Cannabis using teens born with smaller than normal front part of brain

Teenagers who smoke cannabis are likely to have been born with an area of the brain that is significantly smaller than normal that affects memory and decision-making, a new study has found.

According to the study carried out in Melbourne, Australia, the difference in size may mean that the brain is not as effective, so children with a smaller orbitofrontal cortex could be more impulsive and less capable of carefully calculated decision-making.

In turn, this could make them more likely to experiment with cannabis, the Daily Mail reported.

Previous research has found that adults who are heavy cannabis smokers have much smaller brain volumes in this area, but it had, until now, been assumed that the damage was caused by the regular drug use.

However, the new findings suggest that some people are born with the abnormality.

Initially, scientists took detailed scans of the brains of 121 children aged 12 before they had begun to experiment with alcohol, cigarettes and other drugs such as cannabis.

Once they turned 16, the teenagers were asked a series of questions, including whether they had smoked cannabis. Of the 28 who admitted to using it, 23% of the group, most said they had smoked it fewer than ten times.

The researchers then studied the scans again to determine whether there was anything that linked the cannabis smokers.

They discovered that the average volume of the orbitofrontal cortex was 6% smaller in the group who had used the drug. The results were the same even after adjustments for other factors, including psychiatric problems, alcohol consumption and cigarette smoking, had been made.

The study has been published in the journal Biological Psychiatry.