disorder can develop as a result of self-medication. Scoring systems have been derived to assess the likelihood of opiate addiction in chronic pain patients. Healthcare practitioners have long been aware that despite the effective use of opioids for managing pain, empirical evidence supporting long-term opioid use is minimal.Noble M, Tregear SJ, Treadwell JR, Schoelles K. Long-term opioidtherapy for chronic noncancer pain: a systematic review and meta-analysis of efficacy and safety. J Pain Symptom Manag 2008;35:214–28.Kalso E, Edwards JE, Moore RA, McQuay HJ. Opioids in chronic non-cancer pain: systematic review of efficacy and safety. PAIN 2004;112:372–80 Many studies of patients with chronic pain have failed to show any sustained improvement in their pain or ability to function with long-term opioid use.Krebs EE, Gravely A, Nugent S, Jensen AC, DeRonne B, Goldsmith ES, Kroenke K, Bair MJ, Noorbaloochi S. Effect of opioid vs nonopioidmedications on pain-related function in patients with chronic back pain orhip or knee osteoarthritis pain: the SPACE randomized clinical trial. JAMA2018;319:872–82.Chaparro LE, Furlan AD, Deshpande A, Mailis-Gagnon A, Atlas S, TurkDC. Opioids compared with placebo or other treatments for chronic lowback pain: an update of the Cochrane Review. Spine (Phila Pa 1976)2014;39:556–63. According to position papers on the treatment of opioid dependence published by the United Nations Office on Drugs and Crime and the World Health Organization, care providers should not treat opioid use disorder as the result of a weak moral character or will but as a medical condition. Some evidence suggests the possibility that opioid use disorders occur due to genetic or other chemical mechanisms that may be difficult to identify or change, such as dysregulation of brain circuitry involving reward and volition. But the exact mechanisms involved are unclear, leading to debate over the influence of biology and free will. Mechanism Addiction Addiction is a brain disorder characterized by compulsive drug use despite adverse consequences. It is a component of substance use disorder and its most severe form. Overexpression of the gene transcription factor ΔFosB in the nucleus accumbens plays a crucial role in the development of an addiction to opioids and other addictive drugs by sensitizing drug reward and amplifying compulsive drug-seeking behavior. Like other addictive drugs, overuse of opioids leads to increased ΔFosB expression in the nucleus accumbens. Opioids affect dopamine neurotransmission in the nucleus accumbens via the disinhibition of dopaminergic pathways as a result of inhibiting the GABA-based projections to the ventral tegmental