Royal College of Surgeons in Ireland Coláiste Ríoga na Máinleá in Éirinn

RCSI investigators' work on cannabis-induced psychosis highlighted by leading US organisation

15 July 2010

The prestigious AmericanCollege of Neuropsychopharmacology (ACNP), the leading US institution for advancing scientific understanding, prevention and treatment of brain disorders, recently highlighted translational work on cannabis-induced psychosis by Royal College of Surgeons in Ireland investigators, led by Dr. Colm O’Tuathaigh.

Dr. O’Tuathaigh, from Molecular & Cellular Therapeutics (MCT) in RCSI, together with his colleagues, have reported online in the ACNP journal Neuropsychopharmacology that age at exposure and genetic constitution may be important determinants of individual susceptibility to cannabis-induced psychosis, particularly in young males.

Dr. O’Tuathaigh said “While it is well appreciated that smoking cannabis is associated with a doubling of risk for psychotic illness, the challenge has been to understand what determines risk on an individual basis. Our research identified a role for variation in the gene for catechol-O-methyltransferase (COMT), an enzyme that inactivates dopamine, a brain neurotransmitter previously implicated in substance abuse and psychotic illness. This role related primarily to adolescent exposure to THC, the primary psychoactive ingredient of cannabis, among males”. 

These findings, typifying RCSI’s translational research strategy, indicate a genetic influence that, together with developmental factors, contributes to vulnerability of cannabis users to psychosis.

The investigatory team also involves Lieve Desbonnet, Orna Tighe & John Waddington from MCT, Catherine Coughlan of the HRB PhD Scholars Programme in Diagnostics & Therapeutics for Human Disease, Magdalena Hryniewiecka, Aine Behan, Mary Cannon & David Cotter from Psychiatry and Joseph Gogos & Maria Karayiorgou from Columbia University, New York.

The article is available at