People with intermittent explosive disorder, have been significantly linked with toxoplasmosis, an infection commonly associated with cat feces and undercooked meat, according to the Journal of Clinical Psychiatry. "This is definitely not a sign that people should get rid of their cats. We don't understand the mechanisms involved. It could be an increased inflammatory response, direct brain modulation by the parasite, or even reverse causation where aggressive individuals tend to have more cats or eat more undercooked meat," Coauthor Dr. Royce Lee said.

The research consequently showed that those who had been exposed to the parasite scored significantly higher on the aggression tests than those who tested negative for exposure. "Our work suggests that latent infection with the toxoplasma gondii parasite may change brain chemistry in a fashion that increases the risk of aggressive behavior," said senior study author Emil Coccaro, MD, Ellen. C. Manning Professor and Chair of Psychiatry and Behavioral Neuroscience at the University of Chicago. "However, we do not know if this relationship is causal, and not everyone that tests positive for toxoplasmosis will have aggression issues," Coccaro said, adding that additional studies are required.