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The Gut Microbiome in Early Life Stress: A Systematic Review.
Agusti, A, Lamers, F, Tamayo, M, Benito-Amat, C, Molina-Mendoza, GV, Penninx, BWJH, Sanz, Y
Nutrients. 2023;15(11)
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Children exposed to early life stress (ELS) show alterations in brain development and are at increased risk of developing mental illness. This study aims to clarify whether ELS influences the gut microbiome and whether this can be a predictor for the development of mental disorders. 13 articles were included in this systemic review. 4 looked at pre-natal stress and 9 at post-natal stress. Prenatal stress (via maternal stress) may be associated with an increase in Proteobacteria phylum and with a lower abundance of Bifidobacterium and lactic acid bacteria. In the postnatal group, greater microbiome diversity was related to lower depression and anxiety. In boys scores for adaptive skills were higher in those with good levels of Bifidobacterium. A positive association was found between EA (early adversity) experiences and gastrointestinal symptoms and anxiety. This review demonstrates links between ELS and gut microbiome changes. Further research will be necessary to draw more robust conclusions.
Expert Review
Conflicts of interest:
None
Take Home Message:
- This systematic review consolidated and discussed existing evidence on the link between early life stress (ELS) and changes to the human microbiome
- Exposure to ELS, prenatal or postnatal during childhood and adolescence, may impact mental and physical health.
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
A systematic review was conducted to consolidate clinical evidence examining the impact of early life stress (ELS) on the human intestinal microbiome.
Method
Thirteen observational studies were included in the review, sourced from Pubmed, Scopus, Web of Science, and EMBASE. Methodological quality was assessed using the Newcastle-Ottawa Assessment Scale (NOS), with most studies scoring seven or eight out of nine stars.
Study designs varied, including prospective prenatal studies, postnatal longitudinal studies, case-control studies, and cross-sectional studies. Four prenatal studies were prospective in design. The other nine postnatal studies included one longitudinal study, five case-control studies, and three cross-sectional studies. All 13 studies were published between 2015 and 2022. Because study designs and outcome assessments varied, the results were presented in a narrative form. Data was extracted by 2 independent authors.
Results
The primary findings from the review were as follows:
- Four longitudinal stress studies indicated that pregnant mothers experiencing psychological stress, increased cortisol levels, HIV, and lack of social support exhibited a lower abundance of beneficial Bifidobacterium and an increased abundance of Enterobacter genus.
- One postnatal stress longitudinal study (n=260) demonstrated lower depression and anxiety and improved internalising behaviour in patients with high microbiome diversity.
- . One postnatal stress case-control study (n=344) showed changes in the microbiome and an abundance of several bacterial taxa in stressed groups, including genera Prevotella, Bacteroides (Bacteroidetes), Coprococcus, Streptococcus, and Escherichia.
- One cross-sectional study of 128 adults without psychiatric conditions revealed that higher stress correlated with increased levels of Bacteroides, Parabacteroides, Rhodococcus, Methanobrevibacter, and Roseburia at the genus level, as well as lower Phascolarcto bacterium and Firmicutes at the phylum level.
- One large prospective study (n=446) found infants exposed to higher cumulative stress exhibited an increased relative abundance of Proteobacteria groups and lower Bifidobacterium.
Conclusion:
Due to the inconsistency of study designs and their results this review failed to find consensus microbiome signatures associated with pre- or postnatal stress, or both.
Clinical practice applications:
- Early life stress, and alterations in the gut microbiome, have been linked to mental health conditions
- Maternal prenatal stress may be linked to emotional, behavioural, and cognitive outcomes in infants.
Considerations for future research:
- Future research should standardise questionnaires, to ensure consistency and comparability across studies
- Additionally, future studies should consider using standard procedures and specific species and strain resolution shotgun metagenomics sequencing
- Consideration should be given to the influence of environmental variables (diet, physical activity, etc.) and sex in gut microbiome analysis.
Abstract
Exposure to early life stress (ELS), prenatal or postnatal during childhood and adolescence, can significantly impact mental and physical health. The role of the intestinal microbiome in human health, and particularly mental health, is becoming increasingly evident. This systematic review aims to summarize the clinical data evaluating the effect of ELS on the human intestinal microbiome. The systematic review (CRD42022351092) was performed following PRISMA guidelines, with ELS considered as exposure to psychological stressors prenatally and during early life (childhood and adolescence). Thirteen articles met all inclusion criteria, and all studies reviewed found a link between ELS and the gut microbiome in both prenatal and postnatal periods. However, we failed to find consensus microbiome signatures associated with pre- or postnatal stress, or both. The inconsistency of results is likely attributed to various factors such as different experimental designs, ages examined, questionnaires, timing of sample collection and analysis methods, small population sizes, and the type of stressors. Additional studies using similar stressors and validated stress measures, as well as higher-resolution microbiome analytical approaches, are needed to draw definitive conclusions about the links between stress and the human gut microbiome.
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Efficacy of mindfulness-based intervention for the treatment of chronic headaches: A systematic review and meta-analysis.
Aemaz Ur Rehman, M, Waseem, R, Habiba, U, Fahad Wasim, M, Alam Rehmani, S, Alam Rehmani, M, Abdullah, M, Khabir, Y, Rehan Hashmi, M, Almas, T, et al
Annals of medicine and surgery (2012). 2022;78:103862
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The International Headache Society defines chronic daily headache (CDH) as headaches occurring on 15 or more days in a month for at least three months. Many pharmacological treatments are available to minimize the functional disability caused by headaches. However, meditation-based mindfulness techniques have gained popularity in recent years. The main aim of this study was to determine the efficacy of mindfulness-based cognitive therapy (MBCT) and mindfulness-based stress reduction (MBSR) in improving headache frequency, duration, and intensity in patients suffering from chronic headaches. This study is an updated systematic review and meta-analysis which included 10 full-text articles (4 from previous meta-analysis and 6 recently published). Results provide limited evidence that MBSR/MBCT intervention may be effective in reducing the frequency, duration, and pain intensity of headaches, in patients with chronic headaches including tension-type and migraine compared with the usual care but it demonstrated a significant difference between groups in achieving mindfulness. Authors conclude that since their findings are inconclusive, MBSR/MBCT interventions for the treatment of migraine and/or tension-type headaches cannot be recommended.
Abstract
Background: Mindfulness-based stress reduction/cognitive therapy has attained popularity as an adjunctive treatment for a plethora of medical and psychiatric conditions, however, its impact on chronic headaches is inconclusive. This review aims to assess the impact of MBSR/MBCT in alleviating the symptoms of chronic headaches. Data sources and data selection: PubMed and Cochrane CENTRAL were searched from inception till 1st May 2021. Randomized Control Trials evaluating mindfulness-based stress reduction/cognitive therapy with either passive comparators (usual care) or active comparators (e.g., Health education or cognitive behavioral therapy) for chronic headaches (Migraine, Tension-type, or cluster headaches), which evaluated either headache frequency, pain intensity or headache duration as primary outcome were eligible for inclusion. The Risk of Bias was evaluated using the Cochrane Collaboration's Risk of Bias Tool. Results: A total of ten Randomized Controlled Trials (five on migraine; three on tension-type; two with mixed samples) were evaluated. In comparison to usual care, mindfulness-based stress reduction/cognitive therapy did not illustrate significant changes in headache frequency (MD = -0.14; 95% CI -1.26 to 0.97; P = 0.80; Moderate Certainty), headache duration (MD = -0.27; 95% CI -3.51 to 2.97, P = 0.87; Low Certainty) or pain intensity (MD = -0.19; 95% CI -0.46 to 0.07; P = 0.15; Moderate Certainty). Conclusion: The results found are insignificant for the three primary outcomes, which may be due to the low number of participants and often a high or unclear risk of bias in the randomized control trials included. Perhaps more aggressive clinical trials with a larger sample size effectively demonstrate differences in outcomes before and after therapy for MBSR/MBCT could provide a more significant change.
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Effectiveness of wearable activity trackers to increase physical activity and improve health: a systematic review of systematic reviews and meta-analyses.
Ferguson, T, Olds, T, Curtis, R, Blake, H, Crozier, AJ, Dankiw, K, Dumuid, D, Kasai, D, O'Connor, E, Virgara, R, et al
The Lancet. Digital health. 2022;4(8):e615-e626
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A sedentary or physically inactive lifestyle significantly contributes to non-communicable diseases such as coronary heart disease, type 2 diabetes and stroke. Wearable activity trackers are low-cost solutions that encourage users to engage in physical activity. This umbrella review of systematic reviews and meta-analyses investigated the benefits of wearable activity trackers in improving physical activity levels and their beneficial effects on physiological and psychosocial outcomes. This umbrella review included thirty-nine systematic reviews, of which twenty-five systematic reviews included meta-analyses of the benefits of wearable trackers on physical activity levels. Results of this umbrella review suggest that wearable trackers increased physical activity levels, especially daily steps count and energy expenditure. The physiological outcomes included improvements in BMI, blood pressure, cholesterol, glycosylated haemoglobin, waist circumference, and body weight. There was also a slight improvement in the quality of life of the participants who used wearable activity trackers. Further robust studies are required to evaluate the effects of wearable trackers on the psychosocial outcomes in people with mental illness. However, healthcare professionals can use the results of this study to understand the impact of wearable trackers on physiological and psychosocial effects in a non-clinical population.
Abstract
Wearable activity trackers offer an appealing, low-cost tool to address physical inactivity. This systematic review of systematic reviews and meta-analyses (umbrella review) aimed to examine the effectiveness of activity trackers for improving physical activity and related physiological and psychosocial outcomes in clinical and non-clinical populations. Seven databases (Embase, MEDLINE, Ovid Emcare, Scopus, SPORTDiscus, the Cochrane Library, and Web of Science) were searched from database inception to April 8, 2021. Systematic reviews of primary studies using activity trackers as interventions and reporting physical activity, physiological, or psychosocial outcomes were eligible for inclusion. In total, 39 systematic reviews and meta-analyses were identified, reporting results from 163 992 participants spanning all age groups, from both healthy and clinical populations. Taken together, the meta-analyses suggested activity trackers improved physical activity (standardised mean difference [SMD] 0·3-0·6), body composition (SMD 0·7-2·0), and fitness (SMD 0·3), equating to approximately 1800 extra steps per day, 40 min per day more walking, and reductions of approximately 1 kg in bodyweight. Effects for other physiological (blood pressure, cholesterol, and glycosylated haemoglobin) and psychosocial (quality of life and pain) outcomes were typically small and often non-significant. Activity trackers appear to be effective at increasing physical activity in a variety of age groups and clinical and non-clinical populations. The benefit is clinically important and is sustained over time. Based on the studies evaluated, there is sufficient evidence to recommend the use of activity trackers.
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A Systematic Review of the Impact of the First Year of COVID-19 on Obesity Risk Factors: A Pandemic Fueling a Pandemic?
Daniels, NF, Burrin, C, Chan, T, Fusco, F
Current developments in nutrition. 2022;6(4):nzac011
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Coronavirus disease 2019 (COVID-19) is one of the most serious infectious disease outbreaks in recent history. Among the factors that can increase the risk of obesity, some seem to play a more prominent role than others such as depression, emotional eating, sedentary lifestyle and the socioeconomic status. The aim of this study was to explore the indirect effects of the first year of COVID-19 on obesity and its risk factors. This study is a systematic review of 87 studies with over 350,000 participants. Results show that: - overall, there was a general trend of weight gain during the pandemic. - there were differences in dietary changes, with some studies showing an improvement in diet. - some beneficial effects were observed in the dieting domain, such as higher consumption of home-cooked meals and healthy food (e.g., vegetables). However, there was an increasing trend in the overall food and alcohol consumption. - financial hardship and job loss were unavoidable consequences of the pandemic lockdown. However, although the impact of the countermeasures used to curb the COVID-19 pandemic was evident on obesity risk factors, none of the studies included in the research explored the direct impact of the risk factors on obesity itself. Authors conclude by pointing out the need for future research that aims at strengthening the link between stressful circumstances and a rise in risk factors for obesity and weight gain.
Abstract
Obesity is increasingly prevalent worldwide. Associated risk factors, including depression, socioeconomic stress, poor diet, and lack of physical activity, have all been impacted by the coronavirus disease 2019 (COVID-19) pandemic. This systematic review aims to explore the indirect effects of the first year of COVID-19 on obesity and its risk factors. A literature search of PubMed and EMBASE was performed from 1 January 2020 to 31 December 2020 to identify relevant studies pertaining to the first year of the COVID-19 pandemic (PROSPERO; CRD42020219433). All English-language studies on weight change and key obesity risk factors (psychosocial and socioeconomic health) during the COVID-19 pandemic were considered for inclusion. Of 805 full-text articles that were reviewed, 87 were included for analysis. The included studies observed increased food and alcohol consumption, increased sedentary time, worsening depressive symptoms, and increased financial stress. Overall, these results suggest that COVID-19 has exacerbated the current risk factors for obesity and is likely to worsen obesity rates in the near future. Future studies, and policy makers, will need to carefully consider their interdependency to develop effective interventions able to mitigate the obesity pandemic.
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A Low-FODMAP Diet Provides Benefits for Functional Gastrointestinal Symptoms but Not for Improving Stool Consistency and Mucosal Inflammation in IBD: A Systematic Review and Meta-Analysis.
Peng, Z, Yi, J, Liu, X
Nutrients. 2022;14(10)
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The low-FODMAP diet eliminates carbohydrates that cannot be easily digested in order to reduce functional gastrointestinal symptoms associated with irritable bowel disease (IBD). The symptoms of irritable bowel disease include abdominal pain and bloating. This systematic review and meta-analysis aimed to evaluate whether a low-FODMAP diet can alleviate functional gastrointestinal symptoms in individuals with inflammatory bowel disease. In comparison with a regular diet, a low-FODMAP diet significantly reduced symptoms of bloating, wind, flatulence, abdominal pain, fatigue, and lethargy in patients with IBD. In addition, patients with Crohn's disease have achieved remission or reduced symptoms after following a low-FODMAP diet. Healthcare professionals can use this study to understand better the effects of a low-FODMAP diet on patients with IBD who have functional gastrointestinal symptoms. Further robust studies are, however, required to evaluate the evidence's robustness and identify the mechanism behind the improvement of symptoms.
Expert Review
Conflicts of interest:
None
Take Home Message:
- LFD use in IBD improved symptoms of bloating, wind or flatulence, borborygmi, abdominal pain, and fatigue or lethargy, but not nausea and vomiting.
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
This meta-analysis assesses the efficacy of a low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols diet (LFD) in inflammatory bowel disease [IBD: ulcerative colitis (UC) and Crohn’s disease (UC)] participants with functional gastrointestinal symptoms (FGSs).
Methods
A search was performed on PubMed, Web of Science, EMBASE, Cochrane Central Register of Controlled Trials, Chinese National Knowledge Infrastructure (CNKI), WanFang (Chinese) Database up to March 2022. Quality assessment of all included studies was performed.
Results
9 studies (4 randomised controlled trials, 5 non-randomised studies) with a total of 351 participants diagnosed with IBD were included, and compared LFD with a placebo diet or normal diet (ND), overall and individual
LFD Effects of FGS:
- Overall 9 studies: an improvement (0.47, 0.33–0.66, p = 0.0000)
- No difference in the subgroup classified by disease type
- CD and UC: no improvement
Individual improvement:
- Bloating (0.37, 0,24-0,57, p=0.0000); wind or flatulence (0.38, 0,28-0,51, p=0.0000); borborygmi (0.48, 0,26-0,89, p=0.0000), abdominal pain (0.5, 0,37-0,68, p=0.0000), fatigue/lethargy (0.71, 0,61-0,82, p=0.0000)
- No difference in nausea and vomiting (0.54, 0,22-1,32, p=018)
IBS Quality of Life Score:
- 2 studies: reduced Short IBD Questionnaire (SIBDQ) score (11.24, 6.61-15.87, p=0.0000)
Bristol Stool Form Chart:
- 2 studies: normal stool consistency (type 3-4); no difference (5.99, 0.17-216.51, p=0.33)
- 2 other studies: no difference (-0.17, 0.48 - 0.15, p=0.30)
Diseases activity (Harvey-Bradshaw index):
- 2 studies using the Mayo score: no difference (-32, -1,09-0.45, p=0.41)
- 3 studies using BHi score: reduction (-1.09, -1,77-0.42, p=0.002)
Faecal calprotectin:
- 2 studies: no change (-16.03, -36,78-4.73, p=0.13)
Limitations
- Comparison diets were not standardised, suggesting the potential of different dietary habits to bias results..
- Heterogeneity of included studies, and the relatively small sample size of the studies can reduce the reliability of the results.
Conclusion
While the study found inconsistent definition standards for FGS, all the nine studies showed that LFD was associated with an improvement in some symptoms.
Clinical practice applications:
- This study suggests that IBD patients with FGSs may benefit from LFD treatment with the assistance of a healthcare professional.
Considerations for future research:
- This study has shown that LFD can improve FGSs in IBD, but further research with a larger sample size and more comprehensive analysis is warranted to replicate the results.
- The description of the findings and Quality of Life data are a little unclear. The impact on Quality of Life warrants further investigation, as clinicians need to consider the impact of following a restrictive diet on Quality of Life.
Abstract
BACKGROUND A low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols diet (LFD) is claimed to improve functional gastrointestinal symptoms (FGSs). However, the role of LFD in inflammatory bowel disease (IBD) patients with FGSs remains unclear. OBJECTIVE To systematically assess the efficacy of LFD in IBD patients with FGSs. METHODS Six databases were searched from inception to 1 January 2022. Data were synthesized as the relative risk of symptoms improvement and normal stool consistency, mean difference of Bristol Stool Form Scale (BSFS), Short IBD Questionnaire (SIBDQ), IBS Quality of Life (IBS-QoL), Harvey-Bradshaw index (HBi), Mayo score, and fecal calprotectin (FC). Risk of bias was assessed based on study types. A funnel plot and Egger's test were used to analyze publication bias. RESULTS This review screened and included nine eligible studies, including four randomized controlled trials (RCTs) and five before-after studies, involving a total of 446 participants (351 patients with LFD vs. 95 controls). LFD alleviated overall FGSs (RR: 0.47, 95% CI: 0.33-0.66, p = 0.0000) and obtained higher SIBDQ scores (MD = 11.24, 95% CI 6.61 to 15.87, p = 0.0000) and lower HBi score of Crohn's disease (MD = -1.09, 95% CI -1.77 to -0.42, p = 0.002). However, there were no statistically significant differences in normal stool consistency, BSFS, IBS-QoL, Mayo score of ulcerative colitis, and FC. No publication bias was found. CONCLUSIONS LFD provides a benefit in FGSs and QoL but not for improving stool consistency and mucosal inflammation in IBD patients. Further well-designed RCTs are needed to develop the optimal LFD strategy for IBD.
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The neurological symptoms of COVID-19: a systematic overview of systematic reviews, comparison with other neurological conditions and implications for healthcare services.
Wildwing, T, Holt, N
Therapeutic advances in chronic disease. 2021;12:2040622320976979
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COVID-19 has been found to cause neurological manifestations in up to 50% of patients. The aim of this study was to inform future service provision for those who develop long-term neurological symptoms due to COVID-19, as well as exploring the effect of COVID-19 on health professionals’ perceptions towards those with symptoms of functional neurological disorder (FND). This study is a systematic overview of current systematic reviews which included 45 studies in qualitative synthesis. Results show that: - COVID-19 appears to be becoming chronic for some patients, presenting similar neurological symptoms to FND and to chronic fatigue syndrome; - the long-term neurological effects of COVID-19 may impact neurological and wider health care services; - the neurological symptoms seen in COVID-19 may affect health professionals’ perceptions of FND and chronic fatigue syndrome. Authors conclude that there is increasing evidence of the presence of long-COVID symptoms persisting beyond 3 months. Further research is recommended to explore whether the neurological symptoms of COVID-19 will improve acceptance and understanding of FND, or whether this will worsen the experience for those who suffer from FND.
Abstract
AIMS: In response to the rapid spread of COVID-19, this paper provides health professionals with better accessibility to available evidence, summarising findings from a systematic overview of systematic reviews of the neurological symptoms seen in patients with COVID-19. Implications of so-called 'Long Covid' on neurological services and primary care and similarities with other neurological disorders are discussed. METHODS Firstly, a systematic overview of current reviews of neurological symptoms of COVID-19 was conducted. Secondly, the implications of these findings are discussed in relation to the potential effect on neurological services and the similarities in the experience of patients with COVID-19 and those with other neurological disorders. A total of 45 systematic reviews were identified within seven databases, published between 11 April 2020 and 15 October 2020, following a search in June 2020, updated on 20 October 2020. RESULTS The results indicated that COVID-19 exhibits two types of neurological symptoms; life-threatening symptoms such as Guillain-Barre Syndrome (GBS) and encephalitis, and less devastating symptoms such as fatigue and myalgia. Many of these so-called lesser symptoms appear to be emerging as longer-term for some sufferers and have been recently labelled Long Covid. When compared, these less devastating symptoms are very similar to other neurological conditions such as chronic fatigue syndrome (CFS) and functional neurological disorder (FND). CONCLUSION Implications for neurological healthcare services in the United Kingdom (UK) may include longer waiting times and a need for more resources (including more qualified health professionals). There is also a possible change-effect on health professionals' perceptions of other neurological conditions such as CFS and FND. Future research is recommended to explore changes in health professionals' perceptions of neurological symptoms because of COVID-19.
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Practitioner review: health anxiety in children and young people in the context of the COVID-19 pandemic.
Haig-Ferguson, A, Cooper, K, Cartwright, E, Loades, ME, Daniels, J
Behavioural and cognitive psychotherapy. 2021;49(2):129-143
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In response to the Covid-19 pandemic, many individuals have health-related fear of contracting the disease. In some, this has developed into health anxiety (HA) whereby the sufferer is obsessed with contracting or developing a serious illness, impairing their day-to-day functioning. HA is commonplace in adulthood and most research is in adults; however, it is now thought that it can develop in children. This review on HA in adults aimed to identify adaptations needed to ensure diagnosis and interventions are appropriate for children. The review discussed that children may not be diagnosed with HA, as the criteria used for diagnosis may not be age appropriate; HA symptoms in adults may not be the same in children and adolescents. Health-related worries are relatively common in children but may not be diagnosed as HA. The authors then went on to discuss HA in children in the context of Covid-19 and outlined that limited brain development, pre-existing mental health or physical problems and the influence of parent or carer mental health may contribute to its development. Finally, the paper discussed how diagnosis and treatment in adults could be adapted for children, with a strong focus on cognitive behavioural therapy. It was concluded that HA can develop in children and for those individuals an adapted multi-pronged approach to diagnosis and treatment may be of benefit, however more research is needed. This study could be used by healthcare professionals to understand that children can suffer from HA, how it presents itself and possible treatments for children.
Abstract
Health-related fear is a normal and common response in the face of the global pandemic of COVID-19. Children and young people are frequently being exposed to messages about the threat to health, including from the media and authorities. Whilst for most, their anxiety will be proportionate to the threat, for some, existing pre-occupation with physical symptoms and illness will become more problematic. There is a growing body of evidence that health anxiety may occur in childhood, however much of the literature is taken from research using adult samples. This practitioner review aims to give an overview of the assessment and treatment of health-related worries in children and young people in the context of the COVID-19 pandemic. This review is based on the limited existing evidence in this population and the more substantial evidence base for treating health anxiety in adults. We consider the adaptations needed to ensure such interventions are developmentally appropriate.
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Brain Neurotransmitter Modulation by Gut Microbiota in Anxiety and Depression.
Huang, F, Wu, X
Frontiers in cell and developmental biology. 2021;9:649103
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The causes of anxiety and depression are unclear, but growing evidence points to a role of the gut microbiota. One possible way that the gut microbiota may have an influence on mental health is through a group of chemical messengers in the brain, known as neurotransmitters. This review summarised the research surrounding neurotransmitters and gut microbiota. The review began by looking at research in animal models and the roles of various neurotransmitters and how they may be influenced by the gut microbiota. The neurotransmitters outlined were serotonin, dopamine, and noradrenaline and it was stated that there is evidence that gut microbiota may be able to influence them alleviating anxiety and/or depression, however there was limited evidence with noradrenaline. It was concluded that there is a close connection between the gut microbiota and anxiety and depression. There is more research needed in humans, as most work has been completed in animal models. This paper could be used by healthcare professionals to understand the role of the gut microbiota in mental health disorders and the importance of gut health in individuals suffering from these.
Abstract
Anxiety and depression are highly prevalent mental illnesses worldwide and have long been thought to be closely associated to neurotransmitter modulation. There is growing evidence indicating that changes in the composition of the gut microbiota are related to mental health including anxiety and depression. In this review, we focus on combining the intestinal microbiota with serotonergic, dopaminergic, and noradrenergic neurotransmission in brain, with special emphasis on the anxiety- and depression-like behaviors in stress-related rodent models. Therefore, we reviewed studies conducted on germ-free rodents, or in animals subjected to microbiota absence using antibiotics, as well as via the usage of probiotics. All the results strongly support that the brain neurotransmitter modulation by gut microbiota is indispensable to the physiopathology of anxiety and depression. However, a lot of work is needed to determine how gut microbiota mediated neurotransmission in human brain has any physiological significance and, if any, how it can be used in therapy. Overall, the gut microbiota provides a novel way to alter neurotransmitter modulation in the brain and treat gut-brain axis diseases, such as anxiety and depression.
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Effects of Microbiota Imbalance in Anxiety and Eating Disorders: Probiotics as Novel Therapeutic Approaches.
Navarro-Tapia, E, Almeida-Toledano, L, Sebastiani, G, Serra-Delgado, M, García-Algar, Ó, Andreu-Fernández, V
International journal of molecular sciences. 2021;22(5)
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The interest in mental health has increased recently. Anxiety and mood disorders are associated with many disabilities and there is a close relationship between eating disorders and anxiety. Although current medical treatments for anxiety disorders are safer than a few decades ago; the effectiveness in some of them has not improved, they have side effects and can cause addiction. Therefore, the development of new tools to restore mental health without the undesired effects is necessary. Recent studies indicate that patients with generalized anxiety or eating disorders (anorexia nervosa, bulimia nervosa, and binge-eating disorders) show a specific gut microbiota profile, and this imbalance can be partially restored after a single or multi-strain probiotic supplementation. The purpose of this review is to look at the main microbial patterns seen in patients with generalized anxiety and/or eating disorders as well as the importance of probiotics as a preventive or a therapeutic tool in these pathologies. The studies reviewed showed an imbalance of microbial communities in patients with anxiety and with eating disorders. The effect of probiotics in reducing anxiety seems to be more effective the higher the baseline anxiety level of the individual. For eating disorders, the correction of dysbiosis may be associated with the physical and emotional well-being of these subjects. Further study of the intestinal microbiota will enable progress in the study of therapeutic approaches of these areas.
Abstract
Anxiety and eating disorders produce a physiological imbalance that triggers alterations in the abundance and composition of gut microbiota. Moreover, the gut-brain axis can be altered by several factors such as diet, lifestyle, infections, and antibiotic treatment. Diet alterations generate gut dysbiosis, which affects immune system responses, inflammation mechanisms, the intestinal permeability, as well as the production of short chain fatty acids and neurotransmitters by gut microbiota, which are essential to the correct function of neurological processes. Recent studies indicated that patients with generalized anxiety or eating disorders (anorexia nervosa, bulimia nervosa, and binge-eating disorders) show a specific profile of gut microbiota, and this imbalance can be partially restored after a single or multi-strain probiotic supplementation. Following the PRISMA methodology, the current review addresses the main microbial signatures observed in patients with generalized anxiety and/or eating disorders as well as the importance of probiotics as a preventive or a therapeutic tool in these pathologies.
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Evolution of the Human Diet and Its Impact on Gut Microbiota, Immune Responses, and Brain Health.
González Olmo, BM, Butler, MJ, Barrientos, RM
Nutrients. 2021;13(1)
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One explanation for the increased prevalence in chronic disease and mental illness is from the evolutionary perspective. This suggests the rapid shift in diet towards processed foods in the past 200 years has not allowed for sufficient adaptation of the gut microbiome. The gut microbiome plays an important role in the digestive, immune and nervous systems via the gut-brain axis, and may be a key factor in modulating inflammation and disease. The aim of this review is to discuss how what we eat affects the immune system and impacts our brain health. The literature currently shows significant associations between the Western diet and its impact on the health of the gut microbiome and the brain. Increased intake of saturated fats, refined carbohydrates and sugar, coupled with a reduction in fiber, negatively impacts the digestive system and elicits an immune response. This response can lead to neuroinflammation, which is now found to be associated with deficits in learning and memory, as well as increased rates of neurodegenerative disease and depression. Based on the existing literature, the authors conclude the human gut microbiome has not had sufficient time to adapt to many modern foods, thus leading to inflammation and disease. The authors recommend that a diet composed of natural whole foods with minimal processing can help prevent and alleviate some of the burden caused by chronic disease, and suggest future studies focus on improving techniques to evaluate neuroinflammation in humans.
Abstract
The relatively rapid shift from consuming preagricultural wild foods for thousands of years, to consuming postindustrial semi-processed and ultra-processed foods endemic of the Western world less than 200 years ago did not allow for evolutionary adaptation of the commensal microbial species that inhabit the human gastrointestinal (GI) tract, and this has significantly impacted gut health. The human gut microbiota, the diverse and dynamic population of microbes, has been demonstrated to have extensive and important interactions with the digestive, immune, and nervous systems. Western diet-induced dysbiosis of the gut microbiota has been shown to negatively impact human digestive physiology, to have pathogenic effects on the immune system, and, in turn, cause exaggerated neuroinflammation. Given the tremendous amount of evidence linking neuroinflammation with neural dysfunction, it is no surprise that the Western diet has been implicated in the development of many diseases and disorders of the brain, including memory impairments, neurodegenerative disorders, and depression. In this review, we discuss each of these concepts to understand how what we eat can lead to cognitive and psychiatric diseases.