Mental Illness and Marijuana?

This has been a proven study.
What was te study?
To test if there is a connection between mentally ill people and their use of marijuana.
Their findings? There was.
the study showed that 63% of people tested used marijuana.
Of that, 45% tested to be ONLY using marijuana.
Of the 63%, 55% of people tested to be using drugs along with marijuana (for example weed and cocaine)

Works Cited:

Sigmon, Stacey C., Sandra Steingard, Gary J. Badger, Stacey L. Anthony, and Stephen T. Higgins. "Contingent reinforcement of marijuana abstinence among individuals with serious mental illness." psycArticles 8 (2000): n. pag. http://psycnet.apa.org/journals/pha/8/4/509/. Web. 14 Jan. 2013.