Twin Study Finds Cannabis Legalization Did Not Cause Substantial Psychological Harm in Adults

PainRelief.com Interview with:
Stephanie Zellers PhD
Postdoctoral Researcher, Kaprio Group, FIMM
Dr. Zellers began this research as a graduate student at the
University of Colorado Boulder’s Institute for Behavioral Genetics (IBG)

Dr. Zellers PhD

PainRelief.com: What is the background for this study?

Response: Proponents and opponents of cannabis legalization respectively cite various potential benefits and harms that these policies may cause. Many studies have evaluated these outcomes, but drawing causal conclusions is challenging due to the many confounds that may better explain observed effects.

 We investigated the effects of cannabis legalization on a broad range of psychological outcomes, like substance use, psychiatric symptoms, general functioning in daily life, and cognitive ability. We used a longitudinal twin sample with twin pairs living in different types of states (recreationally legal vs. recreationally illegal) to draw causally informative conclusions. Because identical twins share 100% of their genes, as well as environmental factors like the family rearing, SES, and community norms, co-twin control studies can rule out many alternative explanations for an observed relationship.

Bisexuals Found to Use More and Varied Cannabis Products

PainRelief.com Interview with:
Carrie Cuttler, Ph.D.
Assistant Professor
The Health & Cognition (THC) Lab
Department of Psychology
Washington State University

Dr. Cuttler

PainRelief.com: What is the background for this study?

Response: While we know that sexual minorities (such as gay, lesbian, bisexual, etc.) individuals use many substances, including cannabis, more than heterosexual individuals, we don’t know very much about patterns of sexual minorities’ cannabis use or why sexual minorities are motivated to use cannabis. We also don’t know as much as we should about how cannabis use is related to mental health among sexual minorities. Our study used data from Project ART (Addictions Research Team) to examine these questions. The data were collected from 10 different universities across the United States, and we included data from almost 5,000 young adults (aged 18-30) in this study. People answered questions about their cannabis use, motivations for using cannabis, mental health symptoms, and also indicated their sexual attraction on a scale. The majority of our sample identified their sexual attraction as exclusively heterosexual, a small number indicated exclusively same-sex attraction, and almost a quarter indicated that their sexual attraction was somewhere between those two (the group classified as bisexual).

Patients Report Substituting Cannabis for Pain Relief Medications

PainRelief.com Interview with:
Mark Christopher Bicket, MD, PhD
Assistant Professor,Department of Anesthesiology
Assistant Professor,Health Management and Policy
School of Public Health
University of MichiganAnn Arbor, MI 48109

PainRelief.com: What is the background for this study? What are the main findings?

  • Most states have laws that allow people with chronic pain to use cannabis as a treatment. But evidence about whether medical cannabis use lowers the use of other treatments for chronic pain is not clear. 
  • We conducted a rigorous survey of adults living in the 36 states and D.C. in the spring of 2022.
  • Among the 1,661 adults who had chronic pain, we asked about their use of cannabis, prescription opioids, and non-opioid treatments for chronic pain. 
  • Cannabis use for chronic pain was common, reported in roughly 3 in 10 people at any time and 1 in 4 in the past year.
  • In contrast, a minority said cannabis use decreased their use of non-pharmacologic treatments like physical therapy or meditation, and some reported their use increased.

Marijuana May Be Substituting for Opioids for Cancer-Related Pain Relief

PainRelief.com Interview with:
Yuhua Bao, PhD
Department of Population Health Sciences, Department of Psychiatry
Weill Cornell Medicine, New York, New York

Dr. Yuhua Bao

PainRelief.com: What is the background for this study?

Response: We know that opioid use is declining among cancer patients. We also know that marijuana use is increasing among cancer patients; this increase is related to the recent wave of medical marijuana legalization (adopted by 37 states and D.C. as of Feb 2022).

We do not know if medical marijuana legalization has led to changes in opioid use for cancer patients and what were the implications for cancer pain outcomes.

Use of Medical Cannabis Can Expose Patients to Harmful Contaminants

PainRelief.com Interview with:
Maxwell C. K. Leung, Ph.D.
Assistant Professor
Systems Biology and Toxicology
New College of Interdisciplinary Arts and Sciences
Arizona State University, West Campus

PainRelief.com: What is the background for this study?

Response: Over 200 million Americans currently have legal access to medical cannabis, recreational cannabis, or both. Yet, cannabis remains an illicit Schedule 1 substance at the federal level. This limits the efforts of several federal agencies to regulate harmful contaminants – including pesticides, heavy metals, solvents, microbes, and fungal toxins – in cannabis.

Cannabis During Pregnancy May Have Long Term Mental Health Consequences for Children

David-Baranger
Dr. Baranger

PainRelief.com Interview with:

David A. A. Baranger, PhD
Department of Psychological and Brain Sciences

Dr. Brogdan

Ryan Bogdan, PhD
Associate Professor of Psychological & Brain Sciences
Department of Psychiatry
Washington University in St Louis
St Louis, Missouri



PainRelief.com: What is the background for this study? What are the main findings?

David Baranger: Prenatal cannabis use is increasing in the United States. Prior work from our group found that prenatal cannabis exposure, particularly when it occurred after mothers learned they were pregnant, was associated with worse mental health outcomes in children aged 9-10.

In this study we followed up with this same group of children, who are now as old as 12, to ask whether anything has changed. Have they improved, or gotten worse? To our surprise, we found that children with prenatal cannabis exposure still had worse mental health outcomes – things had not gotten better, nor had they gotten worse.  

Twin Study Find Cannabis Legalization Linked to Increased Marijuana Use in Adults

PainRelief.com Interview with:
Stephanie Zellers
Psychology
University of Minnesota

PainRelief.com: What is the background for this study?

Response: Many cross-sectional studies have found increases in adult cannabis consumption after the passage of recreational cannabis legalization. These studies, in large population samples across the USA, provide information about possible effects of recreational legalization in representative samples, but cannot draw causally informative conclusions. There are many confounders, like genes, pre-existing differences, and secular trends, that could be alternative explanations for any effects identified.

We utilized a longitudinal twin study to rule out many additional unmeasured confounds shared within families, like genes and aspects of the rearing environment. Importantly, we have data on identical twins before and after recreational legalization, and we have pairs where one twin lives in a recreationally legal state while their co-twin does not. By comparing these twins, we can estimate the causal impact of recreational legalization, after controlling for unmeasured confounds shared by individuals in a family.

Medical Marijuana Users Also More Likely to Also Use Tobacco

PainRelief.com Interview with:
Marc L. Steinberg, Ph.D.,
Professor, Department of Psychiatry, Rutgers RWJMS
Director, Doctoral Psychology Internship Program, Rutgers UBHC – Piscataway
Research Lab Website: Tobacco Research & Intervention Lab

Dr. Steinberg

PainRelief.com: What is the background for this study? What are the main findings?

Response: As the use of cannabis for therapeutic purposes (often called ‘medical marijuana’) has grown, my colleague, Dr. Mary Bridgeman, and I became interested in exploring more about the population who use marijuana for therapeutic purposes. My research has historically focused on tobacco use and so that was one issue in particular that we focused on in this study.

We know that individuals who use cannabis, in general, are more likely to smoke, but we did not know if that was also true for those who used cannabis for therapeutic purposes.  

Fewer Synthetic Cannabinoid Poisonings in States with Legalized Medical Marijuana

PainRelief.com Interview with:
Tracy Klein, PhD, ARNP, FAANP, FRE, FAAN
Assistant Director, Center for Cannabis Policy, Research and Outreach
Associate Professor, College of Nursing
Washington State University Vancouver
Vancouver, WA

PainRelief.com: What is the background for this study?

Response: This study evaluates data on illicit synthetic cannabinoid poisonings reported to the National Poison Data System (NPDS) which contains data from 55 poison centers in the US (https://aapcc.org/about/our-members). We correlated the 7600 poisonings reported between 2016 and 2019 with the reporting state’s status of cannabis legalization: restrictive, medical and permissive.

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Higher Potency Cannabis Associated With Greater Risk of Addiction

PainRelief.com Interview with:
Kat Petrilli, PhD Student
Addiction and Mental Health Group (AIM)
Department of Psychology
University of Bath

PainRelief.com:  What is the background for this study? 

cannabis marijuana weed pot

Response: Cannabis is the third most used drug globally, after alcohol and nicotine. Experimental studies show that THC, the main psychoactive component, causes intoxication, cognitive impairments, as well as symptoms of anxiety and psychosis-like experiences and these effects are dose-dependent, which means that higher potency cannabis products (products with high THC concentrations) could increase the risk of harm to cannabis users. 

Previous studies have shown that concentrations of THC in cannabis have increased over the years. In the US and Europe concentrations of THC in cannabis have more than doubled over the past 10 years. In addition, new legal markets have facilitated the appearance of cannabis products with higher potencies than earlier products, such as cannabis concentrates. We also know from previous studies that cannabis use is associated with mental health disorders and 22% of people who use cannabis are estimated to meet the criteria for cannabis use disorder (CUD) or cannabis addiction. 

International increases in cannabis potency and the availability of higher potency cannabis products makes it especially pressing to understand the association of cannabis potency with mental health outcomes. 

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