The gut-brain axis mediated by gut microbiota represents bidirectional communication network in gastrointestinal tract and central nervous system this link suggests that changes in gut microbiota could serve as biomarkers for mental health disorders such as depression and anxiety highlighting its vital function and potential impact (Duan et al., 2022; Jia et al., 2020).

Likewise, significant effect has been discovered through recent studies that individuals with mental health disorders have experienced faster recovery compared to the control sample suggesting high value of impact through supplementation and balance of microbiota (Duan et al., 2022; Järbrink-Sehgal & Andreasson, 2020), forming high potential in predictive value of specific microbial taxa as modification in gut microbiota has been linked to positively affect mental health and recovery time compared to individual with an unbalanced microbiota (Yan et al., 2021). Therefore, active manipulation of microbiota levels provider can support individuals in faster and more efficient recovery.

Although specific role of gut microbiota in mental health is not well understood nor can be predicted due to individual differences or response; this research aims to further investigate and explore this topic through active alteration of gut microbiota via introduction of probiotics and prebiotics within participant’s daily diet. This can offer an opportunity to observe participants response to therapy and its respond marked as a predictor of mental health recovery time and state particularly when considering anxiety and depression.

A groundbreaking understanding of gut and mental health

This understanding can be a groundbreaking step for therapists and psychologist to incorporate its finding within their treatment planning and work collaboratively with nutritionist to formulate a more effective and personalized treatment plan making informed decisions with an integrated treatment plan effective for long-term mental health management and recovery time, potentially helping individuals shorten therapy with less reliant on medication through a holistic treatment plan that incorporated a multidimensional perspective incorporating both body and mind.

Formulating this collaboration can be the ground for a new personalized treatment plan. This study theorizes that a balance gut microbiota can serve as a supportive factor for individuals to progress their mental health recovery journey and achieve a desired response through therapy with a lower medication dependency. Therefore, the focuses will be set to explore the potential role of gut microbiota alterations in daily diets seeking to understand its interaction and/or involvement when exploring disorders such as anxiety and depression in via gut microbiota manipulation through supplementation.

Variables Definition

The variables in this study are defined as follows:

• Independent variable (IV): Given the state of this research in this study the IV has been set as the dietary intervention with and without probiotic and prebiotic supplementation. These conditions will be explored in two set levels:

  • Control condition: Through standard diet Participants carry their regular daily diet without any added supplementation.

  • experimental condition: Participants diet will be supplemented with probiotics and prebiotics adjusted by a nutritionist to ensure proper supplementation.

• Dependent variables (DV): Three primary DVs have been set for this study that will be measured and monitored throughout the study:

  • Gut microbiota composition: The gut microbiota composition will be measured through 16S rRNA sequencing of stool samples defined by changes within the microbial taxa.

  • Mental health status: To assess participants mental health status the researcher will utilize standardized scales such including Beck Anxiety Inventory (BAI) and Beck Depression Inventory (BDI).

  • Physiological stress markers: The physiological stress markers will include cortisol levels and inflammatory markers such as C-reactive protein, measured through blood samples.

Set conditions will be defined throughout the study by participants adherence to dietary protocols assigned.

Theoretical Framework and Literature Review

Halverson and Alagiakrishnan (2020) explored gut-brain axis as a well-established pathway impacting mental health through gut microbiota influencing brain function and behavior a process in how gut microbes interact with central nervous system demonstrating significant effect on mental health by neural, endocrine, and immune pathways. Highlighting the modulation of neurotransmitters and other neuroactive compounds through gut bacteria leading to changes in mental and behavioral state.

Likewise, dietary components offer therapeutic approach through altering gut microbiota with potential in improving mental health disorders via healthy diet (Xiong et al., 2023). This study explored the positive effects of diet and its components via gut microbiota by alleviating and/or reducing symptoms of mental health disorders such as anxiety and depression. Xiong et al. (2023) highlights the importance of a healthy dietary plan in support of having a healthy gut microbiota composition an important factor in maintaining a healthy mental health as Implementing a healthy and positive interventions, a promising approach to treat mental health disorders.

Chang et al. (2024) mini review employed faecal microbiota transplants to emphasize the significant progress via mechanistic pathway involved in rebalancing gut microbiota showcasing the positive impact in mental health. Gates et al. (2022) also examined changes in diet and its effects by modifying gut microbiota emphasizing positive impact on mental health suggesting a healthy alteration indicating noteworthy response with Alzheimer's and Parkinson's. Boscaini et al. (2023) explored whey proteins consumption affecting microbiota with positive impact on mental health. Boscaini et al. (2023) highlights mechanisms through which whey protein can enhances the production of beneficial gut bacteria and the production of neuroactive substances that positively affect mental health.

Gut microbiota and mental health

Collective evidence from current research suggests strong link between gut microbiota and mental health. However, as stated by Grajek et al. (2022) the current body of research lacks an understanding on how mental health professionals can utilize such knowledge in formulating treatment plans.

Furthermore, Vindegaard et al. (2021) and Moqbil et al. (2021) highlighted the need for targeted research on predictive value of gut microbiota alterations for a better and more efficient mental health recovery. Madison and Kiecolt-Glaser (2019) in their study emphasized the role of stress and depression in regard to gut microbiota with the inclusion of cortisol and C-reactive protein as dependent variables, Merlo et al. (2024) additionally supported the positive effect of probiotic and prebiotic supplementation with positive impact on mental health.

Thus, this study aims to provide a comprehensive understanding of how alteration in gut microbiota can serve as mean to support individuals who are suffering from mental health disorders and support them in their treatment. This study hypothesizes that incorporating probiotic and prebiotic to daily diet can support individuals in a faster and more personalized recovery from mental health disorders and support positive changes in microbiota composition correlating with mental health improvement. This research has the potential to revolutionize mental health treatment offering a new pathway for therapist to work collaboratively with nutritionist providing scientific basis for the integration of nutritional interventions to not replace traditional treatment but rather to enhance and personalize treatment planing and reduce the possible dependency of medication.

Therefore this study seeks to bridge the gap by allowing therapist and other mental health professionals to better understand the existing link among body and mind, supporting individuals with long-term mental disorders with the hope of more effective response to treatment and recovery creating the foundation for a true personalized treatment plan link with both body and mind.

Existing research limits the connection of gut microbiota and mental health in supporting mental health professionals working collaboratively with nutritionist to support individuals in their recovery journey; therefore, filling a crucial gap by investigating direct impact of targeted gut microbiota manipulation though supplementation of proper probiotic and prebiotic while observing the changes in mental health recovery outcomes.

Although past research established correlation between gut microbiota and mental health disorders (Vindegaard et al., 2021; Moqbil et al., 2021; Merlo et al., 2024) though very limited research has been conducted on its predictive value by intentional alteration of gut microbiota for a faster mental health recovery. Previous research has established correlations between gut microbiota and mental health; though, there is limited research on the predictive value of intentional microbiota alterations for mental health disorder recovery. This study aims to provide a foundation for integrating nutritional interventions into psychological treatment plans, an area that remains underexplored in current clinical practice.

Research Design and Hypotheses

Research Design

Utilizing randomized controlled trial (RCT) design participants are randomly selected and assigned. The selection of this design helps assess the impact of specialized dietary intervention impacting gut microbiota and mental health outcomes. Both groups will also receive cognitive behavioral therapy as an intervention on a weekly basis to support their specific needs such as anxiety or depression.

Methods and Systems

Participant Recruitment

For this study all participants will be recruited through social media platforms such as Instagram and the utilization of advertisement. This can benefit the study by allowing the researcher to be specific in criteria and target their audience. The age group for participants will be 18-65 clinically diagnosed with anxiety and/or depression.

• Exclusion criteria: Individuals that are currently and actively taking antibiotics and/or Individuals who are diagnosed with either gastrointestinal diseases and/or individuals with any form of past gut surgery.

Intervention

The intervention group will receive specialized diet rich in probiotics and prebiotics for three months. This diet will be reviewed and administered by a nutritionist to ensure accuracy. The control group will continue with usual diet without receiving supplements.

Data Collection

1. The gut microbiota composition will be analyzed by 16S rRNA gene sequencing sampled through stool collection at the beginning of the experiment and at the end of the study after the 3-month duration of the study.

2. Psychological testing and assessments will also be conducted by a mental health providers at the beginning of the study to measure beginning levels of anxiety and depression utilizing standardized scales and at the end of the treatment duration to indicate the beginning and the ending of the levels. This study will incorporate the Beck Anxiety Inventory (BAI) and Beck Depression Inventory (BDI) as an assessment for this research

3. Physiological stress markers for this study will be measured via cortisol levels and C-reactive protein measured through blood samples at the beginning and the end of treatment.

Data Analysis

The changes in psychological and physiological markers of mental health will be correlated with changes in gut microbiota composition of participants. Statistical analyses will include t-tests and ANOVA to compare changes also regression analysis will be utilized to predict mental health outcomes based on gut microbiota.

Hypothesis

This study proposes the following hypotheses:

• H₁: Participants who are supplemented with probiotic and prebiotic will show more beneficial gut microbiota revealing a lower levels of stress markers and an improved scores on psychological assessments with a faster recovery time vs the participants who are not receiving the probiotic and prebiotic.

• H₂: Positive alterations in gut microbiota composition will positively correlate with improvements in mental health that can suggesting specific changes in microbial taxa is an effective biomarker for not only predicting but also managing mental health disorders.

Method

Participants

            This study will have 100 adult participants who are between the age of 18 and 55 years. This sample size was selected due to several factors. First to understand the proper number of participants a power analysis was conducted while assuming medium effect size (d=0.5), an alpha level of 0.05, and desired power of 0.80 using G*Power software for our analyses suggesting minimum sample size of 84; therefore, the sample size was increased to 100 to support the study and count for potential attrition and to further enhance statistical power. Likewise this sample size aligns with the possibility of participants dropping out. Furthermore, the larger sample also allows for a more diverse representation of participants, enhancing the external validity of our results.

            Furthermore the sample size can support the study in detecting significant differences among each group the experimental and the control group creating balance and the need for rigorous statistical analysis while accounting for potential dropout and non-compliance typically seen in dietary intervention studies.

Participants Selection

            The selection of participants for this study will be through the use of social media platform. The researchers will utilize Instagram as a mean to recruit participants by incorporating advertisement. Utilizing advertising campaign will allow the researcher to fine tone their criteria and target the correct audience who fall into the participants criteria and are targeted to have a higher chance of interaction with the advertisement. This process will emphasize on the voluntary aspect of this study with all its potentials informing the participants thoroughly on all potential risks and the benefits of the study prior to giving written informed consent.

            To support the diversity of the study and achieve balance within the desired demographic the recruitment advertisement and the consent form will be available in multiple language including but not limited to English, Spanish, and Mandarin. Further efforts will be made to incorporate underrepresented groups.

Sampling Procedure

            For this study the participants are recruited via non-probabilistic, convenience sampling method. Although, this may limit generalizability of the finding vs random sampling; however, due to its feasibility and effectiveness for online settings this method has been chosen. After the completion of the initial response all participants for this study will undergo a screening process to better verify current diagnoses and their suitability based on inclusion and exclusion criteria.            

Group Assignment

Upon successful screening of all active participants, they will be randomly assigned to one of two groups helping the study to achieve and ensure equal distribution within each active groups. The control group will be instructed to maintain their diet without any modification or alteration throughout the study. However, the experimental group will be instructed to adhere a diet supplemented with probiotics and prebiotics selected for them based on their levels provided to them by a nutritionist. To ensure randomization this study will utilized Microsoft Excel and create a computer-generated table to ensure unbiased assignment this code will be created by the research team to ensure ability of replication.

Group Assignment Code:  =IF(B2<MEDIAN($B$2:$B$n), "Control", "Experimental")

Apparatus/Materials and Procedure

Apparatus: The device that will be utilized for this study will be centrifuge Model AC-234 for blood samples processing and stool samples the study will utilize a microbiota analysis system 16S rRNA sequencing kit provided by GenTech Labs.

Materials: The study will utilize two main forms of data collection instruments:

1. Dietary Intake Questionnaire: The dietary intake questionnaire will be primarily built for the use of this study to support the study in tracking adherence of the participants to the provided diet intervention provided in Appendix A.

2. Psychological Measures: The use of Beck Anxiety Inventory (BAI) and Beck Depression Inventory (BDI) also will be utilized in this study to assess participants mental health state both at the beginning of the experiment and at the end of the study. and end of the study period.

Procedure: The specific procedure for this study has been developed in 4 steps to ensure clarity and replicability of future studies.

1. Initial Screening and Group Assignment: upon completion of informed consent by the participants all active participants will be screened via BAI and BDI to confirm current diagnoses of anxiety or depression which then allows the researcher to randomly assign participants to one of two groups, control or experimental.

2. Dietary Intervention: The participants who are within the experimental group will be provided a diet enriched with probiotic and prebiotics vs the participants in control group who will receive their usual diet. During the study all participants will be monitored on a weekly basis via Zoom meeting to ensure compliance and will have access to a direct line to the researcher in case of any needed adjustment or intervention.

3. Biological and Psychological Assessments: At the end of the 3-month period of this study the researcher will collect biological samples from the participants that include a blood and stool sample the blood sample is analyzed for cortisol and C-reactive protein levels and stool samples will be analyzed for microbiota composition; also during this time the researcher with conduct psychological assessment.

4. Data Analysis: The provided data from this study will then be analyzed using a t-test to compare the mean between the two group and analyzed for the difference, the researcher will then utilize ANOVA for a more in-depth analysis within each given groups. Finally, regression analysis will be utilized to explore the predictive relationship of gut microbiota changes and mental health outcome.

5. Follow-Up: To ensure participants engagement and active participation weekly Zoom meetings will be conducted to follow up with participants and ensure the need if any adjustment is needed to be made or any support during the study. Likewise, this can support participants to increase motivation.

Ethical Considerations and Informed Consent

            Prior to the start of the study all participants will be required to sign an informed consent that covers the purpose, procedures, potential risks and benefits. This can ensure full involvement of participants and acknowledgment of all aspects of this study while addressing all questions that participants may have in regard to their participations and their participation reequipment and how their data will be collected and furthermore protected while being used solely for the research. The consent form also assures all participants of their voluntary involvement and ability to withdraw at any point of the study.

            All data will be protected and saved in a local computer that is in a secure location and will only be handled by the researchers to comply with all HIPPA criteria ensuring that all participants information is and will remain confidential. Upon the completion of the study all names and identifying information will be removed.  

Original Paper and Presentation:

References

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