Friday Factoid Catch-Up: Yeast Infection Linked to Mental Illness


Candida albicans is a yeast-like fungus naturally found in small amounts in human digestive tracts. Symptoms cause burning, itching, thrush, and genital yeast infections. In its more serious forms, it can enter the bloodstream. 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. Decreased sugar intake and other dietary modifications, avoidance of unnecessary antibiotics, and improvement of hygiene can prevent Candida infections.


Johns Hopkins researchers focused on a possible association between Candida susceptibility and mental illness. There has been growing evidence suggesting that Schizophrenia may be related to problems with the immune system. For the study, researchers took blood samples from a group of 808 people between the ages of 18 and 65. This group was composed of 277 controls without a history of mental disorder, 261 individuals with Schizophrenia and 270 people with Bipolar Disorder. The researchers used the blood samples to quantify the amount of immunoglobulin G antibodies to Candida, which indicates a past infection.


The research group found that a history of Candida yeast infections was more common in a group of men with Schizophrenia or Bipolar Disorder than in those without these disorders, and that women with Schizophrenia or Bipolar Disorder who tested positive for Candida performed worse on a standard memory test than women with these mental health disorder who had no evidence of past infection. The researchers caution that their findings and do not establish a cause-and-effect relationship between mental illness and yeast infections. This may support the role of lifestyle, immune system weaknesses and gut-brain connections as contributing factors to the risk of psychiatric disorders and memory impairment.


The study found no connection between the presence of Candida antibodies and mental illness overall in the total group. But when the investigators looked only at men, they found 26 percent of those with Schizophrenia had Candida antibodies, compared to 14 percent of the control males. There was not any difference found in infection rate between women with Schizophrenia (31.3 percent) and controls (29.4 percent). Men with Bipolar Disorder had clear increases in Candida as well, with a 26.4 percent infection rate, compared to only 14 percent in male controls. The researchers found that this association could likely be attributed to homelessness. However, the link between men with Schizophrenia and Candida infection could not be explained by homelessness or other environmental factors. Many people who are homeless are subjected to unpredictable changes in stress, sanitation and diet, which can lead to infections like those caused by Candida. The data provided support to the idea that environmental exposures related to lifestyle and immune system factors may be linked to Schizophrenia and Bipolar Disorder.


To determine whether infection with Candida affected any neurological responses, all participants in the study were assessed with the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) Form A to measure immediate memory, delayed memory, attention skills, use of language and visual-spatial skills. Results showed that the control group had no measureable differences. However, the researchers noticed that women with Schizophrenia and Bipolar Disorder who had a history of Candida infection had lower scores on immediate and delayed memory than the controls.


The data showed 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. The researchers are investigating whether pathogens, such as bacteria or viruses, may contribute or trigger certain mental disorders.


Yolken, R., Gressitt, K., Stallings, C., Katsafanas, E., Schweinfurth, L., Savage, C.,…Markus, F. (2016). Candida albicans exposures, sex specificity and cognitive deficits in schizophrenia and bipolar disorder. Nature Paper Journals. doi:10.1038/npjschz.2016.18


Jonathan Torres, M.S.
WKPIC Pre-doctoral Intern


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