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

> **NIH NIH R01** · UNIVERSITY OF COLORADO DENVER · 2024 · $1,150,785

## Abstract

PROJECT ABSTRACT
Recreational cannabis legalization (RCL) is swiftly expanding in the United States. Ideally, such policy shifts
are informed by evidence; however, little is known about the effects of RCL. This is particularly true for long-
term effects. Data from states that were the first to legalize cannabis can help understand RCL’s long-term
effects. With public opinion indicating that further RCL expansion is likely, it is imperative to clearly understand
its public health consequences. Our original grant suggested that adults living in RCL states used cannabis
20% more frequently (than those in non-RCL states) but had virtually no other psychosocial consequences.
However, increasing evidence suggests that cannabis use is most consequential when it is frequent and
persistent. In the context of this literature, it is worth noting that our original grant assessed behavior within
approximately five years of legalization. It is unclear whether continued access to cannabis in RCL
environments increases persistent use, leading to negative consequences. We propose a renewal grant to
examine the long-term impact of RCL in approximately 4,500 participants from two large, prospective twin
cohorts in Colorado (CO; full RCL since 2014) and Minnesota (MN; RCL passed in 2023, dispensaries
expected to open in 2024). Both CO and MN participants have been assessed at least three times before RCL
began in CO (adolescence, emerging adulthood, young adulthood) and twice since RCL began in CO. The
proposed project would collect the third post-RCL assessment in CO and the first since RCL began in MN. We
will leverage this study design to control important familial confounds related to cannabis use and its potential
consequences. Further, we will incorporate the longitudinal nature of these cohorts to control prior behavior
(e.g., cannabis use, mental health) while examining the effects of RCL. Thus, we will use these data to address
whether years of RCL access affect cannabis use, alcohol use, mental health, and physical health (Aim 1). We
hypothesize that having more years of RCL access is associated with greater cannabis use and
consequences. Further, we will determine whether pre-RCL mental and physical health problems predict
increased post-RCL cannabis use (Aim 2). This aim is based on evidence, including our preliminary data, that
suggest health problems are a common motive for cannabis use. Thus, we hypothesize that pre-RCL health
problems are associated with greater post-RCL cannabis use. Finally, we will identify individual differences
uniquely related to post-RCL cannabis use and consequences (Aim 3). We hypothesize that post-RCL
cannabis and its consequences are associated with greater perceived cannabis benefits, greater ease of
access, and personality factors that may have impeded cannabis use in non-legal contexts (higher harm
avoidance, lower rule-breaking). In summary, this study will equip key stakeholders with well-controlled, rich
evidence on...

## Key facts

- **NIH application ID:** 10995030
- **Project number:** 2R01DA042755-06A1
- **Recipient organization:** UNIVERSITY OF COLORADO DENVER
- **Principal Investigator:** Jarrod Martin Ellingson
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $1,150,785
- **Award type:** 2
- **Project period:** 2017-09-01 → 2029-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10995030

## Citation

> US National Institutes of Health, RePORTER application 10995030, The Effects of Cannabis Legalization and Persistent Use: A Longitudinal Study of Two Twin Cohorts (2R01DA042755-06A1). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10995030. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*