Cannabis can disturb the way the brain of teenage boys develop, suggests new research.

The study shows the brains of teenage boys who experiment with cannabis before the age of 16, and have a high genetic risk for schizophrenia, develop differently.

The discovery, made from a combined analysis of more than 1,500 young people, contributes to a growing body of evidence linking marijuana use in teenage years with schizophrenia later in life.

The researchers said the these years mark a period of vulnerability, when psychotic disorders may emerge, especially in boys.

The brains of teenage boys who experiment with cannabis before the age of 16, and have a high genetic risk for schizophrenia, appear to develop differently

Environmental influences on how brain circuits mature during this time is of great interest to neuroscientists and medical professionals, researchers said.

The study's senior author, Professor Tomas Paus, of Toronto University in Canada, said there was solid epidemiological evidence – that which looks at patterns across populations – supporting a link between experimenting with cannabis during adolescence and schizophrenia.

Given this, the team wanted to investigate whether the use of marijuana by 16 years of age is associated with differences in how the brain matures.

They found that cannabis use might interfere with how a particular part of the brain called the cerebral cortex matures in male teenagers who are prone to schizophrenia.

The cerebral cortex is the outer layer of the brain which is made of folded gray matter, and plays an important role in consciousness.

He said: 'Their brains showed lower cortical thicknesss compared with low-risk male participants and low-or-high risk female participants who used the drug.'

Professor Paus, a prominent researcher and pioneer in the field of population neuroscience, strongly cautioned that more research is needed to determine whether lower cortical thickness actually increases the probability of schizophrenia in at-risk men later in life.

To come to their conclusions, the researchers used observations from three large samples of youths in Canada and Europe.

They examined figures from 1,577 people, aged 12 to 21, in Britain, Germany, Franc, Ireland and Canada, that included information on cannabis use and brain imaging results.

Professor Paus added: 'Brain ageing is about brain development.

'Our study shows the importance of understanding environmental influences on the developing brain in early life as this can have important implications for brain health through the lifespan.'