Cannabis psychopharmacology: it’s more complex than you might imagine

January 29, 2016, 6:06 pm




The Cannabis sativa Versus Cannabis indica Debate: An Interview with Ethan Russo, MD. Cannabis and Cannabinoid Research 2016 Jan;1:44-46

Full Text

This short interview with Ethan Russo MD should be of interested to toxicologists and other clinicians who might counsel patients on issues regarding medical marijuana. It contains some interesting information about the different biologically active chemicals contained in cannabis plants, and their effects. These chemicals include:

  • Δ9-tetrahydrocannabinol (THC) – main psychoactive chemical in Cannabis
  • cannabinol – breakdown product of THC with approximately 25% of its potency
  • tetrahydrocannabivarin (THCV)CB1-receptor antagonist at low doses, agonist at high doses
  • cannabidiol (CBD) – component with anti-depressant and anti-inflammatory effects

There are also many additional components of cannabis that may increase or modify the effects of these major chemicals. These include terpenes such as myrcene — a strong sedative that may be responsible for the couch-lock effect caused by some strains of cannabis — and alpha-pinene, a component that may counter the tendency of THC to impair short-term memory.

Dr. Russo argues that while Cannabis sativa and Cannabis indica strains are morphologically different, the common notion that sativa is “uplifting and energetic” while indica is sedating is completely wrong:

“. . .almost all Cannabis on the market has been from high-THC strains. The differences in observed effects in Cannabis are then due to their terpenoid content, which is rarely assayed, let alone reported to potential consumers. The sedation of the so-called indica strains is falsely attributed to CBD content when, in fact, CBD is stimulating in low and moderate doses!”

The psychopharmacology of Cannabis is turning out to be much more complex than initially. As the use of medical and recreational marijuana expands, it is important for clinicians to have a basic familiarity with the basic science involved. This informative open-access interview is a quick read and worth looking at.

Related post:

Effects of marijuana on driving ability


  1. milkshake Says:

    another major psychoactive terpene in cannabis is β-caryophyllene

  2. Leon Says:


    Thank you for the comment. Beta-caryophylline (BCP) is one of many other terpenes found in cannabis. It’s also found in food products such as black pepper, cloves, hops, and rosemary. I’m not sure it’s psychoactive, since the sources I’ve seen state that it is an agonist at the CB2 receptor. It may have anti-oxidant and anti-inflammatory properties.