|Vol. 2, No. 3 , 1996, Page 7|
A new large-scale study suggests that aggressive boys are handicapped by poor "executive functions"-that is, they show impairment in brain functions including planning, abstract reasoning, problem solving, attention, concentration, and controlling short-term behavior to achieve long-term goals.
Jean R. S‚guin et al. followed 177 boys from age 6 to age 12. The subjects were then divided into three groups: "stable aggressive," "unstable aggressive" (those not as consistently aggressive as the first group), and nonaggressive. The researchers administered tests to the boys at adolescence, and found that "tests of executive functions had the strongest association with physical aggressive behavior, over and above tests of verbal learning, cerebral dominance, and incidental spatial learning." Even when social factors were controlled for, the researchers say, aggressive boys exhibited difficulties in executive functions. Unstable aggressive boys also showed impairments.
The researchers note that deficits in executive functions have been linked to hyperactivity, which in turn is associated with aggressive behavior. In addition, such deficits have been reported in alcoholic men's sons, a group with an increased risk of hyperactivity and conduct disorder. Executive functions appear to be performed by the frontal lobes of the brain, and several studies strongly link criminal behavior to frontal lobe defects (See Crime Times, Vol. 1, No. 1/2, Page 1 and Crime Times, Vol. 1, No. 4, Page 6).
"Although early clear-cut frontal damage leads to comportmental difficulties in childhood and adulthood," S‚guin et al. say, "the present impairments in executive functions may be undetectable neuroanatomically and may be solely at a neurochemical or physiological level."
"Cognitive and neuropsychological characteristics of physically aggressive boys," Jean R. S‚guin, Robert O. Pihl, Philip W. Harden, Richard E. Tremblay, and Bernard Boulerice, Journal of Abnormal Psychology, Vol. 104, No. 4, 1995, pp. 614-624. Address: Robert O. Pihl, Psychology Department, McGill University, 1205 Docteur Penfield, Montreal, Quebec, Canada H3A 1B1.