Kava (Piper methysticum) and Anxiety: evidence and sources

Background Anxiety disorder is a common psychiatric illness. Medicinal herbs have become a field of interest in the treatment of anxiety. This study aimed to evaluate and compare the efficacy and acceptability of all possible medicinal herbs for the treatment of anxiety. Methods A Bayesian network meta-analysis was conducted for adults with diagnosed or subthreshold anxiety in randomized controlled trials identified in PubMed, EMBASE, the Cochrane Library, and Web of Science, searched between Jan 1, 1987, and Dec 31, 2021. The outcomes included efficacy (measured by endpoint Hamilton Anxiety Scale [HAMA] Scores) and acceptability (discontinuation by ineffectiveness, worsening of the symptoms, or adverse events). Results A total of 29 trials were reviewed, comparing 12 medicinal herbs. Silexan (mean difference [MD]: -3.84, 95% credible interval [CrI]: -6.31 to -1.34) displayed a significant effect on anxiety, and possibly benefitted the treatment of depression (standard mean difference [SMD]: -0.37, 95% confidence interval [CI]: -0.53 to -0.20) and insomnia (SMD: -0.48, 95% CI: -0.76 to -0.21). Kava was found to be an effective anxiolytic (MD: -2.46, 95% CrI: -4.47 to -0.32) but possibly ineffective in patients with generalized anxiety disorder (MD: -0.17, 95% CrI: -2.55 to -1.97). Ginkgo biloba (MD: -4.63, 95% CrI: -9.01 to -0.23) and Withania somnifera (MD: -4.90, 95% CrI: -9.70 to -0.17) were efficacious, as measured by HAMA scores but the trials were limited by their small sample sizes. Galphimia glauca (MD: -1.23, 95% CrI: -4.68 to 2.23) and Manasamitravn Vataka (MD: -1.35, 95% CrI: -7.39 to 4.68) exhibited the same anxiolytic effect as standard treatments, but both were absent from trials that were rated low risk, highlighting that confidence in their ability to provide an anxiolytic effect requires additional study. Conversely, although Passionflower (MD: -4.20, 95% CrI: -8.82 to 0.16) and Saffron (MD: -2.71, 95% CrI: -6.06 to 0.57) did not reduce HAMA scores significantly in the summary network, both were worthy of further study because of support from separate networks. There was insufficient evidence to confirm the effectiveness of Valerian (MD: 0.95, 95% CrI: -6.57 to 8.42) in standard-controlled estimation or the ineffectiveness of Chamomile (MD: 0.54, 95% CrI: -5.13 to 6.25) compared with a placebo for anxiety. Gamisoyo-san (MD: -0.98, 95% CrI: -6.48 to 4.54) and L-theanine (MD: -0.49, 95% CrI: -6.54 to 5.57) did not outperform a placebo for the treatment of anxiety in terms of statistical certainty. All medicinal herbs were well-tolerated and exhibited a good safety profile compared with control groups. When all herbs were compared, there was no statistical evidence to suggest any comparison significantly reduced HAMA scores except Ginkgo biloba vs Kava (MD: -4.41, 95% CrI: -8.32 to -0.35), although Ginkgo biloba was ranked as worst due to its poor tolerability. Conclusion Medicinal herbs may be promising for the treatment of anxiety. However, these results should be considered preliminary because of the unconvincing sample sizes, together with the potential effectiveness of placebos.

This paper provides a 10-year update of the 2007 systematic review of herbal medicines studied in a broad range of psychiatric disorders, including depression, anxiety, obsessive-compulsive, seasonal affective, bipolar, psychotic, phobic, somatoform, and attention-deficit hyperactivity disorders. Ovid Medline, PubMed, and the Cochrane Library were searched for herbal medicines with both pharmacological and clinical evidence of psychotropic activity. This updated review now covers clinical trial evidence for 24 herbal medicines in 11 psychiatric disorders. High-quality evidence was found to exist for the use of Piper methysticum (Kava), Passiflora spp. (passionflower) and Galphimia glauca (galphimia) for anxiety disorders; and Hypericum perforatum (St John's wort) and Crocus sativus (saffron) for major depressive disorder. Other encouraging herbal medicines with preliminary evidence include Curcuma longa (turmeric) in depression, Withania somnifera (ashwagandha) in affective disorders, and Ginkgo biloba (ginkgo) as an adjunctive treatment in Schizophrenia. Although depression and anxiety are commonly researched, many other mental disorders still require further prospective investigation. Although the previous review suggested increasing the adjunctive study of select herbal medicines with pharmaceuticals, this was still only found to sparingly occur in research designs. Aside from this, future focus should involve the incorporation of more biomarker analysis, in particular pharmacogenomics, to determine genetic factors moderating response to herbal medicines.

Background Constraints on resources and time often render treatments for anxiety such as psychological interventions impracticable, while synthetic anxiolytic drugs are effective, but are often burdened with adverse events. Options which are effective and safe would be of considerable interest and a welcome addition to the therapeutic repertoire. Objectives To assess the effectiveness and safety as reported in rigorous clinical trials of kava extract compared with placebo for treating anxiety. Search strategy All publications describing (or which might describe) randomised, double-blind, placebo-controlled trials of kava extract for anxiety were sought through electronic searches on EMBASE, MEDLINE, AMED (British Library), CISCOM (Research Council for Complementary Medicine, London), Central/CCTR and CCDANCTR. The search terms that were used were kava, kawa, kavain, Piper methysticum and Rauschpfeffer (German common name for Piper methysticum). Additionally, manufacturers of kava preparations and experts on the subject were contacted and asked to contribute published and unpublished material. Hand-searches of relevant medical journals (Erfahrungsheilkunde 1996 - 2002, Forsch Komplementärmed Klass Naturheilkd 1994 - 2002, Phytomed 1994 - 2002, Alt Comp Ther 1995 - 2002), conference proceedings (e.g. FACT - Focus on Alternative and Complementary Therapies 1996 - 2002) and our own files were conducted. The searches were updated to August 2002. No restrictions regarding the language of publication were imposed. Selection criteria To be included studies were required to be randomised, controlled trials (RCTs), i.e. trials with a randomised generation of allocation sequences, and conducted placebo-controlled and double-blind, i.e. trials with blinding of patients and care providers. Trials using oral preparations containing kava extract as the only component (mono-preparation) were considered. Trials using single constituents of kava extract alone, assessing kava extract as one of several active components in a combination preparation or as a part of a combination therapy were excluded. Data collection and analysis Data were extracted systematically according to patient characteristics, interventions and results. Methodological quality of all trials was evaluated using the standard scoring system developed by Jadad and colleagues. The screening of studies, selection, data extraction, validation and the assessment of methodological quality were performed independently by the two reviewers. Disagreements in the evaluation of individual trials were resolved through discussion. Main results Eleven trials with a total of 645 participants met the inclusion criteria. The meta-analysis of six studies using the total score on the Hamilton Anxiety scale as a common outcome measure suggests a significant reduction in patients receiving kava extract compared with patients receiving placebo (weighted mean difference: 5.0, 95% confidence interval: 1.1 to 8.8; p = 0.01; n = 345). Adverse events as reported in the reviewed trials were mild, transient and infrequent. Reviewer's conclusions Compared with placebo, kava extract appears to be an effective symptomatic treatment option for anxiety. The data available from the reviewed studies suggest that kava is relatively safe for short-term treatment (1 to 24 weeks), although more information is required. Further rigorous investigations, particularly into the long-term safety profile of kava are warranted.

Synthetic anxiolytic drugs are effective for treating anxiety, but they are burdened with adverse effects. Constraints on resources and time often render therapies such as psychologic interventions impracticable. Thus, an effective oral medication with few adverse effects would be a welcome addition to the therapeutic repertoire. This systematic review and meta-analysis was aimed at assessing the evidence for or against the efficacy of kava extract as a symptomatic treatment for anxiety. Systematic literature searches were performed in the computerized databases MEDLINE, EMBASE, BIOSIS, AMED, CISCOM, and the Cochrane Library (all from their respective inception to June 1998). The search terms used were kava, kawa, kavain, Piper methysticum, and Rauschpfeffer (German term for Piper methysticum). Experts on the subject were contacted to provide further information. There were no restrictions regarding the language of publication. Double-blind, randomized, placebo-controlled trials of oral kava extract for the treatment of anxiety were included. All publications were blinded before assessment by a person not involved in the study. Data were extracted in a standardized, predefined fashion independently by the two reviewers. The methodologic quality of all trials was assessed. Superiority of kava extract over placebo was suggested by all seven reviewed trials. The meta-analysis of three trials suggests a significant difference in the reduction of the total score on the Hamilton Rating Scale for Anxiety in favor of kava extract (weighted mean difference, 9.69; 95% confidence interval, 3.54-15.83). These data imply that kava extract is superior to placebo as a symptomatic treatment for anxiety. Therefore, kava extract is an herbal treatment option for anxiety that is worthy of consideration.

Objectives To report on the design, significance and potential impacts of the first documented human clinical trial assessing the anxiolytic and thymoleptic efficacy of an aqueous mono-extract of Piper methysticum (kava). The significance of the qualitative element of our clinical trial is also explored. The Kava Anxiety Depression Spectrum Study (KADSS) is a 3-week placebo-controlled, double-blind, cross-over trial involving 60 adult participants (18-65) with elevated stable anxiety and varying levels of depressive symptoms. Aims The aims of KADSS are: (1) to determine whether an aqueous standardised extract of kava is effective for the treatment of anxiety; (2) to assess the effects of kava on differing levels of depression; and (3) to explore participants' experience of taking kava via qualitative research. The study also provides preliminary assessment of the safety of an aqueous extract of kava in humans. Conclusion If results reveal that the aqueous kava preparation exerts significant anxiolytic effects and appears safe, potentially beneficial impacts may occur. Data supporting a safe and effective kava extract may encourage a re-introduction of kava to Europe, UK and Canada. This may provide a major socioeconomic benefit to Pacific Island nations, and to sufferers of anxiety disorders.

Prior to the kava ban of 2002, the indication for kava extracts defined by the German Commission E was "nervous anxiety, tension and restlessness". In 2000, an observational trial was started in Germany with the aim of defining symptoms of these indications best treated with kava extract. The trial was interrupted and archived "unevaluated" in 2001 due to the upcoming safety debate on kava. The data from this study has now been analyzed in order to identify symptoms best treated with kava. Documentation was available from 156 patients. Twelve typical symptoms of nervous anxiety, tension and restlessness were assessed on a five-item rating scale, together with the therapeutic context, the perceived time of onset of effects and the safety of application. The median duration of treatment was 28 days. All individual symptoms showed significant and clinically relevant improvements. The most effective results were seen for nervous tension and restlessness, with better effects in patients with acute versus chronic complaints. The safety of the treatment was found to be excellent, which included the assessment of laboratory data. Overall, the study confirms the effective and safe short-term use of kava in the Commission E-defined indication of "nervous anxiety, tension and restlessness", especially in other than chronic cases. The clinical use of kava might be translated into context-related phobias according to ICD-10 F40, or to nervous tension (ICD10 R45.0) or restlessness and excitation (ICD-10 R45.1).