Kava: herbal panacea or liver poison?

The sub-acute toxicity of kavalactone in rats: a study of the effect of oral doses and the mechanism of toxicity in combination with ethanol

Kava is a herbal supplement and beverage made from the Piper methysticum plant, which is known for its recreational use as a mood enhancer, relaxation, as well as pain relief for centuries. Kava is widely used among alcoholics, but it is dangerous and potentially fatal. The objectives of this study were to examine the sub-acute toxicity effects of different doses of 70% kavalactone (KL) in rats by oral application, as well as to elucidate the mechanisms of toxicity alone and in combination with ethanol (EtOH). The most common side effects observed were abnormal breathing, ataxia, lethargy, loss of appetite, indigestion, and loss of coordination, especially in the 800 mg/kg bw, po bodyweight dosage of kava treatment group alone, and in combination with EtOH. In the sub-acute study, there were dose-related decreases in body weight, feed intake, and water consumption rates. Gross and histopathological findings revealed that the liver was abnormal in color, size, consistency, and the weight significantly increased at a dose of 800 mg/kg bw, po, with KL alone and a greater increase in combination with EtOH. Hepatocellular hypertrophy (HP) and necrosis with Kupffer cells hyperplasia were observed in the periacinar zone of all rats dosed with KL (800 mg/kg bw, po) alone, and extensive changes were observed in combination with EtOH. The periportal (Z1) and mid-zonal (Z2) areas of hepatocytes were less affected as compared to the periacinar zone. These results demonstrate that EtOH exacerbated the sedative and hypnotic activity of KL, and markedly increased toxicity. The histopathological results supported the clinical and biochemical findings and the severity of hepatic damage in a dose-dependent manner.

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.

De-mythologizing and re-branding of kava as the new ‘world drug’ of choice

What seemed impossible 50 years ago is today becoming a reality as ‘soft drugs’ such as cannabis are being decriminalized and accepted for their calming effects as well as their legitimate medicinal properties. Several countries have now made the possession of cannabis legal, with others considering this, while the coffee shops in the Netherlands have been supplying cannabis in different forms for many years. It is now the turn of kava to be re-evaluated, to see whether there are properties in this plant that might be readily substituted for more conventional and harmful drugs, for instance tobacco and alcohol. However, as highlighted by Norton and Ruze (1994), kava like cannabis, has an enduring reputation that still makes it difficult for many to accept. Kava has been mythologized as an illicit alcohol, highly addictive, and causing physical harm. When examining the history of kava use in traditional contexts and considering the evidence now available, it is possible to demythologize this characterization. Looking at the potential benefits, it is time to re-brand kava, not only on the grounds as a relaxant, but in possessing life enhancing medicinal properties and as an alternative to alcohol, understanding that will be beneficial to policy makers, doctors and pharmacists.

Safety and Efficacy of Herbal Sedatives in Cancer Care

Insomnia and other sleep disturbances are common in cancer patients. Insomnia is a multifactorial health concern that currently affects at least 1 in 3 cancer patients, and yet most insomnia sufferers do not consult their physician regarding pharmaceutical options for relief. Use of hypnotic drugs (primarily benzodiazepines) is associated with increasing tolerance, dependence, and adverse effects on the central nervous system. While hypnotic drug use declined substantially in the past decade, the use of herbal sedatives appeared to increase. Mostly self-prescribed by lay people, herbal sedatives hold widespread appeal, presumably because of their lower cost and higher margin of safety when compared to pharmaceuticals. Studies of better-known herbal sedatives, notably valerian and kava, showed moderate evidence for both safety and efficacy for valerian while revealing disturbing toxicity concerns for kava. Milder sedatives or anxiolytics in need of clinical study include German chamomile, lavender, hops, lemon balm, and passionflower; St. John’s wort may have anxiolytic effects with relevance to sleep. Herb-drug interactions are a possibility for some of these species, including St. John’s wort. Although sufficient evidence exists to recommend some of these agents for short-term relief of mild insomnia, long-term trials and observational studies are needed to establish the safety of prolonged use as well as overall efficacy in the context of cancer treatment and management.

Hepatotoxicity Induced by "the 3Ks": Kava, Kratom and Khat

The 3Ks (kava, kratom and khat) are herbals that can potentially induce liver injuries. On the one hand, growing controversial data have been reported about the hepatotoxicity of kratom, while, on the other hand, even though kava and khat hepatotoxicity has been investigated, the hepatotoxic effects are still not clear. Chronic recreational use of kratom has been associated with rare instances of acute liver injury. Several studies and case reports have suggested that khat is hepatotoxic, leading to deranged liver enzymes and also histopathological evidence of acute hepatocellular degeneration. Numerous reports of severe hepatotoxicity potentially induced by kava have also been highlighted, both in the USA and Europe. The aim of this review is to focus on the different patterns and the mechanisms of hepatotoxicity induced by “the 3Ks”, while trying to clarify the numerous aspects that still need to be addressed.

Traditional preparation of Phaleria nisidai, a Palauan tea, reduces exposure to toxic daphnane-type diterpene esters while maintaining immunomodulatory activity

ETHNOPHARMACOLOGICAL RELEVANCE

The leaves of Phaleria nisidai Kaneh. (Thymelaeaceae) are brewed into a tea commonly used as a tonic, strengthening beverage and immune enhancer in Palau, Micronesia. Recently, the leaves of P. nisidai have been shown to contain toxic daphnane diterpene esters which may pose a public health threat to Palauans.

AIMS OF THE STUDY

This project documents the use frequency, preparation and side effects of P. nisidai. The content of daphnane diterpene esters in aqueous and methanol extracts and infusions prepared by healers in Palau is compared to assess the risk of daphnane ingestion associated with traditional consumption. Quantitative results are correlated with an in vitro assessment of the immunomodulating activity of the extracts.

MATERIALS AND METHODS

Research participants, comprising traditional healers and laypeople, were interviewed concerning use patterns and side effects of P. nisidai. Several traditional healers prepared and provided boiled tea samples for chemical analysis. Leaves were collected and methanolic and aqueous extractions were prepared in the laboratory. Peripheral blood mononuclear cells (PBMCs) were cultured with various concentrations of methanol and aqueous leaf extracts and their output of IFNγ was measured using ELISA. Cell proliferation was also assessed using the MTT assay. The concentration of selected daphnane diterpene esters in healer-prepared infusions, lab methanol and lab aqueous extracts was quantified using ultraperformance liquid chromatography-mass spectrometry-triple quadrupole detection (UPLC-MS-TQD).

RESULTS

Through structured interviews it was determined that P. nisidai tea was used frequently, with many participants drinking it daily. The reported side effects were mild, and with the exception of diarrhea (n=2), no side effect was mentioned more than once. Methanol extracts contained 4.0μg simplexin, 17.6μg acetoxyhuratoxin and 2.3μg huratoxin per g dry leaf material. In traditional water infusions provided by healers and in standardized lab-prepared aqueous extracts all three compounds were below the limit of detection (16.3ng/mL) using our UPLC-MS-TQD method. Methanol and aqueous extracts increased the release of IFNγ by PBMCs (p<0.05); however, methanol extracts were significantly more active than aqueous extracts (p<0.05). Methanol and aqueous extracts significantly increased proliferation of PBMCs, causing at least 60% more cell proliferation than negative control (p<0.05).

CONCLUSIONS

The presence of daphnane diterpene esters in a frequently consumed traditional beverage was initially viewed as a public health concern, though interview data reveal that Palauans do not observe toxicity or side effects associated with their use of P. nisidai tea. Concurrently, daphnanes are present in methanolic extracts but not detected in aqueous preparations indicating that the traditional method of preparation avoids the extraction of these potentially toxic compounds, while still maintaining immunostimulant activity.

Contemporary Pacific and Western perspectives on `awa (Piper methysticum) toxicology

In 2010, a National Science Foundation project in Hawai`i assembled a collaboration of Pacific indigenous scientists, Hawaiian cultural practitioners and scientists trained in Western pharmacology. The objective of the collaborative project was to study Kava, a culturally significant Pacific beverage, and to address and ultimately transcend, long-standing barriers to communication and collaboration between these groups. Kava is a product of the `awa plant (Piper methysticum) that has been used ceremonially and medicinally throughout the history of Pacific Island cultures, and is now in widespread recreational and nutraceutical use in the US. This project, culminating in 2015, has enriched the participants, led to published work that integrates cultural and Western pharmacologic perspectives and established a paradigm for collaboration. This review paper integrates cultural and Western perspectives on efficacy, toxicity and the future cultural and commercial significance of `awa in the Pacific. Here we present a detailed review of traditional and non-traditional kava usage, medicinal efficacy and potential toxicological concerns. Recent mechanistic data on physiological action and potential pathological reactions are evaluated and interpreted.

Liver injury induced by herbal complementary and alternative medicine

Herbal and dietary supplement use is common. Most marketed products consist of complex mixtures. Although they are perceived as safe, instances of hepatotoxicity attributable to these products underscore their potential for injury, but the exact component that is responsible for injury is difficult to discern. The lenient regulatory environment in the United States, which opens the possibility of adulteration and contamination, adds to the challenge of disease attribution. Although many different herbal and dietary supplements have been reported to cause liver injury, in the United States, products used for bodybuilding and weight loss are the most commonly implicated.

Kava hepatotoxicity in traditional and modern use: the presumed Pacific kava paradox hypothesis revisited

Kava, a Pacific herb consumed worldwide for medicinal, recreational and cultural purposes, has been associated with rare hepatotoxicity, and there is currently a critical need to determine this causation. The previously proposed Pacific kava paradox was based on the theory that kava hepatotoxicity was not observed following use of traditional aqueous extracts in the Pacific region, but was restricted to use of Western acetonic and ethanolic extracts. Subsequent cases analyzed by the World Health Organization and published case reports revealed that traditional aqueous extracts used in New Caledonia, Australia, the USA and Germany may also be hepatotoxic; thus, there is no longer a basis to sustain the previously proposed Pacific kava paradox. It appears that the primary cause of toxicity may reside in the time before the preparation of the various kava extracts, possibly attributed to poor quality of the raw material caused by mould hepatotoxins. Rigorous testing of kava raw material is urgently advised, in addition to Pan-Pacific kava manufacturing quality standards.

Herbal hepatotoxicity by kava: update on pipermethystine, flavokavain B, and mould hepatotoxins as primarily assumed culprits

Herbal hepatotoxicity by the anxiolytic kava (Piper methysticum Forst. f.) emerged unexpectedly and was observed in a few patients worldwide. Liver injury occurred after the use of traditional aqueous kava extracts in the South Pacific region and of acetonic and ethanolic extracts in Western countries in rare cases, suggesting that the solvents used play no major causative role. In this review, we discuss actual pathogenetic issues of kava hepatotoxicity with special focus on developments regarding pipermethystine, flavokavain B, and mould hepatotoxins as possible culprits. There is abundant data of in vitro cytotoxicity including apoptosis by pipermethystine and flavokavain B added to the incubation media, yet evidence is lacking of in vivo hepatotoxicity in experimental animals under conditions similar to human kava use. Furthermore, in commercial Western kava extracts, pipermethystine was not detectable and flavokavain B was present as a natural compound in amounts much too low to cause experimental liver injury. There is concern, however, that due to high temperature and humidity in the South Pacific area, kava raw material might have been contaminated by mould hepatotoxins such as aflatoxins after harvest and during storage. Whether kava hepatotoxicity may be due to aflatoxicosis or other mould hepatotoxins, requires further studies.

Proposal for a kava quality standardization code

Rare cases of hepatotoxicity emerged with the use of kava drugs and dietary supplements prepared from rhizomes and roots of the South Pacific plant kava (Piper methysticum). Their psychoactive, anxiolytic, relaxing, and recreational ingredients are the kavalactones kavain, dihydrokavain, methysticin, dihydromethysticin, yangonin, and desmethoxyyangonin, but there is little evidence that these kavalactones or the non-kavalactones pipermethystine and flavokavain B are the culprits of the adverse hepatic reactions. It rather appears that poor quality of the kava material was responsible for the liver toxicity. Analysis of existing kava quality standardizations with focus on chemical, agricultural, manufacturing, nutritional, regulatory, and legislation backgrounds showed major shortcomings that could easily explain quality problems. We therefore suggest a uniform, internationally accepted device for kava quality standardizations that are in the interest of the consumers because of safety reasons and will meet the expectations of kava farmers, pharmaceutical manufacturers, regulators of agencies, and legislators. The initial step resides in the establishment of Pan-Pacific kava quality legislation as an important part of the proposed Kava Quality Standardization Code. In conclusion, a sophisticated approach to establish kava quality standardizations is needed for safe human use of kava as relaxing traditional beverages, the anxiolytic drugs, and recreational dietary supplements.

Kava hepatotoxicity solution: A six-point plan for new kava standardization

Kava-induced liver injury has been demonstrated in a few patients worldwide and appears to be caused by inappropriate quality of the kava raw material. When cases of liver disease in connection with the use of kava emerged, this was an unexpected and challenging event considering the long tradition of safe kava use. In order to prevent kava hepatotoxicity in future, a set of quality specifications as standard is essential for the preparation not only of kava drugs and kava dietary supplements in the Western world but also for traditional kava drinks in the South Pacific Islands. For all these purposes a uniform approach is required, using water based extracts from the peeled rhizomes and roots of a noble cultivar such as Borogu with at least 5 years of age at the time of harvest. Cultivated in Vanuatu for centuries, noble varieties (as defined in the Vanuatu Kava Act of December 2002) are well tolerated traditional cultivars with a good safety record. At present, Vanuatu kava legislation is inadequately enforced to meet quality issues for kava, and further efforts are required in Vanuatu, in addition to similar legislation in other kava producing South Pacific Islands. Future regulatory and commercial strategies should focus not only on the standardization of kava drugs, kava dietary supplements, and traditional kava extracts, but also on thorough surveillance during the manufacturing process to improve kava quality for safe human use. The efficacy of kava extracts to treat patients with anxiety disorders is well supported, but further clinical trials with aqueous kava extracts are necessary. We thereby propose a six-point kava solution plan: (1) use of a noble kava cultivar such as Borogu, at least 5 years old at time of harvest, (2) use of peeled and dried rhizomes and roots, (3) aqueous extraction, (4) dosage recommendation of ≤250mg kavalactones per day (for medicinal use), (5) systematic rigorous future research, and (6) a Pan Pacific quality control system enforced by strict policing. In conclusion, at different levels of responsibility, new mandatory approaches are now required to implement quality specification for international acceptance of kava as a safe and effective anxiolytic herb.

Kava hepatotoxicity: comparison of aqueous, ethanolic, acetonic kava extracts and kava-herbs mixtures

ETHNOPHARMACOLOGICAL RELEVANCE

Ethanolic and acetonic kava extracts have previously been causally related to rare hepatotoxicity observed in patients from Germany and Switzerland, but causality assessment was not performed in cases of patients having taken the traditional aqueous kava extracts of South Pacific islands or kava-herbs mixtures.

AIM OF THE STUDY

To study the possible hepatotoxicity of aqueous kava extracts of the South Pacific Islands.

MATERIALS AND METHODS

Causality of hepatotoxicity by aqueous kava extracts and kava-herbs mixtures was assessed, using the updated score of the quantitative CIOMS (Council for the International Organizations of Medical Sciences).

RESULTS

Causality was established in five patients from New Caledonia, Australia, the United States and Germany for aqueous kava extracts and kava-herbs mixtures. A comparison with 9 patients from Germany and Switzerland with established causality of hepatotoxicity by ethanolic and acetonic kava extracts reveals that the clinical picture in all 14 patients is similar, independently whether aqueous, ethanolic and acetonic kava extracts or kava-herbs mixtures were used.

CONCLUSIONS

Kava hepatotoxicity occurs also with traditional aqueous kava extracts of the South Pacific islands and thereby independently from ethanol or acetone as chemical solvents, suggesting that the toxicity is linked to the kava plant itself with a possibly low quality of the used kava cultivar or kava plant part rather than to chemical solvents.

Herbal drugs of abuse: an emerging problem

Some herbal products are emerging as popular drugs for recreational abuse. Plant and herbal supplements used recreationally can have a wide spectrum of clinical effects ranging from euphoric and stimulant effects to hallucinogenic experiences. Despite the potential for abuse, addiction, and serious adverse effects, there may be a false perception that these products are all safe, legal, and organic. These perceptions and the ease of accessibility to herbal products could result in greater potential for recreational abuse and subsequent complications presenting to emergency departments. Health care professionals must be cognizant of this emerging problem as increased media coverage and marketing have made these products accessible and recognizable to many young adults and teenagers.

Illicit drug use and responses in six Pacific Island countries

We report here on the illicit drug situation in six Pacific nations: Fiji, Papua New Guinea, Samoa, Solomon Islands, Tonga and Vanuatu. The report is based on the 'Situational analysis of illicit drug issues and responses in Asia and the Pacific', commissioned by the Australian National Council on Drugs Asia Pacific Drug Issues Committee. The situational analysis was a comprehensive desk-based review; data sources included published and unpublished literature and information from key informants. A range of psychoactive substances have been used traditionally across the Pacific region. Cannabis is the by far the most common and widespread illicit drug used in the six Pacific Islands reviewed. Drugs such as heroin, methamphetamines and cocaine are not used commonly due to their high cost compared to the average income. Currently, there is no overall regional or country-based illicit drug policy for the Pacific and few treatment programs; limited data exist to aid in understanding illicit drug use and the harms associated with its use in the Pacific. This review highlights the urgent need for strategic alcohol and drug research in the Pacific as a foundation for the development of policy.

Hepatotoxicity associated with herbal products

A significant number of herbal products have been associated with hepatotoxicity. Attribution of liver injury to a specific herbal pro-duct may be difficult. There are few clinical or laboratory manifestations that specifically suggest that liver injury is the result of aspecific herbal. Compounding this difficulty is that the patient may have liver disease from another cause, may be consuming other potentially hepatotoxic products, or may be using a contaminated herbal product. The most important clue often is the temporal relationship between initiation of the herbal product and the appearance of liver injury; of equal importance is the resolution of the injury following withdrawal of the herbal product.

The potential impact of the use of homeopathic and herbal remedies on monitoring the safety of prescription products

The purpose of this paper is to explore the possibility that adverse reactions and drug interactions arising from the use of homeopathic and herbal medicines could lead to confusion when adverse reactions to conventional medicines are reported. An extensive literature review was conducted on the occurrence of adverse reactions and drug interactions following the use of homeopathic or herbal remedies, and the potential for these to confound adverse event reporting to conventional medicines considered. The survey demonstrates the potential for herbal remedies and homeopathic products, to produce adverse drug reactions or drug interactions, and shows the scope for potential for confusion with those arising from conventional medicines. There is a need for greater awareness that adverse reactions apparently due to a conventional medicine, might in reality be due to a herbal medicine or a drug interaction between a herbal medicine and a conventional drug, particularly when a health professional is unaware of the extent of a patient's self-medication with alternative therapies.

Molecular mechanisms of toxicity of important food-borne phytotoxins

At present, there is an increasing interest for plant ingredients and their use in drugs, for teas, or in food supplements. The present review describes the nature and mechanism of action of the phytochemicals presently receiving increased attention in the field of food toxicology. This relates to compounds including aristolochic acids, pyrrolizidine alkaloids, beta-carotene, coumarin, the alkenylbenzenes safrole, methyleugenol and estragole, ephedrine alkaloids and synephrine, kavalactones, anisatin, St. John's wort ingredients, cyanogenic glycosides, solanine and chaconine, thujone, and glycyrrhizinic acid. It can be concluded that several of these phytotoxins cause concern, because of their bioactivation to reactive alkylating intermediates that are able to react with cellular macromolecules causing cellular toxicity, and, upon their reaction with DNA, genotoxicity resulting in tumors. Another group of the phytotoxins presented is active without the requirement for bioactivation and, in most cases, these compounds appear to act as neurotoxins interacting with one of the neurotransmitter systems. Altogether, the examples presented illustrate that natural does not equal safe and that in modern society adverse health effects, upon either acute or chronic exposure to phytochemicals, can occur as a result of use of plant- or herb-based foods, teas, or other extracts.

Composition and biological activity of traditional and commercial kava extracts

For centuries the South Pacific islanders have consumed kava (Piper methysticum) as a ceremonial intoxicating beverage. More recently, caplets of kava extracts have been commercialized for their anxiolytic and antidepressant activities. Several cases of hepatotoxicity have been reported following consumption of the commercial preparation whereas no serious health effects had been documented for the traditional beverage. A detailed comparison of commercial kava extracts (prepared in acetone, ethanol or methanol) and traditional kava (aqueous) reveals significant differences in the ratio of the major kavalactones. To show that these variations could lead to differences in biological activity, the extracts were compared for their inhibition of the major drug metabolizing P450 enzymes. In all cases (CYP3A4, CYP1A2, CYP2C9, and CYP2C19), the inhibition was more pronounced for the commercial preparation. Our results suggest that the variations in health effects reported for the kava extracts may result from the different preparation protocols used.

Nutraceuticals--a pharmaceutical viewpoint: part II

PURPOSE OF REVIEW

To review pharmaceutical and pharmacological issues relating to the benefits and risks associated with the use of naturally sourced nutraceuticals when administered singly or in combinations.

RECENT FINDINGS

The application of vegetable extracts or dietary supplementation with selenium or antioxidant vitamins results in positive benefits on immunity and other phenomena associated with chronic diseases, ageing and cancer. However, there appear to be no cardiovascular benefits from vitamin mixtures, which may in fact cause harm. Therefore, although recent publications have increased our understanding of the metabolic actions of nutraceuticals, learning to use them to the best advantage is going to require products with uniform and consistent quality. Unfortunately, a single purified substance will not always have the same antioxidant activity, nor provide the same clinical benefits as nutraceutical mixtures and combinations occurring in natural extracts. In order to perform first-class clinical studies to determine safety and efficacy, the stability, compatibility and other pharmaceutical variables inherent in many of these combination products will have to be better controlled.

SUMMARY

Nutraceuticals have potent biological actions. Their use is increasing dramatically, and there is growing evidence of clinical benefits. No medicinal products are completely safe so their risks need to be characterized and controlled. Imposing pharmaceutical levels of control and regulation would increase costs and reduce patient access to new products, but the evidence is compelling that closer monitoring of raw materials, processing and formulation will be required to maximize the benefits and minimize the risks.

Saccade and cognitive impairment associated with kava intoxication

Kava is an extract from the Piper methysticum Forst. f. plant that has social and spiritual importance in Pacific islands societies. Herbal remedies that contain kava are used for the psychiatric treatment of anxiety and insomnia. Laboratory studies have found only subtle, if any, changes on cognitive or motor functions from the acute effects of consuming small clinical doses of kava products. Intoxication from recreational doses of kava has not been studied. The performance of individuals intoxicated from drinking kava (n=11) was compared with a control group (n=17) using saccade and cognitive tests. On average, intoxicated individuals had consumed 205 g of kava powder each (approximately 150 times clinical doses) in a group session that went for 14.4 h and ended 8 h prior to testing. Intoxicated kava drinkers showed ataxia, tremors, sedation, blepharospasm and elevated liver enzymes (GGT and ALP), together with saccadic dysmetria, saccadic slowing and reduced accuracy performing a visual search task that only became evident as the task complexity increased. Kava intoxication is characterized by specific abnormalities of movement coordination and visual attention but normal performance of complex cognitive functions. Saccade abnormalities suggest disruption of cerebellar and GABAergic functions.