Press release issued 3 March 2009Young children who spend more than two hours watching TV every day double their subsequent risk of developing asthma, indicates research published on-line today in the journal Thorax.
The findings are based on more than 3,000 children whose respiratory health was tracked from birth to 11.5 years of age.
The children were all participants in the Children of the 90s study (ALSPAC), which has been following the long-term health of 14,000 children and their parents.
The parents were quizzed annually on symptoms of wheezing among their offspring and whether a doctor had diagnosed asthma in their child by the time s/he was 7.5 years old, but not before the age of 3.5 years.
Parents were also asked to assess their children's TV viewing habits from the age of 3.5 years.
The amount of time spent in front of the box was used as a proxy measure of inactivity, because personal computers and games consoles were not in widespread use at the time (mid 1990s).
The prevalence of asthma among children at the age of 11.5 years, who had no asthmatic symptoms when they were 3.5 years old was 6 per cent.
But children who watched TV for more than two hours a day were almost twice as likely to have been diagnosed with asthma as those who watched the box less.
By the time the children were 11.5 years old, there was little difference in levels of sedentary behaviour between those with asthma and those without.
The results were not confined to one gender, nor were they related to current weight.
The authors comment that the relationship between physical activity, sedentary behaviour and asthma is complex.
But they point out that recent research has suggested that breathing patterns in children may be associated with sedentary behaviour, sparking developmental changes in the lungs and subsequent wheezing.
Association of duration of television viewing in early childhood with the subsequent development of asthma. Sherriff A, Anirban M, Ness AR, Mattocks C, Riddoch C, Reilly JJ, Paton JY, Henderson AJ. Online First Thorax 2009 doi 10.1136/thx.2008.104406]
Please contact Joanne Fryer for further information.
ALSPAC The Avon Longitudinal Study of Parents and Children (also known as Children of the 90s) is a unique ongoing research project based in the University of Bristol. It enrolled 14,000 mothers during pregnancy in 1991-2 and has followed most of the children and parents in minute detail ever since.
The ALSPAC study could not have been undertaken without the continuing financial support of the Medical Research Council, the Wellcome Trust, and the University of Bristol among many others.
These results do not necessarily imply that TV is a bad thing. Of course reading a book is a sedentary activity too. We are not saying to parents that their child should never watch the TV, or never sit down, but they should bear it in mind.