BBC News
watch One-Minute World News
Last Updated: Thursday, 3 January 2008, 00:07 GMT
Smoking link to hearing problems
Ear
Teenagers were given a series of computer tests
Teenagers who smoke, or whose mother smoked in pregnancy, are at higher risk of hearing and misinterpretation problems, a US study says.

In tests on 67 teenagers, Yale University found those exposed to smoke had trouble focusing and interpreting sounds when there was a distraction.

And the team said scans showed exposure changed the brain's white matter, responsible for transmitting messages.

The findings were reported in New Scientist magazine.

The team, whose work was originally carried by the Journal of Neuroscience, carried out brain scans on the teenagers and found those exposed to smoke were more likely to have more white matter.

Individuals affected will have problems in settings where there is a distraction
Leslie Jacobsen, lead researcher

Previous research has shown that children with overdeveloped white matter have problems transmitting and interpreting sound because the white matter it is out of sync with the rest of the brain.

The researchers believe the over-production of the white matter is caused by nicotine stimulating a chemical compound called acetylcholine.

Further evidence was also provided by the computer tests the teenagers, aged 13 to 18, completed where they were asked to recognise words while being distracted by visual images or background noise.

Among the boys who were tested, those exposed to smoke got 77% right, whereas those not exposed got 85% right.

In girls, the breakdown was 84% to 90%. The researchers said the results were "quite significant".

Problems

Lead researcher Leslie Jacobsen said: "Individuals affected will have problems in settings where there is a distraction.

"This could certainly be the case in classrooms where there may be other people talking and lots of things going on.

"Coupled with other conditions, such as behavioural disorders, this may tip a pupil towards failing at school."

David McAlpine, director of the Ear Institute at University College London, agreed the findings were interesting.

He added: "The fact that smokers show changes in this pathway means they may be less able to hear what's being said."

Richard Todd, from Washington University, added the effect on the white matter was "pretty remarkable".

"It seems the brain remains vulnerable long into adolescence."



SEE ALSO
Hair cell hope for hearing loss
14 Jan 05 |  Health

RELATED INTERNET LINKS
The BBC is not responsible for the content of external internet sites



FEATURES, VIEWS, ANALYSIS
Has China's housing bubble burst?
How the world's oldest clove tree defied an empire
Why Royal Ballet principal Sergei Polunin quit

PRODUCTS & SERVICES

Americas Africa Europe Middle East South Asia Asia Pacific