Date of Award


Degree Type

Selective Evidence-Based Medicine Review

Degree Name

Master of Science in Health Sciences - Physician Assistant


Physician Assistant Studies

Department Chair

John Cavenagh, MBA, PhD, PA-C


OBJECTIVE: The objective of this selective EBM is to determine whether or not, “Are the use of antibiotics an effective treatment for relieving symptoms of depression in adults?”

STUDY DESIGN: Review of three English language primary studies, published between 2010- 2016.

DATA SOURCES: Three randomized controlled trials (RCTs) were found using PubMed- NCBI. These studies analyzed the effectiveness of probiotics in adults with symptoms of depression.

OUTCOME MEASURED: The main outcome measured was improvement of symptoms of depression after the administration of probiotic supplements. Outcomes were assessed using data from self-reported questionnaires, which include the Hopkins Symptom Checklist (HSCL-90), Hospital Anxiety and Depression Scale (HADS), Beck Depression Inventory (BDI), and the Leiden Index of Depression Sensitivity Scale (LEIDS-r). P-values were used to assess the significance of outcomes.

RESULTS: All three studies showed improvement in depressive symptoms with probiotic supplementation. There were significant decreases in depression scores during post-intervention evaluations when compared to pre-assessment data. Differences between probiotic and placebo groups were found to be statistically significant in two out of the three studies. Overall, study participants who were given probiotics had lower depression scores than those who were given the placebo, after probiotic supplementation.

CONCLUSION: The results of the RCTs support probiotics as an effective treatment for relieving symptoms of depression in adults. The possibility of probiotic use in depression offers a safer and more affordable option in comparison to currently available therapies.