Some cases of schizophrenia could be linked to a parasite called Toxoplasma gondii, and researchers used epidemiological modeling methods to determine the proportion of cases that could be attributed to this.
The new research suggests about one-fifth of all cases involve the parasite, the University of Pennsylvania reported.
"Infection with Toxoplasma is very common, so, even if only a small percentage of people suffer adverse consequences, we could be talking about problems that affect thousands and thousands of people," said Gary Smith, professor of population biology and epidemiology at the University of Pennsylvania's School of Veterinary Medicine.
T. Gondi can be contracted when an individual consumes contaminated food or cat feces; it is believed to be linked to schizophrenia because it can infect both the brain and muscles. Other studies have shown antipsychotic drugs can stop the parasite from multiplying, and studies on rodents have found they can trigger personality changes.
To make their findings the researchers worked to calculate the population attributable fraction (PAF) in hopes of determining the risk factor. Using a standard epidemiological modeling format that factored in other risks for the condition, the team PAF during an average lifetime to be 21.4 percent. These findings suggests one-fifth of all cases of schizophrenia could be prevented. The researchers also noted countries with higher instances of T. gondi infection also tended to have more cases of schizophrenia.
"By finding out how important a factor T. gondii infection is, this work might inform our attitude to researching the subject," Smith said. "Instead of ridiculing the idea of a connection between T. gondii and schizophrenia because it seems so extraordinary, we can sit down and consider the evidence. Perhaps then we might be persuaded to look for more ways to reduce the number of people infected with Toxoplasma."
The findings were published in a recent edition of the journal Preventive Veterinary Medicine.
