Bad
behaviour "linked to smoking"
BBC
News, London
Women
who smoke in pregnancy may raise the risk of their child
displaying anti-social behaviour, researchers say.
There was a "small but significant" link between
maternal smoking and both unruly behaviour 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
|
The Institute
of Psychiatry work is in the British Journal of Psychiatry.
The researchers said the findings did not mean unruly behaviour
and attention deficit hyperactivity disorder (ADHD) were linked,
although ADHD is known to increase the risk of anti-social
behaviour.
Previous work
has linked both ADHD and anti-social behaviour with maternal
smoking. However, it was not clear whether the increased risk
of anti-social behaviour was linked to the ADHD rather than
maternal smoking per se. ADHD is a serious behavioural 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 behaviour.
Social
factors
But although ADHD is thought to have a strong medical element,
social factors are often blamed for unruly behaviour. The
new work suggests a biological cause for anti-social behaviour.
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 behaviour.
Behaviour
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 behaviour
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
behaviour and ADHD increased with the number of cigarettes
smoked by the mother.
| 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 foetus, possibly leading to neurological impairment. |
|
"Smoking
can reduce the amount of oxygen getting to the foetus"
Researcher
Dr Tanya Button
|
"Also,
maternal prenatal smoking can reduce the amount of oxygen
getting to the foetus, which may also be detrimental to later
behavioural 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
behaviour" genes to their children.
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