A good friend of mine growing up began smoking weed heavily in high school. This led to mushrooms, and then LSD, the cumulative effect triggering his latent schizophrenia. He's lived with his parents collecting Social Security ever since. **** tragedy, he was such a smart and talented kid, he could've done anything he wanted to with his life.
I think cannabis effects people differently, some are more susceptible to becoming total burnouts and/or losing their marbles than others...to a developing teenage brain, heavy usage is a really bad idea, especially nowadays with all the hydroponic turbocharged stuff that's out there.
I haven't touched the stuff in years, it tended to make me more paranoid than relaxed.