Teenage smokers are destroying their brain cells, reveals new research from the University of Warwick.

People who started smoking by 14 years of age have, on average, "markedly" less grey matter in a section of the left frontal lobe linked to decision-making and rule-breaking, according to the findings.

Grey matter is the brain tissue that processes information, and contains all of the organ's neurons. While brain development continues into adulthood, grey matter growth peaks before adolescence.

A research team, led by scientists at the universities of Cambridge and Warwick and Fudan University in China, analysed brain imaging and behavioural data from more than 800 young people at the ages of 14, 19 and 23.

They said low grey matter volume in the left side of the ventromedial prefrontal cortex may be an "inheritable biomarker" for nicotine addiction – with implications for prevention and treatment.

In addition, the scientists found that the opposite, right part of the same brain region also had less grey matter in smokers.

They said that loss of grey matter in the right prefrontal cortex appears to speed up only after someone has started smoking. That region is linked to the seeking of sensations.

The team argue that less grey matter in the left forebrain could lower cognitive function and lead to "disinhibition": impulsive, rule-breaking behaviour arising from a limited ability to consider consequences.

They believe it may increase the chances of smoking at a young age.

Once a nicotine habit takes hold, grey matter in the right frontal lobe shrinks, which may weaken control over smoking by affecting "hedonic motivation": the way pleasure is sought and managed.

Excessive loss of grey matter in the right brain was also linked to binge drinking and cannabis use.

Taken together, the researchers say that their findings point to a damaged "neuro-behavioural mechanism" that can lead to nicotine use starting early and becoming locked into long-term addiction.

Co-senior author Prof Trevor Robbins, of Cambridge's Department of Psychology, said: "Smoking is perhaps the most common addictive behaviour in the world, and a leading cause of adult mortality.

"The initiation of a smoking habit is most likely to occur during adolescence.

"Any way of detecting an increased chance of this, so we can target interventions, could help save millions of lives."

Annual deaths from cigarettes are expected to reach eight million worldwide by the end of the decade. Currently, one in five adult deaths each year are attributed to smoking in the US alone.

Prof Robbins said: "In our study, reduced grey matter in the left prefrontal cortex is associated with increased rule-breaking behaviour as well as early smoking experiences.

"It could be that this rule-breaking leads to the violation of anti-smoking norms."

Co-author Prof Barbara Sahakian, of Cambridge's Department of Psychiatry, said: "The ventromedial prefrontal cortex is a key region for dopamine, the brain's pleasure chemical.

"As well as a role in rewarding experiences, dopamine has long been believed to affect self-control.

"Less grey matter across this brain region may limit cognitive function, leading to lower self-control and a propensity for risky behaviour, such as smoking."

The study, published in the journal Nature Communications, used data gathered by the IMAGEN project from sites in the UK, Ireland, France and Germany.

The researchers compared brain imaging data for those who had smoked by age 14 with those who had not, and repeated the process for the same participants at ages 19 and 23.

Those who had already smoked by the age of 14 had "significantly" less grey matter in the left prefrontal cortex, on average.

People who started smoking by age 19 also had less grey matter in their left prefrontal cortex at 14, which the research team say indicates a potential causal influence.

The scientists also looked at the right ventromedial prefrontal cortex. Grey matter loss occurs in everyone as they age.

However, those who smoked from age 14 as well as those smoking from age 19 both ended up with excessive grey matter loss in the right frontal lobe.

For the right prefrontal cortex, 19-year-old smokers who did not start during adolescence had similar grey matter levels at age 14 to those who never smoked at all.

The researchers say that suggests a rapid reduction in the right ventromedial prefrontal cortex only begins with the onset of smoking.

Data at age 23 showed that grey matter volume in the right prefrontal cortex shrank at a faster pace in those who continued to smoke, suggesting an influence of smoking itself on prefrontal function.

Researchers also analysed figures from two questionnaires completed by participants to investigate the personality traits of novelty seeking and sensation seeking.

Prof Robbins said: "Both questionnaires examine the pursuit of thrilling experiences, but they measure distinct behaviours.

"The sensation seeking scale focuses on pleasurable experiences, while the novelty seeking questionnaire includes items on impulsiveness and rule-breaking."

Less grey matter in the left prefrontal cortex was associated with novelty seeking, particularly disorderly and rule-breaking behaviour, while reduced grey matter volume in the right prefrontal cortex was linked to sensation seeking only.

Lead author Prof Tianye Jia, of Fudan University, added: "Less grey matter in the left frontal lobes is linked to behaviours that increase the likelihood of smoking in adolescence.

"Smokers then experience excessive loss of grey matter in the right frontal lobes, which is linked to behaviours that reinforce substance use. This may provide a causal account of how smoking is initiated in young people, and how it turns into dependence."