The Merck Manual of Diagnosis and Therapy stated in Section 15, "Psychiatric Disorders," Chapter 195, "Drug Use and Dependence" and published on its website (accessed Nov. 20, 2002):

“Any drug that causes euphoria and diminishes anxiety can cause dependence, and cannabis is no exception. However, heavy use and complaints of inability to stop are unusual.

Cannabis can be used episodically without evidence of social or psychological dysfunction.

The term dependence probably is misapplied to many users. No withdrawal syndrome occurs when the drug is discontinued, but some heavy users report disrupted sleep and nervousness when they stop.”

Nov. 20, 2002