New research proves the use of marijuana have no benefits at all.

A study conducted by the Orygen Research Centre and the University of Melbourne, has shown that long-term heavy use of marijuana may cause the hippocampus and amygdala to shrink in heavy marijuana users. Heavy cannabis users scored much lower than non-users in a verbal learning task. Quitting marijuana caused irritability, anxiety, sleep problems and difficulty concentrating. Teens using marijuana increased their risk of developing a mental disorder by 40%. 45- to 64-year-olds who reported regularly smoking marijuana in the year before a heart attack were two to four times more likely to die within the next four years. An Austrian study conducted at the Medical University of Vienna, found that oral cannabis was ineffective in treating certain types of acute pain and actually increased sensitivity to some other kinds of discomfort. The researchers admitted they were surprised to find an absence of any form of analgesic activity of THC-standardised cannabis extract during their study and instead found that high doses of cannabinoids may even caused increased sensitivity in certain pain conditions.