How cannabis legalization and long-term use affect twins' health and behavior

The Effects of Cannabis Legalization and Persistent Use: A Longitudinal Study of Two Twin Cohorts

NIH-funded research University of Colorado Denver · NIH-11311949

This project follows twins in Colorado and Minnesota over many years to learn how legal recreational cannabis and ongoing use affect people's health, mood, and daily life.

Quick facts

Grant typeR01 grant
Study typeNIH-funded research
Funding institutionUniversity of Colorado Denver NIH-funded
Lab location1 site (Aurora, UNITED STATES)
Project IDNIH-11311949 on NIH RePORTER

What this research studies

Researchers will follow about 4,500 people from two large twin groups—one in Colorado where recreational cannabis has been legal since 2014 and one in Minnesota where legalization was passed more recently—to compare patterns before and after legalization. Participants have already completed multiple assessments from adolescence into adulthood, and the team will collect additional information on cannabis use frequency, other substance use, mental health, and social or work/school functioning. By comparing twins, the study can better separate effects of legalization and persistent use from shared genetic and family background. The analyses focus on whether continued access leads to persistent frequent use and whether that persistent use links to lasting harms or changes in everyday functioning.

Who could benefit from this research

Good fit: Ideal candidates would be adolescents or adults who are twins living in states with or without recreational cannabis access (such as Colorado or Minnesota) and who are willing to complete follow-up surveys or visits.

Not a fit: People who are not twins, who live far from the study cohorts, or who have no history of cannabis exposure are less likely to gain direct benefit from this specific research.

Why it matters

Potential benefit: If successful, the findings could help people and clinicians understand whether long-term legal access to cannabis leads to lasting harms or relatively few problems, supporting more informed personal and policy decisions.

How similar studies have performed: Earlier work with these cohorts found higher cannabis use in legalized states but few short-term psychosocial harms, so this project extends those findings to look for longer-term consequences.

Where this research is happening

Aurora, UNITED STATES

Researchers

About this research

  1. This is an active NIH-funded research project — typically early-stage science, not a clinical trial accepting patient enrollment.
  2. Some NIH-funded labs run parallel clinical studies or seek volunteers for related work. To check, contact the principal investigator or institution listed above.
  3. For full project details, budget, and progress reports, visit the official NIH RePORTER page below.
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.