Effects of probiotics on salivary cortisol in anxiety, negative mood, and ADHD
LE3 .A278 2017
Bachelor of Science
Cortisol is a stress hormone released upon HPA axis activation. Anxiety and depression mental health problems associated with high cortisol levels, whereas ADHD is associated with lower cortisol levels. Researchers have begun to look at the relationship between the gut microbiome, mental health, and cortisol levels. The gut microbiome and the brain communicate through the gut-brain axis, and imbalances in the microbiome have been associated with anxiety, depression, and ADHD. Probiotics represent a potential treatment for these conditions via their beneficial effects on the gut microbiome. The current project examined the effects of probiotics on salivary cortisol levels in 2 randomized, double-blind clinical trials, with: (1) adults with anxiety and/or depressed mood, and (2) children with anxiety and/or ADHD. It was hypothesized that children with ADHD would present with lower baseline cortisol than those with anxiety, and that probiotics would normalize high or low levels. In the adult study it was hypothesized that probiotic supplementation would decrease cortisol. Saliva was analyzed for 25 children at baseline, end of phase 1 (probiotic or placebo), end of the washout period, and end of phase 2 (probiotic or placebo). Saliva from 94 adults was analyzed at baseline and post-intervention (probiotic or placebo). None of the hypotheses were supported by statistically significant results. However, the following trends were in the hypothesized direction: child baseline cortisol levels were lower among children with ADHD than children with anxiety; probiotics normalized child cortisol levels and lowered probiotics lowered adults’ cortisol levels. This study highlights the importance of continuing research on the possible beneficial effects of probiotic supplementation on mental health conditions such as anxiety, depressed mood, and ADHD.
The author retains copyright in this thesis. Any substantial copying or any other actions that exceed fair dealing or other exceptions in the Copyright Act require the permission of the author.