Cognitive deficits in Machado-Joseph disease

Cerebello-cerebral resting-state functional connectivity in spinocerebellar ataxia type 3

Spinocerebellar ataxia type 3 (SCA3) is a neurodegenerative disorder characterized by progressive motor and nonmotor deficits concomitant with degenerative pathophysiological changes within the cerebellum. The cerebellum is topographically organized into cerebello-cerebral circuits that create distinct functional networks regulating movement, cognition, and affect. SCA3-associated motor and nonmotor symptoms are possibly related not only to intracerebellar changes but also to disruption of the connectivity within these cerebello-cerebral circuits. However, to date, no comprehensive investigation of cerebello-cerebral connectivity in SCA3 has been conducted. The present study aimed to identify cerebello-cerebral functional connectivity alterations and associations with downstream clinical phenotypes and upstream topographic markers of cerebellar neurodegeneration in patients with SCA3. This study included 45 patients with SCA3 and 49 healthy controls. Voxel-based morphometry and resting-state functional magnetic resonance imaging (MRI) were performed to characterize the cerebellar atrophy and to examine the cerebello-cerebral functional connectivity patterns. Structural MRI confirmed widespread gray matter atrophy in the motor and cognitive cerebellum of patients with SCA3. We found reduced functional connectivity between the cerebellum and the cerebral cortical networks, including the somatomotor, frontoparietal, and default networks; however, increased connectivity was observed between the cerebellum and the dorsal attention network. These abnormal patterns correlated with the CAG repeat expansion and deficits in global cognition. Our results indicate the contribution of cerebello-cerebral networks to the motor and cognitive impairments in patients with SCA3 and reveal that such alterations occur in association with cerebellar atrophy. These findings add important insights into our understanding of the role of the cerebellum in SCA3.

A survey of protein interactions and posttranslational modifications that influence the polyglutamine diseases

The presence and aggregation of misfolded proteins has deleterious effects in the nervous system. Among the various diseases caused by misfolded proteins is the family of the polyglutamine (polyQ) disorders. This family comprises nine members, all stemming from the same mutation—the abnormal elongation of a polyQ repeat in nine different proteins—which causes protein misfolding and aggregation, cellular dysfunction and disease. While it is the same type of mutation that causes them, each disease is distinct: it is influenced by regions and domains that surround the polyQ repeat; by proteins with which they interact; and by posttranslational modifications they receive. Here, we overview the role of non-polyQ regions that control the pathogenicity of the expanded polyQ repeat. We begin by introducing each polyQ disease, the genes affected, and the symptoms experienced by patients. Subsequently, we provide a survey of protein-protein interactions and posttranslational modifications that regulate polyQ toxicity. We conclude by discussing shared processes and pathways that bring some of the polyQ diseases together and may serve as common therapeutic entry points for this family of incurable disorders.

Cognitive impairment in spinocerebellar ataxia type 12

INTRODUCTION

Cognitive impairment has now been recognised to be present in patients with several of spinocerebellar ataxias (SCAs). Cognitive impairment in patients with spinocerebellar ataxia type 12 has not been evaluated.

OBJECTIVE

To evaluate the cognitive impairment in patients diagnosed with spinocerebellar ataxia type 12 (SCA12).

METHODS

We conducted a cross sectional study and enrolled 30 (20 male and 10 female) genetically confirmed SCA12 patients and 30 healthy, age, gender and education matched individuals as controls. Cognitive domains were tested using a battery of validated neurocognitive tests.

RESULT

Mean age of patients was 51.6 ± 8.0 years and mean disease duration was 5.3 ± 3.0 years. Mean International Cooperative Ataxia Rating Scale (ICARS) score was 29.8 ± 12.5. SCA 12 patients scored significantly lower than controls in executive function and new learning ability. Other tested cognitive domains were also affected but did not reach statistical significance. Age, age at onset, severity of ataxia, disease duration and CAG repeat length did not correlate with cognitive impairment.

CONCLUSION

Cognitive impairment is a part of the spectrum of SCA12 and is characterized by dysfunction in executive function and new learning ability even early in the course of disease.

Spinocerebellar Ataxia Type 3: A Case Report and Literature Review

Spinocerebellar ataxia type 3 (SCA3), also known by the eponym Machado-Joseph disease, is an autosomal dominant CAG trinucleotide (polyglutamine) repeat disease that presents in young- to middle-aged adults. SCA3 was first described in Azorean individuals and has interesting epidemiological patterns. It is characterized clinically by progressive ataxia and neuropathologically by progressive degenerative changes in the spinal cord and cerebellum, along with degeneration of the cortex and basal ganglia. Here, we describe the clinical and neuropathologic features in a case of SCA3 with unique findings, including involvement of the inferior olivary nucleus and cerebellar Purkinje cell layer, which are classically spared in the disease. We also discuss research into the disease mechanisms of SCA3 and the potential for therapeutic intervention.

Selective Procedural Memory Impairment but Preserved Declarative Memory in Spinocerebellar Ataxia Type 3

Spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease, is an autosomal dominant neurodegenerative disorder that affects mainly the cerebellum and less other brain areas. While the ataxic/motor features of the disease have been well described, the cognitive consequences of the degeneration require additional testing. The aim of this study was to evaluate learning abilities in SCA3. We tested 13 SCA3 patients and 14 age-matched healthy controls, all of Yemenite origin, on a neuropsychological battery of procedural and declarative memory tests. SCA3 patients demonstrated impaired sequence learning on the procedural Serial Reaction Time test (SRTt) but normal learning on the procedural Weather Prediction Probabilistic Classification test (WPPCt). SCA3 patients showed normal learning on the declarative Rey Auditory Verbal Learning test (Rey-AVLt). The correlations between the learning measures of the SRTt, WPPCt, and Rey-AVLt tests in SCA3 and controls separately were not significant. These results imply that the cerebellar degeneration in SCA3 causes selective impairment in procedural sequence learning while the procedural probabilistic learning and declarative memory were mostly preserved. These findings support the assumption that procedural learning is not a homogeneous function and could be dissociated in cerebellar neurodegenerative disease.

MR Imaging of SCA3/MJD

Spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD) is a progressive autosomal dominantly inherited cerebellar ataxia characterized by the aggregation of polyglutamine-expanded protein within neuronal nuclei in the brain, which can lead to brain damage that precedes the onset of clinical manifestations. Magnetic resonance imaging (MRI) techniques such as morphometric MRI, diffusion tensor imaging (DTI), functional magnetic resonance imaging (fMRI), and magnetic resonance spectroscopy (MRS) have gained increasing attention as non-invasive and quantitative methods for the assessment of structural and functional alterations in clinical SCA3/MJD patients as well as preclinical carriers. Morphometric MRI has demonstrated typical patterns of atrophy or volume loss in the cerebellum and brainstem with extensive lesions in some supratentorial areas. DTI has detected widespread microstructural alterations in brain white matter, which indicate disrupted brain anatomical connectivity. Task-related fMRI has presented unusual brain activation patterns within the cerebellum and some extracerebellar tissue, reflecting the decreased functional connectivity of these brain regions in SCA3/MJD subjects. MRS has revealed abnormal neurochemical profiles, such as the levels or ratios of N-acetyl aspartate, choline, and creatine, in both clinical cases and preclinical cases before the alterations in brain anatomical structure. Moreover, a number of studies have reported correlations of MR imaging alterations with clinical and genetic features. The utility of these MR imaging techniques can help to identify preclinical SCA3/MJD carriers, monitor disease progression, evaluate response to therapeutic interventions, and illustrate the pathophysiological mechanisms underlying the occurrence, development, and prognosis of SCA3/MJD.

Reconstructing the History of Machado-Joseph Disease

Machado-Joseph disease (MJD), or spinocerebellar ataxia type 3, was originally described in members of the families of Machado, Thomas, and Joseph from São Miguel Island, Azores, Portugal, in 1972. The purpose of this article is to present previous descriptions of hereditary ataxia resembling the heterogeneous phenotypic intra-familiar presentation of MJD. We suggest that the condition would best be called dominant spino-pontine atrophy.

Predictive coding and adaptive behavior in patients with genetically determined cerebellar ataxia--A neurophysiology study

Genetically determined cerebellar ataxias (CA) are a heterogeneous group of disorders with progressive decline of cerebellar functions. The cerebellum influences internal forward models that play a role in cognitive control, but whether these processes are dysfunctional in CA is unclear. Here, we examined sensory predictive coding processes and response adaptation in CA and healthy controls (HC) using behavioral tests with concomitant EEG recordings. N = 23 patients and N = 29 age- and sex-matched HC were studied. Sensory prediction coding was tested with an auditory distraction paradigm and error-related behavioral adaptation with a visual flanker task. As neurophysiological markers we studied different event-related potentials: the P3a for orientation of attention; the N2 and the error-related negativity (ERN) for cognitive adaptation processes/consequences of response errors; error-related positivity (Pe) for error-awareness; the mismatch negativity (MMN) for sensory predictive coding; and reorientation negativity (RON) for reorientation after unexpected events. Overall reaction times were slower in patients compared to HC, but error rates did not differ. Both in patients and HC, P3a amplitudes were larger in distraction trials, but the P3a amplitude was smaller in patients compared to HC. The MMN as well as behavioral and EEG-correlates of response adaptation (ERN/N2) did not differ between groups, while the Pe was attenuated in patients. During sensory predictive coding, RON amplitudes were significantly larger in HC compared to patients. In HC, but not in patients, RON amplitudes were also larger in deviant compared to frequent trials. Processes generating internal forward models are largely intact in genetically determined CA, whereas updating of mental models and error awareness are disturbed in these patients.

Heterozygous STUB1 mutation causes familial ataxia with cognitive affective syndrome (SCA48)

OBJECTIVE

To describe a new spinocerebellar ataxia (SCA48) characterized by early cerebellar cognitive-affective syndrome (CCAS) and late-onset SCA.

METHODS

This is a descriptive study of a family that has been followed for more than a decade with periodic neurologic and neuropsychological examinations, MRI, brain SPECT perfusion, and genetic analysis. Whole exome sequencing was performed in 3 affected and 1 unaffected family member and subsequently validated by linkage analysis of chromosome 16p13.3.

RESULTS

Six patients fully developed cognitive-affective and complete motor cerebellar syndrome associated with vermian and hemispheric cerebellar atrophy, suggesting a continuum from a dysexecutive syndrome slowly evolving to a complete and severe CCAS with late truncal ataxia. Three presymptomatic patients showed focal cerebellar atrophy in the vermian, paravermian, and the medial part of cerebellar lobes VI and VII, suggesting that cerebellar atrophy preceded the ataxia, and that the neurodegeneration begins in cerebellar areas related to cognition and emotion, spreading later to the whole cerebellum. Among the candidate variants, only the frameshift heterozygous c.823_824delCT STUB1 (p.L275Dfs*16) pathogenic variant cosegregated with the disease. The p.L275Dfs*16 heterozygous STUB1 pathogenic variant leads to neurodegeneration and atrophy in cognition- and emotion-related cerebellar areas and reinforces the importance of STUB1 in maintaining cognitive cerebellar function.

CONCLUSIONS

We report a heterozygous STUB1 pathogenic genetic variant causing dominant cerebellar ataxia. Since recessive mutations in STUB1 gene have been previously associated with SCAR16, these findings suggest a previously undescribed SCA locus (SCA48; MIM# 618093).

Motor and cognitive impairments in spinocerebellar ataxia type 7 and its correlations with cortical volumes

Spinocerebellar Ataxia Type 7 (SCA7) is a neurodegenerative disorder caused by cytosine-adenine-guanine (CAG) repeat expansion. It is clinically characterized by ataxia and visual loss. To date, little is known about SCA7 cognitive impairments and its relationship with grey matter volume (GMV) changes. The aim of this study was to explore SCA7 patients' performance in specific components of auditory-verbal neuropsychological tests and to correlate their scores with genetic mutation, severity of ataxia and GMV. We assessed verbal memory and verbal fluency proficiencies in 31 genetically confirmed SCA7 patients, and compared their results with 32 healthy matched volunteers; we also correlated CAG repeats and severity of motor symptoms with performance in the auditory-verbal tests. SCA7 patients exhibited deficiencies in several components of these cognitive tasks, which were independent of motor impairments and showed no relation to CAG repeats. Based on Resonance Images performed in 27 patients we found association between ataxia severity and GMV in "sensoriomotor" cerebellum, as well as correlations of impaired verbal memory and semantic fluency scores with GMV in association cortices, including the right parahippocampal gyrus. To our knowledge, this is the first report of deficits in the organization of semantic information and in the evocation of verbal material, as well as greater susceptibility to proactive interference in SCA7 patients. These findings bring novel information about specific cognitive abilities in SCA7 patients, particularly verbal memory and fluency, and their relation with GMV variations in circumscribed brain regions, including association cortices known to have functional relationships with the cerebellum.

Assessment of Sleep Spindle Density among Genetically Positive Spinocerebellar Ataxias Types 1, 2, and 3 Patients

Objective

The effect of thalamic degeneration in patients with spinocerebellar ataxias (SCA) and sleep spindle (SS) abnormalities has not been studied so far, although there is a strong association between these disorders. This study was done to evaluate and compare the SS densities (SSDs) of genetically proven autosomal dominant SCA1, SCA2 and SCA3 patients with controls.

Methods

Prospectively and genetically confirmed cases of SCA and controls were recruited. Patients were assessed clinically, were evaluated with sleep questionnaires and an overnight polysomnography was performed. SSDs were analyzed using neuroloop gain plugin of Polyman version 1.15 software.

Results

Eighteen patients of SCA1 (n = 6), SCA2 (n = 5), SCA3 (n = 7) and 6 controls were recruited in our study. The mean age of SCA1 patients was 39.2 ± 5.4, of SCA2 patients was 30.8 ± 9.5 and of SCA3 patients was 35.4 ± 6.4 years. The mean duration of illness in SCA1 was 4.7 ± 1.7 years, in SCA2 it was 4.3 ± 4.4 years and in SCA3 it was 5 ± 2.3 years. The median SSD values (percentage loop gain) during stage 2 of non-rapid eye movement sleep were 16.9% in SCA1, 0% in SCA2, 1.2% in SCA3 and 59.5% in controls. There was a significant difference in SSD values in SCA2 (p = 0.04), SCA3 (p = 0.02) patients and controls.

Conclusion

SSDs were significantly decreased in patients with SCA, which is a novel finding. This is likely due to the "thalamic switch" disruption, observed as reduced SSDs in SCA2 and SCA3. Sleep spindle deficits could act as one of the biomarkers of ongoing neurodegeneration in the thalamic circuitry of SCA patients.

Clinical Features of Machado-Joseph Disease

Machado-Joseph disease (MJD) also known as Spinocerebellar ataxia type 3, is a hereditary neurodegenerative disease associated with severe clinical manifestations and premature death. Although rare, it is the most common autosomal dominant spinocerebellar ataxia worldwide and has a distinct geographic distribution, reaching peak prevalence in certain regions of Brazil, Portugal and China. Due to its clinical heterogeneity, it was initially described as several different entities and as had many designations over the last decades. An accurate diagnosis become possible in 1994, after the identification of the MJD1 gene. Among its wide clinical spectrum, progressive cerebellar ataxia is normally present. Other symptoms include pyramidal syndrome, peripheral neuropathy, oculomotor abnormalities, extrapyramidal signs and sleep disorders. On the basis of the presence/absence of important extra-pyramidal signs, and the presence/absence of peripheral signs, five clinical types have been defined. Neuroimaging studies like MRI, DTI and MRS, can be useful as they can characterize structural and functional differences in specific subgroups of patients with MJD. There is no effective treatment for MJD. Symptomatic therapies are used to relieve some of the clinical symptoms and physiotherapy is also helpful in improving quality of live. Several clinical trials have been carried out using different molecules like sulfamethoxazole-trimethoprim, varenicline and lithium carbonate, but the results of these trials were negative or showed little benefit. Future studies sufficiently powered and adequately designed are warranted.

Spinocerebellar ataxia: a critical review of cognitive and socio-cognitive deficits

PURPOSE

The primary aim of this contribution is to provide a critical discussion on cognitive and sociocognitive implications of spinocerebellar ataxias (SCAs) subtypes. The term SCA refers to a group of neurodegenerative disorders that have been increasingly investigated in the last years, sharing the characteristic of progressive ataxia resulting from degeneration of cerebellum and its connections. In past decades only involvement of cerebellum in behaviour and timing has been investigated, bringing to the belief about its central role in timing of movement and sensation, particularly for short intervals of time. Only very recently the cerebellum has been considered as a potentially important centre for cognitive processing and related spheres of social cognition, so that several studies with SCA patients have been carried out on these topics: as a consequence a section of this review will be dedicated to this important aspect.

RESULTS

After a brief discussion on most commonly used methods to assess cognitive and socio-cognitive abilities in SCAs, cognitive and socio-cognitive profiles of principal SCA subtypes have been thoroughly reviewed and critically discussed. Due to the very poor literature in this field the most common SCA variants have been fully included (i.e. SCA1, SCA2, SCA3, SCA6 and SCA7).

CONCLUSIONS

A comparative summary of the main characteristics of cognitive and social cognition deficit in SCA subtypes has been proposed together with a research agenda for future investigation in this field principally aimed at using measures of cognition and/or social cognition as potential predictors of the extent and progression of disease.

Cognitive Changes in the Spinocerebellar Ataxias Due to Expanded Polyglutamine Tracts: A Survey of the Literature

The dominantly-inherited ataxias characterised by expanded polyglutamine tracts—spinocere bellar ataxias (SCAs) 1, 2, 3, 6, 7, 17, dentatorubral pallidoluysian atrophy (DRPLA) and, in part, SCA 8—have all been shown to result in various degrees of cognitive impairment. We survey the literature on the cognitive consequences of each disorder, attempting correlation with their published neuropathological, magnetic resonance imaging (MRI) and clinical features. We suggest several psychometric instruments for assessment of executive function, whose results are unlikely to be confounded by visual, articulatory or upper limb motor difficulties. Finally, and with acknowledgement of the inadequacies of the literature to date, we advance a tentative classification of these disorders into three groups, based on the reported severity of their cognitive impairments, and correlated with their neuropathological topography and MRI findings: group 1—SCAs 6 and 8—mild dysexecutive syndrome based on disruption of cerebello-cortical circuitry; group 2—SCAs 1, 2, 3, and 7—more extensive deficits based largely on disruption of striatocortical in addition to cerebello-cerebral circuitry; and group 3—SCA 17 and DRPLA—in which cognitive impairment severe enough to cause a dementia syndrome is a frequent feature.

Fragile X-associated tremor/ataxia syndrome: phenotypic comparisons with other movement disorders

OBJECTIVE

The purpose of this paper is to review the typical cognitive and motor impairments seen in fragile X-associated tremor/ataxia syndrome (FXTAS), essential tremor (ET), Parkinson disease (PD), spinocerebellar ataxias (SCAs), multiple system atrophy (MSA), and progressive supranuclear palsy (PSP) in order to enhance diagnosis of FXTAS patients.

METHODS

We compared the cognitive and motor phenotypes of FXTAS with each of these other movement disorders. Relevant neuropathological and neuroimaging findings are also reviewed. Finally, we describe the differences in age of onset, disease severity, progression rates, and average lifespan in FXTAS compared to ET, PD, SCAs, MSA, and PSP. We conclude with a flow chart algorithm to guide the clinician in the differential diagnosis of FXTAS.

RESULTS

By comparing the cognitive and motor phenotypes of FXTAS with the phenotypes of ET, PD, SCAs, MSA, and PSP we have clarified potential symptom overlap while elucidating factors that make these disorders unique from one another. In summary, the clinician should consider a FXTAS diagnosis and testing for the Fragile X mental retardation 1 (FMR1) gene premutation if a patient over the age of 50 (1) presents with cerebellar ataxia and/or intention tremor with mild parkinsonism, (2) has the middle cerebellar peduncle (MCP) sign, global cerebellar and cerebral atrophy, and/or subcortical white matter lesions on MRI, or (3) has a family history of fragile X related disorders, intellectual disability, autism, premature ovarian failure and has neurological signs consistent with FXTAS. Peripheral neuropathy, executive function deficits, anxiety, or depression are supportive of the diagnosis.

CONCLUSIONS

Distinct profiles in the cognitive and motor domains between these movement disorders may guide practitioners in the differential diagnosis process and ultimately lead to better medical management of FXTAS patients.

Genetics of dementia

25% of all people aged 55 years and older have a family history of dementia. For most, the family history is due to genetically complex disease, where many genetic variations of small effect interact to increase risk of dementia. The lifetime risk of dementia for these families is about 20%, compared with 10% in the general population. A small proportion of families have an autosomal dominant family history of early-onset dementia, which is often due to mendelian disease, caused by a mutation in one of the dementia genes. Each family member has a 50% chance of inheriting the mutation, which confers a lifetime dementia risk of over 95%. In this Review, we focus on the evidence for, and the approach to, genetic testing in Alzheimer's disease (APP, PSEN1, and PSEN2 genes), frontotemporal dementia (MAPT, GRN, C9ORF72, and other genes), and other familial dementias. We conclude by discussing the practical aspects of genetic counselling.

Consensus paper: the cerebellum's role in movement and cognition

While the cerebellum's role in motor function is well recognized, the nature of its concurrent role in cognitive function remains considerably less clear. The current consensus paper gathers diverse views on a variety of important roles played by the cerebellum across a range of cognitive and emotional functions. This paper considers the cerebellum in relation to neurocognitive development, language function, working memory, executive function, and the development of cerebellar internal control models and reflects upon some of the ways in which better understanding the cerebellum's status as a "supervised learning machine" can enrich our ability to understand human function and adaptation. As all contributors agree that the cerebellum plays a role in cognition, there is also an agreement that this conclusion remains highly inferential. Many conclusions about the role of the cerebellum in cognition originate from applying known information about cerebellar contributions to the coordination and quality of movement. These inferences are based on the uniformity of the cerebellum's compositional infrastructure and its apparent modular organization. There is considerable support for this view, based upon observations of patients with pathology within the cerebellum.

Widespread neuronal damage and cognitive dysfunction in spinocerebellar ataxia type 3

Previous studies demonstrated cognitive impairments in spinocerebellar ataxia type 3 (SCA3/MJD); however, there is no consensus about the cognitive domains affected and the correlation with structural brain abnormalities. We investigated the neuropsychological profile and 3T-MRI findings, including high-resolution T1-images, diffusion tensor imaging and magnetic resonance spectroscopy of 32 patients with SCA3/MJD and 32 age-, gender- and educational level-matched healthy controls. We reviewed patients' clinical history and CAG repeat length, and performed assessment and rating of ataxia (SARA)-Brazilian version and the neuropsychiatric inventory. Patients presented worse performance in episodic and working memory and Beck inventories (depression and anxiety). SCA3/MJD patients had a reduction of gray matter volume (GM) in the cerebellum, putamen, cingulum, precentral and parietal lobe. A positive correlation was identified between the cognitive findings and GM of temporal, frontal, parietal, culmen and insula. We observed positive correlation between the brainstem's fractional anisotropy and digit span-forward. The following cerebellar metabolite groups (measured relative to creatine) were reduced in patients: N-acetyl-aspartate (NAA), NAA + N-acetyl-aspartate-glutamate and glutamate + glutamine (Glx). We found a positive correlation between Corsi's block-tapping task forward with Glx; semantic verbal fluency with phosphorylcholine and glycerophosphorylcholine; digits span-forward with NAA. The cognitive impairments in SCA3/MJD are associated not only with cerebellar and brainstem abnormalities, but also with neuroimaging evidence of diffuse neuronal and axonal dysfunction, particularly in temporal, frontal, parietal and insular areas.

Progressive cognitive dysfunction in spinocerebellar ataxia type 3

BACKGROUND

Although it is well established that there is cognitive dysfunction in spinocerebellar ataxia type 3 (SCA3), it is unknown whether cognition deteriorates with disease progression. We therefore prospectively studied cognitive function in patients with SCA3.

METHODS

Eleven patients with SCA3 were assessed using an extensive neuropsychological test battery and retested after 3.5 ± 0.4 years.

RESULTS

In addition to ataxia and motor control, verbal learning and verbal and figural memory deteriorated significantly during the follow-up period. An increase in depressive symptoms was not observed.

CONCLUSIONS

The observation that memory and learning abilities deteriorated with disease progression suggests that cognitive dysfunction is an integral part of SCA3. Because the applied tests for memory function did not require motor responses, cognitive decline cannot be attributed to progressive cerebellar ataxia. The deterioration of verbal and figural memory can be explained either by extracerebellar pathology or by disruption of cerebellar-cerebral circuitries.

A prospective study of neurocognitive changes 15 years after chronic inhalant abuse

AIMS

In a previous study, neurological and cognitive deficits reflecting central nervous system (CNS) disruption from chronic inhalant abuse showed substantial recovery after 2 years' abstinence. Functional recovery was progressive, with recovery rates dependent on the degree of impairment prior to abstinence, and severity and duration of initial abuse. Persistent deficits occurred in those with previous 'lead encephalopathy' from leaded petrol abuse. The current study examined recovery in the same cohort 15 years after baseline.

DESIGN

Prospective cohort design.

SETTING

Two remote Aboriginal communities in Arnhem Land, Australia.

PARTICIPANTS

Using baseline group classifications, 27 healthy controls, 60 ex-chronic inhalant abusers and an additional 17 with previous lead encephalopathy were assessed.

MEASUREMENTS

Standard neurological, ocular-motor and cognitive functions and blood lead levels.

FINDINGS

Chronic (non-encephalopathic) inhalant abusers showed elevated blood lead levels and abnormal scores on most tasks at baseline. At 2 years' abstinence, blood lead was reduced but remained elevated and most scores had normalized. By 15 years, blood lead and all performance scores were equivalent to healthy controls for this group (P > 0.05). The encephalopathic group was more severely impaired on all scores at baseline and showed little improvement, if any, across all tests after both 2 and 15 years' abstinence. Blood lead for this group declined, and was not significantly different to controls after 15 years.

CONCLUSIONS

Some inhalant abusers experience severe and persistent neurological deficits, suggesting irrecoverable damage attributable to lead encephalopathy. In the absence of this encephalopathy long-term abstinence from inhalants may allow recovery of normal brain function.

Clinical features, neurogenetics and neuropathology of the polyglutamine spinocerebellar ataxias type 1, 2, 3, 6 and 7

The spinocerebellar ataxias type 1 (SCA1), 2 (SCA2), 3 (SCA3), 6 (SCA6) and 7 (SCA7) are genetically defined autosomal dominantly inherited progressive cerebellar ataxias (ADCAs). They belong to the group of CAG-repeat or polyglutamine diseases and share pathologically expanded and meiotically unstable glutamine-encoding CAG-repeats at distinct gene loci encoding elongated polyglutamine stretches in the disease proteins. In recent years, progress has been made in the understanding of the pathogenesis of these currently incurable diseases: Identification of underlying genetic mechanisms made it possible to classify the different ADCAs and to define their clinical and pathological features. Furthermore, advances in molecular biology yielded new insights into the physiological and pathophysiological role of the gene products of SCA1, SCA2, SCA3, SCA6 and SCA7 (i.e. ataxin-1, ataxin-2, ataxin-3, α-1A subunit of the P/Q type voltage-dependent calcium channel, ataxin-7). In the present review we summarize our current knowledge about the polyglutamine ataxias SCA1, SCA2, SCA3, SCA6 and SCA7 and compare their clinical and electrophysiological features, genetic and molecular biological background, as well as their brain pathologies. Furthermore, we provide an overview of the structure, interactions and functions of the different disease proteins. On the basis of these comprehensive data, similarities, differences and possible disease mechanisms are discussed.

Cerebellar cognitive affective syndrome in Machado Joseph disease: core clinical features

The cerebellum is no longer considered a purely motor control device, and convincing evidence has demonstrated its relationship to cognitive and emotional neural circuits. The aims of the present study were to establish the core cognitive features in our patient population and to determine the presence of Cerebellar Cognitive Affective Syndrome (CCAS) in this group. We recruited 38 patients with spinocerebellar ataxia type 3 (SCA3) or Machado–Joseph disease (MJD)-SCA3/MJD and 31 controls. Data on disease status were recorded (disease duration, age, age at onset, ataxia severity, and CAG repeat length). The severity of cerebellar symptoms was measured using the International Cooperative Ataxia Rating Scale and the Scale for the Assessment and Rating of Ataxia. The neuropsychological assessment consisted of the Mini-Mental State Examination, Clock Drawing Test, Wechsler Adult Intelligence Scale, Rey–Osterrieth Complex Figure, Wisconsin Card Sorting Test, Stroop Color–Word Test, Trail-Making Test, Verbal Paired Associates, and verbal fluency tests. All subjects were also submitted to the Hamilton Anxiety Scale and Beck Depression Inventory. After controlling for multiple comparisons, spatial span, picture completion, symbol search, Stroop Color–Word Test, phonemic verbal fluency, and Trail-Making Tests A and B were significantly more impaired in patients with SCA3/MJD than in controls. Executive and visuospatial functions are impaired in patients with SCA3/MJD, consistent with the symptoms reported in the CCAS. We speculate on a possible role in visual cortical processing degeneration and executive dysfunction in our patients as a model to explain their main cognitive deficit.

Machado-Joseph disease/spinocerebellar ataxia type 3

Machado-Joseph disease (MJD), also known as spinocerebellar ataxia type 3 (SCA3), may be the most common dominantly inherited ataxia in the world. Here I will review historical, clinical, neuropathological, genetic, and pathogenic features of MJD, and finish with a brief discussion of present, and possible future, treatment for this currently incurable disorder. Like many other dominantly inherited ataxias, MJD/SCA3 shows remarkable clinical heterogeneity, reflecting the underlying genetic defect: an unstable CAG trinucleotide repeat that varies in size among affected persons. This pathogenic repeat in MJD/SCA3 encodes an expanded tract of the amino acid glutamine in the disease protein, which is known as ataxin-3. MJD/SCA3 is one of nine identified polyglutamine neurodegenerative diseases which share features of pathogenesis centered on protein misfolding and accumulation. The specific properties of MJD/SCA3 and its disease protein are discussed in light of what is known about the entire class of polyglutamine diseases.

Neuropsychological features of patients with spinocerebellar ataxia (SCA) types 1, 2, 3, and 6

A subtype-specific impairment of cognitive functions in spinocerebellar ataxia (SCA) patients is still debated. Thirty-two SCA patients (SCA1, 6; SC2, 3; SCA3, 15; SCA6, 8) and 14 matched healthy controls underwent neuropsychological evaluation testing attention, executive functions, episodic and semantic memory, and motor coordination. Severity of ataxia was assessed with the Scale for the Assessment and Rating of Ataxia (SARA), nonataxia symptoms with the Inventory of Non-Ataxia Symptoms. Depressive symptoms were evaluated with the Beck Depression Inventory. The SARA scores of our SCA patients (range 1–19.5) indicated an overall moderate ataxia, most pronounced in SCA6 and SCA1. Mean number of nonataxia symptoms (range 0–2.2) were most distinct in SCA1 and nearly absent in SCA6. SCA1 performed poorer than controls in 33% of all cognitive test parameters, followed by SCA2, SCA3, and SCA6 patients (17%). SCA 1–3 patients presented mainly attentional and executive dysfunctions while semantic and episodic memory functions were preserved. Attentional and executive functions were partly correlated with ataxia severity and fine motor coordination. All patients exhibited mildly depressed mood. Motor and dominant hand functions were more predictive for depressed mood than cognitive measures or overall ataxia. Besides motor impairments in all patients, SCA patients with extracerebellar pathology (SCA 1–3) were characterized by poor frontal attentional and executive dysfunction while mild cognitive impairments in predominantly cerebellar SCA6 patients appeared to reflect mainly cerebellar dysfunction. Regarding the everyday relevance of symptoms, (dominant) motor hand functioning emerged as a marker for the patient’s mood.

Cognitive dysfunction and health-related quality of life after a cardiac arrest and therapeutic hypothermia

BACKGROUND

Evidence-based treatment protocols including therapeutic hypothermia have increased hospital survival to over 50% in unconscious out-of-hospital cardiac arrest survivors. In this study we estimated the incidence of cognitive dysfunctions in a group of cardiac arrest survivors with a high functional outcome treated with therapeutic hypothermia. Secondarily, we assessed the cardiac arrest group's level of cognitive performance in each tested cognitive domain and investigated the relationship between cognitive function and age, time since cardiac arrest and health-related quality of life (HRQOL).

METHODS

We included 26 patients 13-28 months after a cardiac arrest. All patients were scored using the Cerebral Performance Category scale (CPC) and Mini-Mental State Examination (MMSE). Twenty-five of the patients were tested for cognitive function using the Cambridge Neuropsychological Test Automated Battery (CANTAB). These patients were tested using four cognitive tests: Motor Screening Test, Delayed Matching to Sample, Stockings of Cambridge and Paired Associate Learning from CANTAB. All patients filled in the Short Form-36 for the assessment of HRQOL.

RESULTS

Thirteen of 25 (52%) patients were classified as having a cognitive dysfunction. Compared with the reference population, there was no difference in the performance in motor function and delayed memory but there were significant differences in executive function and episodic memory. We found no associations between cognitive function and age, time since cardiac arrest or HRQOL.

CONCLUSION

Half of the patients had a cognitive dysfunction with reduced performance on executive function and episodic memory, indicating frontal and temporal lobe affection, respectively. Reduced performance did not affect HRQOL.

Psychological and cognitive assessment of Indigenous Australians

OBJECTIVE

The aim of the present review was to evaluate the psychological and cognitive assessments that have been considered suitable for Indigenous Australians. This will provide a basis from which future developments can occur, leading to improved mental health services for Indigenous Australians.

METHOD

Literature searches of key health science databases were conducted using the following search terms in various combinations: Indigenous, Aboriginal, cognitive, assessment, mental health, social emotional well-being, psychological, Australian. Psychological, mental health or social and emotional well-being assessments as well as cognitive assessments that have been utilized and found suitable in Indigenous Australian populations were reviewed.

RESULTS

A limited number of assessments were found and discussed and these varied in their applications.

CONCLUSIONS

Further research and development is necessary to establish a national approach to assessing or screening mental health and cognitive function among Indigenous Australians. This is an important and necessary step to improve mental health and related services for Indigenous Australians.

Cognitive dysfunction in spinocerebellar ataxias

Spinocerebellar ataxias (SCAs) comprise a heterogeneous group of complex neurodegenerative diseases, characterized by the presence of progressive cerebellar ataxia, associated or otherwise with ophthalmoplegia, pyramidal signs, extrapyramidal features, pigmentary retinopathy, peripheral neuropathy, cognitive dysfunction and dementia.

OBJECTIVE

To verify the presence of cognitive dysfunction among the main types of SCA described in the literature.

METHODS

the review was conducted using the search system of the PUBMED and OMIM databases.

RESULTS

Cognitive dysfunction occurs in a considerable proportion of SCA, particularly in SCA 3, which is the most frequent form of SCA worldwide. Dementia has been described in several other types of SCA such as SCA 2, SCA 17 and DRPLA. Mental retardation is a specific clinical feature of SCA 13.

CONCLUSIONS

The role of the cerebellum in cognitive functions has been observed in different types of SCAs which can manifest varying degrees of cognitive dysfunction, dementia and mental retardation.

The thalamus and schizophrenia: current status of research

The thalamus provides a nodal link for multiple functional circuits that are impaired in schizophrenia (SZ). Despite inconsistencies in the literature, a meta analysis suggests that the volume of the thalamus relative to that of the brain is decreased in SZ. Morphometric neuroimaging studies employing deformation, voxel-based and region of interest methodologies suggest that the volume deficit preferentially affects the thalamic regions containing the anterior and mediodorsal nuclei, and the pulvinar. Postmortem design-based stereological studies have produced mixed results regarding volume and neuronal deficits in these nuclei. This review examines those aspects of thalamic circuitry and function that suggest salience to SZ. Evidence for anomalies of thalamic structure and function obtained from postmortem and neuroimaging studies is then examined and directions for further research proposed.

New insights into the pathoanatomy of spinocerebellar ataxia type 3 (Machado-Joseph disease)

PURPOSE OF REVIEW

This review summarizes recent neuropathological findings in spinocerebellar ataxia type 3 and discusses their relevance for clinical neurology.

RECENT FINDINGS

The extent of the spinocerebellar ataxia type 3 related central nervous neurodegenerative changes has been recently systematically investigated in a series of pathoanatomical studies. These studies showed that the extent of the central nervous degenerative changes of spinocerebellar ataxia type 3 has been underestimated so far. The newly described pattern of central nervous neurodegeneration includes the visual, auditory, vestibular, somatosensory, ingestion-related, dopaminergic and cholinergic systems. These pathological findings were correlated with clinical findings and explain a variety of the spinocerebellar ataxia type 3 symptoms observed in clinical practice.

SUMMARY

Systematic pathoanatomical analysis of spinocerebellar ataxia type 3 brains helps to understand the structural basis of this neurodegenerative disease and offers explanations for a variety of disease symptoms. This better understanding of the neuropathology of the condition has implications for the treatment of spinocerebellar ataxia type 3 patients and represents a basis for further biochemical and molecular biological studies aimed at deciphering the pathomechanisms of this progressive ataxic disorder.

Cognitive and social cognitive functioning in spinocerebellar ataxia : a preliminary characterization

INTRODUCTION

The spinocerebellar ataxias (SCAs), are rare neurodegenerative disorders caused by distinct genetic mutations. Clinically, the SCAs are characterised by progressive ataxia and a variety of other features, including cognitive dysfunction. The latter is consistent with a growing body of evidence supporting a cognitive as well as motor role for the cerebellum. Recent suggestions of cerebellar involvement in social cognition have not been extensively explored in these conditions. The availability of definitive molecular diagnosis allows genetically defined subgroups of SCA patients, with distinct patterns of cerebellar and extracerebellar involvement, to be tested comparatively using a common battery of tests of general, social and emotional cognition.

METHODS

: Nine patients with SCA6, and 6 with SCA3 were assessed using a comprehensive battery of neuropsychological instruments, encompassing domains of memory, language, visuo-spatial skills, calculation, attention and executive function, emotional processing and theory of mind (ToM).

RESULTS

There were no deficits in visuo-spatial processing or calculation in either group, while individuals with naming and attentional difficulties were seen in both. Deficits in memory and executive function were present in both conditions, albeit more pronounced in SCA3. By contrast, both groups demonstrated consistently poor performance on ToM tests, and normal attribution of social and emotional responses.

CONCLUSION

The data support the hypothesis that the cerebellum is important for cognitive as well as motor activity. The pattern of overlap of domain impairments provides tentative preliminary evidence that there is a cerebellar contribution to aspects of memory and executive function and ToM, and that other domains depend more on neural system outside the cerebellum. The findings relating to ToM are relevant to the possibility of cerebellar involvement in autism.

Cognition in hereditary ataxia

Apart from motor control the cerebellum has been implicated in higher cortical functions such as memory, fronto-executive functions, visuoconstructive skills and emotion. Clinical descriptions of hereditary ataxias mention cognitive impairment to a variable extent. Systematic neuropsychological studies are limited. Regarding the neuropathological pattern in different SCA types, cognitive deficits in hereditary ataxias are not likely to be contingent upon cerebellar degeneration but to result from disruption of cerebrocerebellar circuitries at various levels in the CNS.

Visuospatial memory deficits in adolescent onset schizophrenia

Visuospatial memory encoding deficits have been reported in adults with schizophrenia, while adolescents with schizophrenia have not been specifically investigated with visuospatial memory encoding and retrieval paradigms. A cross sectional study of delayed matching-to-sample performance in 19 right handed, male, anti-psychotic medication naïve adolescents with undifferentiated schizophrenia and 28 age, gender, IQ and handedness matched healthy participants was completed. The adolescent-onset schizophrenia group demonstrated significant impairment in visuospatial memory, independent of the degree of delay, consistent with an encoding impairment. The impaired encoding phase of visuospatial memory in the adolescent-onset schizophrenia group is consistent with findings in adult onset schizophrenia samples, suggesting a developmental stage-independent deficit.

Depressive Symptoms in Machado-Joseph Disease (SCA3) Patients and Their Relatives

OBJECTIVES

It was the aim of this study to determine the depression scores of Machado-Joseph disease (MJD) patients, their spouses, and individuals at 50% risk for MJD, and second, to verify the existence of a correlation between depressive symptoms and the degree of motor incapacitation.

SUBJECTS AND METHODS

Two hundred and forty-six individuals aged > or =18 years were studied: 79 MJD patients (group 1), 43 spouses of MJD patients (group 2), 80 individuals at risk for MJD (group 3), and a control group (group 4) composed of 44 patients with multiple sclerosis (MS). The following two tools were applied: the Beck Depression Inventory and the Barthel index of physical incapacitation, both in an adapted Brazilian Portuguese version.

RESULTS

Moderate to severe depressive scores were found in 33.5% of patients in the MJD families, in 16.3% of the spouses, and in 6.3% of the individuals at risk. This linear reduction between MJD family members was statistically significant (p < 0.0001, ANOVA). Depressive scores were also associated with age and the female sex. A direct correlation between Beck Depression Inventory scores and motor incapacitation was found in MJD patients (r = 0.507, Pearson correlation, p < 0.0001). Although the depressive symptoms in the control group with MS were higher than those found in MJD patients (59% of MS patients showed moderate to severe scores), depression did not correlate with physical incapacitation, age, or education attainment in the MS group.

CONCLUSIONS

Depressive symptoms are rather common in MJD patients and in their spouses (caregivers). In this condition, depression seemed to be more reactive than primarily related to the disease process itself.

Spinocerebellar ataxia type 3 (SCA3): thalamic neurodegeneration occurs independently from thalamic ataxin-3 immunopositive neuronal intranuclear inclusions

In the last years progress has been made regarding the involvement of the thalamus during the course of the currently known polyglutamine diseases. Although recent studies have shown that the thalamus consistently undergoes neurodegeneration in Huntington's disease (HD) and spinocerebellar ataxia type 2 (SCA2) it is still unclear whether it is also a consistent target of the pathological process of spinocerebellar ataxia type 3 (SCA3). Accordingly we studied the thalamic pathoanatomy and distribution pattern of ataxin-3 immunopositive neuronal intranuclear inclusions (NI) in nine clinically diagnosed and genetically confirmed SCA3 patients and carried out a detailed statistical analysis of our findings. During our pathoanatomical study we disclosed (i) a consistent degeneration of the ventral anterior, ventral lateral and reticular thalamic nuclei; (ii) a degeneration of the ventral posterior lateral nucleus and inferior and lateral subnuclei of the pulvinar in the majority of these SCA3 patients; and (iii) a degeneration of the ventral posterior medial and lateral posterior thalamic nuclei, the lateral geniculate body and some of the limbic thalamic nuclei in some of them. Upon immunocytochemical analysis we detected NI in all of the thalamic nuclei of all of our SCA3 patients. According to our statistical analysis (i) thalamic neurodegeneration and the occurrence of ataxin-3 immunopositive thalamic NI was not associated with the individual length of the CAG-repeats in the mutated SCA3 allele, the patients age at disease onset and the duration of SCA3 and (ii) thalamic neurodegeneration was not correlated with the occurrence of ataxin-3 immunopositive thalamic NI. This lack of correlation may suggest that ataxin-3 immunopositive NI are not immediately decisive for the fate of affected nerve cells but rather represent unspecific and pathognomonic morphological markers of SCA3.

Cognitive impairment in spinocerebellar ataxia type 8

OBJECTIVES

Only a limited number of studies have investigated the cognitive performances of spinocerebellar ataxia (SCA) patients. In none of the SCA8 studies have the neuropsychological test performances been the primary measures. The objective of the current study was to investigate the characteristics of cognitive deficits in SCA8.

METHODS

Ten SCA8 patients and ten case-by-case matched control subjects underwent a comprehensive neuropsychological examination evaluating attention and information processing, concept formation, reasoning and executive functions, verbal production, memory and learning and visuoperceptual and -constructive functions.

RESULTS

SCA8 patients demonstrated deficits primarily in attention and information processing, as well as in concept formation, reasoning, executive functions and verbal production. Visuoperceptual and -constructive functions, as well as most of the performances of memory were unaffected.

CONCLUSIONS

Cognitive impairments, especially those related to attention, information processing and executive functions, seem to be a clinical feature of SCA8 disease.

Neurological and cognitive recovery following abstinence from petrol sniffing

Anecdotal observations suggest that neurological impairments associated with petrol (gasoline) sniffing resolve with abstinence, although these effects have not been proven empirically. Severe exposure to leaded petrol may induce a lead encephalopathy that extends beyond any acute intoxication and requires emergency hospital treatment. Previously, in chronic petrol sniffers, we showed neurological, saccadic, and cognitive abnormalities that were more severe in petrol sniffers with a history of hospitalization for lead encephalopathy, and that correlated with blood lead levels and the length of time of sniffing petrol. Ex-petrol sniffers showed a qualitatively similar but quantitatively less severe pattern of impairment. Petrol sniffing was stopped completely in one of the study communities by modifying social, occupational, and recreational opportunities. After 2 years, we obtained biochemical and neurobehavioral (neurological, saccade, and cognitive) data from all available participants of the earlier study including 10 nonsniffers and 29 chronic petrol sniffers, with six of these individuals previously receiving hospital treatment for lead encephalopathy. Here, we report that blood lead was reduced and that neurobehavioral impairments improved, and in many cases normalized completely. The most severe petrol-related neurobehavioral impairment was observed among individuals who had longer histories of abuse and higher blood lead levels, and among petrol sniffers with a history of lead encephalopathy. Those with the greatest extent of neurobehavioral impairment showed the greatest degree of improvement with abstinence, but were less likely to recover completely. This is the first direct evidence that neurological and cognitive impairment from chronic petrol sniffing ameliorates with abstinence and may recover completely.

Neurological and cognitive impairment associated with leaded gasoline encephalopathy

BACKGROUND

A toxic encephalopathy (or 'lead encephalopathy') may arise from leaded gasoline abuse that is characterised by tremor, hallucinations, nystagmus, ataxia, seizures and death. This syndrome requires emergency and intensive hospital treatment.

METHODS

We compared neurological and cognitive function between chronic gasoline abusers with (n=15) and without (n=15) a history of leaded gasoline encephalopathy, and with controls who had never abused gasoline (n=15).

RESULTS

Both groups of chronic gasoline abusers had abused gasoline for the same length of time and compared to controls, showed equivalently elevated blood lead levels and cognitive abnormalities in the areas of visuo-spatial attention, recognition memory and paired associate learning. However, where gasoline abusers with no history of leaded gasoline encephalopathy showed only mild movement abnormalities, gasoline abusers with a history of leaded gasoline encephalopathy showed severe neurological impairment that manifest as higher rates of gait ataxia, abnormal rapid finger tapping, finger to nose movements, dysdiadochokinesia and heel to knee movements, increased deep tendon reflexes and presence of a palmomental reflex.

CONCLUSIONS

While neurological and cognitive functions are disrupted by chronic gasoline abuse, leaded gasoline encephalopathy is associated with additional and long-lasting damage to cortical and cerebellar functions.

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.

Health effects of kava use in an eastern Arnhem Land Aboriginal community

BACKGROUND

Heavy kava use in Aboriginal communities has been linked to various health effects, including anecdotes of sudden cardiac deaths.

AIMS

To examine associations between kava use and potential health effects.

METHODS

A cross-sectional study was carried out within a kava-using east Arnhem Land Aboriginal community in tropical northern Australia. One-hundred-and-one adults who were current, recent or non-users of kava were enrolled in March 2000. Main outcome measures were physical, anthropometric, biochemical, haematological, immunological and neurocognitive assessments.

RESULTS

Kava users more frequently showed a characteristic dermopathy (P<0.001). They had increased levels of gamma-glutamyl transferase and alkaline phosphatase (P<0.001). Lymphocyte counts were significantly lower in kava users (P<0.001). Fibrinogen, plasminogen activator inhibitor-1 and neurocognitive tests were not different between kava use categories. IgE and IgG antibodies were elevated across the whole group, as were C-reactive protein and homocysteine.

CONCLUSIONS

Kava use was associated with dermopathy, liver function abnormalities and decreased lymphocytes. If kava continues to be used by Aboriginal populations, monitoring should focus on the health consequences of these findings, including a possible increase in serious infections. The interaction between kava, alcohol and other substances requires further study. Although markers of cardiovascular risk are increased across the population, these were not higher in kava users, and this increase may be linked to the large infectious pathogen burden reflective of the socioeconomic disadvantage seen in many remote Aboriginal communities.

Saccade and cognitive function in chronic kava users

Kava is an extract from the Piper methysticum Forst. f. plant that has been consumed in the Pacific islands for millennia and more recently, among indigenous populations, in northern Australia and throughout the Western world as an herbal medicine. Through alterations on neuronal excitation, kava induces muscle relaxation, anasthesia, and has anxiolytic properties. There have been several isolated reports of psychotic syndromes, severe choreoathetosis and possible seizures following kava use. However, there is no conclusive evidence that kava interferes with normal cognitive processes. We tested a group of current, ex, and nonkava users among an indigenous population in northern Australia, using saccade and cognitive tests that have proven cross-cultural validity and are sensitive to subtle disruptions of the brain arising from substance abuse or neuropsychiatric illness. Despite collecting data from among the heaviest reported kava drinkers in the world, we found no impairment in cognitive or saccade function in individuals who were currently heavy kava users (and had been for up to 18 years), nor was there any impairment in individuals who had been heavy kava users in the past but had abstained for longer than 6 months. Current and ex-kava users showed a higher rate of kava dermopathy, lower body mass index, lowered blood lymphocytes and, in addition, current kava users showed elevated liver enzymes. While there has recently been increasing concern about potentially fatal liver damage attributed to kava use, we have found no evidence of brain dysfunction in heavy and long-term kava users.

Executive and emotional dysfunction in Machado-Joseph disease

Machado-Joseph disease (MJD) is an autosomal dominant spinocerebellar ataxia. Few studies have examined the neuropsychological and neurobehavioral profiles of patients with MJD. In this study, six individuals with MJD were given a battery of neuropsychological tests. Relative impairments on timed verbal attention tasks and verbal fluency (Stroop, Oral Symbol Digit Modalities, and Controlled Oral Word Association Test) were found. Other executive impairments also were seen on the Wisconsin Card Sorting Test, independent of motor dysfunction severity. Moderate- to severe levels of depressive symptoms were endorsed by four of the six patients, and caregivers observed increased apathy in the patients. Impaired executive and emotional functioning in MJD does not appear to be related to ataxia severity. These patients did not meet the criteria for dementia. General cognitive abilities, language, list learning, story recall, and untimed tasks of attention were within normal limits. Impaired executive abilities and emotional functioning in MJD patients is consistent with disruption of frontal-subcortical systems.