Do you think substance abuse can be defense mechanism?

Yes, but a poor one. Many if not most people with substance abuse come from dysfunctional families & suffer from anxiety &/or depression. Many are very sensitive souls.They use substances as a way to escape, emotionally numb themselves & self-medicate.Unfortunately, substance abuse not only fails to solve their problems but adds to them.Counseling, appropriate medications/herbs/supplements & meditation will help more.