Kava study delivers unexpected results

26 July 2017

Todd Henry
Kava had little effect on reaction time, perception and attention during in a six-hour session. Photo: Todd Henry

A study into the effects of kava on driver ability and road safety has turned up some surprising results. After six hours of drinking the popular Pacific beverage, reaction time, perception and attention of kava drinkers showed little change.

Dr Apo Aporosa, a research fellow at the University of Waikato, a former police officer and regular kava drinker, carried out the Health Research Council (HRC) funded study measuring the effects of kava on 20 kava drinkers who consumed an average 3.52 litres over six hours against a group of 20 non-drinkers. Each group had 18 males and two females with an average age of 35 years. Computer-mounted tests, donated by Vienna Tests Systems Germany, were used to measure reaction and divided attention.

“At hourly testing points over the six hours there was very little difference both within and between the groups,” Dr Aporosa says. “The data analysis indicated no statistically significant difference between reaction time and divided attention in both groups. It was down to points of milliseconds.”

Dr Aporosa is of Fijian descent and an expert in the area of kava and health. He has advised NZ Police on several kava drink-driving cases.

He says it’s estimated there are more than 20,000 kava users on an average Friday or Saturday night in New Zealand. Most of these users are consuming kava at volumes 32 times greater than pharmacologically recommended doses, with many then driving home.

The Institute of Environmental Science and Research (ESR) report increased identification of kava in the blood of deceased motor vehicle accident victims. The social cost of drug-driving related accidents in New Zealand is estimated to be $6.5 million a year. Additionally, injury resulting from road traffic accidents is the leading cause of hospitalisation for Pasifika men and women living in New Zealand, with anecdotal reports suggesting that kava contributes to this, Dr Aporosa says.

“I did expect my study to show kava having a much more significant effect on reaction and perception, and now I think we need to try a different series of tests to get a more detailed picture as to what’s going on.

“Something is happening, because I was watching the participants as they drank and I could see subtle changes as the hours ticked by. For instance, many of the drinkers sitting on the floor and leaning against the wall tended to lean to their left and most appeared sleepy and slower in their movements. The police have also reported similar observations in drivers they have stopped who they believe have been using kava,” Dr Aporosa says.

“Understanding of how kava effects cognition at the volumes we drink it is still very new. Additionally, my study only targeted two cognitive domains, so we need to be careful not to jump to the conclusion that driving after kava is safe.” Dr Aporosa believes the next step should be to investigate the impacts of kava on the central nervous system (CNS); measuring domains of functioning such as speed, accuracy, time perception, connectivity, change reaction, perception–action relationship and fatigue. “We have recently identified a highly sensitive testing system that measures effect via the central nervous system. This is important as we know kava effects the CNS but tends to leave the brain unclouded; kava does not make you intoxicated like alcohol.”

Dr Aporosa says it’s likely that fatigue also plays a role in kava related accidents. “I think there are two things going on here; kava is one factor with fatigue also contributing. This is because kava sessions typically go into the early hours leading to tiredness.”

He says he’s extremely grateful to the HRC for supporting his study. “As a Pacific Islander, I both use kava and understand its cultural significance. So this research was never a criticism of kava. Therefore, if kava is shown to negatively impact driving, this will not take away the significance of kava as our cultural icon and drink. Times have changed though. In the past we used to walk between villages, but now, even in the Islands, we have become highly mobile, driving to and from kava environments, so we need to consider the safety of ourselves, our passengers and other road users”

Dr Aporosa will present the findings from this study at this month’s British Association for Psychopharmacology’s annual conference in Harrogate, England.

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