Researchers have found new evidence of a link between schizophrenia and frequent infection with a cat parasite, Toxoplasma gondii.
Toxoplasma gondii is a very common parasite of cats, frequently found in their droppings, and which can infect many people, as well as their brains.
It does not cause symptoms in most people infected, but severe cases of toxoplasmosis can be dangerous especially in people with weakened immune systems where it causes flu-like illness and inflammation of the brain.
The same is true during pregnancy: pregnant women should avoid cats, as the parasite can cause fetal abnormalities or even miscarriage.
A link to neurological disorders and diseases
Apart from these known dangers, other neurological and psychiatric risks associated with the parasite are suspected and a growing number of studies suggest that there is something going on in the brains of infected people, even if they have had no symptoms. initial.
A causal relationship has not been established, but the parasite has been frequently associated with a multitude of behavioral changes. Virtually any warm-blooded animal can become infected with Toxoplasma gondii and when the parasite enters their body and brain, unusual behaviors occur. In rodents, animals apparently lose their inhibitions, become more adventurous and even lose their aversion for cat odors.
The same type of risky behavior has been observed in human studies, from car accidents to entrepreneurial activity, where links have been documented with Toxoplasma gondii infections. Other studies even suggest that the parasite is associated with increased suicide rates, and a whole range of neurological disorders, including epilepsy, Alzheimer’s disease and Parkinson’s disease.
An old and growing link with schizophrenia
From this perspective, a new study, led by researchers at the University Hospital in Copenhagen, Denmark, analyzed data from more than 80,000 Danish people who took part in a blood donor study. To determine the links between mental disorders and infections with Toxoplasma gondii and another common pathogen, cytomegalovirus (CMV), the researchers identified 2,591 people in the cohort who also had psychiatric illnesses.
They then searched their blood for antibodies against these two infectious agents.
Regarding Toxoplasma gondii, blood tests revealed that infected subjects are almost 50% more likely (odds ratio = 1.47) to be diagnosed with schizophrenia compared to those without infection. As the researchers explain, the association is even stronger (OR = 2.78) when taking temporality into account, i.e. taking into account only the 28 cases of schizophrenia diagnosed after the date of the blood collection: this indicates that the Toxoplasma gondii infection predates the declaration of the schizophrenic illness.
According to the researchers, this “supports the fact that Toxoplasma gondii has an effect on the rate of schizophrenia” and that infection with this parasite (contained in the feces of cats and associated with chronic inflammation of the brain) could be a contributing factor. of schizophrenia. Although the link between the parasite and schizophrenia has been observed in previous research, the researchers say their study is the first to examine the anteriority of exposure to Toxoplasma gondii.
Causal relationship not yet established
Nevertheless, it is important to note that this is still not definitive proof of the causal relationship between Toxoplasma gondii infection and schizophrenia, particularly because this infection is common and the association may be fortuitous.
Despite these limitations, the researchers say their findings add to the growing body of scientific evidence linking Toxoplasma gondii infection and schizophrenia.
In the meantime, to minimize your risk of toxoplasmosis infection, be sure to always cook food, wash fruits and vegetables thoroughly, wear gardening gloves, and be extra careful when cleaning cat litter.
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