Analysis of Brain and Immune Functions in Adolescents Using Probiotics

Children and adolescents often experience high levels of stress. Age and gender may affect the ability of a child to manage stress. Children and adolescents experiencing stress could be at an increased risk of poor cognitive, social, and emotional functioning, and may have altered immune responses due to stress.

Probiotics are living microorganisms that could positively affect microbiota, support functions of numerous organs and systems, and overall human health. Most probiotics belong to the Lactobacillus genus. It has been suggested that probiotics potentially can support mental health, psychological function, and immune defenses. Recent studies confirmed that the use of pre- and probiotics improves the psychological scores of people predisposed to mood disorders. A supplementation of the diet of healthy volunteers with a probiotic for four weeks resulted in a significant reduction of subjects' rumination and aggressive thoughts. Lactobacillus plantarum DR7 reduces signs of stress and improves immune functions in adults. Consumption of this probiotic for 12 weeks reduced signs of stress and improved the psychological scores of participants. The levels of inflammatory cytokines are higher in people with anxiety. The use of Lactobacillus plantarum DR7 reduced levels of inflammatory cytokines (e.g., IFNgamma).

The purpose of this exploratory clinical trial is to investigate whether supplementation of the diets of adolescents experiencing moderate stress with the probiotic dietary supplement a blend of two Lactobacillus plantarum and one Lactobacillus brevis probiotic strains will support participants emotions (e.g., psychological well-being, social relationship, stress levels, and self-efficacy), cognitive (e.g., attention, episodic and working memory) and immune functions (e.g., salivary IgA and salivary cytokine productions). This study is intended only to evaluate the dietary supplement's effect on the body's structure or function. Our investigation is not intended to mitigate, cure, treat, or prevent disease.

The study will be an exploratory single-blind, randomized clinical trial of a dietary supplement containing 2 billion CFU of a probiotic strains: two Lactobacillus plantarum and one Lactobacillus brevis probiotic strains. Stains are present in the mixture at a ratio of 2:1:1. All strains are currently used as dietary supplements in the United States.

Participants for this trial will be selected based on the following criteria: participants age 12-20 years old, BMI percentile >5% and <97% with moderate stress levels (Perceived Stress Scale (PPS) score 14-26), receiving or not receiving cognitive behavioral therapy, and not on selective serotonin reuptake inhibitors (SSRIs). Investigators planned to enroll 120 participants, with 60 participants in the dietary supplement (Probiotics) arm. The probiotics arm will receive caps with the probiotic blend, and control participants will receive caps containing a placebo for the same period. Participants will be asked to consume the caps with dinner meals for 12 consecutive weeks. If the probiotic was not taken during dinner, then it should be taken within 2 hours after dinner or with the next meal.