Vol. 7, No. 3, 2001 Page 6&7

Explosive violence associated with P100 anomaly

Strong evidence that some children "may have a predisposition for violent or explosive behavior that is an innate characteristic of their central nervous system" comes from a recent study by Donald Bars and colleagues.

Bars et al. evaluated 326 children treated for various disorders at a psychiatric clinic, comparing subjects who exhibited intermittent explosive disorder with those who did not. Each child underwent evoked potential testing (in which brain wave responses to specific stimuli are measured) and an EEG evaluation. The researchers controlled for potentially confounding factors including gender, age, and medication use.

Bars and colleagues say the evoked potential studies revealed that individuals who exhibited higher visual P100 brain wave amplitudes were more likely to exhibit explosive behaviors. "Although not all explosive individuals in our study had a high P100 wave form," they say, "the results suggest that the higher the amplitude, the more probable the explosive behaviors." Abnormal amplitude of the P100 brain wave, which occurs within the first 200 milliseconds after a stimulus, may reflect a defect in processing incoming stimuli.

Explosive subjects also exhibited high delta activity in the right frontal lobe, a finding consistent with earlier studies.

"Overall, these patients constitute a distinct psychiatric population in need of the unique medical treatment provided by the psychiatric community," the researchers say, "not identification and incarceration as sociopaths by the justice system."

The researchers caution that their study involved only subjects with psychiatric problems severe enough to result in a clinic referral. Nonetheless, they say, "the use of noninvasive visual evoked potentials and quantitative EEG data appears to allow accurate identification of this substantial subgroup of patients who have explosive disorders that appear to be biologically based."


"Use of visual evoked-potential studies and EEG data to classify aggressive, explosive behavior of youths," Donald R. Bars, F. La Marr Heyrend, C. Dene Simpson, and James C. Munger, Psychiatric Services, Vol. 52, January 2001, pp. 81-86. Address: Donald Bars, Behavioral Management Centers, 411 North Allumbaugh Street, Boise, ID 83704.

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