The acute effects of kava and oxazepam on anxiety, mood, neurocognition; and genetic correlates: a randomized, placebo-controlled, double-blind study.
BACKGROUND
Kava (Piper methysticum) is a psychotropic plant medicine with history of cultural and medicinal use. We conducted a study comparing the acute neurocognitive, anxiolytic, and thymoleptic effects of a medicinal dose of kava to a benzodiazepine and explored for the first time specific genetic polymorphisms, which may affect the psychotropic activity of phytomedicines or benzodiazepines.


METHODS
Twenty-two moderately anxious adults aged between 18 and 65 years were randomized to receive an acute dose of kava (180 mg of kavalactones), oxazepam (30 mg), and placebo 1 week apart in a crossover design trial.


RESULTS
After exposure to cognitive tasks, a significant interaction was revealed between conditions on State-Trait Anxiety Inventory-State anxiety (p = 0.046, partial ŋ² = 0.14). In the oxazepam condition, there was a significant reduction in anxiety (p = 0.035), whereas there was no change in anxiety in the kava condition, and there was an increase in anxiety in the placebo condition. An increase in Bond-Lader "calmness" (p = 0.002) also occurred for the oxazepam condition. Kava was found to have no negative effect on cognition, whereas a reduction in alertness (p < 0.001) occurred in the oxazepam condition. Genetic analyses provide tentative evidence that noradrenaline (SLC6A2) transporter polymorphisms may have an effect on response to kava.


CONCLUSIONS
Acute "medicinal level" doses of this particular kava cultivar in naive users do not provide anxiolytic activity, although the phytomedicine also appears to have no negative effects on cognition.
The University of Melbourne, Department of Psychiatry, 2 Salisbury St., Richmond, Melbourne, Australia. jsarris@unimelb.edu.au
J
J
Sarris
A
A
Scholey
I
I
Schweitzer
C
C
Bousman
E
E
Laporte
C
C
Ng
G
G
Murray
C
C
Stough
D000293:Adolescent; D000328:Adult; D000368:Aged; D014151:Anti-Anxiety Agents / Q000627:therapeutic use*; D001007:Anxiety / Q000150:complications / Q000188:drug therapy / Q000235:genetics; D003072:Cognition Disorders / Q000188:drug therapy / Q000209:etiology / Q000235:genetics; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D020901:Kava; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008297:Male; D008875:Middle Aged; D019964:Mood Disorders / Q000188:drug therapy / Q000209:etiology / Q000235:genetics; D009483:Neuropsychological Tests; D050484:Norepinephrine Plasma Membrane Transport Proteins / Q000235:genetics*; D010076:Oxazepam / Q000627:therapeutic use*; D008517:Phytotherapy / Q000379:methods*; D028321:Plant Preparations / Q000627:therapeutic use; D011110:Polymorphism, Genetic; D011569:Psychiatric Status Rating Scales; D055815:Young Adult
D014151:Anti-Anxiety Agents; D050484:Norepinephrine Plasma Membrane Transport Proteins; D028321:Plant Preparations; C493227:SLC6A2 protein, human; D010076:Oxazepam