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It makes sense from a neurobiological point of view as well. Addiction works much the same way. It is not really about the substance but about the emotional attachment to a situation. The substance is just the enabler.

Some drugs causes also a physical addiction. It's also about addiction for stimulation of pleasure zones of the brain. There's a complex of factors that plays role. But surely emotional attachment is also in charge. I know the cases when junkies stopped using drugs just because of a bad trips or a bad physical sensations. And there is also an interesting fact that junkies that addicted to injective type of drugs has also an addiction of injecting the needles in their veins.

Read this. There are also articles against this one but I think it makes a strong case. has the PR references as well.

http://www.huffingtonpost.com/johann-hari/the-real-cause-of-addicti_b_6506936.html

an interesting fact that junkies that addicted to injective type of drugs has also an addiction of injecting the needles in their veins.

which might also be connected with self-harm..yet again lack of emotional connection