People with addictive personalities often find something to become addicted to, if not the Internet, a football team, if not a football team, a square of cloth. Addictive personalities are not the problem and nor are virtual worlds, society is the root cause of this addiction. Addictive brains have been scanned and it has been found that part of the brain are differently wired to that of a 'normal' person (if there is such a thing).
Lack of variety of tasks on offer in life, education imbalance that fails to engage the many parts of a person that are needed for a healthy psyche. In fact, I would go as far as to say that virtual worlds are a safety net up to a point. The addictive behaviour that separates part of oneself from everything else could be an alternative to medication. In fact, it could prevent medication totally when a support system is found inside the refuge of virtual worlds.
Also, people are there who can offer comfort, friendship and advice, some even who have gone through the same trials and tribulations. Virtual worlds can also provide an escape from socially restrictive circumstances, a 'hide way' from the harsh realities of life.
I am not saying we all should escape life, but depressives often sleep a lot and live in their dreams, awakening only to find the reality they cannot deal with in the first place. They are then treated with medication and either 'get better' or stay that way. What a better option to have an alternative 'fantasy world' with 'real people' that can help.
I agree with Catriona M. Morrison, DPhil, Institute of Psychological sciences from the University of Leeds Great Britain that “over-engaging in Web sites that serve to replace normal social function might be linked to psychological disorders like depression and addiction.”
However a link does not mean one causes the other. As Skylar Smythe points out, an 'association' does not suggest cause and effect. Many things are associated, yet one does not necessarily cause the one another and the cause / effect may even be reversed. No connection can be assumed until proven.
As a compulsion disorder, Internet Addiction is treated very much as other compulsion disorders, by replacing the addicts' source of 'addiction' with something else. It is not certain that the person may not form a similar addiction to the replacement, as that too may offer the succor that the 'Internet Addiction' provided in the first place.
What I would like to see is the people who treat these issues use virtual worlds to treat their patients with. After all, virtual worlds and virtual reality have been used to help patients with many other psychiatric disorders and phobias. http://vrlab.epfl.ch/~bhbn/psy/index-VR-Psychology.html