Teenagers in polluted areas are more likely to suffer psychotic episodes as scientists fear exhaust fumes could be stunting brain development.
The first ever study of its kind found adolescents in more polluted areas were around 70% more likely to have a psychotic episode.
These are experiences such as being paranoid, hearing voices and believing someone is spying on you or trying to hurt you.
Researchers from King’s College London analysed experiences of 2,232 18-year-olds in England and Wales.
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For the first time this was linked to hourly estimates of air pollution at their home addresses and two other locations where they spent a lot of time the previous year, such as a school.
Three in ten adolescents report having a psychotic episode between the ages of 12 and 18.
For many these do not progress to mental illness but such youngsters are at greater risk of going on to develop conditions such as psychosis and schizophrenia.
Senior author Dr Helen Fisher said: “It could be that the smaller particles are getting in to the brain and causing inflammation. Other studies suggest neuroinflammation is associated with psychosis.
“It could also be stunting brain development during this very sensitive early period.
“Things like having smaller hippocampus are associated with going on to develop these psychotic phenomena.”
Adolescents exposed to the highest level of nitrogen dioxide (NOx) had 71% greater odds of having a psychotic experience, the study also found.
Meanwhile, those exposed to the highest levels of dangerous tiny particulate matter, which can include carbon, liquids, metals and dust, had 45% greater odds.
Co-author Prof Frank Kelly said: “There seems to be some link between potential exposure to air pollution and effects in the brain.
“This is the first study ever that’s asked the question and needs to be replicated.
“There are some theories that suggest the very tiny particles that you breath in will go in to the deep lung and travel around your body to the organs and may even travel to your brain.
“It doesn’t even need to be as complicated as that because we know these tiny carbon particles are covered in chemicals. That’s what you get when you burn fossil fuels. There’s metals there and there’s organic compounds.
“Once those particles go down in to your lungs, the chemicals will come off and dissolve in to the lung lining fluid then move across in to the body.”
Researchers said their study, published in journal JAMA Psychiatry, could not rule out other factors being responsible for causing psychosis, particularly noise pollution.
Dr Fisher added: “We know traffic is noisy, and we know noise can disrupt sleep.
“It can also be very stressful for people and both of those things have been associated with these types of psychotic experiences as well.”
