Smoking cannabis just 5 TIMES as a teenager raises the risk of psychosis, reveals 'worrying' study

• The study bolsters a host of evidence that shows cannabis can lead to psychosis
• Finnish experts found the earlier a child begins smoking it, the higher their risk
• Around 6,000 people were tracked from their 15th birthday until they turned 30

By Stephen Matthews

Smoking cannabis just five times as a teenager raises the risk of psychosis, new research suggests.

Scientists have today uncovered further evidence the drug, commonly smoked by youngsters, leads to poor mental health.

The findings, led by Finnish researchers, back-up an array of evidence that shows cannabis can drive some to the point of suicide.

University of Oulo scientists revealed the earlier someone begins smoking the drug, the more likely they are to develop psychosis.

It comes amid prominent warnings by campaigners that super-strength skunk has flooded Britain's illegal market at a worrying rate.

Scientists have today uncovered further evidence cannabis, commonly smoked by youngsters, leads to poor mental health.

Skunk, the potent form of the drug, is responsible for a quarter of new cases of psychotic mental illness, a landmark study two years ago declared.

And the new research, published in The British Journal of Psychiatry, provides a further link between cannabis and psychosis.

How was the study carried out? 

More than 6,000 volunteers were tracked from their 15th birthday until they turned 30 to assess their risk of the condition.

Figures estimate that around one per cent of the population suffer from psychosis, which can cause delusions, such as hearing voices, and lead to severe distress. 

An analysis, which involved PhD student Antti Mustonen, showed a link between smoking cannabis and going on to develop psychosis.  

DOES CANNABIS INCREASE THE RISK OF PSYCHOSIS?

Going from being an occasional marijuana user to indulging every day increases the risk of psychosis by up to 159 percent, research revealed in July 2017.

Marijuana is thought to cause psychosis-like experiences by increasing a user's risk of depression, a study found. The two mental health conditions have previously been linked.

Frequently abusing the substance also significantly reduces a user's ability to resist socially unacceptable behavior when provoked, the research adds.

Study author Josiane Bourque from the University of Montreal, said: 'Our findings confirm that becoming a more regular marijuana user during adolescence is, indeed, associated with a risk of psychotic symptoms.

'[Psychosis symptoms] may be infrequent and thus not problematic for the adolescent, when these experiences are reported continuously, year after year, then there's an increased risk of a first psychotic episode or another psychiatric condition.'

The researchers, from the University of Montreal, analyzed around 4,000 13-year-olds from 31 high schools in the surrounding area.

Every year for four years, the study's participants completed questionnaires about any substance abuse and psychotic experiences.

Psychotic symptoms included perceptual aberration - for example feeling that something external is part of their body - and thinking they have been unjustly badly treated.

The participants also completed cognitive tasks that allowed the researchers to assess their IQ, memory and stimuli response.

What did the researchers say?

He said: 'We found that young people who had used cannabis at least five times had a heightened risk of psychoses during the follow-up.

'Our findings are in line with current views of heavy cannabis use, particularly when begun at an early age, being linked to an increased risk of psychosis.

'Based on our results, it’s very important that we take notice of cannabis-using young people who report symptoms of psychosis.'

Mr Mustonen, who worked alongside Cambridge and Queensland experts, added: 'If possible, we should strive to prevent early-stage cannabis use.'

Cigarettes linked to psychosis 

A separate study, published in Acta Psychiatrica Scandinavica, delved into the link between smoking cigarettes and psychosis.

An analysis of the same participants revealed teenagers who smoke 10 cigarettes face a higher risk of suffering from psychosis.

The risk is also raised if the smoking starts before the age of 13, according to the research, led by Professor Jouko Miettunen.

He explained the findings were true even when accounting for other factors that raise the risk, including a family history of psychosis.

'Based on the results, prevention of adolescent smoking is likely to have positive effects on the mental health of the population in later life,' he said.

'Worrying' findings 

Ian Hamilton, a lecturer in mental health at York University, told MailOnline that it was 'worrying'. He added: 'People with mental health problems are more likely to smoke.

'This study suggests this is no accident as smoking appears to increase the risk of developing serious mental health problems such as psychosis.

'We need to do much more to encourage people with mental health problems to think about quitting and provide them with the help to do this.

'Smoking is one of the main reasons that people with severe mental health problems die decades before those who don't, something that we can potentially improve.'