I was watching a fairly decent documentary regarding marijuana use and at a certain point a clinical psychologist mentioned that long term patients of his that smoked marijuana from a young age showed very little growth in psychological and emotional maturity. Are there any clinical studies that indicate a connection between marijuana use and unstable psychological growth?

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    Could you give a reference for the documentary, and/or the name of the psychologist? – nico Oct 1 '13 at 20:09
  • I'l try to find it, its been quite a long time since i watched it and ive forgotten the name... – Makis Kar Oct 1 '13 at 20:13
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    FWIW this claim is similar, but not identical: oncampus.macleans.ca/education/2013/08/22/… says, "It’s a distinction supported by science. Doctors are increasingly worried about teens—not adults—using cannabis. ... I’m fairly confident that cannabis is safe for over-18 brains, but risky for under-18 brains," The news article (I don't know about the underlying science) specifically mentions IQ, and mental illness; but it doesn't mention "growth in psychological and emotional maturity". – ChrisW Oct 1 '13 at 21:10
  • could be a case of reverting cause and effect. What if people with a lack mental growth are more likely to drift towards drugs... Though I'd not be at all surprised if drugs use rots your brain, there's ample circumstantial evidence walking around to this date from the 1960s to suggest that. – jwenting Oct 2 '13 at 4:03
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    I'm voting to close because an answer depends on the exact wording/nature of the claim. For example is it claiming cause, or correlation? Little growth, or unstable growth? Immaturity, or mental illness? Emotional maturity, or social maturity? Therefore IMO you should identify and provide a direct quote from a specific claim. – ChrisW Oct 2 '13 at 11:47