Annoying Cat Parasite Has Again Been Linked to Psychotic Episodes, But Only in Men

The evidence hasn't always been clear about the link between a ubiquitous parasites and a host of neurological disorders.

There are a number of studies linking the Toxoplasma gondii with altered behavior or weird patterns in human activity, but there are also data debunking the association.

A new study led by first author and psychiatry residentVincent Paquin from McGill University in Canada could help to explain the parasites and where they may lie.

A study in 1995 found a link between cat ownership in childhood and risk of mental illness later in adulthood, and that the protozoan parasites T. gondii can be transmitted to humans through exposure to feces from an infectious domestic cat.

There might be more to the association than simply owning a cat, as other studies have failed to replicate the cat ownership link.

Paquin and his co-authors write in a new paper that domestic cats can get sick from feeding on rodents and will only be contagious during the days or weeks that follow.

If the cat was known to hunt rodents, it would be a better proxy for exposure to T. gondii.

Paquin explains that cats themselves do not guarantee exposure to parasites, but that cats that are allowed outside, as opposed to indoor-only pets, would probably be more likely to come into contact with T. gondii.

Hypothetically speaking, they might transmit the infection to children, who could go on to develop psychological issues in adulthood, potentially through effects on the immune system.

To examine this hypothetical chain of transmission, the researchers surveyed approximately 2,200 participants in Montreal, asking them questions about childhood cat ownership, as well as other questions about their personal history, such as how much they moved house during childhood, experiences with head trauma, and smoking.

The team found that male participants who owned a cat as a child had an increased risk of having psychotic experiences in their adulthood.

The team said that people who owned only cats during childhood did not show the same increased risk as people who owned cats all their lives.

Smoking, a history of head trauma, and residential moves in childhood or adolescence were some of the factors that were captured in the survey.

The team says their findings show the importance of examining interactions among different kinds of environmental exposures, which may help us to identify with greater

Paquin told Medscape Medical News that there might be combinations of risk factors at play.

Even if the risk is small at the individual level, cats and T. gondii are still present in our society.

The findings are reported in a journal.