Ok, I’ll jump in as well with a rejoinder to Rick. Yes, it is true that a recent study (a single study, I might add) found that cannabidiol, an active ingredient in marijuana, may alleviate symptoms of schizophrenia when taken alone.

However, this news hardly means that marijuana is neutral when it comes to mental disease. THC, the main active ingredient in mairjuana, causes paranoia and alters brain chemistry in a way that can cause schizophrenia later in life. Consequently, here are numerous studies showing a major link between schizophrenia and marijuana. Here’s a small sampling:

One 15-year study of 50,000 young people in Sweden, for example, found those who had tried marijuana by the time they were 18 were 2.4 times more likely to receive a diagnosis of schizophrenia. The Swedish researchers concluded that 13 per cent of schizophrenia cases could be averted if all cannabis use was prevented.

Another study of almost 5,000 subjects in the Netherlands replicated the findings, and also found that marijuana users were more likely to be diagnosed with schizophrenia during the study’s three-year follow-up period. Other studies suggested that subjects who used marijuana in their early teens were more likely to be diagnosed with schizophrenia by their mid-20s.

In a companion article, Hall and Degenhardt argue the evidence has policy implications. Young people should be warned of the marijuana-schizophrenia link, since most schizophrenics are diagnosed by their late teens, about the same time teens are experimenting with cannabis.

Obviously cannabidiol isn’t cancelling out THC.

Think of this in terms of drinking a screwdriver. You have orange juice, and you have vodka. The orange juice counteracts the effects of alcohol to some degree; it contains fructose, which helps the body burn off alcohol, along with essential vitamins and minerals that are taken away by alcohol.

However, it isn’t a wash — not even close. If you drink too many screwdrivers, you’ll be hungover the next day. It’s the same with marijuana; it tends to make you paranoid, and at the end of the day, it increases your risk of schizophrenia significantly. That may be a risk many are willing to take for a temporary high, but it’s something to factor into the calculations.