New research from the Royal College of Surgeons in Ireland (RCSI) published in Nature Publishing Groups Neuropsychopharmacology has shown physical changes to exist in specific brain areas implicated in schizophrenia following the use of cannabis during adolescence.

The COMT gene provides instructions for making enzymes which breakdown a specific chemical messenger called dopamine. Dopamine is a neurotransmitter that helps conduct signals from one nerve cell to another, particularly in the brains reward and pleasure centres. Adolescent cannabis use and its interaction with particular forms of the COMT gene have been shown to cause physical changes in the brain as well as increasing the risk of developing schizophrenia.

Dr Áine Behan, Department of Psychiatry, RCSI and lead author on the study, said: "This is the first study to show that the combined effects of the COMT gene with adolescent cannabis use cause physical changes in the brain regions associated with schizophrenia.. It demonstrates how genetic, developmental and environmental factors interact to modulate brain function in schizophrenia and supports previous behavioural research which has shown the COMT gene to influence the effects of adolescent cannabis use on schizophrenia-related behaviours."

The three areas of the brain assessed in this study were found to show changes in cell size, density and protein levels.

"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 continued.

The research was funded by the Health Research Board and Science Foundation Ireland.

Senior authors include Professor David Cotter and Professor Mary Cannon, Department of Psychiatry and Professor John Waddington, Department of Molecular and Cellular Therapeutics, RCSI. Additional authors in the study included Magdalena Hryniewiecka, Department of Psychiatry, RCSI, Dr Colm O'Tuathaigh and Dr Anthony Kinsella, Department of Molecular and Cellular Therapeutics, RCSI as well as collaborators Professor Maria Karayiorgou and Professor Joseph Gogos from the Department of Neuroscience, Columbia University, New York.