Toxoplasmosis linked to aggression

Although cats are the definitive host, Toxoplasma gondii (T. gondii) infects about a third of humans, spreading through feline faeces, contaminated water and undercooked meat. T. gondii increases risk-taking in rodents, which helps spread the parasite to cats. Human studies link toxoplasmosis with several psychiatric conditions, including schizophrenia, bipolar disorder, personality disorders, suicidal behaviour and, in a new study, intermittent explosive disorder (IED). People with IED show repeated problematic and impulsive aggressive behaviours.

Researchers measured IgG antibodies to T. gondii in 110 adults with IED, 138 people with psychiatric disorders other than IED and 110 healthy controls. The proportion of people seropositive (expressed IgG) for T. gondii was 9.1% among controls, 16.7% in people with psychiatric disorders other than IED and 21.8% in IED patients. People seropositive for T. gondii showed significantly higher aggression and impulsivity scores. But further statistical analysis associated T. gondii with aggression only.