Some children are violent and aggressive - behaviour that predicts later, similar behaviour, and social failure. It would be very desirable to understand the causes of severe aggressive behaviour in children in order to design interventions to alleviate or cure the problem. This article is based on the writings of Craig Ferris of the University of Massachusetts Medical Centre. Ferris and others have shown that childhood trauma can set up biochemical patterns that later cause violent impulses.
Highly aggressive and disruptive behaviour in young children is a risk factor for future problems such as delinquency, violence, depression, drug abuse and suicide. Also, abusive behaviour by parents tends to be mimicked later by the children. However, these correlations are not inevitable. Many troublesome children "grow out" of their problems and some WS victims childhood abuse go on to lead ordinary lives.
Complex behaviour is always the result of interactions between our genetic make-up and the environment. It is known the environment can have a powerful effect on a child's personality. Animal studies have now revealed how the environment can alter the brain's biology. When the wrong environment coincides with critical periods in development, biochemical patterns can become established that put children at risk of developing aggressive behaviour.
Probably the cruellest thing you can do to a child is to take away the primary care-giver. The infant and young child is in a constant state of sensory arousal. The child relies on love and physical contact with the mother and father to calm that arousal into well-being.
In the absence of loving attention, infants and children withdraw into themselves, ignore their surroundings, and stimulate themselves by repetitive rocking and similar movements. They are also at risk of later developing problems in controlling their feelings and responses to stress.
Experiments with monkeys have shown the terrible consequences of isolating a baby from the mother. Babies were separated from their mothers at birth and raised for six months (equivalent to the first two years of a human child's life) with no chance to form bonds with other monkeys. Some of the monkeys were raised in total isolation, some were raised in partial isolation, i.e., able to see and sometimes touch their human keepers.
Monkeys raised in partial isolation develop learning disabilities and these are more severe in completely isolated monkeys. They can learn to perform simple tasks as well as normally reared monkeys, but they fall behind on learning more complex tasks.
The motherless monkeys develop severe social problems. Those raised in partial isolation show exaggerated stereotypical behaviour such as rocking to and fro for hours. Self-mutilation is common. If put into a cage with other monkeys, the isolated animal can become impulsive, fearful and aggressive.
Monkeys raised in complete isolation develop terrible social problems. While many monkeys raised in partial isolation will assimilate over time into a monkey group, it is extremely difficult for monkeys raised in complete isolation to blend into social groups.
Even when monkeys who have been deprived of their mothers later manage to socialise into a group, they carry biochemical scars in their brains. In one experiment, monkeys were raised in isolation, and then joined a group of normally raised monkeys. Sometime later all the monkeys were given small doses of amphetamine. The normally raised monkeys were unaffected by the drug, but the monkeys deprived of their mothers became crazed and killed others in the group.
The possible implications for humans are sobering. Neglected children are at risk for later drug abuse but may be least able to tolerate drugs because their brain biochemistry has been programmed to explode into unpredictable violence.
The body handles stress by interactions between three types of glands, the adrenal glands atop the kidneys, and the hypothalamus and pituitary glands near the brain's base. When the system is activated, the adrenal gland releases hormones called glucocorticoids. Normal levels of glucocorticoids are essential to good health, but excessive amounts can lead to heart, nerve and immune system damage. The brain has detectors that check the level of glucocorticoids in the blood and restricts their release when the levels are dangerously high.
Experiments with rats showed that during critical stages of development, the environment can induce biological changes that have a life-long effect on a particular rat's capacity to handle stress. New-born rats were divided into two groups; one stayed with their mothers undisturbed, and pups in the second group were gently handled for 15 minutes daily. The pups who were handled produced more glucocorticoid receptors in their brains than the rats who were not handled. Later, as adults, the rats that had been handled lived longer, had better immune systems and could cope better with stress than the control group.
Experiments have also shown that puberty is another critical developmental window during which the environment can affect the brain in similar ways to that described for the rat pups. The animal experiments are very interesting and valuable, but we don't know for sure how closely human interaction with the environment will parallel the interaction documented for animals. But it would be surprising if the animal pattern was radically different in humans.
(Dr William Reville is a senior lecturer in bio- chemistry at UCC.