What Have We Learned? A Summary of 20 Years of Marijuana Research


In October 2014, a 20-year study into the effects of recreational marijuana use was published in the scientific journal Addiction. The study, conducted by Dr. Wayne Hall of The University of Queensland Centre for Youth Substance Abuse Research, looks at evidence and marijuana research from 1993 to 2013 and provides extensive analysis on the adverse physical, emotional, and social health effects of chronic cannabis use. With the increase in recreational and medical marijuana states after the 2016 election, the study has once again begun making the rounds on Facebook and Twitter.

Dr. Wayne Hall’s 20 Year Study

Prior to Dr. Hall’s study, a majority of research into the impact of regular cannabis use focused on animal studies and the effect of marijuana on college students after 7-35 days of use. More recently, the rapidly increasing number of smokers has meant there are more users to study, making an extensive investigation like Dr. Hall’s possible. And, the increasing strength of marijuana (up to 4 times stronger than weed just 30 years ago) suggests that research from the 1970s and 80s may not accurately represent the effects of cannabis use today.

So, what did we learn from the 20-year study?

Risk of a Fatal Overdose is Extremely Low

In 1993, studies found it would take somewhere between 15-70 grams of marijuana to trigger an overdose, and that number remains accurate. You would have to consume half an ounce in a day to be at risk – a number that even the heaviest cannabis user is never likely to reach.

Driving While High Doubles the Risk of a Crash

Scientists and policy-makers have long suspected that cannabis use impaired driving ability, and now they have evidence. Driving after or while consuming marijuana approximately doubles your likelihood of being in a car crash.

Cannabis Addiction Isn’t a Myth

Cannabis isn’t a highly addictive drug, like heroin or nicotine. But, that doesn’t mean cannabis users can ignore the risks of addiction. According to Dr. Hall’s study, 1 in 6 adolescents and 1 in 10 adults who regularly consume marijuana will develop a dependency.

Still Unclear if Cannabis is a “Gateway Drug”

Dr. Hall’s study found that there is a correlation between cannabis use and the use of other illicit drugs. But, that doesn’t mean that smoking marijuana causes someone to use other drugs. Rather, many scientists argue that the factors that often lead a person to begin using marijuana (peer pressure, low self-esteem, a desire to escape stress or conflict, etc) are the same that contribute to drinking alcohol or taking other drugs.

Cannabis Smoke May Increase Risk of Cardiovascular Disease

Analysis indicates that smoking marijuana likely increases the risk of cardiovascular disease, but there are a few variables that have made this particular health impact harder to study. Many marijuana smokers previously or currently smoke tobacco, for example, muddying the results of studies into respiratory function and respiratory cancer.

Effects of Long-Term Use on an Individual

Another long-term study tracked the health of more than 1,000 cannabis users in New Zealand over more than 20 years. Conducted by Dr. Madeline Meier of Arizona State University and published in JAMA Psychiatry, the study looked at gum disease, lung function, inflammation (allergies), and metabolism of chronic users. And, while Dr. Meier didn’t find long-term cannabis use to be associated with any specific set of physical health problems in early midlife, there was a correlation between cannabis consumption and periodontal disease. It isn’t that marijuana smoke wreaks havoc on the gums, but many long-term smokers are simply less likely to brush their teeth or floss.

Boulder’s First Recreational Marijuana Dispensary

Karing Kind is Boulder’s first recreational marijuana dispensary. We have been a part of the growing cannabis industry in Colorado from the beginning, and we look forward to continuing to grow and serve Colorado residents and visitors. Our wide selection of clean-grown bud, pure concentrates, and incredible edibles – including our state-low marijuana tax rate and award-winning budtenders – makes us the ideal Colorado cannabis destination.

Karing Kind is located just off of US-36, one mile north of Broadway, open daily from 9am to 10pm.

While we carry a variety of strains, concentrates, edibles, salves and tinctures, inventory and stock levels fluctuate from week to week and month to month. Check our menu and follow us on Twitter for an up-to-date list of edibles, concentrates and buds available now.