Probiotic Treatment in Individuals with Euthymic Bipolar Disorder: A Pilot-Study on Clinical Changes and Compliance

The importance of the microbiome for psychological well-being has gained rising interest in the last decade. A strategy to examine the role of the microbiome in different diseases is the intake of supplements that modulate the gut microbiome. Despite promising results in animal studies, research in humans is sparse to date and especially in individuals with psychiatric disorders almost missing. The current report of the ProbioBIP-one pilot study aims at describing general effects of the intake of the probiotic OMNi-BiOTiC Stress repair® on psychological parameters as well as gastrointestinal symptoms and general compliance in a cohort of euthymic individuals with bipolar disorder (BD), receiving daily probiotic treatment over a time period of 3 months. Twenty-seven individuals with BD took part in the present study (mean age = 50.7 years, SD = 12.2; females 40.7%). In sum, there was a high compliance rate with 81.5% of the study participants completing all 3 study visits and 85% of planned probiotic ingestions taken. Gastrointestinal problems were prevalent in more than half of the patients at the time of inclusion (t1). Expectedly, in the whole cohort, a high proportion of study participants experienced changes concerning digestion during probiotic treatment, around one third reported positive changes (reduced flatulence and easier and more frequent bowel movements) after 1 month (t2) and further after 3 months (t3). In contrast, a smaller part of study participants reported gastrointestinal discomfort after 1 and after 3 months (mainly flatulence and obstipation). We found a significantly reduced cognitive reactivity to sad mood between t2 and t3 indicating that participants under probiotic supplementation perceived themselves to be less distracted by ruminative thoughts. Further changes in psychiatric symptoms were small due to the euthymic state and already low scoring at the time of inclusion. Nevertheless, we found a significant symptom reduction in the rating scales measuring manic symptoms. From a clinical point of view, probiotic supplementation might provide a well-tolerated tool to positively influence gastrointestinal quality of life as well as mental and somatic health, cognition and immune response and potentially have effects on psychiatric symptoms.