The Candida albicans fungus is usually present in the human digestive tract, but if it grows to much it can cause burning, itching, thrush in infants, and a genital infection in adults.
The study found 26 per cent of 261 men with schizophrenia were producing immune-system antibodies designed to fight a Candida infection, compared to 14 per cent of those without the condition.
And, while there was no similar pattern in women, those with schizophrenia and the highest Candida antibody levels performed significantly worse in tests of their memory.
Professor Emily Severance, of the Johns Hopkins University School of Medicine, stressed while they had found a link between the yeast infection and mental illness, it was “far too early to single out Candida infection as a cause of mental illness or vice versa”.
“However, most Candida infections can be treated in their early stages, and clinicians should make it a point to look out for these infections in their patients with mental illness,” she added.
“Although we cannot demonstrate a direct link between Candida infection and physiological brain processes, our data show that some factor associated with Candida infection, and possibly the organism itself, plays a role in affecting the memory of women with schizophrenia and bipolar disorder, and this is an avenue that needs to be further explored.
“Because Candida is a natural component of the human body microbiome, yeast overgrowth or infection in the digestive tract, for example, may disrupt the gut-brain axis.
“This disruption in conjunction with an abnormally functioning immune system could collectively disturb those brain processes that are important for memory.”
Professor Severance added Candida infections can be avoided by reducing sugar consumption, avoiding unnecessary antibiotics and maintaining good hygiene. Normally Candida is controlled by friendly bacteria in the body and the immune system.
The researchers, who published a paper on their work in the journal NPJ-Schizophrenia, now plan to look into whether there is a cause-and-effect relationship between Candida infections and memory problems.
Last year, a separate study published in Nature Communications suggested anxiety and depression could be linked to bacteria in the intestines.
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