Huntington's disease: a review of the literature on prevalence and treatment of neuropsychiatric phenomena

Facilitators and barriers in caring for a person with Huntington's disease: input for a remote support program

OBJECTIVES

This study aims to provide more insight into possible barriers and facilitators caregivers of people with Huntington's disease (HD) encounter, and what their needs and wishes are regarding a remote support program.

METHODS

In total, 27 persons participated in four focus group interviews. Eligible participants were caregivers (n = 19) of a person with HD, and healthcare professionals (n = 8) involved in HD care. Qualitative data were analyzed by two researchers who independently performed an inductive content analysis.

RESULTS

Four major themes emerged from the data, including (1) a paradox between taking care of yourself and caring for others; (2) challenges HD caregivers face in daily life, including lack of HD awareness, taboo and shame, feelings of loneliness, concerns about heredity and children, and coping with HD symptoms; (3) facilitators in the caregiving process, including a social network, professional support, openness, talking in early phases, and daily structure; (4) needs regarding a support program.

CONCLUSION

These insights will be used to develop a remote support program for HD caregivers, using a blended and self-management approach. Newly developed and tailored support should be aimed at empowering caregivers in their role and help them cope with their situation, taking into account barriers and facilitators.

Current and Possible Future Therapeutic Options for Huntington's Disease

Huntington's disease (HD) is an autosomal neurodegenerative disease that is characterized by an excessive number of CAG trinucleotide repeats within the huntingtin gene (HTT). HD patients can present with a variety of symptoms including chorea, behavioural and psychiatric abnormalities and cognitive decline. Each patient has a unique combination of symptoms, and although these can be managed using a range of medications and non-drug treatments there is currently no cure for the disease. Current therapies prescribed for HD can be categorized by the symptom they treat. These categories include chorea medication, antipsychotic medication, antidepressants, mood stabilizing medication as well as non-drug therapies. Fortunately, there are also many new HD therapeutics currently undergoing clinical trials that target the disease at its origin; lowering the levels of mutant huntingtin protein (mHTT). Currently, much attention is being directed to antisense oligonucleotide (ASO) therapies, which bind to pre-RNA or mRNA and can alter protein expression via RNA degradation, blocking translation or splice modulation. Other potential therapies in clinical development include RNA interference (RNAi) therapies, RNA targeting small molecule therapies, stem cell therapies, antibody therapies, non-RNA targeting small molecule therapies and neuroinflammation targeted therapies. Potential therapies in pre-clinical development include Zinc-Finger Protein (ZFP) therapies, transcription activator-like effector nuclease (TALEN) therapies and clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated system (Cas) therapies. This comprehensive review aims to discuss the efficacy of current HD treatments and explore the clinical trial progress of emerging potential HD therapeutics.

Geographic Barriers Drive Disparities in Specialty Center Access for Older Adults with Huntington's Disease

BACKGROUND

Huntington's Disease Society of America Centers of Excellence (HDSA COEs) are primary hubs for Huntington's disease (HD) research opportunities and accessing new treatments. Data on the extent to which HDSA COEs are accessible to individuals with HD, particularly those older or disabled, are lacking.

OBJECTIVE

To describe persons with HD in the U.S. Medicare program and characterize this population by proximity to an HDSA COE.

METHODS

We conducted a cross-sectional study of Medicare beneficiaries ages ≥65 with HD in 2017. We analyzed data on benefit entitlement, demographics, and comorbidities. QGis software and Google Maps Interface were employed to estimate the distance from each patient to the nearest HDSA COE, and the proportion of individuals residing within 100 miles of these COEs at the state level.

RESULTS

Among 9,056 Medicare beneficiaries with HD, 54.5% were female, 83.0% were white; 48.5% were ≥65 years, but 64.9% originally qualified for Medicare due to disability. Common comorbidities were dementia (32.4%) and depression (35.9%), and these were more common in HD vs. non-HD patients. Overall, 5,144 (57.1%) lived within 100 miles of a COE. Race/ethnicity, sex, age, and poverty markers were not associated with below-average proximity to HDSA COEs. The proportion of patients living within 100 miles of a center varied from < 10% (16 states) to > 90% (7 states). Most underserved states were in the Mountain and West Central divisions.

CONCLUSION

Older Medicare beneficiaries with HD are frequently disabled and have a distinct comorbidity profile. Geographical, rather than sociodemographic factors, define the HD population with limited access to HDSA COEs.

Transcranial magnetic stimulation in animal models of neurodegeneration

Brain stimulation techniques offer powerful means of modulating the physiology of specific neural structures. In recent years, non-invasive brain stimulation techniques, such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation, have emerged as therapeutic tools for neurology and neuroscience. However, the possible repercussions of these techniques remain unclear, and there are few reports on the incisive recovery mechanisms through brain stimulation. Although several studies have recommended the use of non-invasive brain stimulation in clinical neuroscience, with a special emphasis on TMS, the suggested mechanisms of action have not been confirmed directly at the neural level. Insights into the neural mechanisms of non-invasive brain stimulation would unveil the strategies necessary to enhance the safety and efficacy of this progressive approach. Therefore, animal studies investigating the mechanisms of TMS-induced recovery at the neural level are crucial for the elaboration of non-invasive brain stimulation. Translational research done using animal models has several advantages and is able to investigate knowledge gaps by directly targeting neuronal levels. In this review, we have discussed the role of TMS in different animal models, the impact of animal studies on various disease states, and the findings regarding brain function of animal models after TMS in pharmacology research.

Assessing Mental Health Difficulties of Persons With Huntington's Disease: Does Informant Presence Make a Difference?

OBJECTIVE

Persons with Huntington's disease (HD) often have communication difficulties and cognitive impairments, making mental health assessment difficult. Informants close to the patient are often included in assessments. The authors investigated effects of informant presence during assessment of persons with HD.

METHODS

Data for four subsamples from ENROLL-HD were examined: manifest for HD (N=4,109), premanifest (N=1,790), genotype negative (N=1,041), and family members with no genetic risk (N=974). Assessment interviews with and without an informant present were identified, and the subsamples were compared on three subscales of the short-form Problem Behaviors Assessment: affect, apathy, and irritability. Differences in scores between participant-only and informant-present interviews were examined via multiple regression, controlling for demographic, disease-related, and individual confounds.

RESULTS

Significant differences in apathy and irritability scores were found between participant-only and informant-present conditions for the premanifest, manifest, and genotype-negative subsamples. Affect subscale scores were not influenced by informant presence. When the analysis controlled for confounds, informant presence significantly increased irritability scores in the manifest, and genotype-negative groups and significantly increased apathy scores in the manifest group.

CONCLUSIONS

Apathy may have been systemically underreported in participant-only interviews, which supports previous findings that persons with HD underreport mental health symptoms. When an informant was present, irritability scores were higher for both HD and non-HD individuals, suggesting that underreporting via self-report may be attributable to non-HD factors. Informant contributions to apathy assessments may be particularly important for persons with HD. Clinicians should note potential underreporting regarding irritability and affect, which was not remediated by informant presence.

The Ties That Bind: Aberrant Plasticity and Networks Dysfunction in Movement Disorders-Implications for Rehabilitation

Background: Movement disorders encompass various conditions affecting the nervous system. The pathological processes underlying movement disorders lead to aberrant synaptic plastic changes, which in turn alter the functioning of large-scale brain networks. Therefore, clinical phenomenology does not only entail motor symptoms but also cognitive and motivational disturbances. The result is the disruption of motor learning and motor behavior. Due to this complexity, the responsiveness to standard therapies could be disappointing. Specific forms of rehabilitation entailing goal-based practice, aerobic training, and the use of noninvasive brain stimulation techniques could "restore" neuroplasticity at motor-cognitive circuitries, leading to clinical gains. This is probably associated with modulations occurring at both molecular (synaptic) and circuitry levels (networks). Several gaps remain in our understanding of the relationships among plasticity and neural networks and how neurorehabilitation could promote clinical gains is still unclear. Purposes: In this review, we outline first the networks involved in motor learning and behavior and analyze which mechanisms link the pathological synaptic plastic changes with these networks' disruption in movement disorders. Therefore, we provide theoretical and practical bases to be applied for treatment in rehabilitation.

Responsiveness to change over time and test-retest reliability of the PROMIS and Neuro-QoL mental health measures in persons with Huntington disease (HD)

BACKGROUND

The majority of persons with Huntington disease (HD) experience mental health symptoms. Patient-reported outcome (PRO) measures are capable of capturing unobservable behaviors and feelings relating to mental health. The current study aimed to test the reliability and responsiveness to self-reported and clinician-rated change over time of Neuro-QoL and PROMIS mental health PROs over the course of a 24-month period.

METHODS

At baseline, 12-months, and 24-months, 362 participants with premanifest or manifest HD completed the Neuro-QoL Depression computer adaptive test (CAT), PROMIS Depression short form (SF), Neuro-QoL Anxiety CAT, PROMIS Anxiety SF, PROMIS Anger CAT and SF, Neuro-QoL Emotional/Behavioral Dyscontrol CAT and SF, Neuro-QoL Positive Affect and Well-Being CAT and SF, and Neuro-QoL Stigma CAT and SF. Participants completed several clinician-administered measures at each time point, as well as several global ratings of change at 12- and 24-months. Reliability (test-retest reliability and measurement error) and responsiveness (using standardized response means and general linear models) were assessed.

RESULTS

Test-retest reliability and measurement error were excellent for all PROs (all ICC ≥ .90 for test-retest reliability and all SEM percentages ≤ 6.82%). In addition, 12- and 24-month responsiveness were generally supported for the Neuro-QoL and PROMIS mental health PROs; findings relative to clinician-rated anchors of change (e.g., SRMs for the group with declines ranged from .38 to .91 for 24-month change and .09 to .45, with the majority above .25 for 12-month change) were generally more robust than those relative to self-reported anchors of change (e.g., SRMs for the group with declines ranged from .02 to .75, with the majority above .39 for 24-month change and .09 to .45, with the majority above .16 for 12-month change).

CONCLUSIONS

The Neuro-QoL and PROMIS mental health PROs demonstrated strong psychometric reliability, as well as responsiveness to self-reported and clinician-rated change over time in people with HD.

Validation of Neuro-QoL and PROMIS Mental Health Patient Reported Outcome Measures in Persons with Huntington Disease

BACKGROUND

Patient-reported outcomes (PROs) for mental health are important for persons with Huntington disease (HD) who commonly experience symptoms of depression, anxiety, irritability, anger, aggression, and apathy. Given this, there is a need for reliable and valid patient-reported outcomes measures of mental health for use as patient-centered outcomes in clinical trials.

OBJECTIVE

Thus, the purpose of this study was to establish the psychometric properties (i.e., reliability and validity) of six Neuro-QoL and PROMIS mental health measures to support their clinical utility in persons with HD.

METHODS

294 individuals with premanifest (n = 102) or manifest HD (n = 131 early HD; n = 61 late HD) completed Neuro-QoL/PROMIS measures of Emotional and Behavioral Dyscontrol, Positive Affect and Well-Being, Stigma, Anger, Anxiety, and Depression, legacy measures of self-reported mental health, and clinician-rated assessments of functioning.

RESULTS

Convergent validity and discriminant validity for the Neuro-QoL and PROMIS measures of Emotional and Behavioral Dyscontrol, Positive Affect and Well-Being, Stigma, Anger, Anxiety, and Depression, were supported in persons with HD. Neuro-QoL measures of Anxiety and Depression also demonstrated moderate sensitivity and specificity (i.e., they were able to distinguish between individuals with and without clinically significant anxiety and depression).

CONCLUSIONS

Findings provide psychometric support for the clinical utility of the Neuro-QoL/PROMIS measures of mental health measures in persons with HD. As such, these measures should be considered for the standardized assessment of health-related quality of life in persons with HD.

How to approach a patient with parkinsonism - red flags for atypical parkinsonism

Parkinsonism is a clinical syndrome defined by bradykinesia plus rigidity or tremor. Though most commonly encountered in the setting of idiopathic Parkinson's disease, a number of neurodegenerative, structural, metabolic and toxic neurological disorders can result in parkinsonism. Accurately diagnosing the underlying cause of parkinsonism is of both therapeutic and prognostic relevance, especially as we enter the era of disease-modifying treatment trials for neurodegenerative disorders. Being aware of the wide array of potential causes of parkinsonism is of paramount importance for clinicians. In this chapter, we present a pragmatic clinical approach to patients with parkinsonism, specifically focusing on 'red flags', which should alert one to consider diagnoses other than idiopathic Parkinson's disease.

Clinical Management of Neuropsychiatric Symptoms of Huntington Disease: Expert-Based Consensus Guidelines on Agitation, Anxiety, Apathy, Psychosis and Sleep Disorders

BACKGROUND

In clinical practice, several strategies and pharmacological options are available to treat neuropsychiatric symptoms of Huntington disease (HD). However, there is currently insufficient data for evidence-based guidelines on the management of these common symptoms.

OBJECTIVE

We aimed to develop expert-based recommendations regarding the management of agitation, anxiety, apathy, psychosis, and sleep disorders.

METHODS

Guideline development was based on a modified Institute of Medicine guideline process that accounted for a lack of evidence base. An international committee of 11 multidisciplinary experts proposed a series of statements regarding the description and management of each symptom. Statement assessment and validation was performed using a web-based survey tool and 84 international HD experts (neurologists and psychiatrists) who assessed the statements and indicated their level of agreement.

RESULTS

High-level agreement (≥85% experts strongly agreed or agreed) was reached for 107 of the 110 statements that have been incorporated into the expert-based clinical recommendations presented herein.

CONCLUSIONS

Clinical statements to guide the routine management of agitation, anxiety, apathy, psychosis, and sleep disorders in HD have been developed. Although not specifically tested in the HD population, clinical experience has shown that most of the neuropsychiatric symptoms discussed, when considered in isolation are treatable using pharmacologic and non-pharmacologic strategies developed for use in other populations. However, the management of neuropsychiatric symptoms in HD can be complex because neuropsychiatric symptoms often co-exist and treatment decisions should be adapted to cover all symptoms while limiting polypharmacy.

[Neuropsychiatry Of Movement Disorders]

Movement disorders can be defined as neurological syndromes presenting with excessive or diminished automatic or voluntary movements not related to weakness or spasticity. Both Parkinson's disease (PD) and Huntington's disease (HD) are well-known examples of these syndromes. The high prevalence of comorbid psychiatric symptoms like depression, anxiety, obsessive-compulsive symptoms, hallucinations, delusions, impulsivity, sleep disorders, apathy and cognitive impairment mean that these conditions must be regarded as neuropsychiatric diseases. In this article, we review neuroanatomical (structural and functional), psychopathological and neuropsychological aspects of PD and HD. The role of fronto-subcortical loops in non-motor functions is particularly emphasised in order to understand the clinical spectrum of both diseases, together with the influence of genetic, psychological and psychosocial aspects. A brief description of the main psychopharmacological approaches for both diseases is also included.

Revisiting the neuropsychiatry of Huntington's disease

Huntington's disease (HD) is an autosomal dominant neurodegenerative disease classified under the choreas. Besides motor symptoms, HD is marked by cognitive and behavioral symptoms, impacting patients' functional capacity. The progression of cognitive impairment and neuropsychiatric symptoms occur in parallel with neurodegeneration. The nature of these symptoms is very dynamic, and the major clinical challenges include executive dysfunction, apathy, depression and irritability. Herein, we provide a focused updated review on the cognitive and psychiatric features of HD.

Psychosis, Treatment Emergent Extrapyramidal Events, and Subsequent Onset of Huntington's Disease: A Case Report and Review of the Literature

Huntington’s disease (HD) is an autosomal dominant neurodegenerative disease characterized by a triad of progressive motor dysfunction, cognitive decline and psychiatric disturbances. The hallmark of HD is the distinctive choreiform movement disorder that typically has a subtle, insidious onset in the fourth to fifth decade of life and gradually worsens over 10 to 20 years until death. Notably, two-thirds of HD patients present with chorea and one third with mental changes. The prevalence of psychiatric symptoms is significantly higher than in the general population, and is estimated to be around 66–73%. Here, we report a unique case of subsequent onset of HD in a patient previously treated for schizophrenia and complicated by the extrapyramidal side effects to antipsychotics.

Counseling Psychology in the Era of Genetic Testing

The field of genetics and the process of testing for genetic disorders have advanced considerably over the past half century, ushering in significant improvements in certain areas of medical diagnosis and disease prediction. However, genetic discoveries are accompanied by many social, emotional, and psychological implications, and counseling psychologists may be uniquely equipped to help clients deal with these issues. The present overview is intended to raise awareness of the multidimensional issues inherent in situations where clients seek genetic testing to diagnose or predict various medical conditions. Initially, the author presents a framework to help counseling psychologists identify and organize information within a genetic-testing context, followed by suggestions for addressing the various psychological, social, and multicultural issues potentially affecting client decision making, mental health, and behavior. Finally, the author raises considerations for training, continuing education, and professional practice to foster continued discussion among counseling psychologists preparing for, or presently working in, research and applied settings involving clients with genetic concerns.

Acute psychosis in a verified Huntington disease gene carrier with subtle motor signs: psychiatric criteria should be considered for the diagnosis

Huntington disease (HD) is an inherited, progressive, autosomal dominant disorder. Some patients develop severe chorea or cognitive symptoms. The genetic defect causes progressive atrophy of the striatum, the cortex and extrastriatal structures (Sheperd GM. Corticostriatal connectivity and its role in disease. Nat Rev Neurosci 2013;14:278-91). The precise timing of clinical diagnosis of HD is poorly characterized and is mainly based on motor symptoms (Huntington, Study and Group. Unified Huntington's Disease Rating Scale: reliability and consistency. Huntington Study Group. Mov Discord 1996:136-42). Patients suffering from HD frequently show cognitive or affective symptoms even before manifesting motor signs. Psychiatric symptoms like depression, apathy, aggression, and disinhibition are common, and suicide rates are over four times higher than in the general population (Di Maio L, Squitieri F, Napolitano G, Campanella G, Trofatter JA, Conneally PM. Suicide risk in Huntington's disease. J Med Genet 1993;30:293-5). This case report of a female patient with genetically proven HD is of special interest because motor or cognitive impairment were absent whereas she suffered from symptoms of an acute and severe psychosis likely to be symptomatic signs of HD.

Neuroprotective effects of psychotropic drugs in Huntington's disease

Psychotropics (antipsychotics, mood stabilizers, antidepressants, anxiolytics, etc.) are commonly prescribed to treat Huntington’s disease (HD). In HD preclinical models, while no psychotropic has convincingly affected huntingtin gene, HD modifying gene, or huntingtin protein expression, psychotropic neuroprotective effects include upregulated huntingtin autophagy (lithium), histone acetylation (lithium, valproate, lamotrigine), miR-222 (lithium-plus-valproate), mitochondrial protection (haloperidol, trifluoperazine, imipramine, desipramine, nortriptyline, maprotiline, trazodone, sertraline, venlafaxine, melatonin), neurogenesis (lithium, valproate, fluoxetine, sertraline), and BDNF (lithium, valproate, sertraline) and downregulated AP-1 DNA binding (lithium), p53 (lithium), huntingtin aggregation (antipsychotics, lithium), and apoptosis (trifluoperazine, loxapine, lithium, desipramine, nortriptyline, maprotiline, cyproheptadine, melatonin). In HD live mouse models, delayed disease onset (nortriptyline, melatonin), striatal preservation (haloperidol, tetrabenazine, lithium, sertraline), memory preservation (imipramine, trazodone, fluoxetine, sertraline, venlafaxine), motor improvement (tetrabenazine, lithium, valproate, imipramine, nortriptyline, trazodone, sertraline, venlafaxine), and extended survival (lithium, valproate, sertraline, melatonin) have been documented. Upregulated CREB binding protein (CBP; valproate, dextromethorphan) and downregulated histone deacetylase (HDAC; valproate) await demonstration in HD models. Most preclinical findings await replication and their limitations are reviewed. The most promising findings involve replicated striatal neuroprotection and phenotypic disease modification in transgenic mice for tetrabenazine and for sertraline. Clinical data consist of an uncontrolled lithium case series (n = 3) suggesting non-progression and a primarily negative double-blind, placebo-controlled clinical trial of lamotrigine.

A Tale of Two Maladies? Pathogenesis of Depression with and without the Huntington's Disease Gene Mutation

Huntington’s disease (HD) is an autosomal dominant disorder caused by a tandem repeat expansion encoding an expanded tract of glutamines in the huntingtin protein. HD is progressive and manifests as psychiatric symptoms (including depression), cognitive deficits (culminating in dementia), and motor abnormalities (including chorea). Having reached the twentieth anniversary of the discovery of the “genetic stutter” which causes HD, we still lack sophisticated insight into why so many HD patients exhibit affective disorders such as depression at very early stages, prior to overt appearance of motor deficits. In this review, we will focus on depression as the major psychiatric manifestation of HD, discuss potential mechanisms of pathogenesis identified from animal models, and compare depression in HD patients with that of the wider gene-negative population. The discovery of depressive-like behaviors as well as cellular and molecular correlates of depression in transgenic HD mice has added strong support to the hypothesis that the HD mutation adds significantly to the genetic load for depression. A key question is whether HD-associated depression differs from that in the general population. Whilst preclinical studies, clinical data, and treatment responses suggest striking similarities, there are also some apparent differences. We discuss various molecular and cellular mechanisms which may contribute to depression in HD, and whether they may generalize to other depressive disorders. The autosomal dominant nature of HD and the existence of models with excellent construct validity provide a unique opportunity to understand the pathogenesis of depression and associated gene-environment interactions. Thus, understanding the pathogenesis of depression in HD may not only facilitate tailored therapeutic approaches for HD sufferers, but may also translate to the clinical depression which devastates the lives of so many people.

Characterization of forebrain neurons derived from late-onset Huntington's disease human embryonic stem cell lines

Huntington's disease (HD) is an incurable neurodegenerative disorder caused by a CAG repeat expansion in exon 1 of the Huntingtin (HTT) gene. Recently, induced pluripotent stem cell (iPSC) lines carrying atypical and aggressive (CAG60+) HD variants have been generated and exhibit disparate molecular pathologies. Here we investigate two human embryonic stem cell (hESC) lines carrying CAG₃₇ and CAG₅₁ typical late-onset repeat expansions in comparison to wildtype control lines during undifferentiated states and throughout forebrain neuronal differentiation. Pluripotent HD lines demonstrate growth, viability, pluripotent gene expression, mitochondrial activity and forebrain specification that is indistinguishable from control lines. Expression profiles of crucial genes known to be dysregulated in HD remain unperturbed in the presence of mutant protein and throughout differentiation; however, elevated glutamate-evoked responses were observed in HD CAG₅₁ neurons. These findings suggest typical late-onset HD mutations do not alter pluripotent parameters or the capacity to generate forebrain neurons, but that such progeny may recapitulate hallmarks observed in established HD model systems. Such HD models will help further our understanding of the cascade of pathological events leading to disease onset and progression, while simultaneously facilitating the identification of candidate HD therapeutics.

Development and evaluation of a telehealth videoconferenced support group for rural spouses of individuals diagnosed with atypical early-onset dementias

Atypical and early-onset dementias can be particularly problematic for family caregivers, and support groups aimed at memory loss and Alzheimer’s disease are not always helpful. Unfortunately, little has been developed specifically for caregivers of individuals with atypical dementias such as the frontotemporal dementias. Compounding the lack of access to interventions targeted specifically at caregivers of individuals with atypical and early-onset dementias are the unique needs of rural caregivers. Due to the relative infrequency of these particular dementias and the large geographical distances between rural caregivers, technology-facilitation is required for any group-based intervention. This paper describes the development of a secure telehealth videoconferenced support group for rural spouses of individuals with atypical and early-onset dementias. In addition, we provide preliminary evidence of effectiveness and describe a template for future groups based on the key therapeutic aspects of this novel technology-facilitated intervention.

Mutation in E1, the ubiquitin activating enzyme, reduces Drosophila lifespan and results in motor impairment

Neurodegenerative diseases cause tremendous suffering for those afflicted and their families. Many of these diseases involve accumulation of mis-folded or aggregated proteins thought to play a causal role in disease pathology. Ubiquitinated proteins are often found in these protein aggregates, and the aggregates themselves have been shown to inhibit the activity of the proteasome. These and other alterations in the Ubiquitin Pathway observed in neurodegenerative diseases have led to the question of whether impairment of the Ubiquitin Pathway on its own can increase mortality or if ongoing neurodegeneration alters Ubiquitin Pathway function as a side-effect. To address the role of the Ubiquitin Pathway in vivo, we studied loss-of-function mutations in the Drosophila Ubiquitin Activating Enzyme, Uba1 or E1, the most upstream enzyme in the Ubiquitin Pathway. Loss of only one functional copy of E1 caused a significant reduction in adult lifespan. Rare homozygous hypomorphic E1 mutants reached adulthood. These mutants exhibited further reduced lifespan and showed inappropriate Ras activation in the brain. Removing just one functional copy of Ras restored the lifespan of heterozygous E1 mutants to that of wild-type flies and increased the survival of homozygous E1 mutants. E1 homozygous mutants also showed severe motor impairment. Our findings suggest that processes that impair the Ubiquitin Pathway are sufficient to cause early mortality. Reduced lifespan and motor impairment are seen in the human disease X-linked Infantile Spinal Muscular Atrophy, which is associated with mutation in human E1 warranting further analysis of these mutants as a potential animal model for study of this disease.

Is Huntington's disease associated with deficits in theory of mind?

OBJECTIVES

People with Huntington's disease (HD) can exhibit interpersonal difficulties and deficits in recognizing emotional facial expressions. We investigated whether individuals with HD exhibit impairments in the understanding of other people's mental states, an aspect of Theory of Mind (ToM).

MATERIALS AND METHODS

Sixteen patients with HD and sixteen healthy controls completed two ToM tasks. One task involved recognising socially inappropriate behaviour and the other task required participants to judge complex mental states from photographs of people's eyes alone. To assess relationships between executive function and ToM, participants completed measures of verbal fluency, working memory and inhibition. The Problem Behaviours Assessment-short form (Neuropsychiatry Neuropsychol Behav Neurol, 14, 2001and 219) was completed twice using information from patients and their close relatives (where possible) to identify relationships between ToM impairment and behavioural problems.

RESULTS

Patients with HD made significantly more errors on ToM tasks than controls, exhibiting difficulties in judging the social appropriateness of story character's behaviour and problems inferring complex mental states from photographs of people's eyes. Patients with HD also exhibited executive dysfunction. However, there was little evidence that executive impairments were related to ToM deficits. No correlations were apparent between problem behaviours and ToM errors.

CONCLUSIONS

HD is associated with deficits in ToM. Furthermore, some of patients' ToM difficulties appear independent of executive dysfunction.

Patterns of serotonergic antidepressant usage in prodromal Huntington disease

Antidepressant usage in prodromal Huntington Disease (HD) remains uncharacterized, despite its relevance in designing experiments, studying outcomes of HD, and evaluating the efficacy of therapeutic interventions. We searched baseline medication logs of 787 prodromal HD and 215 healthy comparison (HC) participants for antidepressant use. Descriptive and mixed-effects logistic regression modeling characterized usage across participants. At baseline, approximately one in five prodromal HD participants took antidepressants. Of those, the vast majority took serotonergic antidepressants (selective serotonin reuptake inhibitor (SSRI) or serotonin/norepinephrine reuptake inhibitor (SNRI)). Significantly more prodromal HD participants used serotonergic antidepressants than their HC counterparts. Because of the prevalence of these medications, further analyses focused on this group alone. Mixed-effects logistic regression modeling revealed significant relationships of both closer proximity to diagnosis and female sex with greater likelihood to be prescribed a serotonergic antidepressant. More prodromal HD participants took antidepressants in general and specifically the subclass of serotonergic antidepressants than their at-risk counterparts, particularly when they were closer to predicted time of conversion to manifest HD. These propensities must be considered in studies of prodromal HD participants.

Longitudinal behavioral, cross-sectional transcriptional and histopathological characterization of a knock-in mouse model of Huntington's disease with 140 CAG repeats

The discovery of the gene mutation responsible for Huntington's disease (HD), huntingtin, in 1993 allowed for a better understanding of the pathology of and enabled the development of animal models. HD is caused by the expansion of a polyglutamine repeat region in the N-terminal of the huntingtin protein. Here we examine the behavioral, transcriptional, histopathological and anatomical characteristics of a knock-in HD mouse model with a 140 polyglutamine expansion in the huntingtin protein. This CAG 140 model contains a portion of the human exon 1 with 140 CAG repeats knocked into the mouse huntingtin gene. We have longitudinally examined the rearing behavior, accelerating rotarod, constant speed rotarod and gait for age-matched heterozygote, homozygote and non-transgenic mice and have found a significant difference in the afflicted mice. However, while there were significant differences between the non-transgenic and the knock-in mice, these behaviors were not progressive. As in HD, we show that the CAG 140 mice also have a significant decrease in striatally enriched mRNA transcripts. In addition, striatal neuronal intranuclear inclusion density increases with age. Lastly these CAG 140 mice show slight cortical thinning compared to non-transgenic mice, similarly to the cortical thinning recently reported in HD.

Huntington's disease: pathogenesis to animal models

Huntington's disease (HD) is an inherited genetic disorder, characterized by cognitive dysfunction and abnormal body movements called chorea. George Huntington, an Ohio physician, described the disease precisely in 1872. HD is a dominantly inherited disorder, characterized by progressive neurodegeneration of the striatum but also involves other regions, primarily the cerebral cortex. The mutation responsible for this fatal disease is an abnormally expanded and unstable CAG repeat within the coding region of the gene encoding the huntingtin protein. Various hypotheses have been put forward to explain the pathogenic mechanisms of mutant huntingtin-induced neuronal dysfunction and cell death. None of these hypotheses, however, offers a clear explanation; thus, it remains a topic of research interest. HD is considered to be an important disease, embodying many of the major themes in modern neuroscience, including molecular genetics, selective neuronal vulnerability, excitotoxicity, mitochondrial dysfunction, apoptosis and transcriptional dysregulation. A number of recent reports have concluded that oxidative stress plays a key role in HD pathogenesis. Although there is no specific treatment available to block disease progression, treatments are available to help in controlling the chorea symptoms. As animal models are the best tools to evaluate any therapeutic agent, there are also different animal models available, mimicking a few or a larger number of symptoms. Each model has its own advantages and limitations. The present review deals with the pathophysiology and various cascades contributing to HD pathogenesis and progression as well as drug targets, such as dopaminergic, gamma-amino butyric acid (GABA)ergic, glutamate adenosine receptor, peptidergic pathways, cannabinoid receptor, and adjuvant therapeutic drug targets such as oxidative stress and mitochondrial dysfunction that can be targeted for future experimental study. The present review also focuses on the animal models (behavioral and genetic) used to unravel pathogenetic mechanisms and the identification of novel drug targets.

A Case of Fahr's Disease Presenting as Chorea Successfully Treated by the Use of Quetiapine

We report a case of 30-year-old man presenting chorea in his legs. A brain computed tomography (CT) scan showed bilateral symmetric calcifications in the basal ganglia, thalamus, cerebellum and subcortical white matter. Laboratory studies showed no abnormalities of serum calcium, phosphate, PTH, lactic acid, pyruvic acid and cerebrospinal fluid. Under the diagnosis of Fahr’s disease (FD), we treated with quetiapine (75 mg/day), which completely abolished his symptoms and he showed no other side effect. Our experience suggests that quetiapine is well tolerated in FD patients and effectively treats chorea without extrapyramidal movement.

Not on the face alone: perception of contextualized face expressions in Huntington's disease

Numerous studies have demonstrated that Huntington's disease mutation-carriers have deficient explicit recognition of isolated facial expressions. There are no studies, however, which have investigated the recognition of facial expressions embedded within an emotional body and scene context. Real life facial expressions are typically embedded in contexts which may dramatically change the emotion recognized in the face. Moreover, a recent study showed that the magnitude of the contextual bias is modulated by the similarity between the actual expression of the presented face and the facial expression that would typically fit the context, e.g. disgust faces are more similar to anger than to sadness faces and, consequently, are more strongly influenced by contexts expressing anger than by contexts expressing sadness. Since context effects on facial expression perception are not explicitly controlled, their pattern serves as an implicit measure of the processing of facial expressions. In this study we took advantage of the face-in-context design to compare explicit recognition of face-expressions by Huntington's disease mutation-carriers, with evidence for processing the expressions deriving from implicit measures. In an initial experiment we presented a group of 21 Huntington's disease mutation-carriers with standard tests of face-expression recognition. Relative to controls, they displayed deficits in recognizing disgust and anger faces despite intact recognition of these emotions from non-facial images. In a subsequent experiment, we embedded the disgust faces on images of people conveying sadness and anger as expressed by body language and additional paraphernalia. In addition, sadness and anger faces were embedded on context images conveying disgust. In both cases participants were instructed to categorize the facial expressions, ignoring the context. Despite the deficient explicit recognition of isolated disgust and anger faces, the perception of the emotions expressed by the faces was affected by context in Huntington's disease mutation-carriers in a similar manner as in control participants. Specifically, they displayed the same sensitivity to face-context pairings. These findings suggest that, despite their impaired explicit recognition of facial expressions, Huntington's disease mutation-carriers display relatively preserved processing of the same facial configurations when embedded in context. The results also show intact utilization of the information elicited by contextual cues about faces expressing disgust even when the actually presented face expresses a different emotion. Overall, our findings shed light on the nature of the deficit in facial expression recognition in Huntington's disease mutation-carriers as well as underscore the importance of context in emotion perception.

The current clinical management of Huntington's disease

Huntington's disease is a neurodegenerative condition, characterized by movement disorders, cognitive decline, and psychiatric disturbance. We review the pharmacological management of the various movement disorders associated with the disease, the cognitive decline and the commonly encountered behavioral disturbances. We discuss the nonclassical features of the disease, important in the management of these patients. Nonpharmacological support including genetic counseling and therapy and the importance of palliative care are also addressed. Finally, experimental approaches that may soon impact upon clinical practice are discussed.

Lamotrigine in motor and mood symptoms of Huntington's disease

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder characterized by midlife onset, progressive course and a combination of motor, cognitive and psychiatric symptoms. Since dysregulation of the glutamate/calcium signalling pathway is beginning to emerge as a potential cause of neuron degeneration, antagonists of glutamate pathways such as lamotrigine, may have beneficial value for treatment of HD. We describe the use of lamotrigine in the treatment of an HD patient with motor abnormality (choreoathetoidic movements) complicated by psychiatric abnormalities (depression, severe mood swing and recurrent high risk of suicidal attempts). The patient's depression, severe mood swing and choreoathetoidic movements significantly improved with 300 mg/day of lamotrigine. Experience from our patient suggests that lamotrigine might be effective in treating HD patients with motor and mood symptoms. Further controlled studies are warranted to confirm its efficacy in patients of this type.

Effect of CAG repeat length on psychiatric disorders in Huntington's disease

There is strong evidence that the length of CAG repeats, in patients with Huntington's disease (HD), govern the age of onset and the rate of clinical progression of neurological symptoms. However, psychiatric manifestations of the disease have not been examined as comprehensively. Seventy two Greek patients with Huntington's disease had DNA testing and were clinically assessed by means of a semi-structured interview (SCID) and four self-rated questionnaires. Genotype-phenotype correlations were examined. The CAG repeat length had a significant negative association with the age of onset of psychiatric disorders, the total level of functioning and the MMSE. However, the probability of developing a psychiatric disorder and the severity of psychiatric symptoms were not determined by the trinucleotide expansion, after controlling for the duration of illness, sex, and age of the subjects. The factors that determine the development of psychiatric symptoms in HD patients seem not to be limited to a dose related toxicity of the expanded Huntington. It is hypothesized that alternative genetic or environmental factors underlie the pathogenesis of the psychiatric phenotype.

Patient and caregiver quality of life in Huntington's disease

Little is known about subjective perceptions of quality of life (QOL) in Huntington's disease (HD). The current study determined correlates of patient and caregiver QOL and assessed change over time. Participants were 22 patient-caregiver dyads, who rated QOL at baseline and 6 months later. Overall, patients' functional and cognitive impairment were significantly correlated with patient and caregiver QOL. Neuropsychiatric symptoms had differential impact on patient and caregiver QOL. Furthermore, when patients recalled their QOL about a previous time, their recall may have been negatively biased. Clinical implications of results are discussed. Future work is needed because subjective QOL is an important outcome measure in therapeutic trials.

Behavioural problems in Huntington's disease using the Problem Behaviours Assessment

OBJECTIVE

To investigate behavioural problems in Huntington's disease (HD).

METHOD

In 152 HD mutation carriers and a control group of 56 noncarriers at initial 50% risk, the Dutch version of the Problem Behaviours Assessment (PBA) was administered. Mutation carriers were divided into three groups according to the motor section of the Unified Huntington's Disease Rating Scale (UHDRS): pre-(motor) symptomatic, early and advanced symptomatic subjects. The factor structure and interrater reliability of the PBA were investigated.

RESULTS

The clinically relevant interrater reliability of the PBA was 0.82 for severity scores and 0.73 for frequency scores. The PBA showed a three-factor solution: apathy, depression and irritability. Mutation carriers, including presymptomatic subjects, portrayed more apathy, depression and irritability than noncarriers. Early symptomatic subjects had more apathy, but not more depression or irritability, compared to presymptomatic subjects. Advanced symptomatic subjects had more apathy than early symptomatic subjects.

CONCLUSIONS

The PBA is a reliable and sensitive instrument. Behavioural problems occur in all stages of HD and arise before the onset of motor symptoms. Apathy is related to disease severity, whereas depression and irritability are not. The broad clinical phenotype of HD therefore requires adequate service delivery with integrated and multidisciplinary patient care.

The tuberous sclerosis complex proteins – a GRIPP on cognition and neurodevelopment

Tuberous sclerosis complex (TSC) is a multi-system disorder associated with mutations in the TSC1 (hamartin) or TSC2 (tuberin) genes. The neurocognitive features of TSC show wide variability and have generally been attributed to structural brain abnormalities and/or seizures. We review the fundamental roles of TSC1 and TSC2 in cell signalling and propose that because the hamartin-tuberin complex (hereafter referred to as TSC1-2) acts as a global regulator and integrator of a range of physiological processes ('GRIPP') the neurocognitive manifestations of TSC result directly from cell-signalling abnormalities. Under the GRIPP hypothesis, the spectrum of neurodevelopmental abnormalities is caused by the biochemical consequences of individual TSC1 and TSC2 mutations. Recognizing the importance of signalling disruption in the brain might improve our understanding of other neurocognitive disorders.

Cognitive, anxiety and mood disorders in the fragile X-associated tremor/ataxia syndrome

OBJECTIVE

We evaluated patients with fragile X-associated tremor/ataxia syndrome (FXTAS), a neurodegenerative disorder associated with a CGG repeat expansion in the premutation range in the fragile X mental retardation 1 (FMR1) gene.

METHODS

Neurological, psychiatric and neuropsychological evaluations were performed on 15 male patients with FXTAS.

RESULTS

Seven cases were diagnosed with dementia, and seven others were diagnosed with mood and/or anxiety disorders. Twelve subjects demonstrated deficits on neuropsychological testing.

CONCLUSIONS

Physicians assessing dementia patients are urged to consider this newly described syndrome, especially in patients with dementia associated with a movement disorder and in those with a family history of mental retardation. If FXTAS is a possible diagnosis, physicians may carry out FMR1 DNA testing; patients who test positive on DNA testing should undergo magnetic resonance imaging, be referred to neurology and receive genetic counseling.

Huntington’s disease

Although available treatments for Huntington's disease (HD) are imperfect, thoughtful application can positively impact quality of life. Dopamine antagonists can provide control of the troublesome hyperkinetic movements. These agents can also diminish the frequency of hallucinations and delusions when symptoms of psychosis occur. Classical neuroleptics have the widest utilization, although atypical antipsychotics are being increasingly used. Suppression of choreiform movements has also been reported with amantadine and tetrabenazine, which is not currently approved in the United States but under investigation. Alteration in mood can be successfully managed with a variety of antidepressant medications. Superior tolerability and value in the management of a variety of behavioral disturbances have lead to extensive use of serotonin reuptake inhibitors. Modest disturbance of mood can sometimes be addressed with anticonvulsant medications. Considered a manifestation of advanced disease, dementia is less commonly addressed therapeutically. However, gathering experience suggests improved cognitive function can occur with cholinesterase inhibitor therapy. Frequently overlooked is the value of rehabilitation services in the management of diverse symptoms. Although the value of a dysphagia evaluation is apparent, the benefit to be derived from physical and occupational therapy involvement cannot be overstated. Current therapeutic trials will undoubtedly provide additional therapies to moderate symptoms, but once the mechanism(s) of selective striatal projection neuron degeneration are delineated, a revolution in the management of HD will occur.

Clinical presentation of juvenile Huntington disease

OBJECTIVE

To describe the clinical presentation a group of patients with juvenile onset of Huntington disease.

METHOD

All patients were interviewed following a structured clinical questionnaire. Patients were genotyped for the trinucleotide cytosine-adenine-guanine (CAG) repeat in the Huntington Disease gene. High resolution brain MRI was performed in all patients.

RESULTS

We identified 4 patients with juvenile onset of disease among 50 patients with Huntington disease followed prospectively in our Neurogenetics clinic. Age at onset varied from 3 to 13 years, there were 2 boys, and 3 patients had a paternal inheritance of the disease. Expanded Huntington disease allele sizes varied from 41 to 69 trinucleotide repeats. The early onset patients presented with rigidity, bradykinesia, dystonia, dysarthria, seizures and ataxia. MRI showed severe volume loss of caudate and putamen nuclei (p=0.001) and reduced cerebral and cerebellum volumes (p=0.01).

CONCLUSION

8% of Huntington disease patients seen in our clinic had juvenile onset of the disease. They did not present with typical chorea as seen in adult onset Huntington disease. There was a predominance of rigidity and bradykinesia. Two other important clinical features were seizures and ataxia, which related with the imaging findings of early cortical atrophy and cerebellum volume loss.

Pharmaceutical, cellular and genetic therapies for Huntington's disease

HD (Huntington's disease) is a devastating neurodegenerative disorder caused by a polyglutamine expansion in the gene encoding the huntingtin protein. Presently, there is no known cure for HD and existing symptomatic treatments are limited. However, recent advances have identified multiple pathological mechanisms involved in HD, some of which have now become the focus of therapeutic intervention. In this review, we consider progress made towards developing safe and effective pharmaceutical-, cell- and genetic-based therapies, and discuss the extent to which some of these therapies have been successfully translated into clinical trials. These new prospects offer hope for delaying and possibly halting this debilitating disease.

The influence of long chain polyunsaturate supplementation on docosahexaenoic acid and arachidonic acid in baboon neonate central nervous system

BACKGROUND

Docosahexaenoic acid (DHA) and arachidonic acid (ARA) are major components of the cerebral cortex and visual system, where they play a critical role in neural development. We quantitatively mapped fatty acids in 26 regions of the four-week-old breastfed baboon CNS, and studied the influence of dietary DHA and ARA supplementation and prematurity on CNS DHA and ARA concentrations.

METHODS

Baboons were randomized into a breastfed (B) and four formula-fed groups: term, no DHA/ARA (T-); term, DHA/ARA supplemented (T+); preterm, no DHA/ARA (P-); preterm and DHA/ARA supplemented (P+). At four weeks adjusted age, brains were dissected and total fatty acids analyzed by gas chromatography and mass spectrometry.

RESULTS

DHA and ARA are rich in many more structures than previously reported. They are most concentrated in structures local to the brain stem and diencephalon, particularly the basal ganglia, limbic regions, thalamus and midbrain, and comparatively lower in white matter. Dietary supplementation increased DHA in all structures but had little influence on ARA concentrations. Supplementation restored DHA concentrations to levels of breastfed neonates in all regions except the cerebral cortex and cerebellum. Prematurity per se did not exert a strong influence on DHA or ARA concentrations.

CONCLUSION

1) DHA and ARA are found in high concentration throughout the primate CNS, particularly in gray matter such as basal ganglia; 2) DHA concentrations drop across most CNS structures in neonates consuming formulas with no DHA, but ARA levels are relatively immune to ARA in the diet; 3) supplementation of infant formula is effective at restoring DHA concentration in structures other than the cerebral cortex. These results will be useful as a guide to future investigations of CNS function in the absence of dietary DHA and ARA.

Chorea and related disorders

Chorea refers to irregular, flowing, non-stereotyped, random, involuntary movements that often possess a writhing quality referred to as choreoathetosis. When mild, chorea can be difficult to differentiate from restlessness. When chorea is proximal and of large amplitude, it is called ballism. Chorea is usually worsened by anxiety and stress and subsides during sleep. Most patients attempt to disguise chorea by incorporating it into a purposeful activity. Whereas ballism is most often encountered as hemiballism due to contralateral structural lesions of the subthalamic nucleus and/or its afferent or efferent projections, chorea may be the expression of a wide range of disorders, including metabolic, infectious, inflammatory, vascular, and neurodegenerative, as well as drug induced syndromes. In clinical practice, Sydenham's chorea is the most common form of childhood chorea, whereas Huntington's disease and drug induced chorea account for the majority of adult onset cases. The aim of this review is to provide an up to date discussion of this disorder, as well as a practical approach to its management.

Neuroprotection in Huntington's disease: a 2-year study on minocycline

Huntington's disease (HD), a relentlessly progressive neurodegenerative disorder, is characterized by a clinical triad of psychiatric, cognitive and motor disturbances. The antibiotic minocycline, a caspase inhibitor exhibiting antiapoptotic properties, has been shown to prolong survival in the transgenic mouse model of HD. We administrated minocycline to 14 patients with genetically confirmed HD. The patients were psychiatrically, neurologically and neuropsychologically evaluated at baseline, and after 6 and 24 months of treatment, using the Unified HD Rating Scale and a neuropsychological test battery. After 12 months, three patients were lost to follow-up so that 11 patients were analysed at the endpoint. Minocycline was well tolerated. Unlike the expected natural course of HD, patients exhibited stabilization in general motor and neuropsychological function at endpoint, after improving in the first 6 months. Moreover, we found a significant amelioration of psychiatric symptoms that was not apparent after the first 6 months. In detail, the Mini-Mental State Examination, the Total Motor Score, the Total Functional Capacity Scale and the Independence Scale, as the most prominent scales in HD, were stabilized after 3 years of treatment. Our results confirm previous animal studies and indicate a neuroprotective effect of this agent in HD. A long-term, double-blind, placebo-controlled trial appears highly warranted for definitively establishing the value of minocycline in HD.