] AT THE end of Jim van Os's street in the pleasant Dutch
] city of Maastricht there is a coffee shop. As with many
] such establishments in the Netherlands, "coffee shop" is
] something of a euphemism: most of its customers go there
] not to drink coffee but to buy and smoke dope. Van Os
] isn't too keen on the place. He doesn't like the shady
] characters it attracts. He doesn't like the fact that his
] children have to walk past it. And most of all he doesn't
] like that fact that the place breaks the law and sells
] marijuana to under-18s.
]
]
] Van Os's fears are rooted in more than the usual parental
] angst. He is a psychiatrist at the University of
] Maastricht who investigates the effect of marijuana on
] people's brains - particularly adolescents' brains. And
] the findings of his research make him worry about the
] effects of all this dope smoking on the kids in his
] neighbourhood.
]
]
] Over the past couple of years van Os and several others
] have been building the case that, for some teenagers,
] smoking cannabis leads to serious mental health problems
] in later life, including schizophrenia. Van Os claims
] that marijuana is responsible for up to 13 per cent of
] schizophrenia cases in the Netherlands. And with cannabis
] use among teenagers on the rise, the age at first use
] falling (see Graphic), and the strength of cannabis on
] the up, he says the figure can only increase

As someone with long term mental health problems possibly caused by heavy cannabis use this was particularly interesting

New Scientist Cannabis: Too much, too young? - Features