Per an interview with Dr. Volkow,

“All drugs of abuse, whether legal or illegal, cause large surges of dopamine in brain areas crucial for motivating our behavior—both the reward regions as well as prefrontal regions that control our higher functions like judgment, decision making, and self-control over our actions. These brain circuits adapt to these surges by becoming much less sensitive to dopamine, a process called receptor downregulation. The result is that ordinary healthy things in our lives, all the pleasurable social and physical behaviors necessary for our survival no longer are enough to motivate a person; the person needs the big surge of dopamine from the drug just to feel temporarily okay … and they must continually repeat this, in an endless vicious cycle.”

Dr. Volkow highlights the connection between chronic pain, opioid use, co-morbid conditions and suicide in her blog from September 2019, which can be found by clicking here.