No, I said unlike other drugs, such as alcohol, tobacco, opiates, etc., marijuana wasn't physically addictive because it doesn't produce the same physical symptoms of withdrawal.
Of course, I'm willing to admit I'm wrong if you can provide a source that definitively proves it and not one full of qualifiers like 'may', 'can' or 'might'.
What my first post was getting at is that all drugs cause physical dependence one way or the other. Drugs affect systems that have varying importance for physical regulation, hence the various relative difficulties of withdrawal.
Any drug mimics the function of the normally occurring endogenous chemical, in marijuana’s case so-called endogenous cannabinoids (although their structure is not like cannabinoids, but is more akin to the “synthetic THC” one hears about).
All physiological systems have some form of feedback to maintain a homeostasis. Psychoactive drugs provide an artificial increase neuronal activity when introduced in to the system at higher concentrations than are normally active in the brain at the synaptic cleft - this the psychological effect, the high.
In response to the high level of the mimic and activity that it activates, the body responds by down-regulating the response in a number of ways, ultimately, with continued use, at a functional genomic or epigenetic level.
The body becomes accustomed to the excess of the foreign drug which serves the role of the natural compounds. As described above, the body down regulates various aspects of the normal activity, e.g. decreases number of receptors expressed, decreases production of the natural compound in the brain that the drug is mimicking, etc...
When the drug is then not administered, withdrawal occurs. The body has modified itself in expectation of the drug, and when not available, the body must re-compensate and re-regulate expression of appropriate genes back to the natural level.
That is the cause of the “jones”, the craving for the drug, the withdrawal and the period of withdrawal until addiction is over.
Below are some references to articles about THC addiction, the third being a molecular study relating to the epigenetic changes associated with addiction that use of THC engenders.
Budney AJ, Hughes JR. The cannabis withdrawal syndrome. Curr Opin Psychiatry. 2006;19(3):233-238. doi:10.1097/01.yco.0000218592.00689.e5.
Gorelick DA, Levin KH, Copersino ML, et al. Diagnostic Criteria for Cannabis Withdrawal Syndrome. Drug Alcohol Depend. 2012;123(1-3):141-147. doi:10.1016/j.drugalcdep.2011.11.007.
Rotter A, Bayerlein K, Hansbauer M, et al. CB1 and CB2 receptor expression and promoter methylation in patients with cannabis dependence. Eur Addict Res. 2013;19(1):13-20. doi:10.1159/000338642.