Probiotics May Influence Schizophrenia Symptoms Through Yeast in Microbiome Interview with:
Emily G. Severance PhD
Stanley Division of Developmental Neurovirology
Department of Pediatrics
Johns Hopkins University School of Medicine
Baltimore, MD 21287 What is the background for this study? What are the main findings?

Response: Previously, we found that people with schizophrenia and bipolar disorder had an increased susceptibility to Candida albicans yeast infections, which was sex specific and associated with memory deficits. Also in an earlier placebo-controlled probiotic study, we found that although probiotics improved the overall bowel function of people with schizophrenia, there was no effect by this treatment on psychiatric symptoms.  Given that C. albicans infections can upset the dynamics of the human microbiome, we decided to re-evaluate the potential benefit of probiotics in the context of a patient’s C. albicans yeast status.  Not only was bowel function again enhanced following intake of probiotics, but yeast antibody levels were decreased by this treatment.

Furthermore, psychiatric symptoms were actually improved over time for men receiving probiotics who did not have elevated C. albicans antibodies. Men who were positive for C. albicans exposure, however, consistently presented with worse psychiatric symptoms irrespective of probiotic or placebo treatment. What should readers take away from your report?

Response: Studies of the human microbiome generally focus on characterizing changes in resident bacterial communities. The human body can also host non-bacterial microbiota, like fungal species, but relatively little is known about the interactions of these fungi with other classes of microbiota inhabiting the intestinal tract. Thus, studies that evaluate the effectiveness of probiotics to treat human conditions should consider the non-bacterial species as well, and especially the yeast, C. albicans, which may become dominant during times of stress, improper diets, infections and exposures to toxins or antibiotics. Once in a pathogenic state, C. albicans can obscure a straightforward interpretation of probiotic effectiveness. What recommendations do you have for future research as a result of this study?

Response: It is conceivable that by knowing a person’s C. albicans positivity status, we may be able to predict who will respond best to certain combinations of bacteria and yeast components in a probiotic preparation. Clinicians might evaluate patients in the context that C. albicans yeast infections are both generally preventable and treatable. Our future research plans are directed toward a better understanding of the gut-brain axis and the mechanisms by which yeast species might become pathogenic to the brain Is there anything else you would like to add?

Response: Our studies of C. albicans in schizophrenia have focused on males, because there continues to be a large degree of sex specificity, presumably as a result of the female reproductive tract being prone to yeast infections irrespective of mental health status. Nevertheless, we are finding that C. albicans positivity does confer a greater risk for memory deficits in women with schizophrenia. Thank you for your contribution to the community.


Emily G. Severance, Kristin L. Gressitt, Cassie R. Stallings, Emily Katsafanas, Lucy A. Schweinfurth, Christina L.G. Savage, Maria B. Adamos, Kevin M. Sweeney, Andrea E. Origoni, Sunil Khushalani, Faith B. Dickerson, Robert H. Yolken. Probiotic normalization of Candida albicans in schizophrenia: A randomized, placebo-controlled, longitudinal pilot studyBrain, Behavior, and Immunity, 2017; 62: 41 DOI: 10.1016/j.bbi.2016.11.019


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Last Updated on April 10, 2017 by Marie Benz MD FAAD