Heavy Cannabis users:
http://www.sciencedaily.com/releases...0630112652.htm
http://marijuana.researchtoday.net/archive/2/4/358.htm
http://www.hnrc.ucsd.edu/publication...348art2003.pdf
http://www.medicalcannabis.com/PDF/Chronic_Cannabis.pdf
http://journals.cambridge.org/action...ine&aid=255433