What We’ve Learned from California’s Cannabis Experiment: High-Potency Puts Young Adults at Risk
Shining a light on integrated care to promote mastery and unlock human potential.
Cannabis in California has undergone a dramatic evolution—from prohibition and criminalization to becoming one of the state’s largest legal industries. Initially banned under the 1937 Marihuana Tax Act, cannabis was long associated with marginalized groups and countercultural movements, fueling stigma and enforcement crackdowns.1 The War on Drugs in the 1980s and 90s intensified penalties, leading to mass incarcerations, particularly in communities of color. A turning point came in 1996 with Proposition 215, which made California the first state to legalize medical cannabis.
This shifted public perception and launched a new, if unevenly regulated, industry. Additional structure came with SB 420 in 2003, and in 2016, Proposition 64 legalized recreational cannabis for adults, creating a regulated marketplace and channeling tax revenues into public health, education, and criminal justice.
Today, California’s cannabis industry generates over $5 billion annually, with more than 800 licensed dispensaries operating statewide. Yet, legalization has also highlighted ongoing challenges: gaps in research on long-term health effects, concerns about young adult use and brain development, and questions about cannabis’s impact on mental health. While California stands as a pioneer in legalization and economic growth, it continues to navigate the social, scientific, and equity issues that legalization leaves unresolved.
Study Examines the Risk of High-Potency Cannabis Use Among Young Adults
With legalization has come rising cannabis use—particularly among young adults. Between 2013 and 2023, past-month use among 19- to 30-year-olds jumped from 18.3% to 28.7%. At the same time, THC levels in cannabis flower have steadily increased. These trends raise a critical question: do we fully understand the risks of high-potency cannabis, especially for younger users?
In 2025, Dr. M. R. Alvaro and colleagues published a study in JAMA Open Network that explored this issue. The research focused on California young adults (ages 18–34) and examined whether using high-potency cannabis flower (defined as THC levels above 15%) was linked to heavier use and higher risks of cannabis use disorder (CUD).
Study Overview
The researchers chose to study flower cannabis because it remains the most widely used form, even as concentrates and edibles have grown in popularity. Legalization in California after Proposition 64 made high-potency products widely available, creating a natural setting to observe changes in consumption patterns.
Key Findings
1. Heavier Consumption:
Young adults who preferred high-potency flower used cannabis more often and in larger quantities compared to those who used lower-potency products.
2. Increased Risk of CUD:
Frequent use of high-potency cannabis was strongly associated with cannabis use disorder, including impaired daily functioning, dependence, and problematic behaviors.
3. Potency and Tolerance:
As users consumed stronger cannabis, they quickly developed tolerance—requiring more THC to achieve the same effect. This cycle reinforced heavier use and heightened risk of dependence.
4. Long-Term Risks:
Regular use of high-potency cannabis poses particular risks for young adults, whose brains are still developing. The study highlighted potential impacts on cognition, memory, and mental health, including vulnerability to psychosis.
Public Health and Policy Implications
The study underscores the public health risks of high-potency cannabis in legalized markets. It calls for:
Regulation of THC levels in consumer products.
Public health education to warn young adults of risks like dependence and impaired cognitive function.
Prevention programs and harm-reduction strategies, including promoting lower-potency options and mindful consumption.
Further research to better understand long-term effects of sustained high-THC use, particularly as legalization expands.
High Potency, High Stakes
The 2025 study on high-potency cannabis flower use provides one of the clearest signals yet about the risks of legalized cannabis for young adults. High-potency products are linked to heavier consumption, greater dependence, and increased risk of cannabis use disorder. As the cannabis industry continues to grow, these findings highlight the need for stronger regulation, targeted education, and sustained research to balance legalization’s benefits with its potential harms.
Free, Online Toolkit for Partnering with Communities in Substance Use Research
Chestnut Health Systems has released the final chapters of its free, online Community-Based Participatory Research (CBPR) toolkit, created to help researchers build meaningful partnerships through Community Boards of people with lived experience with substance use. This resource is informed by years of collaboration with individuals from the HEAL Connections Lived Experience Panel, the JEAP Initiative Community Boards, the CHEARR Community Boards, and the PATH Community Board.
Register now for the Police, Treatment, and Community Collaborative (PTCC) annual conference!
Registration is now open for the Police, Treatment, and Community Collaborative (PTCC) International Deflection & Pre-Arrest Summit, which will be held December 2-4, 2025 in New Orleans, LA. More information is available at: https://ptaccollaborative.org/2025-summit/. Specific topics of interest include innovative treatment programs, successful collaboration models, and strategies for supporting at-risk youth.
The Catalyst Podcast
Former Lit Prof Reinterprets the Employee Experience: a Conversation with Chestnut's Molly Robey
When former lit prof Molly Robey was teaching the works of the relatively little-known late 19th-century writer Charles W. Chestnutt - among other English writers equally and/or more prominent - she couldn’t have imagined the extent to which it foreshadowed her current work with Chestnut Health Systems.
Catalyst Poll
Chestnut Health Systems’ Lighthouse Institute is recruiting Emerging Adults (18-26 years old) facing challenges related to substance use, along with their parents, for a paid research study seeking feedback for a new recovery program called Launch. Participating families will receive Launch services at no cost, be compensated for virtual research visits, and there is no waitlist! Call or Text Alice Dawson today (541-251-8507) or fill out the form on the Launch Website for more information.
We scour all four corners of the Internet to bring you the week’s most insightful, relevant, and actionable articles, studies, and reports.
State Policy Approaches to Expand Naloxone Access. Naloxone is a lifesaving medication that can play a significant role in preventing deaths from opioid overdose. The medication blocks and reverses the effects of opioids by attaching to opioid receptors in the brain. Source: Pew Charitable Trusts
Study Finds that Giving Up Smoking Might Make It Easier To Overcome Substance Abuse Disorders. The findings highlighted that there was a 42% increase in the odds of an individual staying in recovery from their addiction to alcohol or drugs once they quit cigarettes for good. Source: Forbes
Bridging the ‘missing middle’: helping young people with moderate mental health support needs. Research team found significant achievements by a youth mental health service program in northern NSW that works with young people and improved their wellbeing, enhanced life satisfaction and sustained engagement. Source: Charles Sturt University
One Billion People Worldwide are Living with Mental Health Disorders. “Transforming mental health services is one of the most pressing public health challenges,” said Dr Tedros Adhanom Ghebreyesus, WHO Director-General. “Investing in mental health means investing in people, communities, and economies — an investment no country can currently afford to neglect. Source: WHO
Teacher-Delivered Mental Health Interventions: Promises, Challenges, and Recommendations for Future Directions. Teacher-delivered mental health prevention and intervention programs offer an opportunity to integrate mental health support meaningfully into students’ everyday lives, as well as expand the reach and impact of mental health services. Source: Research Gate
Barriers and Facilitators of Seeking Help for Mental Health Challenges Among Adolescents Across 13 Countries: A Qualitative Investigation. Adolescence is a period of developmental transition marked by a high prevalence of mental health challenges. The emergence of these challenges underscores the importance of encouraging help-seeking behaviors among adolescents to mitigate negative psychological outcomes. Source: Science Direct
Loneliness among emerging adults in rural reservation-based communities: longitudinal effects of 12th grade substance use and mental health symptoms. Loneliness is a growing public concern among emerging adults, yet little is known about its predictors in rural and reservation-based communities. This study examines whether substance use and mental health symptoms in 12th grade predict loneliness post-high school among a rural reservation-based sample. Source: Scientific Reports
Cannabis for coping? Why it may trigger paranoia. Using cannabis to self-medicate comes with hidden dangers—new research shows these users face higher paranoia and consume more THC. Childhood trauma further amplifies the risks, especially emotional abuse, which strongly predicts paranoia. Source: Science Daily
Genetic and environmental influences predict early adolescent alcohol use. Alcohol use during adolescence is associated with an increased risk for mental health disorders, cognitive impairments, and later substance use disorders. A new study led by Rutgers and published in Translational Psychiatry examined how genetic, psychological, and environmental factors contribute to the initiation of alcohol use and the transition from a first sip to a first full drink. Source: Contemporary Pediatrics
About Chestnut Health Systems’ Lighthouse Institute
Chestnut Health Systems’™ Lighthouse Institute was established in 1986. Our mission is to help practitioners improve the quality of their services through research, training, and publishing. Serving health and human service organizations through offices in Chicago and Bloomington/Normal, Illinois, and Eugene, Oregon, Lighthouse Institute staff conduct applied research, program evaluation, training, and consultation.
Lighthouse Institute publishes books, monographs, curricula, and manuals on various issues of behavioral health, education, and program management. Institute staff have backgrounds and expertise in addictions, business, education, management information systems, psychology, public health, rehabilitation, research methods, statistics, and social work. For more, visit https://www.chestnut.org/lighthouse-institute/