Schizophrenia is one of the most common severe mental illnesses, affecting some 24 million people—about one in every 300—worldwide. Symptoms range from listlessness and apathy to issues with attention, memory, and concentration to full-blown hallucinations and delusions. Currently, there is no cure for schizophrenia, and treatments focus mainly on managing symptoms. Medications that block the dopamine system, for instance, have proven to be effective in treating delusions and hallucinations. Unfortunately, they don’t show as much promise against the cognitive and motivational aspects of the disorder.
Previous research has linked both imbalances in the gut microbiome and vitamin D deficiency with schizophrenia, suggesting a novel pathway for treatment, and scientists from Iran recently put that idea to the test in a double-blind, placebo-controlled human trial. The results of their study were published in April in the journal Neuropsychopharmacology Reports.
To test whether a combination of probiotics and vitamin D could be used to successfully treat schizophrenia symptoms, scientists from the Psychosis Research Center at the University of Social Welfare and Rehabilitation Sciences in Tehran recruited 70 patients with schizophrenia from the university’s hospital. All participants were between 18 and 65 years of age, suffered no gastrointestinal issues at study onset, and had been stable on their current medications for at least 6 months. Patients who had received antibiotics within 14 days prior to the study were excluded, as were patients with a variety of complicating conditions or drug usage.
Participants were randomly divided into two groups, and both groups received one capsule per day for 12 weeks. The capsule taken by the first group contained a combination supplement consisting of 2 billion CFUs of the probiotic strains Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus reuteri, Lactobacillus paracasei, Bifidobacterium longum, and Bacillus coagulans, plus 400 IU of vitamin D. The capsule taken by the second group contained starch.
The participants’ disease severity and cognitive symptoms were evaluated at baseline and every two weeks during the study period by using the Montreal Cognitive Assessment (MoCA) and the Positive and Negative Syndrome Scale (PNASS), considered the “gold standard” of assessment in schizophrenia studies.
At the end of the three-month study period, results showed that the marginal mean for MoCA score among patients in the supplement group increased by 1.96 units when compared with the placebo group. Also, the percentage of patients with MoCA scores of 26 or higher (indicating normal cognition) rose significantly in the intervention group, while there were no changes in the placebo group. Between-group differences in PANSS scores were not significant.
Conclusions
The researchers acknowledge several limitations to the study, including the small sample size, the fact that all participants came from the same hospital, and the fact that participants’ vitamin D status prior to the study was not recorded. “Although the current [trial] revealed that probiotic supplementation along with vitamin D improves the cognitive function of schizophrenic patients, considering the limitations mentioned before, similar studies should be conducted to achieve a final decision,” the researchers wrote in their conclusion.
That said, the results add to the growing body of evidence supporting the efficacy of probiotic and vitamin D supplementation. “The synergistic effects of co-administration of vitamin D and probiotics on mental health have been suggested by many studies,” the researchers wrote. “Therefore, targeting the microbiota-gut-brain axis with co-administration of probiotics and vitamin D might provide a novel approach to promote mental health.”
