Bad behavior "linked to smoking"
BBC News, London
Women who smoke in pregnancy may raise the risk of their
child displaying anti-social behavior, researchers say.
There was a "small but significant" link between
maternal smoking and both unruly behavior and attention
deficit hyperactivity disorder, they said. The average
symptom scores for both increased with the number of
cigarettes the mother had smoked while pregnant, the
study of 1,896 twins found. |
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"It's probably a direct effect on the developing babies"
Professor Eric Taylor of London's Institute of
Psychiatry
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The
Institute of Psychiatry work is in the British Journal of
Psychiatry.
The researchers said the findings did not mean unruly
behavior and attention deficit hyperactivity disorder (ADHD)
were linked, although ADHD is known to increase the risk of
anti-social behavior.
Previous work
has linked both ADHD and anti-social behavior with maternal
smoking. However, it was not clear whether the increased
risk of anti-social behavior was linked to the ADHD rather
than maternal smoking per se. ADHD is a serious behavioral
disorder which experts estimate may affect up to 6% of
children. People with the condition have a poor attention
span and tend to be impulsive and restless. ADHD is known to
increase the likelihood of anti-social behavior.
Social factors
But although ADHD is thought to have a strong medical
element, social factors are often blamed for unruly
behavior. The new work suggests a biological cause for
anti-social behavior.
A team at
the Institute of Psychiatry, in London, sent questionnaires
to the parents of 723 identical twins and 1,173
non-identical twins. The parents were asked to provide
information on their own smoking habits and on their
children's behavior.
Behavior was
classed as anti-social if the child bullied others, often
destroyed his or her own or others' belongings, had a habit
of stealing things, often told lies or was frequently
disobedient.
A third of
the mothers said they had smoked during pregnancy. Overall,
a small minority of the children had anti-social behavior or
ADHD - 4-11%.
Biological
When the researchers looked at the influence of maternal
smoking, they found it contributed in a small but
significant way to both disorders. The average symptom
scores for both anti-social behavior and ADHD increased with
the number of cigarettes smoked by the mother.
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They said there were several explanations for the trend,
including direct effects of tobacco smoke on the
developing baby. Lead researcher Dr Tanya Button said:
"The most commonly cited one is the influence of
nicotine on brain development in the fetus, possibly
leading to neurological impairment. |
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"Smoking can reduce the amount of oxygen getting to the
fetus"
Researcher Dr Tanya Button
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"Also,
maternal prenatal smoking can reduce the amount of oxygen
getting to the fetus, which may also be detrimental to later
behavioral outcomes." Although factors other than smoking
play a far bigger part in both conditions, the researchers
advised any woman who was pregnant to avoid smoking.
Commenting on the research, Professor Eric Taylor, also from
London's Institute of Psychiatry, but independent from the
research, said: "If it is showing that there is a biological
influence on conduct disorder, that is useful to know.
"Obviously,
we know that pregnant women should not smoke for many health
reasons," said Professor Taylor, who is also an expert for
the ADHD charity ADDISS. He said: "It's probably
dose-related - the more you smoke the greater the risk is -
and it's not just mediated through the personality of the
mother or social disadvantage.
"It's
probably a direct effect on the developing babies." He said
it was possible that the mothers were transmitting
"anti-social behavior" genes to their children.
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