- Boys likely to grow up violent and disruptive can be
identified by analysing their saliva, researchers say.
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- The early onset and persistence of such behaviour is
associated with low saliva levels of the stress hormone cortisol, they
found. Compared with those having higher or fluctuating cortisol levels,
boys aged seven to 12 in this category began anti-social acts at a younger
age, exhibited three times more aggressive symptoms, and were three times
more likely to be labelled "mean or combative" by their classmates.
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- The results of the four-year study may help psychiatrists
better understand the differences between normal adolescent problems and
lasting conduct disorder. Children with persistent conduct disorder remain
disruptive for decades and account for a high percentage of crimes. The
findings indicate that conduct disorder is not merely a fault of upbringing.
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- Professor Keith McBurnett, from the University of Chicago,
who led the study, said: "Children with persistent conduct disorder
may have genes that predispose them to produce certain hormones differently,
or their hormone production may have been altered before or soon after
birth."
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- The researchers studied 38 boys who had been referred
to a psychiatric clinic for disruptive behaviour. They assessed the boys'
aggressive behaviour and recorded symptoms such as starting fights, using
weapons, cruelty, stealing, or forcing sexual acts. Classmates were asked
to rate fellow pupils' behaviour and to name the three boys who were "meanest".
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- A dozen children with low cortisol levels averaged 5.2
symptoms of conduct disorder, whereas the remaining 26 boys with higher
levels averaged only 1.5. More than a third of the boys with low cortisol
were nominated the "meanest". Prof McBurnett said: "Boys
with consistently lower cortisol levels may not be as afraid of retribution."
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