Surprising Research on Cannabis

Photo by Rick Proctor on Unsplash

Photo by Rick Proctor on Unsplash

Much of what we think we know about cannabis may soon change as a result of new research that uncovers some surprising facts. Indeed, the topic, which can be emotionally charged, is the focus of intense scientific study. Is cannabis good for you? Is it addictive? What long-term harms can use cause? The answers to these questions are multi-layered and not always clear-cut, which is why cannabis research continues with even more urgency.


Current estimates are that one in 10 cannabis users will develop cannabis addiction or dependence. The potency of the delta-9-tetrahydrocannabinol (THC), the main psychoactive constituent in marijuana, in today’s cannabis is much higher than in years past. Besides traditional marijuana use, designer drugs created from synthetic cannabinoids are growing in popularity – along with increased concern for their unknown addiction potential and negative health effects. According to a report from the European Monitoring Centre for Drugs and Addiction, at least 169 different synthetic cannabinoid compounds have been discovered since detection of the market’s first synthetic cannabinoid in 2008.

Using gene-based testing, four genes have been identified that are significantly associated with lifetime cannabis use:

  • Neural cell adhesion molecule 1 (NCAM1) – which is also associated with substance abuse
  • Cell adhesion molecule 2 (CADM2)
  • Potassium sodium-activated channel subfamily T member 2 (KCNT2)
  • Short coiled-coil protein (SCOC)

While vulnerability to starting cannabis use and developing cannabis use disorder (CUD) is heritable, other risk factors are believed to speed the transition. These risk factors include:

  • Age of first use of cannabis
  • Drug use by peers
  • Availability of drugs
  • Lower socioeconomic status
  • Childhood sexual abuse
  • Early adolescent smoking and/or drinking
  • Presence of pre- or comorbid psychiatric conditions — including mood disorders, psychosis, attention-deficit hyperactivity disorder (ADHD)

Other studies found certain biological and personality traits – such as impulsivity, sensation-seeking, and schizotypy – are positively correlated with youths and young adults initiating cannabis use.


Comprehensive research published in Frontiers in Behavioral Science outlines some fascinating details of the differences between men and women when it comes to the effect of cannabis. The bottom line is that women are more likely to become addicted to cannabis than men. In addition to genetic background and fluctuations in hormones, here are some of the study’s findings, using animal models:

  • Men are four times more likely than women to try cannabis.
  • Men are also more likely to use cannabis more frequently than their female counterparts.

The male sex steroids (including natural sex steroid testosterone and synthetic steroids such as nandrolone) increase risk-taking and suppress the reward system in the brain. This could explain why men are more willing to experiment with drugs, including cannabis.

Women, on the other hand, seem to be more vulnerable to developing an addiction to cannabis, at least on a neurochemical level. To put it plainly, females can transition from first use to habit more rapidly than men. The rodent studies showed researchers that the female hormone estradiol affects three targets of drug-taking: control of movement, filtering of sensory input to the brain, and social behavior. This occurs through modulation of the endocannabinoid system which, in turn, influences the production of estradiol.

In addition to different levels of endocannabinoids, female rats have more sensitive receptors than males in the specific brain areas related to the three drug-taking targets – plus, significant changes along the female rats’ menstrual cycle.

Researchers noted that the result is that “the interactions between the endocannabinoid system and brain level of dopamine – the neurotransmitter of ‘pleasure’ and ‘reward’ – are sex-dependent.”

They suggest that gaining a deeper understanding of how cannabinoids and sex steroids interact is both crucial to assess the effect of increasing cannabis use and to effectively deal with the results. For example, cannabis addiction detoxification treatments and relapse prevention may be gender-tailored for better effectiveness. Still, much further research needs to be done to make evidence-based progress in this area.


For the millions of Americans suffering with chronic pain, there’s promising research that shows that pinpointing an effective dose of cannabidiol (CBD), an extract from the marijuana plant can provide safe relief from chronic pain minus the adverse effects of THC from marijuana. Researchers from Canada’s McGill University Health Centre, using animal models and administering low doses of CBD over a period of seven days reduced both pain and anxiety – two symptoms commonly associated with chronic or neuropathic pain. The researchers say this is encouraging evidence for the use of CBD over THC or opioids for pain management in conditions that include sciatica, diabetic cancer, back pain, chronic pain and pain that occurs post-trauma. CBD became legal in Canada in mid-October 2018, following passage of the country’s Cannabis Act. More robust clinical trials are needed, say researchers, for the kind of evidence-based proof of CBD’s effectiveness and safety to provide pain relief for humans.

In another study published in JAMA Psychiatry, researchers from Syracuse University found that cannabinoid drugs do not reduce the intensity of chronic pain, but they do perhaps make the pain feel more tolerable and less unpleasant. Even though 30 states allow medical marijuana use, cannabis is still a Schedule 1 Controlled Substance as classified by the Drug Enforcement Agency (DEA). This presents significant challenges for research into the therapeutic effects of cannabis. As a result, there is a lack of high-quality evidence supporting the effectiveness of cannabis in treating chronic pain.


In the largest known imaging study of the brain, researchers affiliated with several California institutions, including Amen Clinics, Inc., Google, Inc., UCLA Medical Center, UCSF Medical Center, and Johns Hopkins University in Baltimore, MD, found that cannabis use is one of the drivers of accelerated brain aging. Using brain SPECT (single photon emission computer tomography) to evaluate 30,000 scans from individuals ranging in age from 9 months to 105 years, researchers say they can now track common disorders and behaviors that prematurely age the brain. Schizophrenia, for example, contributed to an average 4 year early brain aging, while cannabis abuse accelerated brain aging by 2.8 years. Other disorders found to amp up brain aging were bipolar disorder (1.6 years), attention deficit hyperactivity disorder (ADHD) (1.4 years), and alcohol abuse (0.6 years). Researchers pointed out that the results of this study should give everyone pause, especially considering the current cultural perception that cannabis use is innocuous. They added that better treatment of these disorders could slow or even halt the brain aging process.


The most prevalent detected intoxicant in drivers in the United States isn’t alcohol, it’s THC. Approximately 13 percent of drivers tested positive for marijuana, compared with about 8 percent for measurable amounts of alcohol. Despite findings that cannabis intoxication (stoned driving) while driving impairs reaction time and visual-spatial judgement, a plurality of cannabis users believe that cannabis has no effect or decreases crash risk, while only 38 percent think that driving under the influence of cannabis increases crash risk. This underestimation of risks of cannabis intoxication plus current cannabis consumption trends suggest cannabis-impaired driving may significantly contribute to highway injury and death. Alcohol and other drugs combined with cannabis use may “more than additively” increase highway risk.


Research published in the American Journal of Psychiatry found that adolescent cannabis use is associated with concurrent and lagged effect on cognitive functioning, such as working memory, memory recall, perceptual reasoning, and inhibitory control. The lasting effects of cannabis use on inhibitory control is particularly concerning, since inhibitory control is a risk factor for other addictive behaviors. Early onset of cannabis use during adolescence results in even more pronounced cognitive and behavioral effects. Researchers highlighted the importance of protecting youth from the adverse consequences of cannabis consumption through more investment in drug-prevention programs.


Research published in the European Journal of Cardiology has found a three-fold increased risk of death from hypertension due to cannabis use. Compared to non-users, marijuana users had a risk of hypertension death that was 3.42 times higher – and an additional 1.04 greater risk for each year of cannabis use. Researchers pointed out that this finding is not surprising, considering that marijuana use is known to have multiple effects on the cardiovascular system, including increases in heart rate, blood pressure and oxygen demand. Cases of heart attack and angina have been reported in hospital emergency departments after cannabis use. They cautioned that the cardiovascular risk associated with marijuana use may be even greater than the risk already established for cigarette smoking.

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This article was originally published on Psych Central.

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