The health effect of probiotics on high-fat diet-induced cognitive impairment, depression and anxiety: A cross-species systematic review

Astrocyte response to melatonin treatment in rats under high-carbohydrate high-fat diet

The involvement of consumption of high-carbohydrate high-fat (HCHF) diet in cognitive impairment is attributed, at least in part, to the activation of astrocytes, which contributes to the development of neuroinflammation, oxidative stress, and subsequent cognitive deficits. This study aimed to assess the influence of melatonin on cognitive impairment and astrogliosis induced by the HCHF diet in rats. Male Wistar rats were fed an HCHF diet for eight weeks to induce obesity and metabolic syndrome. Subsequently, they received oral melatonin treatment for four weeks at doses of 5 mg/kg, 10 mg/kg, and 30 mg/kg, alongside the HCHF diet. Cognitive function was evaluated using the Y-maze test, while the levels of proinflammatory cytokines, oxidative stress, and the number glial fibrillary acidic protein (GFAP) positive cells were assessed in the hippocampi and hypothalamus. The consumption of the HCHF diet resulted in weight gain, hyperlipidemia, impaired glucose tolerance, cognitive decline, neuroinflammation, oxidative stress damage, and astrogliosis in rats. Although melatonin treatment did not demonstrate beneficial effects on blood glucose and lipid metabolism, it improved the impaired working memory caused by the HCHF diet. Melatonin exhibited a dose-dependent reduction of astrogliosis, neuroinflammation, and lipid peroxidation while restored superoxide dismutase in the hippocampus and hypothalamus of HCHF diet-treated rats. These findings provide evidence that melatonin inhibits astrocyte activation, thereby attenuating inflammation and minimizing oxidative stress damage induced by the HCHF diet.

Gut microbiome-based therapies for alleviating cognitive impairment: state of the field, limitations, and future perspectives

Cognitive impairment (CI) is a multifaceted neurological condition that can trigger negative emotions and a range of concurrent symptoms, imposing significant public health and economic burdens on society. Therefore, it is imperative to discover a remedy for CI. Nevertheless, the mechanisms behind the onset of this disease are multifactorial, which makes the search for effective amelioration difficult and complex, hindering the search for effective measures. Intriguingly, preclinical research indicates that gut microbiota by influencing brain function, plays an important role in the progression of CI. Furthermore, numerous preclinical studies have highlighted the potential of probiotics, prebiotics, fecal microbiota transplantation (FMT), and diet in modulating the gut microbiota, thereby ameliorating CI symptoms. This review provides a comprehensive evaluation of CI pathogenesis, emphasizing the contribution of gut microbiota disorders to CI development. It also summarizes and discusses current strategies and mechanisms centered on the synergistic role of gut microbiota modulation in the microbiota-gut-brain axis in CI development. Finally, problems with existing approaches are contemplated and the development of microbial modulation strategies as therapeutic approaches to promote and restore brain cognition is discussed. Further research considerations and directions are highlighted to provide ideas for future CI prevention and treatment strategies.

Treatment of preterm brain injury via gut-microbiota-metabolite-brain axis

BACKGROUND

Brain injury in preterm infants potentially disrupts critical structural and functional connective networks in the brain. It is a major cause of neurological sequelae and developmental deficits in preterm infants. Interesting findings suggest that the gut microbiota (GM) and their metabolites contribute to the programming of the central nervous system (CNS) during developmental stages and may exert structural and functional effects throughout the lifespan.

AIM

To summarize the existing knowledge of the potential mechanisms related to immune, endocrine, neural, and blood-brain barrier (BBB) mediated by GM and its metabolites in neural development and function.

METHODS

We review the recent literature and included 150 articles to summarize the mechanisms through which GM and their metabolites work on the nervous system. Potential health benefits and challenges of relevant treatments are also discussed.

RESULTS

This review discusses the direct and indirect ways through which the GM may act on the nervous system. Treatment of preterm brain injury with GM or related derivatives, including probiotics, prebiotics, synbiotics, dietary interventions, and fecal transplants are also included.

CONCLUSION

This review summarizes mechanisms underlying microbiota-gut-brain axis and novel therapeutic opportunities for neurological sequelae in preterm infants. Optimizing the initial colonization and microbiota development in preterm infants may represent a novel therapy to promote brain development and reduce long-term sequelae.

Kombucha: Challenges for Health and Mental Health

BACKGROUND

Increasing research into probiotics is showing potential benefits for health in general and mental health in particular. Kombucha is a recent beverage and can be considered a probiotic drink, but little is known about its effects on physical and mental health. This product is experiencing growth in the market; however, there are no scientific results to support its potential for physical and mental health.

AIM

This review article aims to draw attention to this issue and to highlight the lack of studies in this area.

KEY FINDINGS AND CONCLUSIONS

The lack of legislation for the correct marketing of this product may also constrain clinical studies. However, clinical studies are of utmost importance for an in-depth understanding of the effects of this product on the human body. More research is needed, not only to better understand the impact of Kombucha on the human body, but also to ensure the application of regulatory guidelines for its production and marketing and enable its safe and effective consumption.

Brain targeted peptide-functionalized chitosan nanoparticles for resveratrol delivery: Impact on insulin resistance and gut microbiota in obesity-related Alzheimer's disease

The pathology of Alzheimer's disease (AD) is highly correlated with obesity-induced insulin resistance. Resveratrol (Res) is a natural phenol that demonstrates a neuroprotective effect, but the bioactivity of Res is low in vivo. Here, chitosan (CS) was cross-linked with sodium tripolyphosphate (TPP) to encapsulate low water solubility Res. Next, a brain-targeted peptide (TG: TGNYKALHPHNG) was modified on the surface of Res-loaded CS/TPP nanoparticles (TG-Res-CS/TPP-NPs) to specifically deliver Res to the brain. Morris water maze results indicated that cognitive impairments were ameliorated by TG-Res-CS/TPP-NPs in obesity-related AD mice. Obesity-related insulin resistance promotes Tau phosphorylation and Aβ aggregation in the brain. Administration of TG-Res-CS/TPP-NPs alleviated lipid deposition-induced insulin resistance and decreased the level of phosphorylated Tau and Aβ aggregation via the JNK/AKT/GSK3β pathway. Additionally, TG-Res-CS/TPP-NPs transported across blood-brain barrier which in turn increased glucose transporter expression levels, antioxidant enzyme activity and inhibited microglial cell activation. Thus, TG-Res-CS/TPP-NPs were more effective than Res-CS/TPP-NPs at regulating glucose homeostasis, oxidative stress and neuroinflammation in the brain. Moreover, inflammatory, lipid metabolism and oxidative stress-related gut microbiota including Helicobacter, Colidextribacter, Anaerotruncus, Parasutterella, Allobaculum, Alloprevotella, Alistipes, Bifidobacterium and Candidatus_Saccharimonas were also regulated by TG-Res-CS/TPP-NPs. This work indicates the potential use of TG-Res-CS/TPP-NPs for the delivery of Res.

Probiotics therapy show significant improvement in obesity and neurobehavioral disorders symptoms

Obesity is a complex metabolic disease, with cognitive impairment being an essential complication. Gut microbiota differs markedly between individuals with and without obesity. The microbial-gut-brain axis is an important pathway through which metabolic factors, such as obesity, affect the brain. Probiotics have been shown to alleviate symptoms associated with obesity and neurobehavioral disorders. In this review, we evaluated previously published studies on the effectiveness of probiotic interventions in reducing cognitive impairment, depression, and anxiety associated with obesity or a high-fat diet. Most of the probiotics studied have beneficial health effects on obesity-induced cognitive impairment and anxiety. They positively affect immune regulation, the hypothalamic-pituitary-adrenal axis, hippocampal function, intestinal mucosa protection, and glucolipid metabolism regulation. Probiotics can influence changes in the composition of the gut microbiota and the ratio between various flora. However, probiotics should be used with caution, particularly in healthy individuals. Future research should further explore the mechanisms underlying the gut-brain axis, obesity, and cognitive function while overcoming the significant variation in study design and high risk of bias in the current evidence.

Effects of common plastic products heat exposure on cognition: Mediated by gut microbiota

Considering plastic exposure patterns in modern society, the effects of exposure to leachate from boiled-water treated plastic products on cognitive function was probed in mice through changes in gut microbiota diversity. In this study, Institute for Cancer Research (ICR) mice were used to establish drinking water exposure models of three popular kinds of plastic products, including non-woven tea bags, food-grade plastic bags and disposable paper cups. 16S rRNA was used to detect changes in the gut microbiota of mice. Behavioral, histopathology, biochemistry, and molecular biology experiments were used to evaluate cognitive function in mice. Our results showed that the diversity and composition of gut microbiota changed at genus level compared to control group. Nonwoven tea bags-treated mice were proved an increase in Lachnospiraceae and a decreased in Muribaculaceae in gut. Alistipes was increased under the intervention of food grade plastic bags. Muribaculaceae decreased and Clostridium increased in disposable paper cups group. The new object recognition index of mice in the non-woven tea bag and disposable paper cup groups decreased, and amyloid β-protein (Aβ) and tau phosphorylation (P-tau) protein deposition. Cell damage and neuroinflammation were observed in the three intervention groups. Totally speaking, oral exposure to leachate from boiled-water treated plastic results in cognitive decline and neuroinflammation in mammals, which is likely related to MGBA and changes in gut microbiota.

Early Intervention of Elateriospermum tapos Yoghurt in Obese Dams Mitigates Intergenerational Cognitive Deficits and Thigmotactic Behaviour in Male Offspring via the Modulation of Metabolic Profile

Maternal obesity is an intergenerational vicious cycle and one of the primary causes of cognitive deficits and high anxiety levels in offspring, which often manifest independently of sex. It is proven that curbing the intergenerational inheritance of obesity through early intervention during the gestation period has a positive outcome on the body composition, cognitive function, and anxiety level of the offspring. A recent discovery shows that the consumption of Elateriospermum tapos (E. tapos) seed extract modulates body mass and ameliorates stress hormones in obese dams, while a probiotic bacterial strain can cross the placenta and boost a child's memory. Thus, we speculate that probiotics are the best medium to integrate plant extract (E. tapos extract) to access the effect on the child's cognition. Thus, this study aimed to investigate the early intervention of E. tapos yoghurt in obese dams in the cognition and anxiety levels of male offspring. In this study, 40 female rats were fed with a high-fat diet (HFD) to induce obesity before pregnancy, while another 8 rats were fed with standard rat pellets for 16 weeks. Upon successful copulation, treatment was initiated for the obese dams up to the postnatal day (PND) 21. The groups included normal chow and saline (NS), HFD and saline (HS), HFD and yoghurt (HY), HFD and 5 mg/kg E. tapos yoghurt (HYT5), HFD and 50 mg/kg E. tapos yoghurt (HYT50), and HFD and 500 mg/kg E. tapos yoghurt (HYT500). All rats were euthanised on PND 21, and the body mass index (BMI), Lee index, and waist circumference were measured for the male offspring. Hippocampal-dependent memory tests and open field tests were conducted to access for cognition and anxiety status. Fasting blood glucose (FBG), total fat (%), insulin, leptin, lipid profile, and antioxidant parameter on serum and hypothalamus (FRAP and GSH) were accessed on PND 21. The result shows male offspring of 50 mg/kg-supplemented obese dams have comparable total fat (%), lipid profile, insulin level, FBG level, plasma insulin level, recognition index, low anxiety level, and improved hypothalamic FRAP and GSH levels to the normal group. In conclusion, this study highlights that the effect of early intervention of our novel formulation of E. tapos yoghurt in obese dams alleviates cognitive deficits and anxiety in male offspring by modulating metabolic profiles at the dose of 50 mg/kg.

PRO-DEMET Randomized Controlled Trial on Probiotics in Depression—Pilot Study Results

There is a pressing need to identify new treatment options for depression and its comorbidities. Depression often coexists with metabolic complications, and the two may share a pathophysiological overlap, including inflammation and microbiota changes. Microbiota interventions (e.g., probiotics) may represent a safe and easy-to-use treatment option as an adjunctive therapy in patients only partially responsive to pharmacologic treatment. (1) Objective: The paper presents the results of a feasibility and pilot study. The study is an internal part of a randomized controlled trail (RCT) of the effect of probiotic supplementation on psychometric, anthropometric, metabolic, and inflammatory parameters in adult patients with depressive disorders depending on the presence of metabolic syndrome. (2) Methods: The trial has a four-arm, parallel-group, prospective, randomized, double-blind, controlled design. Sixty participants received a probiotic preparation containing Lactobacillus helveticus Rosell®-52 and Bifidobacterium longum Rosell®-175 over 60 days. The feasibility of the study design was assessed, as well as the rates of recruitment, eligibility, consent, and study completion. The following were assessed: depressive, anxiety and stress symptoms, quality of life, blood pressure, body mass index and waist circumference, complete blood count with differential, serum levels of C-reactive protein, high-density lipoprotein cholesterol, triglycerides, fasting glucose, some secondary markers of inflammation and metabolic health, as well as noninvasive biomarkers of liver fibrosis (APRI and FIB-4). (3) Results: The study was found to be generally feasible. The eligibility rate was 52% of recruited participants with 80% completing the study protocol. No differences in sociodemographic or anthropometric factors or basic laboratory findings were found between the placebo and probiotic group at the start of the intervention period. Importantly, the proportion of recruited participants fulfilling the criteria of metabolic syndrome was too low. (4) Conclusions: Whilst the whole study protocol was feasible, some different timepoint procedures require modification. The major weakness of the recruitment methods was that the percentage of metabolic arms participants was insufficient. Overall, the full RCT design on probiotics in depression with vs. without metabolic syndrome was shown to be feasible with little modification.

The Role of Gut Microbiota in Various Neurological and Psychiatric Disorders-An Evidence Mapping Based on Quantified Evidence

Methods

We searched PubMed, Cochrane Library, and Epistemonikos to identify systematic reviews and meta-analysis (SRs). We searched for neurological diseases and psychiatric disorders, including Alzheimer's disease (AD), attention deficit hyperactivity disorder (ADHD), amyotrophic lateral sclerosis (ALS), autism spectrum disorder (ASD), anorexia nervosa (AN), bipolar disorder (BD), eating disorder (ED), generalized anxiety disorder (GAD), major depressive disorder (MDD), multiple sclerosis (MS), obsessive compulsive disorder (OCD), Parkinson's disease (PD), posttraumatic stress disorder (PTSD), spinal cord injury (SCI), schizophrenia, and stroke. We used A Measurement Tool to Assess Systematic Reviews (AMSTAR-2) to evaluate the quality of included SRs. We also created an evidence map showing the role of gut microbiota in neurological diseases and the certainty of the evidence.

Results

In total, 42 studies were included in this evidence mapping. Most findings were obtained from observational studies. According to the AMSTAR-2 assessment, 21 SRs scored "critically low" in terms of methodological quality, 16 SR scored "low," and 5 SR scored "moderate." A total of 15 diseases have been investigated for the potential association between gut microbiome alpha diversity and disease, with the Shannon index and Simpson index being the most widely studied. A total of 12 diseases were investigated for potential link between beta diversity and disease. At the phylum level, Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria, and Verrucomicrobia were more researched. At the genus level, Prevotella, Coprococcus, Parabacteroides, Phascolarctobacterium, Escherichia Shigella, Alistipes, Sutteralla, Veillonella, Odoribacter, Faecalibacterium, Bacteroides, Bifidobacterium, Dialister, and Blautia were more researched. Some diseases have been found to have specific flora changes, and some diseases have been found to have common intestinal microbiological changes.

Conclusion

We found varied levels of evidence for the associations between gut microbiota and neurological diseases; some gut microbiota increased the risk of neurological diseases, whereas others showed evidence of benefit that gut microbiota might be promising therapeutic targets for such diseases.

Anxiety and depression and their interdependent influencing factors among medical students in Inner Mongolia: the cross-sectional survey

BACKGROUND

Mental health has become a global problem, among which anxiety and depression disorder were ranked as the first and sixth leading causes of disability, respectively, according to the World Health Organization (WHO). Medical students experienced higher levels of anxiety and depression than the general population. But there was a lack of research on the emotional situation among medical students in Inner Mongolia. The main objectives of this study were to investigate the prevalence of anxiety and depression symptoms as well as the factors that influence them among medical students in Inner Mongolia.

METHODS

A cross-sectional study was conducted on 1282 students from a university in Inner Mongolia, China, ranging in age from 16 to 27 years. They were assessed demographic indicators, the disorder of anxiety and depression using Zung's Self-Rating Anxiety Scale and Self-Rating Depression Scale (SAS and SDS) by an anonymous, self-administered questionnaire. The internal reliability and validity of the questionnaire were determined using Cronbach's alpha coefficient, Kaiser-Meyer-Olkin (KMO), and Bartlett's sphericity. T-tests and one-way ANOVA were used to explore factors, including demographic and behavioral information influencing anxiety and depression disorder. According to the above results of exploring the influencing factors based on univariate analysis, significant factors (p < 0.05) were entered into multiple linear regressions that sequentially fitted to predictors associated with anxiety and depression. The collected data were entered into EpiData for windows and analyzed using SPSS 26.0. The p < 0.05 was considered to be significantly different.

RESULTS

The questionnaire was completed by 1187 students with a 92.59% response rate. The prevalence of anxiety and depression symptoms among medical students were 10.36% and 24.43%, and the mean ± standard deviation (M ± SD) anxiety and depression scores were 39.60 ± 7.81 and 48.23 ± 9.06, respectively, among the medical students. The specific contributions of the two scales with good reliability and validity were 60.58% and 63.59%, respectively. For univariate analysis, age, whether the daily meal was at a fixed time, grade, the birthplace of students, average daily eating habits, were the factors that influenced both the total score of SAS and SDS (p < 0.05). For further analysis, the results showed that "Birthplace of students" and "Whether daily meals at a fixed time" were significantly associated with anxiety and depression. Furthermore, "Age" and "Mode of delivery" were independent risk factors for depressive disorder.

CONCLUSION

Our findings revealed that high prevalence of mental health problems among medical students in Inner Mongolia. The Ministry of Medical Education should make a targeted intervention for specific risk factors of this study to improve psychological well-being and face uncertain future challenges among university students in Inner Mongolia.