Colin Blakemore, PhD, Chair of the Department of Physiology at Oxford University, and Leslie Iversen, PhD, Professor of Pharmacology at Oxford University, wrote in their editorial "Cannabis, Why It Is Safe," published in The Times [United Kingdom] on Aug. 6, 2001:

“For some users, perhaps as many as 10 per cent, cannabis leads to psychological dependence, but there is scant evidence that it carries a risk of true addiction. Unlike cigarette smokers, most users do not take the drug on a daily basis, and usually abandon it in their twenties or thirties.

Unlike for nicotine, alcohol and hard drugs, there is no clearly defined withdrawal syndrome, the hallmark of true addiction, when use is stopped.”

Aug. 6, 2001