The arteries of teenagers who drink alcohol and smoke -- even very occasionally -- begin to stiffen by the age of 17, increasing their risk of heart attacks and stroke in later life, a study has found.
The findings, published in the European Heart Journal, showed that a combination of high alcohol intake and smoking was linked to even greater arterial damage compared to drinking and smoking separately.
The researchers analysed data from 1,266 adolescents over a five-year period between 2004 and 2008.
"We found that in this large contemporary British cohort, drinking and smoking in adolescence, even at lower levels compared to those reported in adult studies, is associated with arterial stiffening and atherosclerosis progression," said John Deanfield, from University College London in the UK.
"However, we also found that if teenagers stopped smoking and drinking during adolescence, their arteries returned to normal suggesting that there are opportunities to preserve arterial health from a young age," said Deanfield.
Participants provided details of their smoking and drinking habits at ages 13, 15 and 17. Aortic stiffening was then assessed using a Vicorder device to measure the speed at which the arterial pulse propagates through the circulatory system.
"Injury to the blood vessels occurs very early in life as a result of smoking and drinking and the two together are even more damaging," said Marietta Charakida, who carried out the research at UCL.
"Although studies have shown teenagers are smoking less in recent years, our findings indicated approximately one in five teenagers were smoking by the age of 17," said Charakida, now at King's College London in the UK.
"In families where parents were smokers, teenagers were more likely to smoke," she said.
Participants recorded the number of cigarettes they had ever smoked and were grouped by intensity from 'low' (0-20 cigarettes) to 'moderate' (20-99 cigarettes) to 'high' (more than 100 cigarettes).
Exposure to parental smoking was also assessed by questionnaires.
Teenagers in the 'high' intensity smoking group had a relative increase of 3.7 per cent in the stiffening of their arteries (measured by mean increase in pulse wave velocity) compared to those in the 'low' smoking intensity group.
Participants also reported the age they started drinking alcohol and the frequency and intensity of alcohol consumption per month.
Heavy, medium and light intensity drinkers were defined as consuming more than 10 drinks, between 3-9 drinks and fewer than two drinks respectively on a typical day that they were drinking alcohol.
Teenagers showed a preference for beer over wine or spirits, and those who tended to 'binge drink' (have more than 10 drinks in a typical drinking day, with the aim of becoming drunk), had a relative increase of 4.7 per cent in the stiffening of their arteries compared to 'light' intensity drinkers.
Participants in the 'high smoking and 'high' drinking intensity group had a relative increase of 10.8 per cent in the stiffening of their arteries compared to those who had never smoked and low alcohol consumers.