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Probiotics May Decrease Schizophrenia Symptoms in Some

April 10, 2017

Probiotics may decrease delusions and hallucinations in some people with schizophrenia, researchers from Johns Hopkins Medicine and Sheppard Pratt Health System found in a small pilot study. The improvements were largely seen in men without a history of yeast infections, they report in the May 1 issue of Brain, Behavior, and Immunity.

The randomized, longitudinal study included 56 patients, with an average of 46. The investigators said larger and more rigorous studies are needed to validate their findings and determine if women with schizophrenia respond in the same way.

“The tiny living organisms that make up the human microbiome and the overwhelming evidence for a gut-brain axis together represent a new frontier for schizophrenia research,” said Emily Severance, PhD, assistant professor of pediatrics, of the Stanley Division of Developmental Neurovirology at the Johns Hopkins University School of Medicine in Baltimore, Maryland. “We need to rethink how we study brain disorders such as schizophrenia by looking at clues offered by a whole-body approach and identifying and understanding the basis for dysfunctions that are occurring outside the brain.”

Understanding Inflammation and the Microbial World

Study participants took a placebo pill once per day with a meal for 2 weeks, then were split into placebo and control groups. Each day for the next 14 weeks, participants in the control group took a commercially available probiotic pill containing more than 1 billion colony-forming units of Lactobacillus rhamnosus and Bifidobacterium animalis. Neither the researchers nor the participants knew who was taking the real probiotic.

Over the study period, antibody levels to Candida albicans, which is known to cause yeast infections, decreased by 43% in the 22 men taking the probiotic, but only 3% in the 15 men receiving the placebo.

No treatment effect was detected in the women. Researchers reported Candida antibody levels were already much higher in the women on the placebo than in those taking the probiotics, which they attributed to the small sample size.

The Ancient, Genetic Link Between Inflammation and Depression

Participants completed the Positive and Negative Syndrome Scale (PANSS) at the start of the study, then every two weeks. Researchers observed trends towards improvement in positive symptoms in the men treated with probiotics who did not have elevated Candida antibodies, which signify a history of yeast infection. This trend was confirmed in an analysis of a larger study, which found that men with schizophrenia who took probiotics but had no history of a Candida infection saw the most improvement in positive symptoms.

“The biggest change in psychiatric symptoms over time by probiotics in men without elevated Candida levels suggests that introduced bacteria via probiotics might shift the resident bacterial community dynamics more easily to a balanced state when fungal competitors such as Candida are not present,” Dr. Severance said.

“We hope that with additional studies, we can show that something as cost-effective and easy to access as probiotics would be a way to lessen some symptoms of schizophrenia,” she added.

—Terri Airov


Severance EG, Gressitt KL, Stallings CR, et al. Probiotic normalization of Candida albicans in schizophrenia: A randomized, placebo-controlled, longitudinal pilot study. Brain, Behavior, and Immunity. 2017;62:41-45.

Probiotics benefit in schizophrenia shaped by yeast infections [press release]. Baltimore, MD: Johns Hopkins Medicine; April 4, 2017.

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