Cannabis use linked to schizophrenia

The use of cannabis during adolescence increases the risk of developing schizophrenia, a study by researchers at the Royal College of Surgeons in Ireland has found.

There were physical changes in the areas of the brain implicated in the use of schizophrenia following the use of cannabis during adolescence, the research published in Nature's Neuropsychopharmacology journal has found.

The use of cannabis by teenagers can cause changes to the brain by interacting with the COMT gene, the research has shown.

The COMT gene provides instructions for making an enzyme which breaks down dopamine, the neurotransmitter which controls the brain's pleasure and reward centres.

It was the first study to show the combined effects of the gene with adolescence cannabis use can change parts of the brain associated with schizophrenia, the study's lead author Dr Áine Behan,of the RSCI Department of Physiology said.

The study showed that “genetic, developmental and environmental factors interact” to adjust brain function in schizophrenia. Dr Behan said the study supported previous behavioural research.

“Increased knowledge on the effects of cannabis on the brain is critical to understanding youth mental health both in terms of psychological and psychiatric well-being,” Dr Behan said.

Three areas of the brain assessed in this study, which was carried out on mice, were found to show changes in cell size, density and protein levels.