Does Kava affect reaction time?
Andrew, Seattle, WA
There have actually been quite a number of studies regarding reaction times with Kava on its own, when combined with benzodiazepines, and even alcohol. The results are quite interesting, and definitely score another clear victory for Kava.
First, in 1993, a group of researchers investigated the effects of kava extract, a benzodiazepine (a general group of anti-anxiety drugs), and a placebo on behavior and event-related potentials in a word-recognition memory task. The task was structured as a memory task designed as a double-blind crossover study in 12 healthy volunteers. In the word-recognition test, oxazepam elicited “a pronounced slowing of reaction time and a reduction in the number of correct responses… observed.” Wow. They go on to further state, “The behavioral indices indicated a greatly impaired performance after oxazepam and an enhanced memory performance following kava.” Wow again!
Across the board, kava not only did not decrease reaction time, it was shown to improve reaction time in word-recognition tasks.
Also in 1993, a group of researchers assigned 24 subjects (11 male, 13 female) to receive a drink consisting of kava and fruit juice. The drink containted 500 mL of 0.2 g/mL kavalactone, blended with 500 mL of fruit juice. The test group was subjected to a wider range of tests that included cognitive performance, physiological functions, and mood. No differences were found between the kava drinkers and the control group in measurements of various psychological parameters, including respiration, heart rate, blood pressure, and stress levels. Although what was not measured is what was most interesting, the researchers did conclude that kava, at least at the above dose, does not impair one’s cognitive functioning.
As a third example to present you with, there was a study conducted in 1989 by Saletu and co-workers. The purpose of their study was to measure the physiological effects of kavain, a main kavalactone in kava, on brain activity compared to the benzodiazepine drug clobazapam . In this placebo-controlled double-blind study, 15 healthy volunteers received single oral doses of either an inactive placebo, 30mg of clobazapam, or synthetic kavain at either 200, 400, or 600mg .
The researchers recorded the subjects’ EEG (electroencephalogram, a measure of brain wave activity) and other psychophysiological measures every 2 hours for 8 hours during each study session. The EEGs showed that, though kavain exerted a significant effect on brain waves, it modulated this activity differently than the clobazapam; specifically, the kavain increased delta, theta and alpha waves while decreasing beta waves (the clobazapam showed the opposite effect).
Even more encouragingly, the psychophysiological tests given by the researchers determined that subjects who had taken the kavain showed behavioral improvements in attention, reaction time, motor reflex, and intellectual performance. The people in the kavain group also noted improvements in mood, alertness and feelings of well-being after taking 200mg of kavain. The 600mg dose produced greater sedation, but still less than the clobazapam .
The last example I’ll offer is a study in 1987 by a team of researchers led by Russell . The purpose of their study was to assess the effects of a low dose of kava on alertness, as well as the speed of accessing information from long-term memory. Posner’s letter-recognition task was used to measure the speed and accuracy of long-term memory access: subjects have to press a button within a time limit to indicate whether a pair of letters appearing on a screen is identical to a previous pair, the same sequence in a different font, or a different letter pair .
Russell’s study involved two rounds of testing. In the first, 9 healthy subjects (5 male, 4 female) were given 250ml of water infused with 30g of kava root and tested against a control group given no kava. the Posner test was then repeated a few days later with the same experimental group, this time given 500ml of water infused with kava at a rate of 1g/kg of body weight .
And surprise, surprise… the researchers reported no differences in speed of long-term memory access or error rate between the control group and the people who had taken kava! In their conclusion, they wrote the result demonstrated that kava acts to induce relaxation without impairing memory, reaction time or mental focus–indeed,  and  show mental focus actually improves with kava. So you can imbibe your kava with confidence, knowing that not only will kava not impair reaction time, it can actually benefit it!
1. Münte, T.F. Heinze, H.J., Matzke, M. and Steitz, J. (1993). “Effects of oxazepam and an extract of kava roots (Piper methysticum) on event-related potentials in a word-recognition task. Neuropsychobiology 27: 46-53.
2. Prescott, J., Jamieson, D., Emdur, N., and Duffield, P. (1993). Acute effects of kava on measures of cognitive performance, physiological function, and mood. Drug and Alcohol Review 12: 49-58.
3. Saletu, B., Grünberger, J., and Linzmayer, L. (1989). EEG-brain mapping, psychometric and psychophysiological studies on central effects of kavain–A kava plant derivative. Human Psychopharmacology 4: 169-190.
4. Russell, P.N., Bakker, D., and Singh, N.N. (1987). The effects of kava on alerting and speed of access of information from long-term memory. Bulletin of Psychonomic Society 25: 236-237.