Scientists at São Paulo State have shown that a non-psychoactive component of cannabis called cannabidiol (CBD) can reduce symptoms of depression over a sustained period. In fact, the ingredient is so powerful that just one dose was enough to see benefits lasting a full week – at least in mice. The results of the study were published in the journal Molecular Biology earlier this year.
You may have heard quite a bit about CBD over the past year. In June, the FDA approved a cannabidiol oral solution for the treatment of two rare and debilitating forms of epilepsy. In November, cannabis-based medicinal products were made available on the NHS. Again, primarily for the treatment of epilepsy. But studies also have linked CBD to various other conditions, including chronic pain, nausea associated with chemotherapy, and even psychosis.
Unlike tetrahydrocannabinol (THC), the cannabis compound primarily responsible for getting you high, CBD can actually suppress some of the psychoactive properties of the plant. That means that while CBD supplements may offer you certain health benefits, it probably won't get you high.
To test its effect on depression, the researchers adopted an animal model, using rats and mice bred to develop depressive symptoms. The rodents (367 in total) were given a 7, 10 or 30 milligram/kilogram dose of cannabidiol before being submitted to tests designed to monitor their reaction to stress, for example, the forced swimming test.
The results suggest that the cannabidiol was both fast-acting and sustained – a single dose offered not just immediate relief, but persistent relief for seven days (something that cannot be said for conventional antidepressants). This effect was supported by the increase in synaptic proteins in the prefrontal cortex, which is strongly associated with depression in humans, one week after treatment.
"In light of this finding, we believe cannabidiol rapidly triggers neuroplastic mechanisms that help repair the neuronal circuitry that gets damaged in depression," study author Samia Joca from Aarhus Institute of Advanced Studies, Netherlands, and the University of São Paulo, Brazil, said in a statement.
What's more, a second study, published in the Journal of Psychopharmacology, suggests that CBD also effects the neuroplastic mechanisms in the hippocampus, which is, again, associated with depression in people.
While this is all extremely encouraging, the results so far have only been proven in rodents. The researchers will have to take the study to human trials to confirm CBD's efficacy in people, but they remain optimistic that this discovery could pave the way for more effective antidepressants in the future.
Currently, there are more than 300 million people affected by depression globally and, if the latest stats are anything to go by, this figure is only rising. While anti-depressants are an effective and invaluable treatment for millions of people worldwide, they don't always work. The researchers hope that CBD may offer a solution.
"We're studying whether cannabidiol would also be effective in patients who don't respond to conventional therapy and whether combining it with antidepressants would improve their symptoms," said Joca.
She added, "there's a possibility that combining cannabidiol with SSRIs [selective serotonin reuptake inhibitors] might allow the latter to be used in lower doses, perhaps reducing their adverse side-effects while maintaining the therapeutic effect of higher doses."