A certain type of parasite that is passed to a human by a cat is the reason why a person is having bouts of temper.
Researchers discovered road rage and other inexplicable extreme bursts of anger may be caused by a parasite that people have been exposed to which is commonly found in the faeces of infected cats.
Researchers from the University of Chicago said that people who have been exposed to the parasite, known as toxoplasma gondii, are more than twice as likely to have short bursts of anger and increased aggression.
The parasite, which burrows into brain tissue, is fairly common, with about 30 per cent of all humans carrying it but it is typically harmless.
However, the new study, published in the Journal of Clinical Psychiatry, claims that it may be leading to heightened anger in short bursts, such as road rage.It can also be found in contaminated water and raw meat.
Dr Emil Coccaro, lead author of the study, said: “Our work suggests that latent infection with the toxoplasma gondii parasite may change brain chemistry in a fashion that increases the risk of aggressive behaviour.
“However, we do not know if this relationship is causal, and not everyone that tests positive for toxoplasmosis will have aggression issues.”
The team say that the parasite could be causing intermittent explosive disorder (IED), which is where “explosive eruptions occur suddenly, with little or no warning, and usually last less than 30 minutes. These episodes may occur frequently or be separated by weeks or months of nonaggression,” according to Mayo Clinic.
It is thought that around 16 million Americans suffer from IED, although many people go undiagnosed.
The team of scientists analysed 358 adults who were evaluated for IED, personality disorder, depression and other psychiatric disorders and were then split into three groups.
About a third of the participants had IED, another third were healthy and the final third were deemed to have a psychiatric disorder other than IED.
By analysing the blood of the IED sufferers, the researchers found that they were more than twice as likely to have been exposed to toxoplasma gondii than the healthy group (22 per cent to 9 per cent), whereas around 16 per cent of the group who had other psychiatric disorders had been exposed to the parasite.