Mothers who smoke during pregnancy put their
children at greater risk of developing psychotic symptoms in their
teenage years.
New
research published in the October issue of the British Journal of
Psychiatry shows a link between maternal tobacco use and
psychotic symptoms.
Researchers from the universities of Bristol,
Cardiff, Nottingham and Warwick studied 6,356 12-year-olds from the
Avon Longitudinal Study of Parents and Children. All the children
completed an interview for psychotic-like symptoms, such as
hallucinations or delusions. Just over 11% of the children (734)
had suspected or definite symptoms of psychosis.
Smoking during pregnancy was found to be
associated with an increased risk of psychotic symptoms in the
children. The researchers observed a ‘dose-response effect’,
meaning that the risk of psychotic symptoms was highest in the
children whose mothers smoked the most heavily during
pregnancy.
The study also examined whether alcohol use
and cannabis use during pregnancy was associated with a higher risk
of psychotic symptoms.
Drinking during pregnancy was associated with
increased psychotic symptoms, but only in the children of mothers
who had drunk more than 21 units of alcohol a week in early
pregnancy. Only a few mothers in the study said they had smoked
cannabis during pregnancy, and this was not found to have any
significant association with psychotic symptoms.
The reasons for the link between maternal
tobacco use and psychotic symptoms are uncertain. But the
researchers suggest that exposure to tobacco in the womb may have
an indirect impact by affecting children’s impulsivity, attention
or cognition. They have called for further studies to investigate
how exposure to tobacco in utero affects on the
development and function of children’s brains.
It is estimated that between 15 and 20 per
cent of women in the UK continue to smoke during their
pregnancy.
Dr Stanley Zammit, a psychiatrist at Cardiff
University and lead author of the study, said “In our cohort,
approximately 19 per cent of adolescents who were interviewed had
mothers who smoked during pregnancy.
“If our results are non-biased and reflect a
causal relationship, we can estimate that about 20 per cent of
adolescents in this cohort would not have developed psychotic
symptoms if their mothers had not smoked. Therefore, maternal
smoking may be an important risk factor in the development of
psychotic experiences in the population.”
For further information, please
contact:
Liz Leicester
or Deborah Hart in the Communications
Department.
Telephone: 020 7235 2351 Extensions. 6298 or 6127
References:
Zammit S, Thomas K, Thompson A, Horwood J, Menezes P, Gunnell D, Hollis C, Wolke D, Lewis G and Harrison G (2009) Maternal tobacco, cannabis and alcohol use during pregnancy and risk of adolescent psychotic symptoms in offspring, British Journal of Psychiatry, 195: 294-300