HUMAN use of the cannabis plant for medical purposes dates back thousands of years. The Ebers Papyrus, dating back to 1550 BC, describes its use to sooth inflammation in ancient Egypt. Archaeologists have unearthed evidence that it was being cultivated at this time in China, by which time, some say, its medicinal properties were probably already known. Cannabis is mentioned in Ayurvedic medicine texts from 800 BC from ancient India where practitioners used it to treat epilepsy, anxiety and rabies. Its use spread west and by the 19th century it was well known as a painkiller in Europe and sold in over-the-counter medicines in North America.


Maintaining bodily balance

While long-held, traditional beliefs about the healing powers of cannabis were mostly experience-based, today’s researchers have used modern scientific methods to identify the biological mechanisms involved. The plant contains dozens of different compounds called cannabinoids that have a variety of effects on the human mind and body. Delta-9-tetrahydrocannabinol (THC), for example, generates the “high” for which cannabis is best known.


Cannabidiol (CBD), another abundant component of cannabis plants, does not generate the changes in perception triggered by THC. Our current understanding of CBD is rooted in the discovery of the endocannabinoid system (ECS) three decades ago. This key molecular signalling system has roles in many core bodily functions, from metabolism, pain and motor control, to sleep, stress and the cardiovascular system.


Researchers are still working to understand the ECS, however many highlight what is thought to be its central role in maintaining homeostasis. In other words, it helps keep internal conditions such as temperature, water content and blood sugar levels stable and optimal in response to external changes. The ECS does so by synthesizing chemicals called endocannabinoids, which, by binding to cannabinoid receptors, set in train changes in the body.


A multitasking molecule

CBD is known as a pytocannabinoid because of it plant origins. Like endocannabinoids, it interacts with the two known cannabinoid receptors CB1 and CB2. Scientists are still trying to figure out some of the details of how CBD interacts with the ECS, however research shows it inhibits an enzyme that breaks down anandamide, an endocannabinoid that, as well as being produced in the body, is found in chocolate and black truffles. Sometimes described as the “bliss molecule” or the body’s natural antidepressant, anandamide was named after the sanskrit for divine joy.


Beyond helping anandamide stick around for longer, CBD also binds to 5-HT1A serotonin receptors, which have roles in mood, anxiety and depression. Scientists believe its interactions with yet another receptor, called GPR55, explain CBD’s ability to counter some epileptic symptoms. Purified CBD has been approved by drug regulators in the US and Europe as a way to reduce the frequency of seizures in certain forms of childhood epilepsy. 


Beyond epilepsy, many scientists believe CBD has effects on other functions and sensations including pain, mood, memory, sleep and digestion. While work to determine its precise impacts and the best ways to deliver them is ongoing, a growing body of research points to potential benefits as part of a holistic approach to maintaining health and wellbeing.


The latest from the lab

In a study published in 2015, for example, scientists at the New York School of Medicine who reviewed previous animal research concluded CBD has potential as a treatment for generalized anxiety disorder, panic disorder, social anxiety disorder (SAD), obsessive–compulsive disorder, and post-traumatic stress disorder. Their findings underlined those of researchers in Brazil who asked people with SAD to do a simulated public speaking test. Half were given a large single dose of CBD and half a placebo 90 minutes beforehand. Participants were “blinded”, meaning they didn’t know which group they were in. Self assessment scores and psychological measurements showed those who took CBD had much lower levels of anxiety, cognitive impairment and discomfort during the test than those given placebos.


Another group assessed the experiences of 72 adults attending a psychiatric clinic in Colorado, US, as outpatients who were given CBD for anxiety or sleep problems. All but a handful took doses of 25mg daily. After one month, anxiety scores declined significantly, with four in five reporting feeling less anxious. Two-thirds of participants reported sleeping better, however the improvements were modest.


In another study published last year, Graham Gulbransen, a GP and addiction specialist carried out an audit of 400 patients prescribed CBD oil at his clinic in Auckland, New Zealand. Almost half presented with pain symptoms, while others were treated for conditions including anxiety, depression, insomnia, neurological problems and cancer-related symptoms. After around a month of treatment, self-reported scores for pain, anxiety and depression among a subset of 110 who completed before and after questionnaires were on average lower. Patients rated their overall health to be on average 13.6 points higher on a scale of 0-100.


“I have found CBD to be very effective for anxiety,” says Dr Gulbransen, who has now prescribed 

CBD oil to around 1600 patients, and plans to publish a larger clinical audit later his year. “For people reporting different forms of anxiety, including social anxiety, performance anxiety and panic attacks, it seems very helpful in relieving or preventing their symptoms. I sometimes prefer the phrase emotional distress, because anxiety and depression often occur together. CBD can also provide relief for patients with chronic pain, especially those with fibromyalgia, in my experience.”


In another study published in 2020, researchers at Samford University in Birmingham, Alabama, reviewed previous research on the use of CBD to treat generalized anxiety disorder, social anxiety disorder, and post-traumatic stress disorder. The group found that: “CBD consistently demonstrated improved clinical outcomes”.


However, the doses used varied from 6mg to 400mg. The researchers said more large-scale clinical trials were needed to establish optimal dosing and evaluate the long-terms effects on anxiety disorders. Identifying the best doses of CBD to recommend at a population level is difficult. Not only does it vary according by conditions and symptoms, but also other factors such as individual genetics.


Science meets history

Beyond the rare epileptic conditions for which CBD has been approved, researchers still have some way to go to convince regulators of its merits in other circumstances. Scientific research has been slowed by the legal barriers and social taboos around cannabis. As some legislators adopt more nuanced approaches to the different chemical constituents in cannabis, scientists are filling in the gaps in our knowledge about CBD and its effects. While far from complete, the emerging picture seems to fit not only with the anecdotal reports from growing number of modern CBD users, but also with some of the lessons passed down the generations from our ancestors.