Addictions are a widespread global phenomenon. The thought that Addiction is a brain disorder is unlikely, mainly due to its enormous scale. A brain disorder is a "malfunction" of natural mechanisms. There can be no fault in our body on such a scale! Therefore, the cause of Addiction is probably not a "brain disorder."
Link: Addictions Unifying Model with its Unique Energy-reward Mechanism.
https://www.sf-healing.com/page/226 (Copy & Paste)