Johns Hopkins: In a small pilot study of men with schizophrenia, researchers at Johns Hopkins Medicine and Sheppard Pratt Health System say they have evidence that adding probiotics — microorganisms, such as bacteria found in yogurts — to the patients’ diets may help treat yeast infections and ease bowel problems. Probiotics may also decrease delusions and hallucinations, but in the study, these psychiatric benefits mostly affected those without a history of yeast infections. The findings, published in the May 1 issue of Brain, Behavior, and Immunity, support growing evidence of close links between the mind and the gut.
The investigators caution that larger and more rigorous studies
are needed to validate their findings and determine if women with
schizophrenia respond similarly to probiotics before this fairly simple
and cost-effective treatment strategy should be recommended widely to
people with schizophrenia.
“The mental health field is in desperate need of new treatments
for psychiatric disorders, yet there’s been very little progress toward
this goal for too long a time. 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,” says Emily Severance, Ph.D.,
assistant professor of pediatrics and part of the Stanley Division of
Developmental Neurovirology at the Johns Hopkins University School of
Medicine. “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.”
In an initial study published in 2014,
the researchers looked at whether probiotics could treat general
psychiatric symptoms and bowel function in people with schizophrenia.
They did notice bowel improvement but didn’t notice any effect on total
psychiatric symptoms. Also, in a recent publication from this year, the group observed greater memory problems in people with schizophrenia who also had Candida yeast infections.
This new analysis included 56 adult participants with an average
age of 46. Nineteen participants were women, and 61 percent were white.
At the start of the trial, each participant gave a blood sample and
completed the Positive and Negative Syndrome Scale (PANSS) exam used for
measuring a standard set of symptoms of schizophrenia.
Each participant took a placebo pill once per day with a meal for
the next two weeks and then were split into groups so that neither the
researchers nor the participants could tell who would be given a real
probiotic or the placebo for the next 14 weeks.
The commercially available probiotic contained over 1 billion
colony-forming units of Lactobacillus rhamnosus and Bifidobacterium
animalis in each pill. PANSS scores were reassessed every two weeks, and
the participants self-reported on the ease of their bowel movements
weekly on a scale of 0 to 4. At the end of the study, the researchers
collected another blood sample.
Using the blood samples, the researchers measured antibody levels
to yeast Saccharomyces cerevisiae, known as brewer’s yeast, and Candida
albicans, known to cause yeast infections, before and after the
probiotic treatment. Both types of yeast are elevated in people with
The researchers found Candida antibody levels decreased by 43
percent over time in the 22 men taking probiotics but saw only a 3
percent decrease of antibodies in the 15 men receiving the placebo.
Eighteen men responded to the treatment with reduced antibody levels;
four men didn’t respond to the treatment. Antibody levels for the
brewer’s yeast didn’t change over the course of the study in the
participants after probiotic treatment. A treatment effect wasn’t
detected in the women because their starting Candida antibody levels
were already much higher in those on the placebo than in those taking
the probiotics, which the researchers attributed to the small sample
size of the trial.
For the next analysis, the researchers focused on the men who had
evidence of a yeast infection due to elevated Candida antibodies. The
five men in the placebo group with Candida had more difficulty with
bowel movements over time, with an average bowel score of 0.74, compared
to the 10 men without evidence of infection, who had an average score
of 0.19. Severance says these results are consistent with the group’s
earlier 2014 analysis of bowel function, but the current study
reinforces that Candida yeast contribute to bowel difficulties in men
Severance next analyzed whether PANSS psychiatric symptom scores
varied between those males with schizophrenia if they had a Candida
infection or not. The PANSS exams measure symptoms on three scales: the
positive symptoms, such as delusions, hostility, grandiosity and
hallucinations; negative symptoms, like social withdrawal and poor
socialization; and general psychological symptoms, such as guilt,
anxiety and depression. For this analysis, the researchers examined
previous data from a larger study of schizophrenia and found that 165
men with Candida infections had higher levels of positive symptoms, like
delusions and hostility, with an average PANSS score of 19.5 out of 24,
compared to those 219 men without Candida infections who scored on
average less than 18.5. In patients treated with probiotics, PANSS
scores on positive symptoms improved the most — from an average of 18
down to 14.6 on their PANSS score after 13 weeks — in those who didn’t
have a Candida infection to begin with.
“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,” says Severance. “Compared
to the bacterial microbiome, relatively little is known about the fungal
community in the gut and how it interacts with other classes of
“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,” says Severance.
According to Severance, probiotics can cause gas and bloating in
some people, and they shouldn’t be given to anyone with a severely
weakened immune system, like those with HIV or on immunosuppressive
medications. Most over-the-counter probiotics cost less than $1 a day.
Other authors on the study include Kristin Gressitt and Robert
Yolken of The Johns Hopkins University, and Cassie Stallings, Emily
Katsafanas, Lucy Schweinfurth, Christina Savage, Maria Adamos, Kevin
Sweeney, Andrea Origoni, Sunil Khushalani and Faith Dickerson of
Sheppard Pratt Health System.
This research was funded by a grant from the National Institute
of Mental Health (MH-94268) and the Stanley Medical Research Institute.
Yolken is a member of the Stanley Medical Research Institute board of directors and Scientific Advisory Board.