Short answers, pulled from the story.
Substance dependence is a biopsychological state in which a person's functioning relies on repeated re-consumption of a psychoactive substance, with withdrawal occurring when use stops. Addiction is a distinct concept defined as compulsive, out-of-control drug use that continues despite negative consequences. The gene transcription factor ΔFosB is a common factor in virtually all addictions but not in dependence.
In the DSM-5, released in 2013, substance abuse and substance dependence were eliminated and replaced with the single diagnosis of substance use disorders. The change was made because the tolerance and withdrawal that previously defined dependence are normal responses to prescribed central nervous system medications and do not necessarily indicate addiction.
An article in The Lancet that scored 20 drugs from zero to three ranked heroin and morphine highest with a mean dependence score of 3.00 and perfect threes across pleasure, psychological dependence, and physical dependence. Cocaine followed at 2.39, tobacco at 2.21, barbiturates at 2.01, and alcohol at 1.93, while ecstasy scored lowest at 1.13.
Capture rates measure the percentage of users who reported becoming dependent at some point. Tobacco had the highest capture rate at 31.9 percent, followed by heroin at 23.1 percent, cocaine at 16.7 percent, and alcohol at 15.4 percent, while cannabis and caffeine were lowest at 9 percent each.
Opioid replacement therapy substitutes a drug like illicitly-obtained heroin, dilaudid, or oxycodone with a legally administered opioid such as methadone or buprenorphine that reduces or eliminates cravings without producing a high. It is the gold standard for treating opioid dependence in developed countries, with the lowest risk of fatality and relapse. Among those attempting abstinence-based recovery with clonidine and loperamide, 90 percent relapse within eight months.
In 2021 data for people aged 12 and older, American Indian and Alaskan Native populations had the highest substance use disorder rate at 27.6 percent, followed by mixed race at 25.9 percent. Asian populations had the lowest rate at 8.0 percent. Globally, the United States and Eastern Europe show the highest occurrence at 5 to 6 percent.