Does a medicinal dose of kava impair driving? A randomized, placebo-controlled, double-blind study

An Updated Review on the Psychoactive, Toxic and Anticancer Properties of Kava

Kava (Piper methysticum) has been widely consumed for many years in the South Pacific Islands and displays psychoactive properties, especially soothing and calming effects. This plant has been used in Western countries as a natural anxiolytic in recent decades. Kava has also been used to treat symptoms associated with depression, menopause, insomnia, and convulsions, among others. Along with its putative beneficial health effects, kava has been associated with liver injury and other toxic effects, including skin toxicity in heavy consumers, possibly related to its metabolic profile or interference in the metabolism of other xenobiotics. Kava extracts and kavalactones generally displayed negative results in genetic toxicology assays although there is sufficient evidence for carcinogenicity in experimental animals, most likely through a non-genotoxic mode of action. Nevertheless, the chemotherapeutic/chemopreventive potential of kava against cancer has also been suggested. Both in vitro and in vivo studies have evaluated the effects of flavokavains, kavalactones and/or kava extracts in different cancer models, showing the induction of apoptosis, cell cycle arrest and other antiproliferative effects in several types of cancer, including breast, prostate, bladder, and lung. Overall, in this scoping review, several aspects of kava efficacy and safety are discussed and some pertinent issues related to kava consumption are identified.

The impact of traditional kava (Piper methysticum) use on cognition: Implications for driver fitness

ETHNOPHARMACOLOGICAL RELEVANCE

Few studies have examined the impact of kava (Piper methysticum G. Forst. f.) on cognition when consumed at traditionally influenced volumes; most have used modified tablet-form kava, with the results erroneously overlaid on naturalistic kava consumption. Kava is a culturally significant Pacific drink with similar effects to Benzodiazepine. Traditionally influenced kava use sessions last, on average, 6 h in which attendees consume 3.6 L (7.6 pints) each of beverage kava, with some then driving home.

AIM OF THE STUDY

This study evaluated the impact of traditionally influenced kava consumption on participants' neurological functioning. Testing occurred before, throughout and immediately following a typical faikava (kava-drinking) session, with the data then used to assess kava's potential impacts on driver functionality and safety.

METHODS

Kava using participants (n = 20) were assessed with the Brain Gauge following and during a traditionally influenced kava session and compared against control (n = 19). Brain Gauge measures slight changes to six cognitive faculties: Speed, Accuracy, Temporal Order Judgement (TOJ), Timing Perception, Plasticity, and Focus.

RESULTS AND CONCLUSIONS

Comparisons of the within-cohort data showed a positive change in the Focus for the active group at the final testing point following 6-h of kava consumption. Between-cohort data showed a significant level of regression in the active participants' TOJ at the final testing point. No statistically significant level of impairment for the other five cognitive domains was detected. Although the results suggest that kava when consumed at traditional levels may have a slight positive effect on Focus, this result needs to be treated with caution, given the significant level of impairment noted at the final testing point for participants' TOJ. Temporal Order Judgement is associated with executive function, including decision making, behavioral control and information processing, all crucial aspects of driver safety. This is a new finding and suggests kava effects following traditional use differ from those caused by other substances commonly used for social or recreational purposes, such as cannabis, alcohol and other euphoric substances, and may impair driver safety, although again, in a different way to other commonly consumed recreational substances. The findings also add quantitative understanding to ethnographic data on kava effects, suggesting the often-used term 'kava intoxication' is misleading and incorrect.

Kava as a Clinical Nutrient: Promises and Challenges

Kava beverages are typically prepared from the root of Piper methysticum. They have been consumed among Pacific Islanders for centuries. Kava extract preparations were once used as herbal drugs to treat anxiety in Europe. Kava is also marketed as a dietary supplement in the U.S. and is gaining popularity as a recreational drink in Western countries. Recent studies suggest that kava and its key phytochemicals have anti-inflammatory and anticancer effects, in addition to the well-documented neurological benefits. While its beneficial effects are widely recognized, rare hepatotoxicity had been associated with use of certain kava preparations, but there are no validations nor consistent mechanisms. Major challenges lie in the diversity of kava products and the lack of standardization, which has produced an unmet need for quality initiatives. This review aims to provide the scientific community and consumers, as well as regulatory agencies, with a broad overview on kava use and its related research. We first provide a historical background for its different uses and then discuss the current state of the research, including its chemical composition, possible mechanisms of action, and its therapeutic potential in treating inflammatory and neurological conditions, as well as cancer. We then discuss the challenges associated with kava use and research, focusing on the need for the detailed characterization of kava components and associated risks such as its reported hepatotoxicity. Lastly, given its growing popularity in clinical and recreational use, we emphasize the urgent need for quality control and quality assurance of kava products, pharmacokinetics, absorption, distribution, metabolism, excretion, and foundational pharmacology. These are essential in order to inform research into the molecular targets, cellular mechanisms, and creative use of early stage human clinical trials for designer kava modalities to inform and guide the design and execution of future randomized placebo controlled trials to maximize kava's clinical efficacy and to minimize its risks.

Buckle up!

Die Verkehrsmedizin als Teil der Rechtsmedizin erfüllt in der Schweiz eine wichtige präventive Aufgabe in der Sicherung aller Verkehrsteilnehmer: Sie begutachtet die medizinisch basierte Fahrfähigkeit und Fahreignung. Als empirisch konsolidiertes Querschnittsfach hat sie Informationen aus einer Vielzahl von medizinischen Fachgebieten. Wie reagiert die Verkehrsmedizin aber auf den vermehrten Anspruch evidenzbasierter Gutachten und auf anstehende Herausforderungen?

Über einen historischen Abriss motivierten wir die Vorteile und das Potential einer teilweise durch Fahrsimulation ergänzten Untersuchung und einer dediziert auf Fahrsimulation basierenden, klinisch-prospektiven Forschung.

Neben vorhandener Literatur stützen sich historische Aspekte u.a. auf vorhandene Expertise. Die Bewertung der Fahrsimulation für die Verkehrs- bzw. Rechtsmedizin der Schweiz stützt sich auf die Diskussion selektierter Literatur.

Auftrag und Anspruch der Verkehrsmedizin haben sich mehrfach verändert. Eine übersichtsartige Betrachtung existenter Literatur legt nahe, dass massgeschneiderte Fahrsimulatoren Teil einer modernisierten Verkehrsmedizin sein können, um anstehende Herausforderungen adäquat adressieren zu können. Bisher existiert kein derartiges dediziertes Forschungsinstrument in der Schweiz.

Eine auf verkehrsmedizinische Fragestellungen massgeschneiderte, realitätsnahe und niedrigschwellige Fahrsimulation als Werkzeug für klinische Studien und Individualuntersuchungen verspricht neben einer wissenschaftlichen Produktivität einen umsetzbaren und vermittelbaren Mehrwert für das übergeordnete Ziel der Sicherheit aller Verkehrsteilnehmer.

Kava drinking in traditional settings: Towards understanding effects on cognitive function

BACKGROUND

Kava drinking is a tradition among Pacific Island people, although growing in popularity with other ethnicities. However, drinking substantial quantities of kava has raised concerns regarding physical manifestations of slow response and lack of precision in bodily control. These impairments can have significant consequences when after consuming large volumes of kava an individual makes a choice to drive.

AIMS

The objective of this study was to measure selected cognitive functions following high traditionally consumed kava volumes (greater than 2,000 mg of kavalactones) aimed at identifying potential risks for kava drink-drivers.

METHODS

The reaction and divided attention of 20 control participants was assessed against 20 active kava-drinking participants during and following a 6-hr kava session in a "naturalised" setting. Assessment measures were drawn from Vienna Test System-Traffic's test battery.

RESULTS/OUTCOMES

Results showed no statistical significant difference between control and active participants at any measurement point over a 6-hr testing period regardless that the movements and speech of the active participants were observed to slow as the test session and kava consumption progressed.

CONCLUSION

Inconsistencies between test results and observations during testing and by road policing officers demonstrate an urgent need for more research in this field.

Driving following Kava Use and Road Traffic Injuries: A Population-Based Case-Control Study in Fiji (TRIP 14)

Objective

To investigate the association between kava use and the risk of four-wheeled motor vehicle crashes in Fiji. Kava is a traditional beverage commonly consumed in many Pacific Island Countries. Herbal anxiolytics containing smaller doses of kava are more widely available.

Methods

Data for this population-based case-control study were collected from drivers of ‘case’ vehicles involved in serious injury-involved crashes (where at least one road user was killed or admitted to hospital for 12 hours or more) and ‘control’ vehicles representative of ‘driving time’ in the study base. Structured interviewer administered questionnaires collected self-reported participant data on demographic characteristics and a range of risk factors including kava use and potential confounders. Unconditional logistic regression models estimated odds ratios relating to the association between kava use and injury-involved crash risk.

Findings

Overall, 23% and 4% of drivers of case and control vehicles, respectively, reported consuming kava in the 12 hours prior to the crash or road survey. After controlling for assessed confounders, driving following kava use was associated with a four-fold increase in the odds of crash involvement (Odds ratio: 4.70; 95% CI: 1.90–11.63). The related population attributable risk was 18.37% (95% CI: 13.77–22.72). Acknowledging limited statistical power, we did not find a significant interaction in this association with concurrent alcohol use.

Conclusion

In this study conducted in a setting where recreational kava consumption is common, driving following the use of kava was associated with a significant excess of serious-injury involved road crashes. The precautionary principle would suggest road safety strategies should explicitly recommend avoiding driving following kava use, particularly in communities where recreational use is common.

Is driving under the influence of kava associated with motor vehicle crashes? A systematic review of the epidemiological literature

OBJECTIVE

Kava is marketed as a herbal anxiolytic in several countries and is consumed recreationally in high doses in many indigenous Pacific and Australian Aboriginal communities. We reviewed the published literature examining the association (if any) between kava use and motor vehicle crashes (MVCs), MVC-related injuries or driving performance.

METHODS

Search of MEDLINE, EMBASE, PsycINFO, CINAHL, Scopus, AMED, Australian Medical Index, Australian Transport Index and trials registries and injury journals up to August 2014.

RESULTS

No studies quantifying the effects of kava on MVCs or related injury were located. Four experimental studies using computer-based driving simulation examined the effects of pharmacological doses of kavalactones on cognitive and visuomotor performance. While no statistically significant adverse changes attributable to kava were found, there was weak evidence of slowed reaction time. One study found the visuo-motor performance on driving simulation to be significantly impaired when kava was consumed with alcohol.

CONCLUSIONS

With equivocal evidence limited to experimental studies using simulated driving settings, the contribution of kava to MVCs is unknown.

IMPLICATIONS

The gap in knowledge regarding the potential risk of injuries associated with therapeutic and recreational use of kava requires priority attention.