“All addictions—whether to drugs or to non-drug behaviors—share the same brain circuits and brain chemicals. On the biochemical level the purpose of all addictions is to create an altered physiological state in the brain. This can be achieved in many ways, drug taking being the most direct. So an addiction is never purely “psychological”; all addictions have a biological dimension.”
― Gabor Maté, In the Realm of Hungry Ghosts: Close Encounters with Addiction