EA) promotes the survival and synaptic plasticity of hippocampal neurons by activating brain‐derived neurotrophic factor (BDNF)/tyrosine receptor kinase (TrkB)/extracellular signal‐regulated kinase (Erk) signaling, thereby improving spatial memory deficits in rats under SD.

Methods

In vivo, Morris water maze (MWM) was used to detect the effect of EA on learning and memory, at the same time Western blotting (WB), immunofluorescence (IF), and transmission electron microscopy (TEM) were used to explore the plasticity of hippocampal neurons and synapses, and the expression of BDNF/TrkB/Erk signaling. In vitro, cultured hippocampal neurons were treated with exogenous BDNF and the TrkB inhibitor K252a to confirm the relationship between BDNF/TrkB/Erk signaling and synaptic plasticity.

Results

Our results showed that EA mitigated the loss of hippocampal neurons and synapses, stimulated hippocampal neurogenesis, and improved learning and memory of rats under SD accompanied by upregulation of BDNF and increased phosphorylation of TrkB and Erk. In cultured hippocampal neurons, exogenous BDNF enhanced the expression of synaptic proteins, the frequency of the postsynaptic currents, and the phosphorylation of TrkB and Erk; these effects were reversed by treatment with K252a.

Conclusions

Electroacupuncture alleviates SD‐induced spatial memory impairment by promoting hippocampal neurogenesis and synaptic plasticity via activation of BDNF/TrkB/Erk signaling, which provided evidence for EA as a therapeutic strategy for countering the adverse effects of SD on cognition.

Memory Modulation Factors in Hippocampus Exposed to Radiation

Although the key scene of the hippocampus in memory processes is obvious, the specificity of its participation in information processing is far from being established. Current advanced neuroimaging enables to operate with precise morphometric parameters. The aim of the study was to reveal fine memory rearrangements under mechanical impact on the hippocampus by a neoplasm and radiation exposure in the course of therapy.

Materials and Methods

We used a homogeneous sample of 28 patients with parasellar meningiomas adjacent to hippocampus. In 10 patients (5 with left-sided and 5 with right-sided meningiomas), the tumor was located near the hippocampus but exhibited no mechanical effect on it. In 18 patients (10 with left-sided and 8 with right-sided tumors), the neoplasm compressed the adjacent hippocampus. The control group consisted of 39 healthy subjects. All three groups were comparable in age, education, and gender characteristics. In order to control tumor growth, the patients underwent radiotherapy when the hippocampus involuntary was exposed to a dose comparable to that in the tumor (30 sessions with a single focal dose of 1.8 Gy, total dose - 54.0 Gy).Based on the literature data on hippocampus involved in mnestic processes, a special methodology to investigate memory was developed. Incorrect responses the subjects made when identifying previously memorized images were classified as neutralizing the novelty factor of an identified stimulus or as wrongly emphasizing its novelty.

Results

At the first observation point (before radiation therapy) all groups underwent a complete standardized neuropsychological examination and performed a battery of cognitive tests. The overall results of the tests assessing attention, memory, thinking processes, and neurodynamic indicators corresponded to standard values. A mild brain compression by the tumor without brain tissue destruction was not accompanied by focal neuropsychological symptoms and deficit manifestations in the cognitive sphere. However, as early as in the first observation point, the number of "pattern separation" errors in the clinical group was significantly higher than that in healthy subjects.The second observation point (immediately after radiotherapy) and the third observation point - 6 months after the treatment - showed that, in general, the patients' cognitive sphere condition was not deteriorating, and in a number of parameters was characterized by positive dynamics, apparently associated with some tumor reduction due to the therapy provided. However, the distribution of errors in the original method significantly changed. When previously memorized stimuli were recognized, the errors neutralizing the novelty factor of the evaluated stimulus increased, while the number of errors with overestimating the stimuli novelty decreased.All tendencies hypothetically (according to the published data) associated with the changes in functional activity of the hippocampus were more pronounced in the subgroup of patients with mechanical impact of the tumor on hippocampus.

Conclusion

The continuous flow of impressions any person has at any moment of his activity is most likely marked by the hippocampus in a continuum "old-similar-new". The present study has shown that mechanical impact on the hippocampus combined with radiation exposure changes the range of assessments towards the prevailing labeling "old, previously seen, already known".

proNGF Involvement in the Adult Neurogenesis Dysfunction in Alzheimer's Disease

In recent decades, neurogenesis in the adult brain has been well demonstrated in a number of animal species, including humans. Interestingly, work with rodents has shown that adult neurogenesis in the dentate gyrus (DG) of the hippocampus is vital for some cognitive aspects, as increasing neurogenesis improves memory, while its disruption triggers the opposite effect. Adult neurogenesis declines with age and has been suggested to play a role in impaired progressive learning and memory loss seen in Alzheimer's disease (AD). Therefore, therapeutic strategies designed to boost adult hippocampal neurogenesis may be beneficial for the treatment of AD. The precursor forms of neurotrophins, such as pro-NGF, display remarkable increase during AD in the hippocampus and entorhinal cortex. In contrast to mature NGF, pro-NGF exerts adverse functions in survival, proliferation, and differentiation. Hence, we hypothesized that pro-NGF and its p75 neurotrophin receptor (p75NTR) contribute to disrupting adult hippocampal neurogenesis during AD. To test this hypothesis, in this study, we took advantage of the availability of mouse models of AD (APP/PS1), which display memory impairment, and AD human samples to address the role of pro-NGF/p75NTR signaling in different aspects of adult neurogenesis. First, we observed that DG doublecortin (DCX) + progenitors express p75NTR both, in healthy humans and control animals, although the percentage of DCX+ cells are significantly reduced in AD. Interestingly, the expression of p75NTR in these progenitors is significantly decreased in AD conditions compared to controls. In order to assess the contribution of the pro-NGF/p75NTR pathway to the memory deficits of APP/PS1 mice, we injected pro-NGF neutralizing antibodies (anti-proNGF) into the DG of control and APP/PS1 mice and animals are subjected to a Morris water maze test. Intriguingly, we observed that anti-pro-NGF significantly restored memory performance of APP/PS1 animals and significantly increase the percentage of DCX+ progenitors in the DG region of these animals. In summary, our results suggest that pro-NGF is involved in disrupting spatial memory in AD, at least in part by blocking adult neurogenesis. Moreover, we propose that adult neurogenesis alteration should be taken into consideration for better understanding of AD pathology. Additionally, we provide a new molecular entry point (pro-NGF/p75NTR signaling) as a promising therapeutic target in AD.

A comprehensive score reflecting memory-related fMRI activations and deactivations as potential biomarker for neurocognitive aging

Older adults and particularly those at risk for developing dementia typically show a decline in episodic memory performance, which has been associated with altered memory network activity detectable via functional magnetic resonance imaging (fMRI). To quantify the degree of these alterations, a score has been developed as a putative imaging biomarker for successful aging in memory for older adults (Functional Activity Deviations during Encoding, FADE; Düzel et al., Hippocampus, 2011; 21: 803-814). Here, we introduce and validate a more comprehensive version of the FADE score, termed FADE-SAME (Similarity of Activations during Memory Encoding), which differs from the original FADE score by considering not only activations but also deactivations in fMRI contrasts of stimulus novelty and successful encoding, and by taking into account the variance of young adults' activations. We computed both scores for novelty and subsequent memory contrasts in a cohort of 217 healthy adults, including 106 young and 111 older participants, as well as a replication cohort of 117 young subjects. We further tested the stability and generalizability of both scores by controlling for different MR scanners and gender, as well as by using different data sets of young adults as reference samples. Both scores showed robust age-group-related differences for the subsequent memory contrast, and the FADE-SAME score additionally exhibited age-group-related differences for the novelty contrast. Furthermore, both scores correlate with behavioral measures of cognitive aging, namely memory performance. Taken together, our results suggest that single-value scores of memory-related fMRI responses may constitute promising biomarkers for quantifying neurocognitive aging.

Memory Deficit in Patients With Temporal Lobe Epilepsy: Evidence From Eye Tracking Technology

Objective: To explore quantitative measurements of the visual attention and neuroelectrophysiological relevance of memory deficits in temporal lobe epilepsy (TLE) by eye tracking and electroencephalography (EEG).

Methods: Thirty-four TLE patients and twenty-eight healthy controls were invited to complete neurobehavioral assessments, cognitive oculomotor tasks, and 24-h video EEG (VEEG) recordings using an automated computer-based memory assessment platform with an eye tracker. Visit counts, visit time, and time of first fixation on areas of interest (AOIs) were recorded and analyzed in combination with interictal epileptic discharge (IED) characteristics from the bilateral temporal lobes.

Results: The TLE patients had significantly worse Wechsler Digit Span scores [F(1, 58) = 7.49, p = 0.008]. In the Short-Term Memory Game with eye tracking, TLE patients took a longer time to find the memorized items [F(1, 57) = 17.30, p < 0.001]. They had longer first fixation [F(1, 57) = 4.06, p = 0.049] and more visit counts [F(1, 57) = 7.58, p = 0.008] on the target during the recall. Furthermore, the performance of the patients in the Digit Span task was negatively correlated with the total number of IEDs [r(28) = −0.463, p = 0.013] and the number of spikes per sleep cycle [r(28) = −0.420, p = 0.026].

Conclusion: Eye tracking appears to be a quantitative, objective measure of memory evaluation, demonstrating memory retrieval deficits but preserved visual attention in TLE patients. Nocturnal temporal lobe IEDs are closely associated with memory performance, which might be the electrophysiological mechanism for memory impairment in TLE.

Severe Fatigue and Memory Impairment Are Associated with Lower Serum Level of Anti-SARS-CoV-2 Antibodies in Patients with Post-COVID Symptoms

Background: Post-COVID manifestation is defined as persistent symptoms or long-term complications beyond 4 weeks from disease onset. Fatigue and memory impairment are common post-COVID symptoms. We aimed to explore associations between the timeline and severity of post-COVID fatigue and anti-SARS-CoV-2 antibodies. Methods: Fatigue and memory impairment were assessed in a total of 101 post-COVID subjects using the Chalder fatigue scale (CFQ-11) and a visual analogue scale. Using the bimodal scoring system generated from CFQ-11, a score ≥4 was defined as severe fatigue. Serum anti-SARS-CoV-2 spike (anti-S-Ig) and nucleocapsid (anti-NC-Ig) antibodies were examined at two time points: 4–12 weeks after onset of symptoms, and beyond 12 weeks. Results: The serum level of anti-S-Ig was significantly higher in patients with non-severe fatigue compared to those with severe fatigue at 4–12 weeks (p = 0.006) and beyond 12 weeks (p = 0.016). The serum level of anti-NC-Ig remained high in patients with non-severe fatigue at both time points. In contrast, anti-NC-Ig decreased significantly in severe fatigue cases regardless of the elapsed time (4–12 weeks: p = 0.024; beyond 12 weeks: p = 0.005). The incidence of memory impairment was significantly correlated with lower anti-S-Ig levels (−0.359, p < 0.001). Conclusion: The systemic immune response reflected by antibodies to SARS-CoV-2 is strongly correlated with the severity of post-COVID fatigue.

High Cholesterol Diet Exacerbates Blood-Brain Barrier Disruption in LDLr-/- Mice: Impact on Cognitive Function

Background:

Evidence has revealed an association between familial hypercholesterolemia and cognitive impairment. In this regard, a connection between cognitive deficits and hippocampal blood-brain barrier (BBB) breakdown was found in low-density lipoprotein receptor knockout mice (LDLr–/–), a mouse model of familial hypercholesterolemia.

Objective:

Herein we investigated the impact of a hypercholesterolemic diet on cognition and BBB function in C57BL/6 wild-type and LDLr–/–mice.

Methods:

Animals were fed with normal or high cholesterol diets for 30 days. Thus, wild-type and LDLr–/–mice were submitted to memory paradigms. Additionally, BBB integrity was evaluated in the mice’s prefrontal cortices and hippocampi.

Results:

A tenfold elevation in plasma cholesterol levels of LDLr–/–mice was observed after a hypercholesterolemic diet, while in wild-type mice, the hypercholesterolemic diet exposure increased plasma cholesterol levels only moderately and did not induce cognitive impairment. LDLr–/–mice presented memory impairment regardless of the diet. We observed BBB disruption as an increased permeability to sodium fluorescein in the prefrontal cortices and hippocampi and a decrease on hippocampal claudin-5 and occludin mRNA levels in both wild-type and LDLr–/–mice treated with a hypercholesterolemic diet. The LDLr–/–mice fed with a regular diet already presented BBB dysfunction. The BBB-increased leakage in the hippocampi of LDLr–/–mice was related to high microvessel content and intense astrogliosis, which did not occur in the control mice.

Conclusion:

Therefore, LDLr–/–mice seem to be more susceptible to cognitive impairments and BBB damage induced by exposure to a high cholesterol diet. Finally, BBB disruption appears to be a relevant event in hypercholesterolemia-induced brain alterations.

Increased Contact System Activation in Mild Cognitive Impairment Patients with Impaired Short-Term Memory

An activated plasma contact system is an abnormality observed in many Alzheimer's disease (AD) patients. Since mild cognitive impairment (MCI) patients often develop AD, we analyzed the status of contact system activation in MCI patients. We found that kallikrein activity, high molecular weight kininogen cleavage, and bradykinin levels- measures of contact system activation- were significantly elevated in MCI patient plasma compared to plasma from age- and education-matched healthy individuals. Changes were more pronounced in MCI patients with impaired short-term recall memory, indicating the possible role of the contact system in early cognitive changes.

The Hippocampal Vulnerability to Herpes Simplex Virus Type I Infection: Relevance to Alzheimer's Disease and Memory Impairment

Herpes simplex virus type 1 (HSV-1) as a possible infectious etiology in Alzheimer’s disease (AD) has been proposed since the 1980s. The accumulating research thus far continues to support the association and a possible causal role of HSV-1 in the development of AD. HSV-1 has been shown to induce neuropathological and behavioral changes of AD, such as amyloid-beta accumulation, tau hyperphosphorylation, as well as memory and learning impairments in experimental settings. However, a neuroanatomical standpoint of HSV-1 tropism in the brain has not been emphasized in detail. In this review, we propose that the hippocampal vulnerability to HSV-1 infection plays a part in the development of AD and amnestic mild cognitive impairment (aMCI). Henceforth, this review draws on human studies to bridge HSV-1 to hippocampal-related brain disorders, namely AD and aMCI/MCI. Next, experimental models and clinical observations supporting the neurotropism or predilection of HSV-1 to infect the hippocampus are examined. Following this, factors and mechanisms predisposing the hippocampus to HSV-1 infection are discussed. In brief, the hippocampus has high levels of viral cellular receptors, neural stem or progenitor cells (NSCs/NPCs), glucocorticoid receptors (GRs) and amyloid precursor protein (APP) that support HSV-1 infectivity, as well as inadequate antiviral immunity against HSV-1. Currently, the established diseases HSV-1 causes are mucocutaneous lesions and encephalitis; however, this review revises that HSV-1 may also induce and/or contribute to hippocampal-related brain disorders, especially AD and aMCI/MCI.

Vegetarian Dietary Patterns and Cognitive Function among Older Adults: The Adventist Health Study-2

We explored effects on cognitive function of following plant-based vegetarian compared with non-vegetarian dietary patterns in otherwise healthy older community-dwelling members of the Adventist Health Study-2 cohort (n = 132). Cognition was assessed using a comprehensive neuropsychological battery; a principal components analysis derived processing speed, executive function, and memory/language factors. Mild memory impairment (MMI) (n = 26, 19.7%) was identified by memory tests. Vegetarians consumed (a) meats, fish, and dairy <1 time/month, (b) dairy ≥1 time/month and meats, and fish <1 time/month, or (c) fish ≥1 time/month, no limits on dairy, and meats <1 time/month. Dietary patterns were determined at baseline, for each decade, and at cognitive assessment; a diet stability score was calculated. Factor scores were not different between vegetarians and non-vegetarians, nor was dietary pattern associated with a lower odds of MMI. A more stable diet over the life course was associated with better memory/language [β = 0.021 SE(β) = 0.008; p = 0.01]. This exploratory study did not support differences in processing speed, executive function, or memory/language abilities between vegetarians and non-vegetarians but did suggest that a more stable dietary pattern which was characteristic of vegetarians was associated with better memory/language abilities.

Xanthohumol ameliorates memory impairment and reduces the deposition of β-amyloid in APP/PS1 mice via regulating the mTOR/LC3II and Bax/Bcl-2 signalling pathways

OBJECTIVES

Xanthohumol (XAN) is a unique component of Humulus lupulus L. and is known for its diverse biological activities. In this study, we investigated whether Xanthohumol could ameliorate memory impairment of APP/PS1 mice, and explored its potential mechanism of action.

METHODS

APP/PS1 mice were used for in vivo test and were treated with N-acetylcysteine and Xanthohumol for 2 months. Learning and memory levels were evaluated by the Morris water maze. Inflammatory and oxidative markers in serum and hippocampus and the deposition of Aβ in the hippocampus were determined. Moreover, the expression of autophagy and apoptosis proteins was also evaluated by western blot.

KEY FINDINGS

Xanthohumol significantly reduced the latency and increased the residence time of mice in the target quadrant. Additionally, Xanthohumol increased superoxide dismutase level and reduced Interleukin-6 and Interleukin-1β levels both in serum and hippocampus. Xanthohumol also significantly reduced Aβ deposition in the hippocampus and activated autophagy and anti-apoptotic signals.

CONCLUSIONS

Xanthohumol effectively ameliorates memory impairment of APP/PS1 mice by activating mTOR/LC3 and Bax/Bcl-2 signalling pathways, which provides new insight into the neuroprotective effects of Xanthohumol.

Oxygen Enrichment Mitigates High-Altitude Hypoxia-Induced Hippocampal Neurodegeneration and Memory Dysfunction Associated with Attenuated Tau Phosphorylation

Cai, Jing, Junyong Ruan, Xi Shao, Yuanjun Ding, Kangning Xie, Chi Tang, Zedong Yan, Erping Luo, and Da Jing. Oxygen enrichment mitigates high-altitude hypoxia-induced hippocampal neurodegeneration and memory dysfunction associated with attenuated tau phosphorylation. High Alt Med Biol 00:000-000, 2021. Background: Brain is predominantly vulnerable to high-altitude hypoxia (HAH), resulting in neurodegeneration and cognitive impairment. The technology of oxygen enrichment has proven effective to decrease the heart rate and improve the arterial oxygen saturation by reducing the equivalent altitude. However, the efficacy of oxygen enrichment on HAH-induced cognitive impairments remains controversial based on the results of neuropsychological tests, and its role in HAH-induced hippocampal morphological and molecular changes remains unknown. Therefore, this study aims to systematically investigate the effects of oxygen enrichment on the memory dysfunction and hippocampal neurodegeneration caused by HAH. Materials and Methods: Fifty-one male Sprague-Dawley rats were equally assigned to three groups: normal control, HAH, and HAH with oxygen enrichment (HAHO). Rats in the HAH and HAHO groups were exposed to hypoxia for 3 days in a hypobaric hypoxia chamber at a simulated altitude of 6,000 m. Rats in the HAHO group were supplemented with oxygen-enriched air, with 12 hours/day in the hypobaric hypoxia chamber. Results: Our results showed that oxygen enrichment improved the locomotor activity of HAH-exposed rats. The Morris water maze test revealed that oxygen enrichment significantly ameliorated HAH-induced spatial memory deficits. Oxygen enrichment also improved morphological alterations of pyramidal cells and the ultrastructure of neurons in the hippocampal CA1 region in rats exposed to acute HAH. Tau hyperphosphorylation at Ser396, Ser262, Thr231, and Thr181 was also significantly attenuated by oxygen enrichment in HAH-exposed rats. Conclusions: Together, our study reveals that oxygen enrichment can ameliorate HAH-induced cognitive impairments associated with improved hippocampal morphology and molecular expression, and highlights that oxygen enrichment may become a promising alternative treatment against neurodegeneration for humans ascending to the plateau.

Maternal high-sugar diet results in NMDA receptors abnormalities and cognitive impairment in rat offspring

Cognitive impairment affects patients suffering from various neuropsychiatric diseases, which are often accompanied by changes in the glutamatergic system. Epidemiological studies indicate that predispositions to the development of neuropsychiatric diseases may be programmed prenatally. Mother's improper diet during pregnancy and lactation may cause fetal abnormalities and, consequently, predispose to diseases in childhood and even adulthood. Considering the prevalence of obesity in developed countries, it seems important to examine the effects of diet on the behavior and physiology of future generations. We hypothesized that exposure to sugar excess in a maternal diet during pregnancy and lactation would affect memory as the NMDA receptor-related processes. Through the manipulation of the sugar amount in the maternal diet in rats, we assessed its effect on offspring's memory. Then, we evaluated if memory alterations were paralleled by molecular changes in NMDA receptors and related modulatory pathways in the prefrontal cortex and the hippocampus of adolescent and young adult female and male offspring. Behavioral studies have shown sex-related changes like impaired recognition memory in adolescent males and spatial memory in females. Molecular results confirmed an NMDA receptor hypofunction along with subunit composition abnormalities in the medial prefrontal cortex of adolescent offspring. In young adults, GluN2A-containing receptors were dominant in the medial prefrontal cortex, while in the hippocampus the GluN2B subunit contribution was elevated. In conclusion, we demonstrated that a maternal high-sugar diet can affect the memory processes in the offspring by disrupting the NMDA receptor composition and regulation in the medial prefrontal cortex and the hippocampus.