REVIEW OF: Wang X et al, J Psychopharmacol 2025;39(1):1–11
STUDY TYPE: Nationwide matched cohort with twin comparison

Benzodiazepines and Z-drugs are widely prescribed for anxiety and insomnia. Many clinicians worry that starting these medications might increase the risk of later addiction, but it’s difficult to separate medication effects from the vulnerability of the people who receive them.

This Swedish registry study followed nearly 1 million people newly prescribed a benzodiazepine or Z-drug and compared them with about 1 million similar non-users. Participants had no prior substance-related diagnoses and were tracked for up to 14 years for serious alcohol- or drug-related outcomes, including specialty treatment, poisonings, criminal offenses, and deaths.

Because prescribed patients often differ in ways that affect addiction risk, the authors adjusted for psychiatric and pain diagnoses, socioeconomic factors, and parental substance problems. They also compared twins in which one received a prescription and the other did not, helping account for shared genetic and family influences.

After these adjustments, recipients had about a 50% higher risk of alcohol-related problems and roughly double the risk of drug-related problems. The association remained in the twin analysis. Over 10 years, alcohol-related problems occurred in 4.2% of users versus 2.5% of non-users, and drug-related problems in 2.9% versus 1.4%—about 1 additional case of each per 50–60 treated patients. Risks were higher in younger patients and increased with greater cumulative dose.

CARLAT TAKE
This study does not prove causation, and some of the association likely reflects baseline vulnerability. Still, the increased risk persisted after extensive adjustment and in twin comparisons. The absolute increase was modest, but the outcomes were serious and likely underestimate milder misuse. When prescribing benzodiazepines or Z-drugs, use clear indications, limit duration, and reassess regularly.