View From Europe: 'Appraising The Risks Of Reefer Madness'

I was leafing through my Cerebrum the other day.

That is to say, as a longtime follower of the Dana Foundation — a philanthropy that supports brain research and issues helpful updates on the brain in the news — I was electronically leafing through the foundation's journal, Cerebrum, when an alarming piece stopped me: Appraising the Risks of Reefer Madness, by Sir Robin Murray, M.D.

It cites a growing scientific consensus that in a small minority of users, particularly younger users, cannabis use raises the risk of psychosis, and it suggests that newer, higher-potency strains of pot may pose particular risks. It opens:

Beginning in the mid-1980s, European psychiatrists like me started seeing an increasing number of previously well-functioning teenagers who had developed hallucinations and delusions: the characteristic picture of schizophrenia. These troubled patients puzzled us because most had been bright and sociable and had no ties to the usual risk factors such as a family history of the disorder or developmental insult to the brain. Family and friends would often say, “Maybe it was all the cannabis they have been smoking,” and we would confidently reassure them that they were mistaken and tell them that cannabis was known to be a safe drug.

My view began to shift when a colleague, Peter Allebeck from the Karolinska Institute in Stockholm, launched his own investigation. He had been struck similarly by seeing well-adjusted young people develop schizophrenia for no apparent reason. The wonderful Swedish national records system enabled him to trace the outcome of 45,750 young men who had been asked about their drug use when they were conscripted into the Swedish army. From analysis of these data, Allebeck and his colleagues1 reported in 1987 that conscripts who had used cannabis more than fifty times were six times more likely to develop schizophrenia over the next fifteen years than those who had never used it.

Read the full piece here. Sir Robin (he was knighted in 2011) notes that marijuana remains highly controversial in Europe, with a political pendulum swinging between liberalization and restriction. Do you see value in his views?