Cannabis can increase depression risk

Young people with a genetic predisposition to depression could increase their risk by smoking cannabis, scientists have revealed.

Research carried out by Roy Otten at the Behavioural Science Institute of Radboud University Nijmegen, published in the online version of Addiction Biology, revealed that smoking cannabis leads to an increasing risk of developing depressive symptoms.

Furthermore, two-thirds of the population have a gene that increases the vulnerability for depression.

Mr Otten explained that the effect of smoking cannabis with a genetic vulnerability to depression is "robust".

"Some people might think that young people with a disposition for depression would start smoking cannabis as a form of self-medication, and that the presence of depressive symptoms is therefore the cause of cannabis use. However, in the longer term that is definitely not the case," he said.

The study involved the collection of data from 428 families, each with two adolescent children, over a five year period.