Characterization of depression in prodromal Huntington disease in the neurobiological predictors of HD (PREDICT-HD) study

Sex differences in Huntington's disease from a neuroinflammation perspective

Huntington's disease (HD) is a debilitating neurodegenerative condition characterized by motor, cognitive and psychiatric abnormalities. Immune dysregulation, prominently featuring increased immune activity, plays a significant role in HD pathogenesis. In addition to the central nervous system (CNS), systemic innate immune activation and inflammation are observed in HD patients, exacerbating the effects of the Huntingtin (HTT) gene mutation. Recent attention to sex differences in HD symptom severity underscores the need to consider gender as a biological variable in neurodegenerative disease research. Understanding sex-specific immune responses holds promise for elucidating HD pathophysiology and informing targeted treatment strategies to mitigate cognitive and functional decline. This perspective will highlight the importance of investigating gender influence in HD, particularly focusing on sex-specific immune responses predisposing individuals to disease.

Associations of inflammatory cytokines and cortisol with nonmotor features of Huntington's disease

OBJECTIVE

Huntington's disease (HD) is an inherited neurodegenerative disease involving progressive motor abnormalities, cognitive decline, and psychiatric disturbances. Depression and cognitive difficulties are among the most impactful symptoms of HD, yet the pathogenesis of these symptoms is not fully understood. HD involves low-level chronic inflammation and dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, which are linked to depression and cognitive impairment in non-HD populations. However, previous research on the relationships of these pathologies with depression and cognition in HD is limited and inconsistent.

METHODS

Fifty-three adults with the HD gene expansion (30 premanifest and 23 manifest) completed measures of depression and cognitive functioning. Forty-eight out of 53 participants provided hair samples for quantification of cortisol, and 34 participants provided blood samples for quantification of peripheral inflammatory cytokines. We examined the associations of four cytokines (interleukin [IL]-6, IL-10, IL-1β, and tumor necrosis factor [TNF]-α) and cortisol levels with depression and cognitive scores.

RESULTS

In unadjusted models, higher levels of plasma IL-6, IL-10, and TNF-α correlated with higher depression scores, and higher levels of IL-10 and TNF-α correlated with poorer cognitive performance. After controlling for age, sex, and body mass index, only the correlations of IL-10 with depression and cognitive performance remained significant. No correlations were evident with hair cortisol.

INTERPRETATIONS

Peripheral inflammation is associated with depression symptoms and cognitive impairment in HD. Our findings suggest that interactions between the immune and nervous systems are important in HD, and highlight the potential of chronic inflammation as a therapeutic target in early stages of HD.

The relationship between disease-specific psychosocial stressors and depressive symptoms in Huntington's disease

BACKGROUND

Huntington's disease (HD) is an inherited neurodegenerative disease involving motor abnormalities, cognitive decline, and psychological difficulties. Depression is among the most common psychological difficulties in HD. People with HD encounter numerous stressors related to their diagnosis and the impact of HD on their daily lives. Understanding the relationship between HD-specific psychosocial stressors and depression symptoms is critical for optimising treatment and developing a holistic, disease-specific model of depression in HD.

METHODS

Fifty-seven adults with the HD gene expansion (33 pre-symptomatic, 24 symptomatic) completed a self-report depression questionnaire and rated how much stress they experienced in relation to 20 psychosocial challenges commonly associated with HD. We examined associations between depression symptoms and each stressor individually, and after clustering using principal components analysis.

RESULTS

Depression symptoms were significantly associated with most of the psychosocial stressors assessed. Clustering with principal components analysis revealed that higher depression scores had significant independent associations with greater stress related to the future implications of HD (β = .44, p = .001) and sleep and psychological difficulties (β = .28, p = .005), but not with stress related to functional limitations (β = .11, p = .33) or interpersonal issues caused by HD (β = .15, p = .21).

CONCLUSIONS

Stressful experiences associated with HD constitute an important risk factor for depression in HD. Our findings support the use of more psychologically informed models of depression in HD and necessitate further research on tailored psychosocial interventions for HD patients with depression.

Advances in the Diagnosis and Management of Psychotic Symptoms in Neurodegenerative Diseases: A Narrative Review

Background: Approximately 15% of older adults may experience psychotic phenomena. Primary psychiatric disorders that manifest with psychosis (delusions, hallucinations, and disorganized thought or behavior) account for less than half. Up to 60% of late-life psychotic symptoms are due to systemic medical or neurological conditions, particularly neurodegenerative diseases. A thorough medical workup including laboratory tests, additional procedures if indicated, and neuroimaging studies is recommended. This narrative review summarizes current evidence regarding the epidemiology and phenomenology of psychotic symptoms encountered as part of the neurodegenerative disease continuum (including prodromal and manifest stages). Results: Prodromes are constellations of symptoms that precede the onset of overt neurodegenerative syndromes. Prodromal psychotic features, particularly delusions, have been associated with an increased likelihood of receiving a neurodegenerative disease diagnosis within several years. Prompt prodrome recognition is crucial for early intervention. The management of psychosis associated with neurodegenerative diseases includes behavioral and somatic strategies, although evidence is scarce and mostly limited to case reports, case series, or expert consensus guidelines, with few randomized controlled trials. Conclusion: The complexity of psychotic manifestations warrants management by interprofessional teams that provide coordinated, integrated care.

The temporal dynamics of mood and their association with depressive symptoms in Huntington's disease

BACKGROUND

Huntington's disease (HD) is an inherited neurodegenerative disorder characterised by progressive motor abnormalities, cognitive decline, and neuropsychiatric disturbances. Depression is among the most common neuropsychiatric syndromes in HD. Research in neurologically healthy samples has shown that depression is associated with distinct patterns of short-term fluctuations in mood, which may exacerbate negative effects on psychological wellbeing. The short-term dynamics of mood and their relationship with depression have not yet been investigated in HD.

METHODS

Fifty-five adults with the HD CAG expansion (33 pre-manifest, 22 manifest) completed single timepoint measures of depression, demographic factors, and clinical disease outcomes on day 1, then rated their mood daily for 28 consecutive days. Average mood, mood variability, and mood inertia (auto-correlation) were calculated across the 28 days.

RESULTS

Depression severity on day 1 was significantly associated with average mood across the 28 days, but not with day-to-day mood variability or inertia. Additionally, female HD CAG expansion carriers experienced more day-to-day variability in mood compared to males.

LIMITATIONS

Our sample did not include HD CAG expansion carriers with severe depressive symptoms or advanced HD, which limits the generalisability of the findings. Additionally, findings may have been affected by antidepressant and antipsychotic medication use among many participants.

CONCLUSIONS

In HD, short-term patterns of change in mood appear to be relatively independent of depression severity. Moreover, in female CAG-expansion carriers particularly, mood variability may warrant further clinical attention. These findings should be replicated in larger and more diverse samples, with different timescales and measures for assessing mood.

A systematic review and meta-analysis of depression and apathy frequency in adult-onset Huntington's disease

Depression and apathy are associated with decreased functional capacity in Huntington's disease (HD) but frequency of depression and apathy in HD is largely unknown. Systematic literature searching was conducted across 21 databases until 30 June 2021. Inclusion criteria was limited to clinician-rated assessments of depression and apathy and adult-onset HD. Inverse-variance heterogeneity meta-analyses were conducted exploring depression and apathy frequency within individuals from families affected by HD, and within individuals with confirmed HD gene-positive status. Screening identified 289 articles for full-text review; nine remained for meta-analysis. Depression frequency in the lifetime in adults affected by or at-risk for HD was 38%, I² = 99%. Apathy frequency in the lifetime in adults affected by or at-risk for HD was 40%, I² = 96%. The robustness of the findings improved when limiting the analysis to gene-positive individuals only where apathy was found to be slightly more common than depression, 48% and 43% respectively. Future studies may consider reporting results from juvenile-onset HD and adult-onset HD cohorts separately to further explore phenotypic profiles.

A Randomized Controlled Trial of Probiotics Targeting Gut Dysbiosis in Huntington’s Disease

Background: Gastrointestinal symptoms are clinical features of Huntington’s disease (HD), which adversely affect people’s quality of life. We recently reported the first evidence of gut dysbiosis in HD gene expansion carriers (HDGECs). Here, we report on a randomized controlled clinical trial of a 6-week probiotic intervention in HDGECs. Objective: The primary objective was to determine whether probiotics improved gut microbiome composition in terms of richness, evenness, structure, and diversity of functional pathways and enzymes. Exploratory objectives were to determine whether probiotic supplementation improved cognition, mood, and gastrointestinal symptoms. Methods: Forty-one HDGECs, including 19 early manifest and 22 premanifest HDGECs were compared with 36 matched-healthy controls (HCs). Participants were randomly assigned probiotics or placebo and provided fecal samples at baseline and 6-week follow-up, which were sequenced using 16S-V3-V4 rRNA to characterize the gut microbiome. Participants completed a battery of cognitive tests and self-report questionnaires measuring mood and gastrointestinal symptoms. Results: HDGECs had altered gut microbiome diversity when compared to HCs, indicating gut dysbiosis. Probiotic intervention did not ameliorate gut dysbiosis or have any effect on cognition, mood, or gastrointestinal symptoms. Gut microbiome differences between HDGECs and HCs were unchanged across time points, suggesting consistency of gut microbiome differences within groups. Conclusion: Despite the lack of probiotic effects in this trial, the potential utility of the gut as a therapeutic target in HD should continue to be explored given the clinical symptomology, gut dysbiosis, and positive results from probiotics and other gut interventions in similar neurodegenerative diseases.

Sexual Dimorphism in Neurodegenerative Diseases and in Brain Ischemia

Epidemiological studies and clinical observations show evidence of sexual dimorphism in brain responses to several neurological conditions. It is suggested that sex-related differences between men and women may have profound effects on disease susceptibility, pathophysiology, and progression. Sexual differences of the brain are achieved through the complex interplay of several factors contributing to this phenomenon, such as sex hormones, as well as genetic and epigenetic differences. Despite recent advances, the precise link between these factors and brain disorders is incompletely understood. This review aims to briefly outline the most relevant aspects that differ between men and women in ischemia and neurodegenerative disorders (AD, PD, HD, ALS, and SM). Recognition of disparities between both sexes could aid the development of individual approaches to ameliorate or slow the progression of intractable disorders.

Recent approaches on Huntington's disease (Review)

Huntington's disease (HD) is a neurodegenerative disorder characterized by severe motor, cognitive and psychiatric symptoms. Patients of all ages can present with a dysfunction of the nervous system, which leads to the progressive loss of movement control and disabilities in speech, swallowing, communications, etc. The molecular basis of the disease is well-known, as HD is related to a mutated gene, a trinucleotide expansion, which encodes to the huntingtin protein. This protein is linked to neurogenesis and the loss of its function leads to neurodegenerative disorders. Although the genetic cause of the disorder has been known for decades, no effective treatment is yet available to prevent onset or to eliminate the progression of symptoms. Thus, the present review focused on the development of novel methods for the timely and accurate diagnosis of HD in an aim to aid the development of therapies which may reduce the severity of the symptoms and control their progression. The majority of the therapies include gene-silencing mechanisms of the mutated huntingtin gene aiming to suppress its expression, and the use of various substances as drugs with highly promising results. In the present review, the latest approaches on the diagnosis of HD are discussed along with the need for genetic counseling and an up-to-date presentation of the applied treatments.

Psychological discomfort in carriers and non-carriers of the Huntington disease mutation and its relationship with disease burden

INTRODUCTION

Huntington's disease (HD) is a neurodegenerative and hereditary disorder. Due to the predictive diagnosis, incipient clinical characteristics have been described in the prodromal phase. Several studies have reported an increase in psychiatric symptoms in carriers of the HD gene without motor symptoms.

OBJECTIVE

To identify psychological distress in carriers of the mutation that causes HD, without motor symptoms, utilizing the Symptom Checklist 90 (SCL-90), and to correlate with the burden and proximity of the disease.

METHOD

A sample of 175 participants in a HD Predictive Diagnostic Program (PDP-HD) was divided into HEP carriers (39.4%) and NPEH non-carriers (61.6%) of the HD-causing mutation. By means of mathematical formulas, the disease burden and proximity to the manifest stage in the PEH group were obtained and it was correlated with the results of the SCL-90-R.

RESULTS

Comparing the results obtained in the SCL-90-R of the PEH and NPEH, the difference is observed in the positive somatic male index, where the PEH obtains higher average scores. The correlations between disease burden and psychological distress occur in the domains; obsessions and compulsions, interpersonal sensitivity, hostility, global severity index and positive somatic distress index. A low correlation is observed between the burden of disease and the scores obtained in psychological discomfort.

CONCLUSIONS

In general, we found that the PEH group obtained a higher score in the dimensions evaluated with the SCL-90-R, showing a relationship with the burden and differences due to the proximity of the disease. Higher scores on the SCL-90-R dimensions in carriers of the HD gene may suggest an early finding of psychological symptoms in the disease.

Behavioral features in child and adolescent huntingtin gene-mutation carriers

INTRODUCTION

We compared neuropsychiatric symptoms between child and adolescent huntingtin gene-mutation carriers and noncarriers. Given previous evidence of atypical striatal development in carriers, we also assessed the relationship between neuropsychiatric traits and striatal development.

METHODS

Participants between 6 and 18 years old were recruited from families affected by Huntington's disease and tested for the huntingtin gene expansion. Neuropsychiatric traits were assessed using the Pediatric Behavior Scale and the Behavior Rating Inventory of Executive Function. Striatal volumes were extracted from 3T neuro-anatomical images. Multivariable linear regression models were conducted to evaluate the impact of group (i.e., gene nonexpanded [GNE] or gene expanded [GE]), age, and trajectory of striatal growth on neuropsychiatric symptoms.

RESULTS

There were no group differences in any behavioral measure with the exception of depression/anxiety score, which was higher in the GNE group compared to the GE group (estimate = 4.58, t(129) = 2.52, FDR = 0.051). The growth trajectory of striatal volume predicted depression scores (estimate = 0.429, 95% CI 0.15:0.71, p = .0029), where a negative slope of striatal volume over time was associated with lower depression/anxiety.

CONCLUSIONS

The current findings show that GE children may have lower depression/anxiety compared to their peers. Previously, we observed a unique pattern of early striatal hypertrophy and continued decrement in volume over time among GE children and adolescents. In contrast, GNE individuals largely show striatal volume growth. These findings suggest that the lower scores of depression and anxiety seen in GE children and adolescents may be associated with differential growth of the striatum.

The Lived Experiences of Depression in Huntington's Disease: A Qualitative Study

BACKGROUND

Depression is a common neuropsychiatric syndrome in Huntington's disease (HD) and has debilitating consequences, including poorer sleep, exacerbation of cognitive and functional decline, and suicidality. To date, no published studies have documented the lived experience of depression in HD, despite clinical evidence that depression may be experienced differently in HD compared to the general population.

OBJECTIVE

The aim of this study was to investigate the lived experiences of depression in people with the CAG expansion for HD using qualitative methods.

METHODS

We conducted semi-structured interviews with HD CAG expansion carriers who had current or previous experiences of depression, until data saturation was achieved. This resulted in interviews from 17 HD CAG expansion carriers (11 premanifest, 6 manifest) which were analyzed using thematic analysis.

RESULTS

The four key themes that emerged related to the temporal characteristics of depression in HD, the qualitative changes associated with depression, psychosocial stressors perceived to contribute to depression, and the perception of depression as an endogenous feature of HD.

CONCLUSION

This study provides an enriched understanding of the unique characteristics of depression in HD, and the attributions that CAG expansion carriers make for their depression symptoms. The themes identified in this study can be used to guide more targeted assessment and treatment of depression in HD.

Clinical Correlates of Depression and Suicidality in Huntington Disease: An Analysis of the Enroll-HD Observational Study

BACKGROUND

Depression and suicidality are commonly experienced by Huntington disease (HD) gene carriers. Research on these behavioral symptoms is imperative, not only to increase our understanding of the symptoms and how they relate to HD, but also to contribute to improving patients' care and quality of life.

OBJECTIVE

To identify clinical variables associated with a history of depression and suicidality in HD gene carriers.

METHOD

We conducted a cross-sectional study of HD gene carriers from the Enroll-HD database PDS4 (periodic data set 4; N = 11,582). Data from baseline visits were obtained, and binary logistic regression models were used to ascertain the effects of clinical variables on the likelihood that HD gene carriers would have previous depression and suicidal ideation/attempts.

RESULTS

Approximately 65% (n = 7526) of the HD gene carriers had a history of depression, and ~27% (n = 3152) had previous suicidal ideation/attempts. Female sex; diagnosis of manifest HD; history of perseverative/obsessive behavior, apathy, and psychosis; and previous suicidal ideation/attempts were significantly associated with a history of depression in the HD gene carriers. Medical history of apathy, psychosis, and depression, as well as worse scores on the Total Functional Capacity and Irritability Scales, were significantly associated with previous suicidal ideation/attempts in the HD gene carriers.

CONCLUSION

The prevalence of depression and suicidality is high among HD gene carriers. An improved understanding of the risk factors for depression and suicide in HD gene carriers can assist providers in recognizing at-risk individuals and allow providers to implement therapeutic strategies.

The structure of mental health symptoms in Huntington's disease: Comparisons with healthy populations

INTRODUCTION

Mental health difficulties are common among people with Huntington's disease (HD). However, such difficulties are only weakly associated with HD progression, suggesting their causes may be multifactorial rather than purely disease-related. Genetically unaffected family members have been shown to experience similar levels of mental distress to people with HD, potentially due to systemic stressors and life disruption. These factors may also influence mental wellbeing in people with HD. Accordingly, this study aimed to compare patterns and occurrence of mental distress between people with HD and genetically unaffected control groups, to determine systemic and environmental contributions to HD-related distress.

METHOD

Exploratory and confirmatory factor analysis was used to compare the structure of mental distress in 5,294 individuals from four groups: manifest or premanifest HD, family control, and genotype-negative. Data were from the Enroll-HD study, using scores from the Problem Behaviors Assessment, the Hospital Anxiety and Depression Scale, and the Snaith Irritability Scale. We then evaluated consistency of the identified constructs over three annual assessments using analysis of variance.

RESULTS

Four factors consistently emerged across all groups, comprising depression, anxiety, temper and self-harm; these remained stable across time. People with HD did not report significantly different anxiety scores to control groups. The manifest group reported significantly higher depression, temper and self-harm than the genotype-negative group, but only differed in some cases from family-controls.

CONCLUSIONS

The findings suggest greater similarity in the severity and structure of mental health symptoms between people with and without HD than previously believed. This suggests contributions from systemic as well as genetic factors in families affected by HD, especially in terms of anxiety symptoms.

Research Paper5,6,7 trihydroxy flavone armoured neurodegeneration caused by Quinolinic acid induced huntington's like disease in rat striatum - reinstating the level of brain neurotrophins with special reference to cognitive-socio behaviour, biochemical and histopathological aspects

Huntington Disease (HD), a predominant Neurodegenerative Disorder which might be induced by endogenous neurotoxin called Quinolinic Acid (QA), an N-methyl-D aspartate receptor (NMDAR) agonist, the bilaterally intrastriatal administration (200 nm/2 μL of saline) offers rise to the toxic events like neuronal death, neuroinflammation by inflicting excitotoxicity and oxidative stress in the striatum of male Wistar rats by exhibiting the behavioural changes which was accessed by rotarod, open field analysis. In this study, the neuropharmacological effect of Baicalein (BC) against QA induced HD was evaluated. Baicalein (BC), scientifically 5,6,7 trihydroxy flavone present naturally in the edible plants like Scutellaria baicalensis and Oroxylum indicum possess a better neuroprotective effect in the dosage of 10 mg/kg and 30 mg/kg intraperitoneally in the striatum of HD induced rats. This study proved that BC is efficient to revive the level of enzymatic & non-enzymatic antioxidants and mitochondrial complexes by decreasing the number of inflammatory mediators such as MDA, protein carbonyls and Nitric Oxide at the significance of P < 0.01 and restores the amount of BDNF and GDNF thereby preventing the neurophysiological changes which were analysed by haematoxylin & eosin staining. Thus finally, the protective effect of Baicalein displays the up-gradation of psychological and behavioural changes induced by QA.

Sex Differences in Huntington's Disease: Evaluating the Enroll-HD Database

BACKGROUND

Identifying sex-related differences is critical for enhancing our understanding of factors that may impact prognosis and advance treatments in Huntington's disease (HD).

OBJECTIVES

To investigate if sex-related differences exist in clinical HD.

METHODS

Longitudinal study of the Enroll-HD database. Manifest HD patients were included in the analysis (N = 8401). Linear mixed models were used to assess motor, behavioral, and cognitive functioning over a series of four annual visits, and compared male and female HD gene carriers.

RESULTS

HD patients showed significant sex-dependent differences in motor, cognitive, and behavioral symptoms. Both sexes had worsened motor symptoms over the course of four visits, but there was a significant disparity between sexes, with females consistently presenting with more symptoms than males. For behavioral symptoms, specifically depressive symptoms, females had significantly more depressive symptoms, although self-reported symptoms in both sexes became less severe throughout time.

CONCLUSIONS

Our analyses suggest that women have worse symptoms than men during the course of HD.

The Neuropsychiatry of Huntington Disease-Like 2: A Comparison with Huntington's Disease

BACKGROUND

Huntington Disease-Like 2 (HDL2) is a rare autosomal dominant disorder caused by an abnormal CAG/CTG triplet repeat expansion on chromosome 16q24. The symptoms of progressive decline in motor, cognitive and psychiatric functioning are similar to those of Huntington's disease (HD). The psychiatric features of the HDL2 have been poorly characterized.

OBJECTIVE

To describe the neuropsychiatric features of HDL2 and compare them with those of HD.

METHODS

A blinded cross-sectional design was used to compare the behavioural component of the Unified Huntington's Disease Rating Scale (UHDRS) in participants with HDL2 (n = 15) and HD (n = 13) with African ancestry.

RESULTS

HDL2 patients presented with psychiatric symptoms involving mood disturbances and behavioural changes that were not significantly different from those in the HD group. Duration of disease and motor performance correlated (p < 0.001) with the Functional Capacity score and the Independence score of the UHDRS. HD patients reported movement dysfunction as the first symptom more frequently than HDL2 Patients (p < 0.001).

CONCLUSION

The psychiatric phenotype of HDL2 is similar to that of HD and linked to motor decline and disease duration. Psychiatric symptoms seem more severe for HDL2 patients in the early stages of the disease.

A Systematic Review of Neuropsychiatric Symptoms and Functional Capacity in Huntington's Disease

OBJECTIVE

Neuropsychiatric symptoms are known to increase caregiver burden and decrease patient quality of life among patients with Huntington's disease. Functional capacity is an outcome commonly used in Huntington's disease clinical trials to quantify disease progression or intervention response. Some studies have examined the relationship between neuropsychiatric symptoms and functional capacity; however, this evidence has not been synthesized. The authors reviewed existing evidence on the association between neuropsychiatric symptoms and functional capacity in Huntington's disease.

METHODS

A systematic review was conducted using PubMed and CINAHL. Articles were included if they described primary research in humans with Huntington's disease, measured one or more neuropsychiatric symptoms and functional capacity, and reported statistical methods to identify associations between the two concepts. Additional eligible articles were identified through reference mining and review of other relevant literature.

RESULTS

Fourteen articles were eligible for review. Neuropsychiatric symptoms were measured individually, in clusters (i.e., depression, anxiety, and suicide items contributing to a depression cluster score), or with an overall score. Significant associations with decreased functional capacity were found most commonly with depression (N=7, median r=0.48) and apathy (N=5, median r=0.47). Other neuropsychiatric symptoms, clusters, and overall scores were all associated with functional capacity in three or fewer studies.

CONCLUSIONS

There is some evidence that depression and apathy are associated with decreased functional capacity in Huntington's disease. Other neuropsychiatric symptoms have been infrequently examined. Further knowledge of the relationships between neuropsychiatric symptoms and functional capacity will identify areas for intervention and improvement of outcomes in patients with Huntington's disease.

Measuring Functional Status in Huntington's Disease

BACKGROUND

Neuropsychiatric and cognitive symptoms account for substantial morbidity in Huntington's disease (HD), but their impact on functional status may not be captured using the Total Functional Capacity (TFC) scale. The objective of this study was to assess the impact of motor, cognitive, and neuropsychiatric symptoms on functional status in persons with HD, comparing two instruments.

METHODS

Multiple regression analyses assessed the relationship between neuropsychiatric, cognitive, and motor symptoms and functional status as measured using TFC and Adult Functional Adaptive Behavior (AFAB) scales.

RESULTS

Greater burden of neuropsychiatric (P = 0.017), cognitive (P = 0.001), and motor (P = 0.001) symptoms was associated with greater impairments to functional status as measured by the AFAB scale. Only motor symptoms were associated with TFC scores (P = 0.002). The 3 symptom domains explained more of the variance in AFAB than TFC scores (P = 0.016).

CONCLUSIONS

TFC may have limited applicability, particularly in early-stage HD patients, as a measure of functional status. The AFAB scale can be used in HD studies as a more holistic measure of functional status. © 2020 International Parkinson and Movement Disorder Society.

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.

Gut dysbiosis in Huntington's disease: associations among gut microbiota, cognitive performance and clinical outcomes

Huntington's disease is characterized by a triad of motor, cognitive and psychiatric impairments, as well as unintended weight loss. Although much of the research has focused on cognitive, motor and psychiatric symptoms, the extent of peripheral pathology and the relationship between these factors, and the core symptoms of Huntington's disease, are relatively unknown. Gut microbiota are key modulators of communication between the brain and gut, and alterations in microbiota composition (dysbiosis) can negatively affect cognition, behaviour and affective function, and may be implicated in disease progression. Furthermore, gut dysbiosis was recently reported in Huntington's disease transgenic mice. Our main objective was to characterize the gut microbiome in people with Huntington's disease and determine whether the composition of gut microbiota are significantly related to clinical indicators of disease progression. We compared 42 Huntington's disease gene expansion carriers, including 19 people who were diagnosed with Huntington's disease (Total Functional Capacity > 6) and 23 in the premanifest stage, with 36 age- and gender-matched healthy controls. Participants were characterized clinically using a battery of cognitive tests and using results from 16S V3 to V4 rRNA sequencing of faecal samples to characterize the gut microbiome. For gut microbiome measures, we found significant differences in the microbial communities (beta diversity) based on unweighted UniFrac distance (P = 0.001), as well as significantly lower alpha diversity (species richness and evenness) between our combined Huntington's disease gene expansion carrier group and healthy controls (P = 0.001). We also found major shifts in the microbial community structure at Phylum and Family levels, and identified functional pathways and enzymes affected in our Huntington's disease gene expansion carrier group. Within the Huntington's disease gene expansion carrier group, we also discovered associations among gut bacteria, cognitive performance and clinical outcomes. Overall, our findings suggest an altered gut microbiome in Huntington's disease gene expansion carriers. These results highlight the importance of gut biomarkers and raise interesting questions regarding the role of the gut in Huntington's disease, and whether it may be a potential target for future therapeutic intervention.

Why Woody got the blues: The neurobiology of depression in Huntington's disease

Huntington's disease (HD) is an extraordinary disorder that usually strikes when individuals are in the prime of their lives, as was the case for the influential 20th century musician Woody Guthrie. HD demonstrates the exceptionally fine line between life and death in such 'genetic diseases', as the only difference between those who suffer horribly and die slowly of this disease is often just a handful of extra tandem repeats (beyond the normal polymorphic range) in a genome that constitutes over 3 billion paired nucleotides of DNA. Furthermore, HD presents as a complex and heterogenous combination of psychiatric, cognitive and motor symptoms, so can appear as an unholy trinity of 'three disorders in one'. The autosomal dominant nature of the disorder is also extremely challenging for affected families, as a 'flip of a coin' dictates which children inherit the mutation from their affected parent, and the gene-negative family members bear the burden of caring for the other half of the family that is affected. In this review, we will focus on one of the earliest, and most devastating, symptoms associated with HD, depression, which has been reported to affect approximately half of gene-positive HD family members. We will discuss the pathogenesis of HD, and depressive symptoms in particular, including molecular and cellular mechanisms, and potential genetic and environmental modifiers. This expanding understanding of HD pathogenesis may not only lead to novel therapeutic options for HD families, but may also provide insights into depression in the wider population, which has the greatest burden of disease of any disorder and an enormous unmet need for new therapies.

International Guidelines for the Treatment of Huntington's Disease

The European Huntington's Disease Network (EHDN) commissioned an international task force to provide global evidence-based recommendations for everyday clinical practice for treatment of Huntington's disease (HD). The objectives of such guidelines are to standardize pharmacological, surgical and non-pharmacological treatment regimen and improve care and quality of life of patients. A formalized consensus method, adapted from the French Health Authority recommendations was used. First, national committees (French and English Experts) reviewed all studies published between 1965 and 2015 included dealing with HD symptoms classified in motor, cognitive, psychiatric, and somatic categories. Quality grades were attributed to these studies based on levels of scientific evidence. Provisional recommendations were formulated based on the strength and the accumulation of scientific evidence available. When evidence was not available, recommendations were framed based on professional agreement. A European Steering committee supervised the writing of the final recommendations through a consensus process involving two rounds of online questionnaire completion with international multidisciplinary HD health professionals. Patients' associations were invited to review the guidelines including the HD symptoms. Two hundred and nineteen statements were retained in the final guidelines. We suggest to use this adapted method associating evidence base-medicine and expert consensus to other rare diseases.

Depression and risk of cognitive dysfunctions in amyotrophic lateral sclerosis

OBJECTIVES

Amyotrophic lateral sclerosis (ALS) is not only a motor disorder: More than 50% of patients have cognitive dysfunctions over the course of the disease. At the same time, mood disorders may also occur in ALS patients following diagnosis due to the fatal prognosis; however, little data are available on any depression beforehand. Starting from these considerations, the aim of our study was to investigate the occurrence of depression in Italian ALS patients prior to diagnosis, evaluating its prevalence in the subjects who have developed cognitive dysfunctions and in those who did not.

MATERIALS AND METHODS

We included 318 patients, establishing the presence of depression in the 5 years before ALS diagnosis. Patients underwent a complete battery of neuropsychological tests with the aim to evaluate the executive functions, behavior, language, and memory.

RESULTS

Before diagnosis, 40 patients with ALS had been diagnosed with depression: Among them, 29 patients had cognitive impairment over the course of the disease and only 11 did not develop any cognitive alteration (OR 1.46; 95% CI: 1.26-1.66, adjusted for sex, age, and disease phenotype, P: 0.038). Moreover, there is a significant difference in survival time between ALS patients with depression before ALS, compared to ALS patients without previous depression (P: 0.006).

CONCLUSIONS

We reported a high prevalence of depression in the past in patients with ALS and cognitive impairment, as compared to patients without cognitive deficits, showing also that patients with both had a shorter survival time. These aspects require multidisciplinary approach at disease onset.

Rating scales for behavioral symptoms in Huntington's disease: Critique and recommendations

Behavioral symptoms are an important feature of Huntington's disease and contribute to impairment in quality of life. The Movement Disorder Society commissioned the assessment of the clinimetric properties of rating scales in Huntington's disease to make recommendations regarding their use, following previously used standardized criteria. A systematic literature search was conducted to identify the scales used to assess behavioral symptoms in Huntington's disease. For the purpose of this review, 7 behavioral domains were deemed significant in Huntington's disease: irritability, anxiety, depression, apathy, obsessive-compulsive behaviors, psychosis, and suicidal ideation. We included a total of 27 behavioral rating scales, 19 of which were of a single behavioral domain and the remaining 8 scales included multiple behavioral domains. Three rating scales were classified as "recommended" exclusively for screening purposes: the Irritability Scale for irritability, the Beck Depression Inventory-II, and the Hospital Anxiety and Depression Scale for depression. There were no "recommended" scales for other purposes such as diagnosis, severity, or change in time or to treatment. The main challenges identified for assessment of behavioral symptoms in Huntington's disease are the co-occurrence of multiple behavioral symptoms, the particular features of a behavioral symptom in Huntington's disease, and the need to address stage- and disease-specific features, including cognitive impairment and lack of insight. The committee concluded that there is a need to further validate currently available behavioral rating scales in Huntington's disease to address gaps in scale validation for specific behavioral domains and purpose of use. © 2016 International Parkinson and Movement Disorder Society.

Neuropsychiatric Burden in Huntington's Disease

Huntington's disease is a disorder that results in motor, cognitive, and psychiatric problems. The symptoms often take different forms and the presence of disturbances of the psychic sphere reduces patients' autonomy and quality of life, also impacting patients' social life. It is estimated that a prevalence between 33% and 76% of the main psychiatric syndromes may arise in different phases of the disease, often in atypical form, even 20 years before the onset of chorea and dementia. We present a narrative review of the literature describing the main psychopathological patterns that may be found in Huntington's disease, searching for a related article in the main database sources (Medline, ISI Web of Knowledge, Scopus, and Medscape). Psychiatric conditions were classified into two main categories: affective and nonaffective disorders/symptoms; and anxiety and neuropsychiatric features such as apathy and irritability. Though the literature is extensive, it is not always convergent, probably due to the high heterogeneity of methods used. We summarize main papers for pathology and sample size, in order to present a synoptic vision of the argument. Since the association between Huntington's disease and psychiatric symptoms was demonstrated, we argue that the prevalent and more invalidating psychiatric components should be recognized as early as possible during the disease course in order to best address psychopharmacological therapy, improve quality of life, and also reduce burden on caregivers.

Roos R, Leavitt BR, Scahill RI, Clark CA, Langbehn DR, Rees G, Tabrizi SJ. Structural and functional brain network correlates of depressive symptoms in premanifest Huntington's disease

Depression is common in premanifest Huntington's disease (preHD) and results in significant morbidity. We sought to examine how variations in structural and functional brain networks relate to depressive symptoms in premanifest HD and healthy controls. Brain networks were constructed using diffusion tractography (70 preHD and 81 controls) and resting state fMRI (92 preHD and 94 controls) data. A sub-network associated with depression was identified in a data-driven fashion and network-based statistics was used to investigate which specific connections correlated with depression scores. A replication analysis was then performed using data from a separate study. Correlations between depressive symptoms with increased functional connectivity and decreased structural connectivity were seen for connections in the default mode network (DMN) and basal ganglia in preHD. This study reveals specific connections in the DMN and basal ganglia that are associated with depressive symptoms in preHD. Hum Brain Mapp 38:2819-2829, 2017. © 2017 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.

Cognitive Control, Learning, and Clinical Motor Ratings Are Most Highly Associated with Basal Ganglia Brain Volumes in the Premanifest Huntington's Disease Phenotype

OBJECTIVES

Huntington's disease (HD) is a debilitating genetic disorder characterized by motor, cognitive and psychiatric abnormalities associated with neuropathological decline. HD pathology is the result of an extended chain of CAG (cytosine, adenine, guanine) trinucleotide repetitions in the HTT gene. Clinical diagnosis of HD requires the presence of an otherwise unexplained extrapyramidal movement disorder in a participant at risk for HD. Over the past 15 years, evidence has shown that cognitive, psychiatric, and subtle motor dysfunction is evident decades before traditional motor diagnosis. This study examines the relationships among subcortical brain volumes and measures of emerging disease phenotype in prodromal HD, before clinical diagnosis.

METHODS

The dataset includes 34 cognitive, motor, psychiatric, and functional variables and five subcortical brain volumes from 984 prodromal HD individuals enrolled in the PREDICT HD study. Using cluster analyses, seven distinct clusters encompassing cognitive, motor, psychiatric, and functional domains were identified. Individual cluster scores were then regressed against the subcortical brain volumetric measurements.

RESULTS

Accounting for site and genetic burden (the interaction of age and CAG repeat length) smaller caudate and putamen volumes were related to clusters reflecting motor symptom severity, cognitive control, and verbal learning.

CONCLUSIONS

Variable reduction of the HD phenotype using cluster analysis revealed biologically related domains of HD and are suitable for future research with this population. Our cognitive control cluster scores show sensitivity to changes in basal ganglia both within and outside the striatum that may not be captured by examining only motor scores. (JINS, 2017, 23, 159-170).

Cognitive and behavioral changes in Huntington disease before diagnosis

Phenotypic manifestations of Huntington disease (HD) can be detected at least 15 years prior to the time when a motor diagnosis is given. Advances in clinical care and future research will require consistent use of HD definitions and HD premanifest (prodromal) stages being used across clinics, sites, and countries. Cognitive and behavioral (psychiatric) changes in HD are summarized and implications for ongoing advancement in our knowledge of prodromal HD are suggested. The earliest detected cognitive changes are observed in the Symbol Digit Modalities Test, Stroop Interference, Stroop Color and Word Test-interference condition, and Trail Making Test. Cognitive changes in the middle and near motor diagnostic stages of prodromal HD involve nearly every cognitive test administered and the greatest changes over time (i.e., slopes) are found in those prodromal HD participants who are nearest to motor diagnosis. Psychiatric changes demonstrate significant worsening over time and remain elevated compared with healthy controls throughout the prodromal disease course. Psychiatric and behavior changes in prodromal HD are much lower than that obtained using cognitive assessment, although the psychiatric and behavioral changes represent symptoms most debilitating to independent capacity and wellness.

The Confluence of Psychiatric Symptoms and Neurodegenerative Disease: Impact on Genetic Counseling

Hereditary neurodegenerative diseases can present with a psychiatric prodrome that overlaps with psychiatric symptoms that are not primary to these diseases. When individuals present for predictive testing while experiencing such symptoms, clinicians including genetic counselors, must proceed with caution and evaluate each situation on a case-by-case basis. Legitimate reasons may exist for moving forward with testing. Additionally predicting the consequences of testing is unrealistic so that the clinicians must do their best to prepare patients for both positive and negative results. A multidisciplinary team following the Huntington disease protocol remains the gold standard care for predictive testing for such patients. We discuss 3 case histories that demonstrate the complex nature of genetic counseling and testing in the presence of psychiatric symptoms, whether emanating from the disease itself or the results of living in an affected family.

Gene suppression strategies for dominantly inherited neurodegenerative diseases: lessons from Huntington's disease and spinocerebellar ataxia

RNA-targeting approaches are emerging as viable therapeutics that offer an alternative method to modulate traditionally 'undrugable' targets. In the case of dominantly inherited neurodegenerative diseases, gene suppression strategies can target the underlying cause of these intractable disorders. Polyglutamine diseases are caused by CAG expansions in discrete genes, making them ideal candidates for gene suppression therapies. Here, we discuss the current state of gene suppression approaches for Huntington's disease and the spinocerebellar ataxias, including the use of antisense oligonucleotides, short-interfering RNAs, as well as viral vector-mediated delivery of short hairpin RNAs and artificial microRNAs. We focus on lessons learned from preclinical studies investigating gene suppression therapies for these disorders, particularly in rodent models of disease and in non-human primates. In animal models, recent advances in gene suppression technologies have not only prevented disease progression in a number of cases, but have also reversed existing disease, providing evidence that reducing the expression of disease-causing genes may be of benefit in symptomatic patients. Both allele- and non-allele-specific approaches to gene suppression have made great strides over the past decade, showing efficacy and safety in both small and large animal models. Advances in delivery techniques allow for broad and durable suppression of target genes, have been validated in non-human primates and in some cases, are currently being evaluated in human patients. Finally, we discuss the challenges of developing and delivering gene suppression constructs into the CNS and recent advances of potential therapeutics into the clinic.

Sex Differences in Circadian Dysfunction in the BACHD Mouse Model of Huntington's Disease

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder that affects men and women in equal numbers, but some epidemiological studies indicate there may be sex differences in disease progression. One of the early symptoms of HD is disruptions in the circadian timing system, but it is currently unknown whether sex is a factor in these alterations. Since sex differences in HD could provide important insights to understand cellular and molecular mechanism(s) and designing early intervention strategies, we used the bacterial artificial chromosome transgenic mouse model of HD (BACHD) to examine whether sex differences in circadian behavioral rhythms are detectable in an animal model of the disease. Similar to BACHD males, BACHD females display circadian disruptions at both 3 and 6 months of age; however, deficits to BACHD female mouse activity levels, rhythm precision, and behavioral fragmentation are either delayed or less severe relative to males. These sex differences are associated with a smaller suprachiasmatic nucleus (SCN) in BACHD male mice at age of symptom onset (3 months), but are not associated with sex-specific differences in SCN daytime electrical activity deficits, or peptide expression (arginine vasopressin, vasoactive intestinal peptide) within the SCN. Notably, BACHD females exhibited delayed motor coordination deficits, as measured using rotarod and challenge beam. These findings suggest a sex specific factor plays a role both in non-motor and motor symptom progression for the BACHD mouse.

Longitudinal Psychiatric Symptoms in Prodromal Huntington's Disease: A Decade of Data

OBJECTIVE

Psychiatric symptoms are a significant aspect of Huntington's disease, an inherited neurodegenerative illness. The presentation of these symptoms is highly variable, and their course does not fully correlate with motor or cognitive disease progression. The authors sought to better understand the development and longitudinal course of psychiatric manifestations in individuals who carry the Huntington's disease mutation, starting from the prodromal period prior to motor diagnosis.

METHOD

Longitudinal measures for up to 10 years of psychiatric symptoms from the Symptom Checklist-90-Revised were obtained from 1,305 participants (1,007 carrying the Huntington's disease mutation and 298 without [classified as controls]) and 1,235 companions enrolled in the Neurobiological Predictors of Huntington's Disease (PREDICT-HD) study. Participants with the mutation were stratified into three groups according to probability of motor diagnosis within 5 years. Using linear mixed-effects regression models, differences in psychiatric symptoms at baseline and over time between the mutation-positive groups and the controls were compared, as well as between ratings by mutation-positive participants and their companions.

RESULTS

Nineteen of 24 psychiatric measures (12 participant ratings and 12 companion ratings) were significantly higher at baseline and showed significant increases longitudinally in the individuals with the Huntington's disease mutation compared with controls. The differences were greatest in comparisons of symptom reports from companions compared with self-reports, especially in participants who were closest to motor diagnosis.

CONCLUSIONS

The results indicate that psychiatric manifestations develop more often than previously thought in the Huntington's disease prodrome. Symptoms also increase with progression of disease severity. Greater symptom ratings by companions than by mutation-positive participants suggest decreasing awareness in those affected.

Disease stage, but not sex, predicts depression and psychological distress in Huntington's disease: A European population study

OBJECTIVE

Depression and anxiety significantly affect morbidity in Huntington's disease. Mice. models of Huntington's disease have identified sex differences in mood-like behaviours that vary across disease lifespan, but this interaction has not previously been explored in humans with Huntington's disease. However, among certain medical populations, evidence of sex differences in mood across various disease stages has been found, reflecting trends among the general population that women tend to experience anxiety and depression 1.5 to 2 times more than men. The current study examined whether disease stage and sex, either separately or as an interaction term, predicted anxiety and depression in Huntington's disease.

METHODS

A cross-sectional study of REGISTRY data involving 453 Huntington's disease participants from 12 European countries was undertaken using the Hospital Anxiety and Depression Scale. A series of multiple regression analyses were undertaken to discover to what extent disease stage and sex predicted anxiety, depression, and general distress after controlling for a number of known predictors of mood difficulties.

RESULTS

Disease stage, but not sex, was found to predict depressive symptoms and general distress. Neither disease stage nor sex predicted anxiety. Furthermore, an interaction term computed for disease stage and sex did not contribute to the models tested.

CONCLUSION

In terms of considering risks to developing depression and anxiety in the Huntington's disease population, practitioners may need to pay special attention to disease stage progression (but not sex differences) to enable early detection and treatment of depression (but not anxiety).

Behavioral phenotyping of minipigs transgenic for the Huntington gene

BACKGROUND

While several novel therapeutic approaches for HD are in development, resources to conduct clinical trials are limited. Large animal models have been proposed to improve assessment of safety, tolerability and especially to increase translational reliability of efficacy signals obtained in preclinical studies. They may thus help to select candidates for translation to human studies. We here introduce a battery of novel tests designed to assess the motor, cognitive and behavioral phenotype of a transgenic (tg) HD minipig model.

NEW METHODS

A group of tgHD and wildtype (wt) Libechov minipigs (n=36) was available for assessment with (1) a gait test using the GAITRite(®) automated acquisition system, (2) a hurdle-test, (3) a tongue coordination test, (4) a color discrimination test, (5) a startbox back and forth test and (6) a dominance test. Performance of all tests and definition of measures obtained is presented.

RESULTS

Minipigs were able to learn performance of all tests. All tests were safe, well tolerated and feasible. Exploratory between group comparisons showed no differences between groups of tgHD and wt minipigs assessed, but low variability within and between groups.

COMPARISON WITH EXISTING METHOD(S)

So far there are no established or validated assessments to test minipigs in the domains described.

CONCLUSIONS

The data shows that the tests presented are safe, well tolerated and all measures defined can be assessed. Prospective longitudinal application of these tests is warranted to determine their test-retest reliability, sensitivity and validity in assessing motor, cognitive and behavioral features of tg and wt minipigs.

Genetic testing and counseling in the diagnosis and management of young-onset dementias

Young-onset dementia is hereditary, multifactorial, or sporadic. The most common hereditary dementias include Alzheimer disease, frontotemporal degeneration, Huntington disease, prion diseases, and cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy. Careful attainment of family history assists with diagnosis and determining the likelihood of a genetic cause, and can direct genetic testing. The type of genetic testing depends on confidence of the diagnosis, patient's and affected relatives' symptoms, and the number of disease genes. Single gene, disease-specific gene panels, and large dementia panels are available. Genetic counseling should be given and informed consent obtained. Predictive testing follows the Huntington disease protocol.

Multivariate clustering of progression profiles reveals different depression patterns in prodromal Huntington disease

OBJECTIVE

Although Huntington disease (HD) is caused by an autosomal dominant mutation, its phenotypic presentation differs widely. Variability in clinical phenotypes of HD may reflect the existence of disease subtypes. This hypothesis was tested in prodromal participants from the longitudinal Neurobiological Predictors of Huntington Disease (PREDICT-HD) study.

METHOD

We performed clustering using longitudinal data assessing motor, cognitive, and depression symptoms. Using data from 521 participants with 2,716 data points, we fit growth mixture models (GMM) that identify groups based on multivariate trajectories.

RESULTS

In various GMM, different phases of disease progression were partitioned by progression trajectories of motor and cognitive signs, and by overall level of depression symptoms. More progressed motor signs were accompanied by more progressed cognitive signs, but not always by higher levels of depressive symptoms. In several models, there were at least 2 groups with similar trajectories for motor and cognitive signs that showed different levels for depression symptoms-one with a very low level of depression and the other with a higher level of depression.

CONCLUSIONS

Findings indicate that at least intermediate HD progression might be associated with different levels of depression. Depression is one of the few symptoms that is treatable in HD and has implications for clinical care. Identification of potential depression subtypes may also help to select appropriate patients for clinical trials.

Everyday cognition in prodromal Huntington disease

OBJECTIVE

Assessment of daily functions affected by cognitive loss in prodromal Huntington's disease (HD) is necessary in practice and clinical trials. We evaluated baseline and longitudinal sensitivity of the Everyday Cognition (ECog) scales in prodromal HD and compared self- and companion-ratings.

METHOD

Everyday cognition was self-assessed by 850 participants with prodromal HD and 768 companions. We examined internal structure using confirmatory factor analysis (CFA) on baseline data. For longitudinal analysis, we stratified participants into Low, Medium, and High disease progression groups. We examined ECog scores for group differences and participant-and-companion differences using linear mixed effects regression (LMER). Comparison with the Total Functional Capacity (TFC) scale was made.

RESULTS

CFA revealed good fit of a 5-factor model having a global factor (total score), and subfactors (subscales) of memory, language, visuospatial perception, and executive function. At study entry, participants and companions in the Medium and High groups reported significantly worsened everyday cognition as well as significant functional decline over time. Losses became more pronounced and participant and companion ratings diverged as individuals progressed. TFC showed significant functional loss over time in the High group but not in the Medium group.

CONCLUSIONS

Disease progression is associated with reduced self- and companion-reported everyday cognition in prodromal HD participants who are less than 13 years to estimated motor onset. Our findings suggest companion ratings are more sensitive than participants' for detecting longitudinal change in daily cognitive function. ECog appears more sensitive to specific functional changes in the prodrome of HD than the TFC.

Prediction of manifest Huntington's disease with clinical and imaging measures: a prospective observational study

BACKGROUND

Although the association between cytosine-adenine-guanine (CAG) repeat length and age at onset of Huntington's disease is well known, improved prediction of onset would be advantageous for clinical trial design and prognostic counselling. We compared various measures for tracking progression and predicting conversion to manifest Huntington's disease.

METHODS

In this prospective observational study, we assessed the ability of 40 measures in five domains (motor, cognitive, psychiatric, functional, and imaging) to predict time to motor diagnosis of Huntington's disease, accounting for CAG repeat length, age, and the interaction of CAG repeat length and age. Eligible participants were individuals from the PREDICT-HD study (from 33 centres in six countries [USA, Canada, Germany, Australia, Spain, UK]) with the gene mutation for Huntington's disease but without a motor diagnosis (a rating below 4 on the diagnostic confidence level from the 15-item motor assessment of the Unified Huntington's Disease Rating Scale). Participants were followed up between September, 2002, and July, 2014. We used joint modelling of longitudinal and survival data to examine the extent to which baseline and change of measures analysed separately was predictive of CAG-adjusted age at motor diagnosis.

FINDINGS

1078 individuals with a CAG expansion were included in this analysis. Participants were followed up for a mean of 5·1 years (SD 3·3, range 0·0-12·0). 225 (21%) of these participants received a motor diagnosis of Huntington's disease during the study. 37 of 40 cross-sectional and longitudinal clinical and imaging measures were significant predictors of motor diagnosis beyond CAG repeat length and age. The strongest predictors were in the motor, imaging, and cognitive domains: an increase of one SD in total motor score (motor domain) increased the risk of a motor diagnosis by 3·07 times (95% CI 2·26-4·16), a reduction of one SD in putamen volume (imaging domain) increased risk by 3·32 times (2·37-4·65), and a reduction of one SD in Stroop word score (cognitive domain) increased risk by 2·32 times (1·88-2·87).

INTERPRETATION

Prediction of diagnosis of Huntington's disease can be improved beyond that obtained by CAG repeat length and age alone. Such knowledge about potential predictors of manifest Huntington's disease should inform discussions about guidelines for diagnosis, prognosis, and counselling, and might be useful in guiding the selection of participants and outcome measures for clinical trials.

FUNDING

US National Institutes of Health, US National Institute of Neurological Disorders and Stroke, and CHDI Foundation.

Diagnostic criteria for Huntington's disease based on natural history

Huntington's disease (HD) is currently diagnosed based on the presence of motor signs indicating 99% "diagnostic confidence" for HD. Recent advances in the understanding of HD natural history and neurobiology indicate that disease-related brain changes begin at least 12 to 15 years before the formal diagnosis based on motor onset. Furthermore, subtle motor dysfunction, cognitive changes, and behavioral alterations are often seen before diagnosis made according to the current criteria. As disease-modifying treatments are developed, likely beginning therapy early will be desirable. We therefore suggest that expanded diagnostic criteria for HD should be adapted to better reflect the natural history of the disease, to enable the conduct of clinical trials in premanifest subjects targeting prevention of neurodegeneration, and to facilitate earlier symptomatic treatment. We propose a new set of criteria for HD diagnostic categories in the International Classification of Diseases that reflect our current understanding of HD natural history and pathogenesis. Based on defined criteria, for example, the Diagnostic Confidence Level and the Total Functional Capacity scales of the Unified Huntington's Disease Rating Scale, HD should be divided in the categories "genetically confirmed" with the subcategories "presymptomatic," "prodromal," and "manifest" and "not genetically confirmed" subdivided into "clinically at risk," "clinically prodromal," and "clinically manifest."

The neuroanatomy of subthreshold depressive symptoms in Huntington's disease: a combined diffusion tensor imaging (DTI) and voxel-based morphometry (VBM) study

BACKGROUND

Depressive symptoms are prominent psychopathological features of Huntington's disease (HD), making a negative impact on social functioning and well-being.

METHOD

We compared the frequencies of a history of depression, previous suicide attempts and current subthreshold depression between 61 early-stage HD participants and 40 matched controls. The HD group was then split based on the overall HD group's median Hospital Anxiety and Depression Scale-depression score into a group of 30 non-depressed participants (mean 0.8, s.d. = 0.7) and a group of 31 participants with subthreshold depressive symptoms (mean 7.3, s.d. = 3.5) to explore the neuroanatomy underlying subthreshold depressive symptoms in HD using voxel-based morphometry (VBM) and diffusion tensor imaging (DTI).

RESULTS

Frequencies of history of depression, previous suicide attempts or current subthreshold depressive symptoms were higher in HD than in controls. The severity of current depressive symptoms was also higher in HD, but not associated with the severity of HD motor signs or disease burden. Compared with the non-depressed HD group DTI revealed lower fractional anisotropy (FA) values in the frontal cortex, anterior cingulate cortex, insula and cerebellum of the HD group with subthreshold depressive symptoms. In contrast, VBM measures were similar in both HD groups. A history of depression, the severity of HD motor signs or disease burden did not correlate with FA values of these regions.

CONCLUSIONS

Current subthreshold depressive symptoms in early HD are associated with microstructural changes - without concomitant brain volume loss - in brain regions known to be involved in major depressive disorder, but not those typically associated with HD pathology.

Mood disorders in Huntington's disease: from behavior to cellular and molecular mechanisms

Huntington's disease (HD) is a neurodegenerative disorder that is best known for its effect on motor control. Mood disturbances such as depression, anxiety, and irritability also have a high prevalence in patients with HD, and often start before the onset of motor symptoms. Various rodent models of HD recapitulate the anxiety/depressive behavior seen in patients. HD is caused by an expanded polyglutamine stretch in the N-terminal part of a 350 kDa protein called huntingtin (HTT). HTT is ubiquitously expressed and is implicated in several cellular functions including control of transcription, vesicular trafficking, ciliogenesis, and mitosis. This review summarizes progress in efforts to understand the cellular and molecular mechanisms underlying behavioral disorders in patients with HD. Dysfunctional HTT affects cellular pathways that are involved in mood disorders or in the response to antidepressants, including BDNF/TrkB and serotonergic signaling. Moreover, HTT affects adult hippocampal neurogenesis, a physiological phenomenon that is implicated in some of the behavioral effects of antidepressants and is linked to the control of anxiety. These findings are consistent with the emerging role of wild-type HTT as a crucial component of neuronal development and physiology. Thus, the pathogenic polyQ expansion in HTT could lead to mood disorders not only by the gain of a new toxic function but also by the perturbation of its normal function.

Risk-taking and pathological gambling behavior in Huntington's disease

Huntington's disease (HD) is a genetic, neurodegenerative disorder, which specifically affects striatal neurons of the indirect pathway, resulting in a progressive decline in muscle coordination and loss of emotional and cognitive control. Interestingly, predisposition to pathological gambling and other addictions involves disturbances in the same cortico-striatal circuits that are affected in HD, and display similar disinhibition-related symptoms, including changed sensitivity to punishments and rewards, impulsivity, and inability to consider long-term advantages over short-term rewards. Both HD patients and pathological gamblers also show similar performance deficits on risky decision-making tasks, such as the Iowa Gambling Task (IGT). These similarities suggest that HD patients are a likely risk group for gambling problems. However, such problems have only incidentally been observed in HD patients. In this review, we aim to characterize the risk of pathological gambling in HD, as well as the underlying neurobiological mechanisms. Especially with the current rise of easily accessible Internet gambling opportunities, it is important to understand these risks and provide appropriate patient support accordingly. Based on neuropathological and behavioral findings, we propose that HD patients may not have an increased tendency to seek risks and start gambling, but that they do have an increased chance of developing an addiction once they engage in gambling activities. Therefore, current and future developments of Internet gambling possibilities and related addictions should be regarded with care, especially for vulnerable groups like HD patients.

Biomarker development for Huntington's disease

Huntington's disease (HD) is a fatal inherited neurodegenerative disorder, treatment to slow the progression of which has not yet been found. Human clinical trials to test a number of therapeutic strategies are underway or imminent, facilitated in part by the recent development of biomarkers that might be used as surrogate endpoints in such trials. However, although much progress in developing HD biomarkers has been made, ongoing work seeks to improve the sensitivity and reliability of current measures, and to demonstrate that they correspond to clear meaningful benefit to patients. Of particular importance is the identification of state biomarkers that can be used in pre-manifest HD gene carriers to test therapies hoped to delay symptom onset in these individuals. Functional, neuroimaging and biochemical biomarkers continue to be investigated for use in the development of disease-modifying treatments of HD.

Neuroanatomical correlates of cognitive functioning in prodromal Huntington disease

INTRODUCTION

The brain mechanisms of cognitive impairment in prodromal Huntington disease (prHD) are not well understood. Although striatal atrophy correlates with some cognitive abilities, few studies of prHD have investigated whether cortical gray matter morphometry correlates in a regionally specific manner with functioning in different cognitive domains. This knowledge would inform the selection of cognitive measures for clinical trials that would be most sensitive to the target of a treatment intervention.

METHOD

In this study, random forest analysis was used to identify neuroanatomical correlates of functioning in five cognitive domains including attention and information processing speed, working memory, verbal learning and memory, negative emotion recognition, and temporal processing. Participants included 325 prHD individuals with varying levels of disease progression and 119 gene-negative controls with a family history of HD. In intermediate analyses, we identified brain regions that showed significant differences between the prHD and the control groups in cortical thickness and striatal volume. Brain morphometry in these regions was then correlated with cognitive functioning in each of the domains in the prHD group using random forest methods. We hypothesized that different regional patterns of brain morphometry would be associated with performances in distinct cognitive domains.

RESULTS

The results showed that performances in different cognitive domains that are vulnerable to decline in prHD were correlated with regionally specific patterns of cortical and striatal morphometry. Putamen and/or caudate volumes were top-ranked correlates of performance across all cognitive domains, as was cortical thickness in regions related to the processing demands of each domain.

CONCLUSIONS

The results underscore the importance of identifying structural magnetic resonance imaging (sMRI) markers of functioning in different cognitive domains, as their relative sensitivity depends on the extent to which processing is called upon by different brain networks. The findings have implications for identifying neuroimaging and cognitive outcome measures for use in clinical trials.