Researchers from the University of Oxford, the Karolinska Institutet, Stockholm, the University of Colorado, and Örebro University, Sweden, studied more than 21,000 individuals in Sweden who received treatment with at least one of four medications used to treat alcohol and opioid use disorders (acamprosate, naltrexone, methadone, and buprenorphine).

They compared rates of suicidal behavior, accidental overdose, and crime for the same individuals during the period when they were receiving the medication compared with the period when they were not.

Most of the drugs were effective in reducing incidence of all of the outcome measures (suicidal behavior, arrest for any crime, arrest for violent crime, accidental overdose). These medications reduced the risk of suicidal behavior by up to 40%, accidental overdoses up to 25%, arrest for any crime by up to 23%, and arrest for violent crime by up to 35%. However, methadone treatment increased the risk of accidental overdose by 25%.

Professor Seena Fazel of Oxford’s Department of Psychiatry, the lead author on the study, said: "While it has been established that these medications are effective in reducing alcohol and opioid abuse, this is the first time that real-world improvements in these key health and social outcomes have been demonstrated."

"Substance abuse has huge effects on public health, including premature mortality, infectious diseases, and chronic health problems, which makes it imperative that we find a safe and effective way of helping people with addictions to regain control of their lives."

"There are still questions to ask about why methadone in particular appears to be less effective than the other drugs for accidental overdose, but this could be partly due to it sometimes being used in conjunction with other substances."

Deaths from overdoses of prescription and illicit opioids have increased in many countries, contributing to substantially reduced life expectancy. Nonfatal overdoses are also common. Studies have shown that 30%-80% of people who use illicit drugs regularly have experienced at least one nonfatal overdose.

The full paper can be read in the American Journal of Psychiatry.