CBD for anxiety: style over science

Why CBD for anxiety and why now?

The legalisation and mainstreaming of cannabis around the world has opened the door to cannabis-derived healthcare products like CBD. CBD is a chemical compound found naturally in the cannabis plant that does not get you high – THC is the psychoactive component.

Cannabis is the most widely used illegal drug in the world. Recently, there has been a small but significant global push to change the law and make cannabis legal to consume. A few countries have legalised the drug for recreational use (e.g. Canada, Uruguay) but the majority have looked again at cannabis because of its medicinal benefits. Medical cannabis is now legal in 27 countries and 37 US states and has been used to treat conditions like chronic pain and muscle spasms and nausea in chemotherapy patients. Since cannabis as a medicine is becoming part of the social consciousness, governments, policymakers and scientists are taking a second look at CBD’s potential benefits too.

Although it’s unknown how CBD affects the brain, scientists have theorised it could increase serotonin levels (a neurotransmitter involved in mood, sleep, pain, and appetite). Low serotonin levels have been associated with anxiety, so if CBD boosts serotonin, this could reduce anxiety.

CBD’s newly minted popularity can also be traced to the past few years. The pandemic has aided and abetted mental health problems, especially anxiety, which have almost doubled from pre-pandemic levels in the UK. Anxiety and anxiety-related disorders are the most common mental health issues in the United States with an estimated 31% of American adults experiencing these conditions in their lifetime. Mental healthcare systems have yet to catch up and sufferers are understandably searching for solutions. Add rocketing anxiety levels to the early mainstream adoption of cannabis and voilà – CBD touted as a cure for anxiety.

The scientific evidence

Neuro-imaging studies have found evidence to suggest that CBD reduced blood flow in certain areas of the brain implicated in anxiety but this did not link with reported anti-anxiety effects.

Studies performed with ‘healthy’ participants (i.e., anyone without a diagnosable physical or mental health condition) have produced mixed results. Four studies found that when anxiety is measured before and after a CBD dose, the drug has no effect for healthy participants. However, CBD did seem to reduce anxiety when healthy participants completed an anxiety-inducing task (either a simulated public speaking task where participants give a presentation to a camera or going inside a claustrophobic brain scanner). The same anti-anxiety effect was found in participants with social anxiety disorder. So, the early evidence indicates CBD reduces anxiety when there is a specific trigger for that anxiety, like public speaking, and this holds true for people with and without an anxiety disorder.

Yet a note of caution should be struck. CBD studies are relatively few and far between, and certainly not plentiful enough to build a solid evidence base. There are also a number of problems with the existing studies we have.

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Problems with CBD studies

Problem 1. Not enough people!

CBD studies tend to recruit very low numbers (one study had just eight participants) – whereas researchers have argued at least 100 participants are needed. If there aren’t enough people in the study, this makes the sample less representative of the population, and the study is more likely to miscalculate the effect – either giving a false positive (saying CBD treats anxiety when it does not) or a false negative (saying CBD does nothing for anxiety, when it does). Not recruiting enough participants also poses a problem when CBD studies use multiple statistical tests (which they often do). If you run multiple statistical tests and your sample size is too small, you are more likely to find a positive effect for CBD regardless of whether it's actually making a difference.

Problem 2. Not enough people with anxiety

The majority of studies have worked with ‘healthy’ participants and these findings do not necessarily translate to people with a clinical diagnosis of anxiety. If CBD helps people manage everyday feelings of worry, this indicates CBD might be useful for people who experience clinical anxiety, but is no guarantee. There could be crucial differences between these two populations which affect the impact of CBD, and until more studies are performed with clinical populations, we simply don’t know.

Problem 3. Hard to translate to real life

Where CBD has an effect on anxiety, the anxiety is acute and induced (e.g., a simulated public speaking task) and therefore hard to translate to everyday use of CBD. Will CBD maintain and build its effect cumulatively, or is it best as an ad-hoc solution? Besides, the simulated public speaking task could also struggle to translate to the real world, as the task doesn’t have the same physiological signs of anxiety as an actual public speaking test.

Problem 4. CBD for sale is not the right dose

CBD doses are very high in studies (300mg or more) compared to the generic over-the-counter dose (around 20mg). This means that many CBD consumers are taking doses 15 times smaller than the therapeutically active dose.

Conclusion.

So, CBD might reduce situation-specific anxious feelings if taken at high enough does, but this evidence is preliminary and subject to change.

Why are anecdotal reports of CBD so positive?

The placebo effect. We all know it exists but how powerful is it really? The reality is that a placebo has a huge impact. An eye-opening study analysing the effect of antidepressants revealed that only 18% of the response is due to antidepressants’ pharmacological effects; 82% was attributed to the placebo effect. If the placebo effect is doing most of the work for an FDA-approved treatment, imagine its explanatory power for an over-the-counter supplement that has not undergone extensive testing.

Another explanation for the abundance of positive CBD testimonials is that someone rarely tries just one solution to alleviate anxiety. It is much more common to try a few different things at once: maybe kickstart a new exercise regime, meditate and add a couple of drops of CBD oil to their morning coffee. If their anxiety then improves, it’s hard to distinguish which treatment is producing the anti-anxiety effect.

Summary - Make better use of your money!

The most promising evidence for CBD centres on doses of 300mg or more for an anxiety-inducing situation like public speaking, although even these studies are still in their infancy. CBD is expensive in whatever form it is consumed – oil, powder, vaping, gummies, drinks etc. To replicate the active therapeutic doses in clinical trials would cost around £23 or $30 dollars a pop on the commercial market. This is simply out of reach for most consumers. So, rather than spending a lot of money on an unproven product, consider treatments that are more effective or less expensive: talk therapy (especially cognitive behavioural therapy), anti-anxiety medications, exercise and meditation, to name a few.

To recap, there doesn’t seem to be any harm in trying CBD (excluding the financial cost). However, CBD’s weak evidence base and the existence of other scientifically backed treatments makes CBD products a hard sell.