What is CBD?
Before exploring the scientific literature on CBD for anxiety, it's important to first understand what CBD is.
What is CBD? Cannabidiol, or CBD for short, is a type of cannabinoid found naturally in cannabis plants.
Thankfully it contains no psychoactive properties so you don’t have to worry about strange feelings of intoxication or dependence that you may experience with its cousin THC! (Tetrahydrocannabinol).
The cannabinoid is commonly taken in the form of CBD oil as well as creams, balms or sprays.
Background
In 1940, for the first time, ever CBD was first extracted from Cannabis in the laboratories of R. Adams and colleagues in the U.S.A.
Multiple animal studies were then conducted in the late 20th century and onwards, to assess the efficacy and safety of the drug. Many of these studies found that at a particular dose, CBD was shown to be safe and highly effective in reducing anxiety for Rats and Mice. (1) (2) (3) (4) (5) (6)
This led to the approval and research in multiple human studies described below.
Human studies
In 2004, a double-blind placebo-controlled crossover study involving 10 healthy male volunteers, tested the hypothesis that CBD would affect neural activity in areas that normally mediate anxiety. Anxiety was temporarily induced when tracer injections and scanning procedures were performed. Brain images in the CBD group suggested that the relaxation that they reported may have been caused by the effect of CBD on activity in the limbic and paralimbic brain system. These areas of the brain are associated with emotional processing, memory, and cognitive processes. (7)
CBD and Social Anxiety Disorder
The original study that first hypothesised and tested the anti-anxiety effects of CBD in humans was done in 1993 by A.W. Zuardi and colleagues. In the study, 18 males and 22 females aged between 20 and 30 years were recruited and asked to perform a simulated public speaking task. This was done to temporarily induce anxiety to allow the anti-anxiety effects of CBD to be measured.
They were then randomly selected to receive either the placebo or the drug. The results showed that individuals that took CBD had lower levels of stress-induced anxiety when compared with the placebo group. (8)
Later in 2010, Crippa and colleagues assessed the brain activity and anxiety of people with generalized social anxiety disorder. The results showed that CBD reduced anxiety in the participants and suggested that this is related to its effects on activity in the limbic and paralimbic brain areas. (9)
The following year Bergamaschi and colleagues conducted a randomised double-controlled trial involving 24 people with social anxiety, speaking in public in order to induce their anxiety.
Participants were randomly split into a CBD or a placebo group. Once their anxiety was induced, it was then self-reported and measured by assessing the person’s heart rate and blood pressure.
The results found that CBD significantly reduced anxiety, cognitive impairment and discomfort in their speech performance. The placebo group presented higher anxiety, cognitive impairment, and discomfort when compared with the control group. (10)
More recently in 2019, Masataka performed a randomized double-blind placebo study involving 37 Japanese adolescents with social anxiety disorder. The results showed that CBD significantly reduced anxiety unlike the placebo; there was no significant anxiety reduction found in the placebo group. (11)
CBD and Obsessive-Compulsive Disorder (OCD)
OCD is a type of anxiety disorder in which people have obsessive thoughts which make them feel driven to undertake repetitive and systematic behaviours in order to reduce anxiety or to avoid some feared outcome.
One randomised, placebo-controlled study of 14 adults conducted by Reilly and colleagues in 2019 assessed the effect of smoking cannabinoids with different concentrations of CBD and THC. The highest CBD concentration was 0.4% THC/ 10.4% CBD.
Surprisingly, the results showed that when compared to the placebo group, the reduction in anxiety was lower for all concentrations and that there was little acute impact on OCD symptoms. Further randomised control trials with larger sample sizes are needed to explain these findings. (12)
CBD and Post Traumatic Stress Disorder (PTSD)
PTSD is a type of anxiety disorder that arises when a person experiences a traumatic event and is manifested through hyperarousal, anxiety, depressive symptoms, and sleep disturbances.
In 2019 Lucas and colleagues conducted a retrospective case series, examining the effect of oral CBD administration on symptoms of PTSD in 11 adult patients. During the case series, patients were also given psychiatric medications and psychotherapy. The results showed that 10 out of 11 patients showed a decrease in PTSD symptom severity. (13)
Whilst these results are promising, additional clinical investigation, including double-blind, placebo-controlled trials, is necessary to further substantiate the hypothesis of this study.
Summary of CBD for Anxiety
As of 2021 several human randomised controlled trials have suggested that CBD may be effective in treating anxiety, especially in relation to social anxiety disorder. The evidence accumulated from these studies is just the tip of the iceberg, and in the foreseeable future (within the next few years) we expect to see more studies with a greater sample size that reinforce the benefits of CBD for mental health.
Future Research
For people that suffer from the side effects of antidepressants like Sertraline, these studies offer a glimpse of a possible alternative. I’m especially looking forward to seeing new studies discussing if it is safe to take CBD with other medications at specific doses and highlighting any potential drug interactions that could arise.
This could also be useful for people that want to take CBD whilst lowering their antidepressant dose to minimise its side effects.
Since CBD was shown to reduce experimentally induced anxiety, another potential future hypothesis could be to determine if CBD is effective when combined with exposure therapy for anxiety disorders such as PTSD.
DISCLAIMER: Please consult your doctor before changing or coming off any medication.
References
1: https://pubmed.ncbi.nlm.nih.gov/28424834/
2: https://pubmed.ncbi.nlm.nih.gov/21867717/
3: https://journals.sagepub.com/doi/10.1177/0269881110389095
4: https://pubmed.ncbi.nlm.nih.gov/24321837/
5: https://link.springer.com/article/10.1007%2Fs00213-012-2878-7
6: https://academic.oup.com/ijnp/article/16/6/1407/754216
7: https://pubmed.ncbi.nlm.nih.gov/14583744/
8: https://journals.sagepub.com/doi/abs/10.1177/026988119300700112
9: https://pubmed.ncbi.nlm.nih.gov/20829306/
10: https://pubmed.ncbi.nlm.nih.gov/21307846/
11: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6856203/
12: https://pubmed.ncbi.nlm.nih.gov/32383271/
13: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6482919/
