Could your inadequate cooking skills be making you angrier? A recent study in the field of psychiatry has found that a parasite of the brain known as toxoplasma gondii could be linked to the development of aggression disorders; in particular, intermittent explosive disorder (IED). This parasite (which resides in undercooked meat and cat faeces) is found within 1/3 of the global population, but more commonly those who frequently feel angry and aggressive.
This particular study evaluated 358 subjects in the US, who were tested for a variety of psychiatric disorders, including IED, personality disorder, and depression. IED has been defined by the Diagnostic and Statistical Manual of Mental Disorders (5th Ed) as a condition in which the sufferer will recurrently have outbursts of anger (be it verbally or physically) that are inappropriate for the context of the situation. The subjects were also scored on their levels of anger, aggression and impulsivity.
It was found that 1/3 of the subjects had IED, 1/3 were healthy with no history of psychiatric disorders, and the final 1/3 had a psychiatric disorder that was not IED. In terms of how this links to parasitic exposure, it was found that the IED group were more than twice as likely to give a positive blood test for toxoplasmosis (having been exposed to the parasite) compared to the healthy control group. 16% of the non-IED group that did have another psychiatric disorder tested positive for toxoplasmosis, but their levels of aggression and impulsivity were similar to those seen in the healthy group. Overall it was found that those who had been exposed to the parasite scored significantly higher on scores of anger and aggression.
This study holds promise for those who suffer from aggression disorders such as IED, in that if a cause can be identified then more appropriate treatments can be developed. However, the researchers in this study emphasised that correlation does not imply causation, and further research needs to be done into whether treating parasitic infection reduces aggression in sufferers. After all, it may simply be that aggressive people are more likely to eat undercooked meat, or own more cats.