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

Factors Influencing the Total Functional Capacity Score as a Critical Endpoint in Huntington's Disease Research

Background: The Total Functional Capacity (TFC) score is commonly used in Huntington's disease (HD) research. The classification separates each disease stage (1-5), e.g., as an inclusion criterion or endpoint in clinical trials accepted by the Food and Drug Administration (FDA). In addition to the quantification of age- and CAG-repeat-dependent effects as well as interacting effects of both on the TFC, we aimed to investigate factors influencing the TFC, such as neuropsychiatric, educational, and cognitive disease burden using data from the largest HD observational study to date. In addition, we analyzed data from pre-manifest stages to investigate the influence of the above-mentioned factors on the TFC in that stage. Methods: A moderated regression analysis was conducted to analyze the interaction effects of age and CAG-repeat length on the TFC in HD patients. A simple slope analysis was calculated to illustrate the effects. Depending on TFC results, motor-manifest patients were grouped into five stages. Data from pre-manifest participants were analyzed with regard to years to onset and CAP scores. Results: We identified N = 10,314 participants as manifest HD. A significant part of variance on the TFC was explained by age (R2 = 0.029, F (1;10,281) = 308.02, p < 0.001), CAG-repeat length (∆R2 = 0.132, ∆F (1;10,280) = 1611.22, p < 0.001), and their interaction (∆R2 = 0.049, ∆F (1;10,279) = 634.12, p < 0.001). The model explained altogether 20.9% of the TFC score's variance (F = 907.60, p < 0.001). Variance of psychiatric and cognitive symptoms significantly differed between stages. Exploratory analysis of median data in pre-manifest participants revealed the highest scores for neuropsychiatric changes between 5 to <20 years from the disease onset. Conclusions: TFC is mainly explained by the neurobiological factors, CAG-repeat length, and age, with subjects having more CAG-repeats showing a faster decline in function. Our study confirms TFC as a robust measure of progression in manifest HD.

Longitudinal analysis of neuropsychiatric symptoms in a large cohort of early-moderate manifest Huntington's disease patients

BACKGROUND

The relationship between neuropsychiatric symptoms (NPS) and other clinical dimensions in Huntington's disease (HD) is controversial. This longitudinal study analyzed the association between NPS and motor, cognitive and functional aspects of the disease along with other variables related to its clinical onset and progression.

METHODS

639 early-moderate HD patients were assessed longitudinally (mean: 4.95 visits/5 years). Generalized linear mixed models were used to explore associations between NPS and the aforementioned aspects. Other variables previously reported as significant in smaller or cross-sectional studies were included in the models.

RESULTS

Significant associations found included a negative linear relationship between presence of depressed mood and illness duration (7.2% odds reduction of being depressed per year), a 7.6% increase in the odds of having irritability with increased chorea scores, a negative association (4.3% reduction in odds) between age at onset and aggression (i.e. earlier onset was related to a higher probability of having aggressive behaviors) and a negative association between irritability and the interference component of the Stroop test (3% odds change). Total functional capacity (TFC) was the most frequently associated factor with NPS, with apathy and perseverative behavior having the strongest relations with TFC (22% and 18% increases in odds per unit reduction in TFC respectively).

CONCLUSIONS

With the exception of irritability, NPS are not related to motor or cognitive variables in early-moderate HD. Total functional capacity (TFC) is the most frequently associated factor with NPS, with apathy and perseverative behavior having the strongest relations with TFC.

The relationship between non-motor features and weight-loss in the premanifest stage of Huntington's disease

Weight-loss is an integral part of Huntington's disease (HD) that can start before the onset of motor symptoms. Investigating the underlying pathological processes may help in the understanding of this devastating disease as well as contribute to its management. However, the complex behavior and associations of multiple biological factors is impractical to be interpreted by the conventional statistics or human experts. For the first time, we combine a clinical dataset, expert knowledge and machine intelligence to model the multi-dimensional associations between the potentially relevant factors and weight-loss activity in HD, specifically at the premanifest stage. The HD dataset is standardized and transformed into required knowledge base with the help of clinical HD experts, which is then processed by the class rule mining and self-organising maps to identify the significant associations. Statistical results and experts' report indicate a strong association between severe weight-loss in HD at the premanifest stage and measures of certain cognitive, psychiatric functional ability factors. These results suggest that the mechanism underlying weight-loss in HD is, at least partly related to dysfunction of certain areas of the brain, a finding that may have not been apparent otherwise. These associations will aid the understanding of the pathophysiology of the disease and its progression and may in turn help in HD treatment trials.

Electroconvulsive therapy for severe depression, psychosis and chorea in a patient with Huntington's disease: case report and review of the literature

AIMS AND METHOD

The psychiatric manifestations of Huntington's disease are myriad and difficult to control. The use of electroconvulsive therapy (ECT) is not commonly considered for this condition. We describe a patient with severe depression, psychomotor retardation, delusions and weight loss who responded to ECT with good control of her symptoms.

RESULTS

Both our case and the literature appear to confirm the efficacy of ECT in the treatment of depression in Huntington's disease and suggest that other psychiatric manifestations of Huntington's are also responsive.

CLINICAL IMPLICATIONS

ECT is an effective and safe treatment that should be considered earlier in the course of the disease in cases that show limited response to pharmacological therapy. It should also be considered as an adjunct to medical therapy that may simplify polypharmacy and allow better control in patients with debilitating psychiatric manifestations of the disease. There is limited and conflicting evidence for its efficacy in chorea.

Timing and Impact of Psychiatric, Cognitive, and Motor Abnormalities in Huntington Disease

Objective

To assess the prevalence, timing, and functional impact of psychiatric, cognitive, and motor abnormalities in Huntington disease (HD) gene carriers, we analyzed retrospective clinical data from individuals with manifest HD.

Methods

Clinical features of patients with HD were analyzed for 6,316 individuals in an observational study of the European Huntington's Disease Network (REGISTRY) from 161 sites across 17 countries. Data came from clinical history and the patient-completed Clinical Characteristics Questionnaire that assessed 8 symptoms: motor, cognitive, apathy, depression, perseverative/obsessive behavior, irritability, violent/aggressive behavior, and psychosis. Multiple logistic regression was used to analyze relationships between symptoms and functional outcomes.

Results

The initial manifestation of HD is increasingly likely to be motor and less likely to be psychiatric as age at presentation increases and is independent of pathogenic CAG repeat length. The Clinical Characteristics Questionnaire captures data on nonmotor symptom prevalence that correlate specifically with validated clinical measures. Psychiatric and cognitive symptoms are common in HD gene carriers, with earlier onsets associated with longer CAG repeats. Of patients with HD, 42.4% reported at least 1 psychiatric or cognitive symptom before motor symptoms, with depression most common. Each nonmotor symptom was associated with significantly reduced total functional capacity scores.

Conclusions

Psychiatric and cognitive symptoms are common and functionally debilitating in HD gene carriers. They require recognition and targeting with clinical outcome measures and treatments. However, because it is impossible to distinguish confidently between nonmotor symptoms arising from HD and primary psychiatric disorders, particularly in younger premanifest patients, nonmotor symptoms should not be used to make a clinical diagnosis of HD.

Trial Registration Information

ClinicalTrials.gov Identifier: NCT01590589

Psychosis and longitudinal outcomes in Huntington disease: the COHORT Study

OBJECTIVE

Huntington disease (HD) is an autosomal dominant neurodegenerative disease involving motor disturbances, cognitive decline and psychiatric symptoms. Psychotic symptoms occur in a significant proportion of patients. We sought to characterise the clinical outcomes of this group of patients.

METHODS

Data were drawn from the Cooperative Huntington Observational Research Trial, a prospective, multi-centre observational study. 1082 patients with HD were recruited. Measures of cognition, function, behavioural disturbance and motor function were completed annually over 5 years.

RESULTS

Overall, 190 patients (17.6%) displayed psychotic symptoms. These patients demonstrated worse cognition, function and behavioural disturbances than patients without psychosis over time. Patients with psychosis also demonstrated lower levels of chorea than patients without psychosis, despite adjusting for concurrent antipsychotic and tetrabenazine use.

CONCLUSIONS

Psychosis in HD is associated with poorer outcomes in cognition, function and behavioural symptoms. Patients with psychotic symptoms may also have less chorea. Altogether, the findings suggest patients with psychosis have a distinct clinical course.

FGF2 and dual agonist of NCAM and FGF receptor 1, Enreptin, rescue neurite outgrowth loss in hippocampal neurons expressing mutated huntingtin proteins

In the present study, we developed an in vitro model of Huntington disease (HD) by transfecting primary rat hippocampal neurons with plasmids coding for m-htt exon 1 with different number of CAG repeats (18, 50 and 115) and demonstrated the influence of the length of polyQ sequence on neurite elongation. We found that exogenously applied FGF2 significantly rescued the m-htt-induced loss of neurite outgrowth. Moreover, the Enreptin peptide, an FGFR1 and NCAM dual agonist, had a similar neuritogenic effect to FGF2 in clinically relevant m-htt 50Q-expressing neurons. This study has developed an in vitro model of primary hippocampal neurons transfected with m-htt-coding vectors that is a powerful tool to study m-htt-related effects on neuronal placticity.

Huntington's disease: Neuropsychiatric manifestations of Huntington's disease

OBJECTIVES

Huntington's disease (HD) is a profoundly incapacitating, and ultimately fatal, neurodegenerative disease. HD is presently incurable, so the current goal is to allow affected individuals to live as well as possible with the illness, to maximise functional independence and quality of life for the person with HD, their carers and family members. This clinical update review focuses on the common neuropsychiatric manifestations in HD, and outlines and evaluates the various neuropsychiatric facets of HD, including the aetiology, symptoms and diagnosis.

CONCLUSIONS

Neuropsychiatric symptoms can precede the classic motor clinical symptoms of HD (prodromal HD) by decades, and cause significant functional impairment. HD provides key insights and understanding into the organic psychiatric disorders, including contemporary clinical insights into the process of neurodegeneration and manifestation of neuropsychiatric symptoms.

A review of psychiatric co-morbidity described in genetic and immune mediated movement disorders

Psychiatric symptoms are an increasingly recognised feature of movement disorders. Recent identification of causative genes and autoantibodies has allowed detailed analysis of aetiologically homogenous subgroups, thereby enabling determination of the spectrum of psychiatric symptoms in these disorders. This review evaluates the incidence and type of psychiatric symptoms encountered in patients with movement disorders. A broad spectrum of psychiatric symptoms was identified across all subtypes of movement disorder, with depression, generalised anxiety disorder and obsessive-compulsive disorder being most common. Psychosis, schizophrenia and attention deficit hyperactivity disorder were also identified, with the psychiatric symptoms often predating onset of the motor disorder. The high incidence of psychiatric symptoms across such a wide range of movement disorders suggests a degree of common or overlapping pathogenic mechanisms. Our review demonstrates the need for increased clinical awareness of such co-morbidities, which should facilitate early neuropsychiatric intervention and allied specialist treatment for patients.

Two Ethnic Clusters with Huntington Disease in Israel: The Case of Mountain Jews and Karaites

BACKGROUND

Worldwide prevalence estimates of Huntington disease (HD) vary widely, with no reliable information regarding the Jewish population in Israel.

METHODS

This specialized tertiary single-center cross-sectional study assessed clinical, cognitive, and demographic characteristics of 84 HD patients who were treated at the Movement Disorder Unit of the Tel Aviv Medical Center, Israel.

RESULTS

Our cohort was composed of one-third Ashkenazi Jews, 27% Mountain Jews (Caucasus Jews), 18% Sephardi Jews, and 21% Karaites, with both Mountain Jews and Karaites over-represented compared to their relevant proportion in the population of the state of Israel, which is less than 1%. No between-group differences were detected regarding the number of CAG (cytosine-adenine-guanine) repeats, age at onset, disease duration, years from symptom onset to diagnosis, gender, years of education, Unified Huntington Disease Rating Scale scores, or the Montreal Cognitive Assessment scores.

CONCLUSION

We detected clustering of HD among the population treated at our Medical Center, which has the only specialized HD clinic in the country, with a high percentage of HD among 2 relatively small subpopulations of Jews: Mountain Jews and Karaites.

Risk factors for the onset and progression of Huntington disease

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder characterized by chorea, behavioural and psychiatric manifestations, and dementia, caused by a CAG triplet repeat expansion in the huntingtin gene. Systematic review of the literature was conducted to determine the risk factors for the onset and progression of HD. Multiple databases were searched, using terms specific to Huntington disease and to studies of aetiology, risk, prevention and genetics, limited to studies on human subjects published in English or French between 1950 and 2010. Two reviewers independently screened the abstracts and identified potentially relevant articles for full-text review using predetermined inclusion criteria. Three major categories of risk factors for onset of HD were identified: CAG repeat length in the huntingtin gene, CAG instability, and genetic modifiers. Of these, CAG repeat length in the huntingtin gene is the most important risk factor. For the progression of HD: genetic, demographic, past medical/clinical and environmental risk factors have been studied. Of these factors, genetic factors appear to play the most important role in the progression of HD. Among the potential risk factors, CAG repeat length in the mutant allele was found to be a relatively consistent and significant risk factor for the progression of HD, especially in motor, cognitive, and other neurological symptom deterioration. In addition, there were many consistent results in the literature indicating that a higher number of CAG repeats was associated with shorter survival, faster institutionalization, and earlier percutaneous endoscopic gastrostomy.

Screening for cognitive dysfunction in Huntington's disease with the clock drawing test

BACKGROUND

The aim of the study is to investigate the performance of the clock drawing test as a screening tool for cognitive impairment in Huntington's disease (HD) mutation carriers.

METHODS

The performance of the clock drawing test was assessed in 65 mutation carriers using the Shulman and the Freund scoring systems. The mini-mental state examination, the Symbol Digit Modalities Test, the Verbal Fluency Test, and the Stroop tests were used as comparisons for the evaluation of cognitive functioning. Correlations of the clock drawing test with various cognitive tests (convergent validity), neuropsychiatric characteristics (divergent validity) and clinical characteristics were analysed using the Spearman's rank correlation coefficient. Receiver-operator characteristic analyses were performed for the clock drawing test against both the mini-mental state examination and against a composite variable for executive cognitive functioning to assess optimal cut-off scores.

RESULTS

Inter-rater reliability was high for both the Shulman and Freund scoring systems (ICC = 0.95 and ICC = 0.90 respectively). The clock drawing tests showed moderate to high correlations with the composite variable for executive cognitive functioning (mean ρ = 0.75) and weaker correlations with the mini-mental state examination (mean ρ = 0.62). Mean sensitivity of the clock drawing tests was 0.82 and mean specificity was 0.79, whereas the mean positive predictive value was 0.66 and the mean negative predictive value was 0.87.

CONCLUSION

The clock drawing test is a suitable screening instrument for cognitive dysfunction in HD, because it was shown to be accurate, particularly so with respect to executive cognitive functioning, and is easy and quick to use. Copyright © 2016 John Wiley & Sons, Ltd.

Psychiatric disorders, spinocerebellar ataxia type 3 and CAG expansion

Few studies have investigated the association between spinocerebellar ataxia type 3 (SCA3) and psychiatric disorders, using mainly screening scales to assess signs and symptoms of depression and anxiety. With these limitations in mind, we assessed the prevalence of DSM-IV Axis I psychiatric disorders in SCA3 patients and their possible associations with the length of CAG repeats and socio-demographic characteristics, highlighting potential risk factors. DNA samples were collected from 59 adults diagnosed with SCA3 for the quantification of CAG repeats. Next, the patients were assessed in respect to the presence of psychiatric disorders with the Structured Clinical Interview for DSM-IV. Approximately half of the sample had at least one psychiatric disorder (mood disorders 45.2 %), mainly dysthymia and current depression. There were no statistically significant differences in the length of CAG repeats between subjects with and without psychiatric disorders. The perception that SCA3 has a negative impact on life and the subjective assessment of current health status as poor emerged as risk factors for the occurrence of psychiatric disorders in the sample. There is a higher prevalence of psychiatric disorders in SCA3 patients compared to the general population. The lack of association between CAG repeats and occurrence of psychiatric disorders lends support to the hypothesis that psychiatric disorders in this group are associated with adaptive emotional responses to becoming ill.

Hypothalamic-pituitary-adrenal axis functioning in Huntington's disease and its association with depressive symptoms and suicidality

Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis has been reported in Huntington's disease (HD). In non-HD populations, alterations in HPA axis activity have been associated with depression and suicidality. The present study aims to compare HPA axis activity between HD mutation carriers and controls, and examine its association with depressive symptoms and suicidality. To this end, salivary cortisol concentrations at seven time points, as well as depressive symptoms and suicidality, were assessed in 49 pre-motor, 102 motor symptomatic mutation carriers and 55 controls, at baseline and follow-up combined. Differences in parameters of HPA axis activity between these three groups, and their associations with depressive symptoms and suicidality in HD mutation carriers, were analysed using multilevel regression analyses. There were no differences in parameters of HPA axis activity between mutation carriers and controls, whereas pre-motor symptomatic mutation carriers had a significantly higher area under the curve to the increase (AUCi ) compared to motor symptomatic mutation carriers. In the entire HD cohort, HPA axis activity was not associated with depressive symptoms or suicidality. After stratifying mutation carriers into pre-motor, early and advanced disease stages, β values differed between these groups. Remarkably, a higher AUCi was significantly associated with depressive symptoms in pre-motor and early disease stage mutation carriers, with a reverse nonsignificant association in advanced disease stage mutation carriers. The lower AUCi in motor symptomatic mutation carriers and the varying associations with depressive symptoms and suicidality in pre-motor, early and advanced disease stages could possibly be explained by exhaustion of the HPA axis after prolonged stress-induced HPA axis hyperactivity and deserves further longitudinal study.

Acute-phase proteins in relation to neuropsychiatric symptoms and use of psychotropic medication in Huntington's disease

Activation of the innate immune system has been postulated in the pathogenesis of Huntington's disease (HD). We studied serum concentrations of C-reactive protein (CRP) and low albumin as positive and negative acute-phase proteins in HD. Multivariate linear and logistic regression was used to study the association between acute-phase protein levels in relation to clinical, neuropsychiatric, cognitive, and psychotropic use characteristics in a cohort consisting of 122 HD mutation carriers and 42 controls at first biomarker measurement, and 85 HD mutation carriers and 32 controls at second biomarker measurement. Significant associations were found between acute-phase protein levels and Total Functioning Capacity (TFC) score, severity of apathy, cognitive impairment, and the use of antipsychotics. Interestingly, all significant results with neuropsychiatric symptoms disappeared after additional adjusting for antipsychotic use. High sensitivity CRP levels were highest and albumin levels were lowest in mutation carriers who continuously used antipsychotics during follow-up versus those that had never used antipsychotics (mean difference for CRP 1.4 SE mg/L; P=0.04; mean difference for albumin 3 SE g/L; P<0.001). The associations found between acute-phase proteins and TFC score, apathy, and cognitive impairment could mainly be attributed to the use of antipsychotics. This study provides evidence that HD mutation carriers who use antipsychotics are prone to develop an acute-phase response.

Suicidal ideation in a European Huntington's disease population

BACKGROUND

Previous studies indicate increased prevalences of suicidal ideation, suicide attempts, and completed suicide in Huntington's disease (HD) compared with the general population. This study investigates correlates and predictors of suicidal ideation in HD.

METHODS

The study cohort consisted of 2106 HD mutation carriers, all participating in the REGISTRY study of the European Huntington's Disease Network. Of the 1937 participants without suicidal ideation at baseline, 945 had one or more follow-up measurements. Participants were assessed for suicidal ideation by the behavioural subscale of the Unified Huntington's Disease Rating Scale (UHDRS). Correlates of suicidal ideation were analyzed using logistic regression analysis and predictors were analyzed using Cox regression analysis.

RESULTS

At baseline, 169 (8.0%) mutation carriers endorsed suicidal ideation. Disease duration (odds ratio [OR]=0.96; 95% confidence interval [CI]: 0.9-1.0), anxiety (OR=2.14; 95%CI: 1.4-3.3), aggression (OR=2.41; 95%CI: 1.5-3.8), a previous suicide attempt (OR=3.95; 95%CI: 2.4-6.6), and a depressed mood (OR=13.71; 95%CI: 6.7-28.0) were independently correlated to suicidal ideation at baseline. The 4-year cumulative incidence of suicidal ideation was 9.9%. Longitudinally, the presence of a depressed mood (hazard ratio [HR]=2.05; 95%CI: 1.1-4.0) and use of benzodiazepines (HR=2.44; 95%CI: 1.2-5.0) at baseline were independent predictors of incident suicidal ideation, whereas a previous suicide attempt was not predictive.

LIMITATIONS

As suicidal ideation was assessed by only one item, and participants were a selection of all HD mutation carriers, the prevalence of suicidal ideation was likely underestimated.

CONCLUSIONS

Suicidal ideation in HD frequently occurs. Assessment of suicidal ideation is a priority in mutation carriers with a depressed mood and in those using benzodiazepines.

Course of irritability, depression and apathy in Huntington's disease in relation to motor symptoms during a two-year follow-up period

BACKGROUND

Irritability, depression and apathy are frequently reported neuropsychiatric symptoms of Huntington's disease (HD).

OBJECTIVE

This study investigated the course of irritability, depression and apathy in HD during a 2-year follow-up period.

METHODS

In 121 HD mutation carriers the presence of irritability, depression and apathy was measured with the Problem Behaviours Assessment (PBA). Multivariate linear regression analysis was performed to assess their relationships with the change of the motor score of the Unified Huntington's Disease Rating Scale (UHDRS-m) in premotor symptomatic (n = 46) and motor symptomatic mutation carriers (n = 75).

RESULTS

The median depression score of all participants decreased (p = 0.002), whereas irritability and apathy scores did not change significantly. In the total group of mutation carriers, a borderline significant association was found between an increase in motor symptoms and an increase in irritability (p = 0.05), and a trend was found for the association between an increase in motor symptoms and a decrease in depression (p = 0.06). Only in the at baseline premotor symptomatic mutation carriers was an increase in motor symptoms significantly related to an increase in irritability (p = 0.02).

CONCLUSION

An increase in motor symptoms in the at baseline premotor symptomatic mutation carriers is related to an increase in irritability, which may be an early and sensitive marker for disease progression.

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 the Huntington intermediate CAG repeat expansion phenotype in PHAROS

OBJECTIVES

We aimed to describe the clinical phenotype conferred by the intermediate-length huntingtin allele CAG repeat expansion in a population-based study.

METHODS

The Prospective Huntington At Risk Observational Study (PHAROS) enrolled adults at risk for Huntington disease (HD). They were assessed approximately every 9 months with the Unified Huntington's Disease Rating Scale (UHDRS) by investigators unaware of participants' gene status. UHDRS scores were compared according to the Huntingtin gene CAG repeat number: expanded >36, intermediate 27-35, and nonexpanded controls <26.

RESULTS

Fifty (5.1%) of the 983 participants had an intermediate allele (IA). They were similar to controls on UHDRS motor, cognitive, and functional measures, but significantly worse behaviorally on apathy and suicidal ideation. On 5 of the 9 other behavioral items and on total behavior, the IA group's scores were worse than those of controls and expanded participants, who themselves scored significantly worse than controls on 6 behavioral measures. Retention rates at 4 years were 48% for the IA group compared to 58% and 60% for the expanded and control groups.

CONCLUSIONS

In a cohort at risk for HD, the IA was associated with significant behavioral abnormalities but normal motor and cognition. This behavioral phenotype may represent a prodromal stage of HD, with the potential for subsequent clinical manifestations, or be part of a distinct phenotype conferred by pathology independent of the CAG expansion length.

Concise review: adult mesenchymal stem cells, adult neural crest stem cells, and therapy of neurological pathologies: a state of play

Adult stem cells are endowed with in vitro multilineage differentiation abilities and constitute an attractive autologous source of material for cell therapy in neurological disorders. With regard to lately published results, the ability of adult mesenchymal stem cells (MSCs) and neural crest stem cells (NCSCs) to integrate and differentiate into neurons once inside the central nervous system (CNS) is currently questioned. For this review, we collected exhaustive data on MSC/NCSC neural differentiation in vitro. We then analyzed preclinical cell therapy experiments in different models for neurological diseases and concluded that neural differentiation is probably not the leading property of adult MSCs and NCSCs concerning neurological pathology management. A fine analysis of the molecules that are secreted by MSCs and NCSCs would definitely be of significant interest regarding their important contribution to the clinical and pathological recovery after CNS lesions.

Irritability in Huntington's disease

Irritability is a frequent neuropsychiatric symptom in patients with Huntington's disease (HD). The Irritability Scale (IS) and the irritability factor of the Problem Behaviours Assessment (PBA) was used to assess irritability among 130 HD mutation carriers and 43 verified non-carriers. The IS was tested using receiver operating characteristic analysis against different cut-offs of the PBA irritability factor. A robust IS cut-off score of ≥14 points was found indicating that 45 (35%) of the 130 mutation carriers were irritable vs. 4 (9%) of the 43 non-carriers (P=0.001). The level of agreement between self-report and informant-report IS was of moderate strength (intraclass correlation=0.61). Using univariate and multivariate regression analyses, independent correlates of irritability were being married/living together (P=0.02), CAG repeat length (P=0.01), and use of benzodiazepines (P=0.008). Using the same model with the informant's irritability score, use of benzodiazepines was the only significant independent correlate of irritability (P=0.005). Irritability is a prominent symptom of HD and can be reliably assessed with the IS using a cut-off score ≥14 points. Although it is unclear whether benzodiazepine use causes irritability, or irritability leads to the prescription of benzodiazepines, clinical evaluation with respect to the use of benzodiazepines in HD warrants attention.

Psychiatric disorders in Huntington's disease: a 2-year follow-up study

OBJECTIVE

This study investigates the presence and course of formal psychiatric disorders according to the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) in 142 Huntington's disease (HD) mutation carriers in a two-year follow-up design.

METHOD

Of the 142 mutation carriers, 106 (75%) participated in the second measurement of an ongoing cohort study on psychopathology in HD. Presence of psychiatric disorders was assessed using the Composite International Diagnostic Interview.

RESULTS

Of the 91 patients without a formal psychiatric disorder at baseline, 14 (15%) had a psychiatric disorder after 2 years, mostly a major depressive disorder (MDD) (64%). The baseline characteristics of lower education, having no children, a lower level of global daily functioning, a lifetime psychiatric diagnosis, and the use of psychotropic medication were predictive of incident psychiatric disorders after 2 years. Of the 15 patients with a psychiatric diagnosis at baseline, eight (53%) no longer had a psychiatric disorder at follow-up. All seven patients (47%) with a persistent psychiatric disorder were female and their most prevalent diagnosis was generalized anxiety disorder.

CONCLUSION

This cohort study confirms that psychiatric disorders, in particular MDD, frequently occur in patients with HD. Professionals working with HD patients should therefore be aware of the high risk of psychopathology in HD because early diagnosis and treatment of psychiatric disorders may improve the quality of life of patients and their caregivers.

Suicidality in Huntington's disease

BACKGROUND

In Huntington's disease (HD) the risk of suicide is increased. Since suicidality may precede suicide, this study investigates prevalence, clinical associations and predictors of suicidality in HD.

METHODS

Suicidality was investigated in 152 mutation carriers and 56 non-carriers, and was considered present if the score on the item 'suicidal ideation' of the Problem Behaviours Assessment (PBA) was >1 point. After 2 years, 100 mutation carriers who were free of suicidality at baseline were re-assessed. Associations and predictors of suicidality were analyzed using multivariate logistic regression analysis.

RESULTS

Eleven (20%) pre-motor and 20 (20%) motor symptomatic mutation carriers were considered suicidal compared to none of the non-carriers. Cross-sectionally, suicidal mutation carriers were more likely to use antidepressants (odds ratio=5.3), were more often apathetic (OR=2.8), more often had a depressed mood according to the PBA (OR=5.9), and were more often diagnosed with a DSM-IV depression diagnosis (OR=4.7). Independent associations were more frequent use of antidepressants (OR=4.0) and presence of a depressed mood (OR=4.2). Longitudinally, depressed mood (OR=10.6) at baseline was the only independent predictor of suicidality at follow-up.

LIMITATIONS

Selection bias might have occurred which could have affected the suicidality rate.

CONCLUSION

It is important to screen both pre-motor and motor symptomatic HD mutation carriers for suicidality. The presence of a depressed mood is both associated with and predictive of suicidality in HD and assessment of depressed mood can help to identify individuals with increased risk for suicide.

Adult bone marrow: which stem cells for cellular therapy protocols in neurodegenerative disorders?

The generation of neuronal cells from stem cells obtained from adult bone marrow is of significant clinical interest in order to design new cell therapy protocols for several neurological disorders. The recent identification in adult bone marrow of stem cells derived from the neural crests (NCSCs) might explain the neuronal phenotypic plasticity shown by bone marrow cells. However, little information is available about the nature of these cells compared to mesenchymal stem cells (MSCs). In this paper, we will review all information available concerning NCSC from adult tissues and their possible use in regenerative medicine. Moreover, as multiple recent studies showed the beneficial effect of bone marrow stromal cells in neurodegenerative diseases, we will discuss which stem cells isolated from adult bone marrow should be more suitable for cell replacement therapy.

A GAG trinucleotide-repeat polymorphism in the gene for glutathione biosynthetic enzyme, GCLC, affects gene expression through translation

A guanine-adenine-guanine (GAG) repeat polymorphism with 5 different alleles (4, 7, 8, 9, and 10 repeats) in the 5' untranslated region (UTR) of GCLC has been associated with altered GCL activity and glutathione (GSH) levels. We investigated whether this polymorphism affects either transcription or translation using luciferase reporter constructs containing variant GCLC 5' UTRs. Higher luciferase activity was observed in HepG2 and human embryonic kidney 293 (HEK293) cells transfected with constructs containing either 8 or 9 repeats than in constructs containing 4, 7, or 10 repeats (P<0.05). In cell-free lysates, GAG repeat number had no effect on luciferase mRNA yield. In vitro translation of mRNAs from luciferase constructs resulted in differences similar to those found in cell cultures (P<0.05). A similar association of GAG repeat with GCLC phenotype was observed in vivo in healthy adults, as individuals with GAG-7/7 genotype had lower GCL activity and GSH levels in lymphocytes compared to those with GAG-9/9 (P<0.05). Higher GCL activity and GSH levels observed in red blood cells (RBCs) from individuals with GAG-7/7 compared to GAG-9/9 are likely due to differences in GCL regulation in RBCs. Altogether, these results suggest that GAG polymorphism affects GCLC expression via translation, and thus may be associated with altered risk for GSH-related diseases and toxicities.

Huntington's disease

Huntington's disease (HD) is an inherited disorder that causes neurological, cognitive, and psychiatric symptoms. Most patients with HD develop symptoms in all three of these domains, often concurrently. Problems in one area can impact and magnify symptoms in another domain. Limited treatment options exist for neurological and cognitive symptoms at this time, and no treatment exists to slow disease progression. In contrast, many behavioral symptoms respond to psychiatric medication. Thorough and aggressive treatment of psychiatric symptoms can positively impact both patient and caregiver quality of life, and may allow patients to remain longer in the home. There are currently numerous treatment trials not only for symptomatic therapy, but also for disease-modifying agents.

Measurement of psychopathology in Huntington's disease: the critical role of caregivers

Assessment of psychopathology in Huntington's disease (HD) using formal DSM-IV criteria is complex because of comorbid somatic and cognitive disturbances and diminished disease awareness. Using dimensional tests in 152 HD mutation carriers, both the total score of the Problem Behaviors Assessment (PBA) scale and the behavioral section of the Unified Huntington's Disease Rating Scale (UHDRS-b) corresponded with presence of DSM-IV diagnoses. Receiver operating characteristic curves showed an area under the curve of 0.87 for the PBA and 0.91 for the UHDRS-b, demonstrating moderate to strong discriminatory power. Using caregiver information, subjects who were too cognitively impaired for composite international diagnostic interview assessment showed similar high PBA and UHDRS-b scores, with both a negative predictive value of 96% and a positive predictive value of 40% and 44%, respectively, for the presence of formal psychiatric disorders, indicating that dimensional rating scales and caregiver information allow for the assessment of psychopathology in advanced-stage HD.

The hOGG1 Ser326Cys polymorphism and Huntington's disease

Increasing evidence supports a role for oxidative DNA damage and impaired DNA repair mechanisms in the pathogenesis of age related neurodegenerative diseases. Within this context there is a current interest in the understanding of the role played by polymorphisms of DNA repair genes in the inter-individual risk to develop neurodegenerative pathologies, as well as in the onset and the progression of disease symptoms. Particularly, somatic CAG repeat expansion of the gene encoding for huntingtin has been observed in tissues of patients affected by Huntington's disease (HD), including blood and brain. Recent evidence suggests that somatic CAG repeat expansion in HD cells might contribute to disease age at onset and is mediated by the DNA repair OGG1 enzyme, during the removal of 8-oxoguanine (8-oxoG) from the DNA. There is also evidence that the expression of hMTH1, which removes 8-oxoG from the nucleotide pool, protects mice from HD-like symptoms, and progenitor striatal cells from the toxic effects of the mutant huntingtin. The hOGG1 Ser326Cys polymorphism results in reduced OGG1 activity and increased 8-oxoG formation. In the present study, performed on blood DNA from 91 HD subjects, we observed that bearers of the mutant Cys326 allele (Ser326Cys+Cys326Cys) tend to have an increased number of CAG repeats of the expanded HD allele (P=0.049); moreover bearers of at least one copy of the mutant Cys326 allele, mainly heterozygous subjects, showed a significant (P=0.041) earlier disease onset than Ser326Ser wild-type individuals, suggesting a possible role of the hOGG1 Ser326Cys polymorphism in HD phenotype.

A genome-wide association scan for asthma in a general Australian population

To date, almost every chromosome has been implicated in genetic susceptibility to asthma to some degree. When compared with single nucleotide polymorphism, microsatellite markers exhibit high levels of heterozygosity and therefore provide higher statistical power in association. The objective of this study was to perform a genome-wide association study using 23,465 in-house microsatellite markers to detect asthma susceptibility regions in the Busselton population. In this study, three separate pooled DNA screenings yielded 18 markers with significantly different estimated frequencies in the three separate "case and control" pools: each pool consisting of 60 males and 60 females. These markers were evaluated by individual typing in 360 cases and 360 controls. Two markers showed significant differences between cases and controls (P = 0.001 and P = 0.003). Regions surrounding the two markers were subjected to high-density association mapping with a total of 14 additional markers. We were able to confirm and fine map the association in these two regions by typing 14 additional microsatellite markers (1805A09 (D18S0325i), P = 0.002; 1806D05 (D18S0181i), P = 0.001). Each region contains a predicted gene that showed strong associations with asthma. Further studies are underway to characterize the novel candidate asthma susceptibility genes identified in this genome-wide study.