Research Papers

Gut Microbiota in Anxiety and Depression: Unveiling the Relationships and Management Options​

• Published: April 6, 2022

• Source: Pharmaceuticals (Open Access Journal)

• Focus: Investigates the relationship between gut microbiota composition and anxiety/depression, with implications for mood regulation.

• Study Design: Systematic review of human studies, including observational and interventional designs, analysing microbiome profiles in individuals with anxiety and depression compared to healthy controls.

• Findings: Dysbiosis was consistently linked to increased anxiety and depressive symptoms, with reduced microbial diversity and altered metabolite production affecting mood regulation via the gut-brain axis. 

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The Gut Microbiome in Adult ADHD: Associations with Symptom Severity and Cognitive Function​​

• Published: January 15, 2023

• Source: Journal of Psychiatric Research

• Focus: Examines gut microbiome differences in adults with ADHD, focusing on symptom severity (inattention, hyperactivity) and cognitive functions like focus and learning.

• Study Design: Cross-sectional study with 85 adults diagnosed with ADHD and 60 healthy controls; stool samples analysed via 16S rRNA sequencing, cognitive tests (e.g., Continuous Performance Test) conducted.

• Findings: ADHD patients exhibited lower microbial diversity and distinct microbial profiles compared to controls. Reduced focus and learning capacity correlated with dysbiosis, suggesting a gut-brain link in ADHD - related cognitive deficits.

 

Gut Microbiota Alterations in Children with ADHD: Links to Behavioural and Cognitive Outcomes​

• Published: March 10, 2021

• Source: Frontiers in Psychiatry

• Focus: Explores gut microbiota composition in children with ADHD and its association with behavioural symptoms, concentration, and learning difficulties.

• Study Design: Case - control study involving 72 children with ADHD and 68 age-matched controls; microbiome analysis via shotgun metagenomics, paired with behavioural assessments (e.g., ADHD Rating Scale) and cognitive tests.

• Findings: Children with ADHD showed reduced gut microbial diversity and altered metabolic pathways (e.g. dopamine precursor synthesis). Poor concentration and learning performance were associated with these microbial shifts, supporting a role in ADHD pathology.

 

The Role of the Gut Microbiome in Mood and Cognitive Performance: A Randomised Controlled Trial of Probiotics​

• Published: June 28, 2022

• Source: Nutrients

• Focus: Assesses the effects of probiotic supplementation on mood regulation and cognitive performance (concentration, focus) in healthy adults with subclinical mood disturbances.

• Study Design: Randomized controlled trial (RCT) with 120 participants; 8-week intervention with multi-strain probiotics vs. placebo; mood (PHQ-9, GAD-7) and cognitive tests (e.g., Stroop Test) measured pre- and post-intervention.

• Findings: Targeted probiotic supplementation improved mood stability and concentration compared to placebo, with shifts in microbiota composition suggesting a mechanistic link. Enhanced focus was tied to increased bacterial metabolite production.

 

Dysbiosis and Neurodevelopmental Disorders: A Longitudinal Study of Gut-Brain Interactions in ADHD​

• Published: September 14, 2023

• Source: Brain, Behaviour, and Immunity

• Focus: Investigates longitudinal changes in gut microbiota and their association with ADHD symptoms, mood regulation, and cognitive functions (learning, focus) in children.

• Study Design: Prospective cohort study with 150 children (75 ADHD, 75 controls) followed for 2 years; microbiome sequencing, ADHD symptom tracking (Conners’ Rating Scale), and cognitive assessments performed at multiple time points.

• Findings: Persistent dysbiosis in ADHD children was linked to worsening inattention, mood instability, and learning difficulties over time. Specific microbial imbalances influenced neurotransmitter-related pathways (e.g. serotonin, dopamine).

 

Gut Microbiome and Emotional Regulation in Young Adults: Implications for Attention and Learning​

• Published: November 20, 2020

• Source: Psychoneuroendocrinology

• Focus: Examines the association between gut microbiota, emotional regulation, and attention/learning capacities in young adults.

• Study Design: Observational study with 200 university students; gut microbiome analysed via 16S rRNA sequencing, emotional regulation assessed (DERS), and attention/learning measured via neuropsychological tests.

• Findings: Dysbiosis was associated with poorer emotional regulation and reduced attention span, impacting learning outcomes. Microbial diversity positively correlated with better cognitive performance.

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Examining the Influence of the Human Gut Microbiota on Cognition and Stress: A Systematic Review of the Literature​

• Published: October 2022

• Source: Nutrients

• Focus: Investigating the relationship between gut microbiota, cognition, and stress, including the impact of microbiota modulation on brain function and emotional well-being.

• Study Design: Systematic review of 25 studies published between October 2018 and August 2021, encompassing both cross-sectional and intervention studies.

• Findings and Key Insights: The review suggests that gut microbiota is linked to brain connectivity and cognitive performance. Modulating gut microbiota could be a promising strategy for enhancing cognition and emotional well-being in both stressed and non-stressed situations.​

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The Gut Microbiota in Anxiety and Depression: A Systematic Review​

• Published: 2020

• Source: PubMed

• Focus: To systematically review existing literature on the association between gut microbiota composition and anxiety and depressive disorders in humans.

• Study Design: A systematic review of 26 studies, including case-control comparisons and assessments of symptom severity related to anxiety and depression.

• Findings: The review found inconsistent results regarding overall microbial diversity (alpha and beta diversity). However, specific bacterial taxa were consistently associated with these mental health conditions. Notably, there was a higher abundance of proinflammatory species and a lower presence of short-chain fatty acid-producing bacteria in individuals with anxiety and depression.

• Key Insights: The findings suggest that an imbalance in certain gut bacteria may contribute to the pathophysiology of anxiety and depression, potentially through mechanisms involving peripheral inflammation affecting brain function. ​​​

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