Cat owners may be at risk of suffering from schizophrenia, researchers say


Researchers have established a possible link between schizophrenia and cat ownership and this is because of the possible transmission of Toxoplasma gondii, a single-cell parasite many cats carry.

Researchers at Stanley Medical Research Institute say that this single-cell parasite is known to get into brain of humans and form microscopic cysts. Researchers think that it then becomes activated in late adolescence and causes disease, probably by affecting the neurotransmitters.

Researchers have equated entry of T. gondii into the human brain to that of a Trojan Horse, wherein it uses a type of white blood cell in the immune system as a Trojan horse into the central nervous system. They add that the parasite can live in many different species but it can only complete its life cycle in cats when it is secreted in feline faeces.

As the cat feces dry, the oocysts may become aerosolized. They can thus be inhaled by a person changing cat litter or just walking in an area where cats have defecated.

Gardens are also commonly used by cats for defecation and are also thought to be a common source of infection by inhalation for gardeners. Unwashed vegetables from gardens can also carry oocysts. Studies have also shown that cockroaches and flies can carry oocysts from cat feces to fruits and vegetables. Researchers have also established in prior research that a possible mode of transmission is by dogs that roll in cat feces. One study reported that 23 percent of dogs did this, suggesting “the contamination of fur, after rolling in cat feces containing oocysts, might make these accessible to children who pet dogs”.

E. Fuller Torrey, a scientist from the Stanley Medical Research who participated in the latest study, found in an earlier study that acute human infection with T. gondii can “produce psychotic symptoms similar to those displayed by persons with schizophrenia”.

Schizophrenia is a long-term mental illness that causes symptoms including hallucinations, delusions and changes in behaviour.

Through the latest study, published in Schizophrenia Research, researchers say that cat ownership is more common in families in which children are later diagnosed with schizophrenia or another serious mental illness – as much as 50.6 per cent.

Based on their analysis of the results of a 1982 National Institute of Health questionnaire, researchers found that over 50 per cent of people who developed schizophrenia had a cat in their home during childhood.