Neurocognitive effects of kava (Piper methysticum): A systematic review

Brain Sciences Institute, University of Technology, Melbourne, Victoria, Australia.
Human Psychopharmacology Clinical and Experimental (Impact Factor: 2.19). 03/2011; 26(2):102-11. DOI: 10.1002/hup.1180
Source: PubMed


Kava (Piper methysticum) elicits dose-dependent psychotropic effects and thus may potentially deleteriously affect cognitive performance. Clinical trials have assessed the effects of kava on cognition, however, to our knowledge no systematic review has been conducted in this area.
To systematically review the effects of kava on cognition, providing an analysis of the individual study's methodological quality, results and effect sizes.
A systematic review was conducted of publications up to June 15th 2010, using the electronic databases MEDLINE, PsychINFO, CINAHL, Web of Science and The Cochrane Library. The search criteria involved kava and cognition related terms, e.g. memory and attention.
Ten human clinical trials met inclusion criteria (acute n = 7, chronic n = 3). One acute study found that kava significantly improved visual attention and working memory processes while another found that kava increased body sway. One chronic study found that kava significantly impaired visual attention during high-cognitive demand. Potential enhanced cognition may be attributed to the ability of kava to inhibit re-uptake of noradrenaline in the pre-frontal cortex, while increased body sway may be due to GABA pathway modulation.
The majority of evidence suggests that kava has no replicated significant negative effects on cognition.

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    • "In dem darauf folgenden Widerspruchsverfahren , das ein Ruhen der Zulassung des Medikaments nach sich zog, konnten von den betroffenen pharmazeutischen Unternehmen keine neuen Wirksamkeitsbeweise für Kava vorgebracht werden, die die Wirksamkeit von Kava in dem Maße belegten, dass die hepatotoxischen Wirkungen vertretbar wären. Deshalb wurde die bis dahin ruhende Zulassung 2007 endgültig widerrufen (LaPorte et al. 2011; Frohne 2002; BfArM 2002; BfArM 2007 "
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    ABSTRACT: Die Bewohner der südpazifischen Inseln benutzen die Kavapflanze (Piper methysticum) traditionell zur Herstellung eines Getränks mit entspannender Wirkung. Seit den 1990er Jahren ist Kava auch in den westlichen Län-dern populär und wurde in Europa und Amerika als Arzneimittel vor allem in Tabletten-und Kapselform bei Angststörungen angewendet. Kava zeigt am Menschen angstlösende und schlafverbessernde Effekte, an Tieren konnten unter anderem sedieren-de, antikonvulsive und zentral muskelrelaxierende Wirkungen nachgewiesen werden, die auf Kavalac-tone als Hauptinhaltsstoffe von Kava zurückgeführt werden. Bereits im Jahre 2002 verlor Kava die Zulas-sung als Arzneimittel aufgrund nicht unerheblicher Nebenwirkungen, vor allem Leberschädigungen. Testbestellungen und Untersuchungen haben gezeigt, dass als Arzneimittel einzustufende Produkte mit pharmakologisch wirksamen Konzentrationen an Kavalactonen weiterhin über den Internethandel als vorgebliche Nahrungsergänzungsmittel illegal an den deutschen Verbraucher abgegeben werden. Die natürliche Herkunft wird werblich als Vorteil gegenüber synthetischen Tranquilizern hervorgeho-ben. Die kürzlich erfolgte Einstufung von Kava durch die International Agency for Research on Cancer (IARC) der WHO als ,,möglicherweise krebserregend für den Menschen'' (Gruppe 2B) verleiht einer verstärkten Kontrolle des Internethandels mit Kava-Produkten besonderen Nachdruck. Abstract The inhabitants of the South Pacific islands traditionally use the kava plant (Piper methysticum) for producing a beverage with relaxing effects. Since the 1990s, Kava is also popular in the western countries and has been used in Europe and America in tablet and capsule form to treat anxiety disorders. Kava exhibits anxiolytic and sleep-enhancing effects in humans. Re-search in experimental animals has proven sedative, anticonvulsant and central muscle relaxant effects, which may be caused by kavalactones as major con-stituents of kava. In 2002, kava has lost its authorisation as a medicinal product because of considerable side effects, particularly damage to the liver. Test purchases and analyses show that medicinal products containing pharmacologically active concentrations of kavalacto-nes are still sold over the internet to the German consumer as food supplements. The natural origin is highlighted as an advantage over synthetic tranquilizers. A high priority to control the internet market with kava products may arise from its recent evaluation as ''possibly carcinogenic to humans'' (Group 2B) by the WHO International Agency for Research on Cancer (IARC).
    Journal für Verbraucherschutz und Lebensmittelsicherheit 02/2014; 9(1):3-11. DOI:10.1007/s00003-013-0849-5 · 0.72 Impact Factor
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    • "As this has been documented with many other psychotropic pharmacotherapies such as antidepressants, mood stabilizers, antipsychotics, and benzodiazepines, we considered this would be important to assess with kava (Schweitzer et al., 2009). Finally, no studies to our knowledge have assessed any withdrawal or addiction issues for kava, which has been shown in animal models to increase dopamine in the nucleus accumbens (LaPorte et al., 2011). "
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    ABSTRACT: Presently, little is known about a number issues concerning kava (Piper methysticum), including (i) whether kava has any withdrawal or addictive effects; (ii) if genetic polymorphisms of the cytochrome (CYP) P450 2D6 liver enzyme moderates any potential adverse effects; and (iii) if medicinal application of kava has any negative or beneficial effect on sexual function and experience. The study design was a 6-week, double-blind, randomized controlled trial (n = 75) involving chronic administration of kava (one tablet of kava twice per day; 120 mg of kavalactones per day, titrated in non-response to two tablets of kava twice per day; 240 mg of kavalactones) or placebo for participants with generalized anxiety disorder. Results showed no significant differences across groups for liver function tests, nor were there any significant adverse reactions that could be attributed to kava. No differences in withdrawal or addiction were found between groups. Interesting, kava significantly increased female's sexual drive compared to placebo (p = 0.040) on a sub-domain of the Arizona Sexual Experience Scale (ASEX), with no negative effects seen in males. Further, it was found that there was a highly significant correlation between ASEX reduction (improved sexual function and performance) and anxiety reduction in the whole sample. Copyright © 2013 John Wiley & Sons, Ltd.
    Phytotherapy Research 11/2013; 27(11). DOI:10.1002/ptr.4916 · 2.66 Impact Factor
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    • "There were no cognitive deficits associated with kava administration. This finding is consistent with previous studies that have found that acute or chronic administration of the plant medicine does not impair RT, memory, or attention (LaPorte et al., 2011). Although oxazepam was found to reduce alertness, surprisingly, no other cognitive deficits were identified. "
    Dataset: hup2216

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