Impact of diet-derived signaling molecules on human cognition: exploring the food-brain axis

Gut microbiota, nutrition, and mental health

The human brain remains one of the greatest challenges for modern medicine, yet it is one of the most integral and sometimes overlooked aspects of medicine. The human brain consists of roughly 100 billion neurons, 100 trillion neuronal connections and consumes about 20-25% of the body's energy. Emerging evidence highlights that insufficient or inadequate nutrition is linked to an increased risk of brain health, mental health, and psychological functioning compromise. A core component of this relationship includes the intricate dynamics of the brain-gut-microbiota (BGM) system, which is a progressively recognized factor in the sphere of mental/brain health. The bidirectional relationship between the brain, gut, and gut microbiota along the BGM system not only affects nutrient absorption and utilization, but also it exerts substantial influence on cognitive processes, mood regulation, neuroplasticity, and other indices of mental/brain health. Neuroplasticity is the brain's capacity for adaptation and neural regeneration in response to stimuli. Understanding neuroplasticity and considering interventions that enhance the remarkable ability of the brain to change through experience constitutes a burgeoning area of research that has substantial potential for improving well-being, resilience, and overall brain health through optimal nutrition and lifestyle interventions. The nexus of lifestyle interventions and both academic and clinical perspectives of nutritional neuroscience emerges as a potent tool to enhance patient outcomes, proactively mitigate mental/brain health challenges, and improve the management and treatment of existing mental/brain health conditions by championing health-promoting dietary patterns, rectifying nutritional deficiencies, and seamlessly integrating nutrition-centered strategies into clinical care.

A novel set of volatile urinary biomarkers for late-life major depressive and anxiety disorders upon the progression of frailty: a pilot study

Mood and anxiety disorders are frequent in the elderly and increase the risk of frailty. This study aimed to identify novel biomarkers of major depressive disorder (MDD) and anxiety in the elderly. We examined 639 participants in the community-dwelling Otassha Study (518 individuals considered healthy control, 77 with depression, anxiety, etc.), mean age 75 years, 58.4% of female. After exclusion criteria, we analyzed VOCs from 18 individuals (9 healthy control, 9 of MDD/agoraphobia case). Urinary volatile and semi-volatile organic compounds (VOCs) were profiled using solid-phase microextraction and gas chromatography-mass spectrometry. Six urinary VOCs differed in the absolute area of the base peak between participants with MDD and/or agoraphobia and controls. High area under the receiver-operating characteristic curve (AUC) values were found for phenethyl isothiocyanate (AUC: 0.86, p = 0.009), hexanoic acid (AUC: 0.85, p = 0.012), texanol (AUC: 0.99, p = 0.0005), and texanol isomer (AUC: 0.89, p = 0.005). The combined indices of dimethyl sulfone, phenethyl isothiocyanate, and hexanoic acid, and texanol and texanol isomer showed AUCs of 0.91 (p = 0.003) and 0.99 (p = 0.0005) and correlated with the GRID-HAMD and the Kihon Checklist (CL score), respectively. These VOCs may be valuable biomarkers for evaluating MDD and/or agoraphobia in the elderly.

Circular RNA: A novel and potential regulator in pathophysiology of schizophrenia

Circular RNAs (CircRNAs) are a sub-class of non-coding RNA, which are covalently closed at the ends through a non-canonical process called, backsplicing from the precursor linear RNAs. These molecules are involved in several biological phenomena including regulation of gene expression, synaptic plasticity, and cognition. Several studies have shown that circRNA are present abundantly inside the mammalian brain and they are believed to be associated with the development of neurons and neuronal functions. It is also evident that alterations in intracellular and extracellular levels of circRNAs are linked with various neurological and neuropsychiatric disorders including schizophrenia (SZ). Detailed studies of circRNAs are required to decode the molecular mechanism behind the onset of SZ and the related biological activities during disease progression. This can help unravel their role in this neurobehavioral disorder and develop effective therapeutics against the disease. The present review mainly focuses on the expression and activities of the circRNAs in the post-mortem brain, peripheral blood, and exosomes. It also gives an insight into the role of circRNA interaction with RNA binding proteins (RBPs) and nucleotide modification and their therapeutic potential in the context of schizophrenia.

Brain on food: The neuroepigenetics of nutrition

Humans have known for millennia that nutrition has a profound influence on health and disease, but it is only recently that we have begun mapping the mechanisms via which the dietary environment impacts brain physiology and behavior. Here we review recent evidence on the effects of energy-dense and methionine diets on neural epigenetic marks, gene expression, and behavior in invertebrate and vertebrate model organisms. We also discuss limitations, open questions, and future directions in the emerging field of the neuroepigenetics of nutrition.

Consumption of vitamin A-deficient diet elevates endoplasmic reticulum stress marker and suppresses high fructose-induced orexigenic gene expression in the brain of male Wistar rats

OBJECTIVE

Here, we assessed the impact of vitamin A deficiency (both alone and in combination with fructose) on the retinol status, phospholipids fatty acid composition and pathways associated with the endoplasmic reticulum (ER) stress and energy homeostasis of the brain. For this purpose, weanling male Wistar rats were divided into four groups consisting of 8 rats each, except 16 for the second group and they received one of the following diets; control, vitamin A-deficient (VAD), high fructose (HFr) and HFr with VAD for 16 weeks, except half of the VAD diet-fed rats, were shifted to HFr diet, after 8 weeks period.

RESULTS

The retinol content of the whole brain remained comparable across the groups, despite a significant reduction in the plasma at the end of VAD diet feeding. However, it suppressed the HFr-induced neuropeptide Y and agouti-related peptide, while rescuing the leptin receptor mRNA. Among ER stress markers, CCAAT/Enhancer-binding protein homologues protein levels were elevated significantly in the VAD diet-fed group. Further, the long-chain polyunsaturated fatty acid levels showed an increase in the brain phospholipids across the experimental groups, compared to that of the control.

CONCLUSION

Vitamin A deficiency causes ER stress in the brain, and retinol seems to play a regulatory role in the fructose-mediated transcriptional regulation of the genes involved in energy homeostasis.

Functional Foods: An Approach to Modulate Molecular Mechanisms of Alzheimer's Disease

A new epoch is emerging with intense research on nutraceuticals, i.e., "food or food product that provides medical or health benefits including the prevention and treatment of diseases", such as Alzheimer's disease. Nutraceuticals act at different biochemical and metabolic levels and much evidence shows their neuroprotective effects; in particular, they are able to provide protection against mitochondrial damage, oxidative stress, toxicity of β-amyloid and Tau and cell death. They have been shown to influence the composition of the intestinal microbiota significantly contributing to the discovery that differential microorganisms composition is associated with the formation and aggregation of cerebral toxic proteins. Further, the routes of interaction between epigenetic mechanisms and the microbiota-gut-brain axis have been elucidated, thus establishing a modulatory role of diet-induced epigenetic changes of gut microbiota in shaping the brain. This review examines recent scientific literature addressing the beneficial effects of some natural products for which mechanistic evidence to prevent or slowdown AD are available. Even if the road is still long, the results are already exceptional.

Assessment of Changes over Time of Lipid Profile, C-Reactive Protein Level and Body Mass Index in Teenagers and Young Adults on Different Diets Belonging to Autism Spectrum Disorder

Background: Numerous scientific studies on patients with autism spectrum disorder (ASD) suggest a significant role of inflammation processes or lipid disorders in this spectrum of neurodevelopmental disorders. Unfortunately, there is a lack of assessments of changes over time regarding level of lipids and inflammatory markers in people diagnosed with ASD using different diets. The aim of this study was to evaluate changes in lipid profile, high sensitivity C-reactive protein (hs-CRP) and body mass index (BMI) in individuals diagnosed with ASD and healthy controls. Variables were assessed at two time points (2015/17 and 2017/20) for each subject. Methods: After applying the selection criteria, for the first assessment period, 96 participants were qualified (the group consisted of 59 males with ASD and 37 healthy volunteers, i.e., age-matched control group—CG). The final assessment included 93 participants (57 from ASD group and 36 from CG). Subjects were on low-fat diet (LFD), gluten–casein-free diet (GF–CF) and regular diet (RD), respectively. All members of CG were on regular diet. A fasting lipid profile and hs-CRP level were analyzed. BMI and percentiles were calculated. Eating habits were checked by analyzing data from questionnaires. Principal component analysis (PCA) was used separately for every assessment. The Mann–Whitney U test was used to compare the medians of variables in the scheme of pairwise comparisons between control and ASD groups on different diets for separate assessment, while differences over time between variables were tested by Wilcoxon signed-rank test. Results: Statistically significant differences between BMI, CRP, triglycerides (TG), total cholesterol (TC), high-density lipoprotein (HDL), non-HDL-C and TC/HDL ratio were found in ASD group in comparison to healthy volunteers (increased BMI, CRP and TC/HDL and decreased HDL-C for all types of diets, increased TG in the group of LFD and RD individual and increased non-HDL-C in the group of GF–CF and RD individuals) during the first assessment period. The second assessment over time also showed increased levels of TC, non HDL-C and TC/HDL and decreased level of HDL-C for all ASD individuals regardless of diets used, while BMI and CRP increased only for individuals on LFD and RD. No statistically significant correlations between age of participants and other variables comparing with CG were found. Conclusions: Our studies suggest that targeted, individualized nutritional pattern and periodic screening for lipid and immune disorders would be beneficial for teenagers and adults diagnosed with ASD.

The relationship between diet and cognitive function in adult cancer survivors: a systematic review

PURPOSE

To perform a systematic review identifying how dietary factors are related to cognitive function in cancer survivors who are not currently undergoing primary treatment.

METHODS

Using the PRISMA framework, a search was conducted for studies published before February 2019 across multiple databases, identifying 2304 unique articles. Twelve met final inclusion criteria and were evaluated through narrative synthesis. This review was registered with the International Prospective Register Of Systematic Reviews (CRD42018111941).

RESULTS

Included studies were heterogeneous in methodology and in dietary and cognitive variables investigated making direct comparisons difficult. Evidence of a relationship between diet and cognition was mixed; the most consistent evidence was identified in relation to a positive relationship between fruit and vegetable intake and cognitive function (both self-reported and objectively tested) in five out of six studies, but was not concordant across all studies.

CONCLUSION

Preliminary evidence exists that a greater fruit and vegetable intake is associated with better cognitive functioning in cancer survivors, as has been reported in healthy populations; however, these data are correlational and include relatively small samples. Most evidence related to breast cancer survivors, with individual studies extending to colorectal and stomach cancer survivors. Experimental trials are needed to identify causal attribution of dietary factors on cognitive function in cancer survivors.

IMPLICATIONS FOR CANCER SURVIVORS

At this time, there is not sufficient evidence to make dietary or nutritional recommendations specifically for improving cognitive function in cancer survivors. This should be considered in light of the general paucity of research on this subject, necessitating further investigations.

A cross-talk between blood-cell neuroplasticity-related genes and environmental enrichment in working dogs

This study aims to identify a panel of blood-cell neuroplasticity-related genes expressed following environmental enrichment stimulation (EE). The Drug detection (DD) training course was an excellent model for the study of EE in the working dog. This research is divided into two experimental trials. In the First Trial, we identified a panel of blood-cell neuroplasticity related-genes associated with DD ability acquired during the training course. In the Second Trial, we assessed the EE additional factor complementary feeding effect on blood-cell neuroplasticity gene expressions. In the First and Second Trials, at different time points of the DD test, blood samples were collected, and NGF, BDNF, VEGFA, IGF1, EGR1, NGFR, and ICE2 blood-cell neuroplasticity related-genes were analyzed. As noted in the First Trial, the DD test in working dogs induced the transient up-regulation of VEGFA, NGF, NGFR, BDNF, and IGF, immediately after the DD test, suggesting the existence of gene regulations. On the contrary, the Second Trial, with feeding implementation, showed an absence of mRNA up-regulation after the DD test. We suppose that complementary feeding alters the systemic metabolism, which, in turn, changes neuroplasticity-related gene blood-cell mRNA. These findings suggested that, in working dogs, there is a cross-talk between blood-cell neuroplasticity-related genes and environmental enrichment. These outcomes could be used to improve future treatments in sensory implementation.