Like full-spectrum CBD, products labeled as broad-spectrum contain multiple cannabinoids, which are purported to provide the therapeutic benefits of the entourage effect without the psychoactive effects of THC.
The review concluded that there is not enough evidence to support the use of CBD in the treatment of mental health conditions.
There are also three main types of CBD available.
However, the authors of the study note that while the substance has considerable potential, further research is needed to better determine the therapeutic benefits and long-term effects.
There are a number of conditions that CBD is purported to help, although more research is needed to determine the potential effects and benefits of CBD. Some of the existing studies suggest that CBD holds promise in the treatment of a number of conditions including depression, anxiety, epilepsy, and sleep issues, among other things.
CBD may potentially have an effect on your condition or may interact with a medication that you are taking. For example, CBD can sometimes worsen symptoms of anxiety. CBD can also interfere with the metabolism of certain medications, which may change how your medications affect your body.
Post-Traumatic Stress Disorder (PTSD)
There has been a growing interest in the potential mental health benefits of CBD in recent years. A 2019 research letter published by JAMA Network Open reported a significant increase in Internet searches for CBD in the United States. While search rates remained steady between 2004 and 2014, there was a 125.9% increase between 2016 and 2017. In April 2019 alone, there were 6.4 million Google searches for CBD information.
It is also important to note that while hemp-derived CBD that contains less than 0.3% THC is legal by federal law, it is still illegal in some states. You should always check your state laws before purchasing a CBD product.
Their antipsychotic, neuroprotective, anxiolytic, and sedating properties suggest a potential therapeutic role of CBD and nabiximols to treat various psychiatric disorders. The use of CBD at higher doses (above 1200 mg per day) showed promising results in case studies of schizophrenia and psychosis in patients with Parkinson’s disease, except in treatment-resistant cases. Regarding the use of CBD to treat anxiety disorders, its anxiolytic effect can help patients with PTSD-related and social performance-related anxiety, and nabiximols can reduce the anxiety associated with the onset of tics. There is also favorable evidence in patients with ASD for reducing hyperactivity, self-injurious behaviors, anxiety, and insomnia. Nabiximols showed no credible effect in the treatment of ADHD, while CBD was also found to be ineffective for bipolar disorder. Of all the cases examined, the strongest evidence was found for the treatment of cannabis-related disorders. The use of nabiximols yielded positive results in multiple studies of moderate to severe cannabis use disorder; however, the use of CBD alone has not been adequately documented outside a few cases and case series. Notably, CBD compounds were helpful in alleviating psychotic symptoms and improving cognitive impairment in patients across a variety of conditions.
Four of these studies evaluated the efficacy of nabiximols, and four others reported the use of CBD. The doses tested ranged from 20 mg CBD to a maximum of 1200 mg/day. Nabiximols was used in spray form at doses ranging from an average of 28.9 sprays/day (equivalent to 77.5 mg THC or 71.7 mg CBD) to 40 sprays/day (equivalent to 108 mg THC or 100 mg CBD). In CBD-only studies the dose of CBD ranged from 200 to 600 mg/day in divided doses. All three RCTs in this section provided evidence for the use of nabiximols for moderate to severe cannabis use disorder. These trials tested different doses of nabiximols ranging from 21.6 mg THC and 20 mg CBD (twice a day) to 113.4 mg THC or 105 mg CBD per day. All trials reported lower withdrawal rates, better tolerance, and retention rates in the experimental group. Moreover, no serious adverse effects were reported in any of these studies. In one RCT, nabiximols (total dose of 21.6 mg THC and 20 mg CBD at 4 and 10 in evening and night, respectively) was associated with marked improvement in cannabis withdrawal symptoms, leading to shorter withdrawal times and higher retention rates (Allsop et al., 2014). In a second RCT, a fixed dose of nabiximols produced more positive results compared to self-titrated administration (Trigo et al., 2016a). Patients in the fixed-dose group had four sprays of medications every hour compared to four sprays as needed every hour in self-titrated dose group. The maximum dose was 40 sprays/day in the self-titrated dose group. Medication intake was higher with fixed doses, which were associated with fewer withdrawal symptoms compared to the self-titrated regimen (Trigo et al., 2016a). In another RCT, the efficacy and safety of nabiximols were compared to a placebo while all participants also received weekly motivational enhancement therapy (MET) and cognitive–behavioral therapy (CBT) (Trigo et al., 2018). The dose range of 4.1 to 12.8 sprays/day was reported among nabiximols group. The withdrawal scores in this study were similar in both groups (Trigo et al., 2018). Only one of the studies reported decreased appetite, while the number and severity of adverse effects were not reported or observed in the other two RCTs.
The Oxford Centre for Evidence-Based Medicine 2011 Levels of Evidence was used to grade the quality of evidence (OCEBM, 2019). Level 1 evidence is for systematic review of RCTs or individual RCT of narrow confidence interval, Level 2 for cohort studies or systematic review of cohort studies, Level 3 for case-control studies or systematic review of case-control studies, and Level 4 for case-series for studies focused on therapy, prevention, etiology and harm (OCEBM, 2019). These levels of evidence are used to generate Grades of Recommendation. Grade A is for consistent level 1 studies, Grade B for consistent level 2 or 3 studies or extrapolations from level 1 studies, and Grade C for level 4 studies or extrapolations from level 2 or 3 studies. Grade D is ranked for level 5 evidence or inconsistent or inclusive studies of any level (OCEBM, 2019).
The present article provides a comprehensive review of the evidence supporting the use of CBD and CBD-containing compounds such as nabiximols to treat psychiatric disorders. CBD and nabiximols were effective in cannabis use-related disorders, and preliminary evidence was found in support of their use for other psychiatric disorders. Of the 23 studies reviewed here, level 2 evidence was found in eight RCTs, level 3 evidence in four open-label trials and one clinical trial, and level 4 evidence in one retrospective chart review, seven case reports, and two case series, according to the Oxford Centre for Evidence-Based Medicine 2011 Levels of Evidence (OCEBM, 2019). This review covers the evidence for different routes of administration, e.g. oral, inhalation spray, and sublingual. The bioavailability of these routes (11–13% for oral vs. 11–43% for inhalation) varies significantly – a factor that can impact the efficacy of different formulations.
Recommendations for future research
Cannabis sativa, a species of cannabis plant, is well known to humankind, with its earliest use in ancient Chinese culture dating as far back as 2700 B.C. (Zuardi, 2006). The use of medical cannabis in China was reported in the world’s oldest pharmacopoeia (Martin et al., 1999). However, interest in the role of cannabis flourished in the late twentieth century after the recognition of an endogenous cannabinoid system in the brain (Zuardi, 2006; Martin et al., 1999). More recently, research has centered on the description and cloning of specific receptors and the therapeutic effects of medical cannabis, and different cannabinoids in the cannabis plant have gained interest (Martin et al., 1999). Recent studies have focused on the therapeutic role of medical cannabis in different disorders. As a result, there is a growing need to summarize and review the evidence for its therapeutic and adverse effects as an aid to public health policy development, and to provide direction and impetus to pharmaceutical research in this field.
The therapeutic application of cannabidiol (CBD) is gaining interest due to expanding evidence for its use.
This review article has several limitations that should be considered. This review article provides evidence for CBD and CBD-containing nabiximols are two different pharmacological agents. Nabiximols has two active compounds and included studies do not consider the separate effects of THC VS CBD. There is need for future analyses to carefully consider their benefits individually. Only one-third of studies (8/23) in this review article are RCTs and most of these RCTs had a small sample size decreasing the power of the study to draw robust conclusions.
Results & discussion
The search of eight electronic databases and our manual screening method generated 511 results. After the removal of duplicates, titles and abstracts were screened, resulting in the exclusion of 459 articles. Full-text screening of 52 articles was performed, and 23 articles meeting the inclusion criteria were analyzed. Figure 1 summarizes the screening process.
Previous efforts to synthesize the evidence for medical cannabis use in patients with psychiatric disorders have been published (Hoch et al., 2019; Lowe et al., 2019). For example, Hoch et al. conducted an excellent systematic review that summarized four systematic reviews and 14 randomized controlled trials (RCTs), but did not consider non-clinical trial evidence (case reports and case series) (Hoch et al., 2019). A review by Mandolini et al. recently summarized the clinical findings from 14 studies of psychiatric disorders, but these authors did not provide information about nabiximols (Mandolini et al., 2018). In contrast to the review articles noted above, the present article aims to provide a more comprehensive review of the use of CBD and CBD-containing compounds such as nabiximols to treat psychiatric disorders. The present review included studies focused on schizophrenia, cannabis-related disorders, attention deficit hyperactivity disorder (ADHD), comorbidities in autism spectrum disorder (ASD), social anxiety disorder (SAD), other anxiety disorders, insomnia, bipolar disorder, post-traumatic stress disorder (PTSD), psychosis in Parkinson’s disease, and Tourette syndrome. This article broadly reviews the efficacy, safety, and psychiatric benefits of CBD and CBD-containing compounds (nabiximols). We distinguish clearly here between the clinical findings for CBD and nabiximols, as the latter also contains THC.