For years, therapists would attempt to treat smokers and alcoholics using real-life triggers. Let addicts see a lighter or an empty bottle, or even a photo of something smoking or drinking related, to trigger cravings, then teach them coping strategies. It was limited because patients could tell they were in a lab and their new found coping skills were not always transferrable to the real world. Enter Virtual Reality:
The theory being that the immersive VR world better approximates the real world, allowing better skills transference and allowing researchers to easily AB test different scenarios. A pilot program at Duke run by assistant professor Zach Rosenthal with funding from the National Institute on Drug Abuse and the Department of Defense has already run about 90 people through this VR rehab trial. No formal conclusions have been reached, but preliminary data suggests effectiveness. More reading here.