Internet addiction?

Mind Hacks discusses an editorial in the American Journal of Psychiatry that argues that the DSM-IV -- the diagnostic manual that psychiatrists use to diagnose mental disorders -- should include internet addiction. Vaughan is quite legitimately skeptical:

Rather curiously, the editorial mentions the figure that 86% of people with 'internet addiction' have another mental illness. What this suggests is that heavy use of the internet is not the major problem that brings people into treatment.

In fact, 'internet addiction', however it is defined, is associated with depression and anxiety but no-one has ever found this to be a causal connection.

Recent research shows that shy or depressed people use the internet excessively to (surprise, surprise) meet people and manage their shyness.

And in fact, as I mentioned in an earlier article, one of the only longitudinal studies [pdf] on the general population found that internet use is generally associated with positive effects on communication, social involvement, and well-being, although interestingly, those who were already introverts show increased withdrawal.

In other words, the internet is a communication tool and people use it manage their emotional states, like they do with any other technology.

Of course there are some people who are depressed and anxious who use the internet (or follow sports teams, or read books, or watch TV...) to excess, but why we have to describe this as an addiction still completely baffles me. (Links in the original.)

A couple things...

First, I totally hear Vaughan on this. I fail to see how they are going to differentiate between normal and abnormal internet use in this case. Not unlike the DSM criterion for personality disorders, a condition is defined as abnormal if it has negative consequences in the patient's life. But who determines what is negative? If you have someone who is extremely shy, their baseline social behavior might be a negative for me but works just fine for them. Abnormality in this case is a shifting baseline.

Second, I have a proposal. Could we have a single entry in the DSM for all addictions regardless of the focus? I am talking about throwing alcoholism, nymphomania, fanatical running, and smack use into one basket. Why is this a good idea? Well, what evidence I have read from brain imaging shows that addiction affects a neurological system for reward regardless of the origin of that reward. Whether you are getting your jollies from food or sex or drugs, you are getting them through the same neural system. So it stands to reason that the mechanisms of these diseases are relatively similar, and their treatments should be relatively similar. Why not put them all together as the same disease for simplicity's sake?

This is of course a horrible over-simplification. Drugs of abuse short-circuit the reward system by imitating neurotransmitters or affecting channels at different steps. However, I think that you could make an argument related to purely behavioral addictions -- food, sex, running, being an academic, whatever so long as drugs aren't involved -- that the mechanism of potentiating the reward system and leading to addiction is similar. Maybe we could have a drug addiction and a behavioral addiction category. (The common elements between obesity and addiction are reviewed here. The differences in the effects of food and drugs on the dopamine system is discussed in this review.)

Discuss.