Intermittent Explosive Disorder

Intermittent Explosive Disorder, abbreviated to IED, is a behavioural disorder characterized by explosive outbursts of anger and violence, often to the point of rage, that are disproportionate to the current situation. Symptoms include impulsive shouting, screaming or excessive reprimanding triggered by relatively inconsequential events.

This impulsive aggression is not premeditated, and is defined by a disproportionate reaction to any provocation, real or perceived. Some individuals have reported affective changes prior to an outburst, such as increased tension, mood changes, energy changes, etc.

Individuals, diagnosed with Intermittent Explosive Disorder, report their outbursts as being brief (lasting less than an hour), with a variety of bodily symptoms (sweating, stuttering, chest tightness, twitching, palpitations).

Aggressive acts are frequently reported accompanied by a sensation of relief and in some cases even pleasure, but often followed by remorse.

The disorder is currently categorized in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) in the category 'Disruptive, Impulse-Control, and Conduct Disorders'.  The disorder itself is not easily characterized and often exhibits co-morbidity with other mood disorders, particularly bipolar disorder.

Psychiatrists try to control or treat these outbursts through cognitive behavioural therapy and psychotropic medication, though the pharmaceutical options have shown limited success.

But now there is some new evidence that Intermittent Explosive Disorder might be the result of an earlier brain infection with Toxoplasma gondii, a protozoan parasite found in cat faeces or undercooked meat[1].

[Image: phys.org - Toxoplasma gondii]

In the study of some 350 adults, those with Intermittent Explosive Disorder were twice as likely to have been infected by the toxoplasmosis parasite compared with healthy individuals with no psychiatric diagnosis.

The study adds to a growing body of evidence suggesting that toxoplasmosis — usually a mild or non-symptomatic infection with Toxoplasma gondii — may somehow alter people's brain chemistry to cause long-term behavioural problems.

Previous studies have linked toxoplasmosis to schizophrenia, bipolar disorder, impulsivity, and suicidal behaviour[2].

[1] Desmettre: Toxoplasmosis and behavioural changes in Journal Français d'Ophtalmologie – 2020
[2] Elsheikha et al: The known and missing links between Toxoplasma gondii and schizophrenia in Metabolic Brain Disease - 2016