Language Disorders in Huntington Disease: A Systematic Literature Review

Prodromal Cognitive Changes as a Prognostic Indicator of Forthcoming Huntington's Disease Severity: A Retrospective Longitudinal Study

BACKGROUND

Cognitive changes in Huntington's disease (HD) precede motor manifestations. ENROLL-HD platform includes four cognitive measures of information processing speed (IPS). Our group is eager to seek clinical markers in the life stage that is as close as possible to the age of onset (ie, the so called prodromal HD phase) because this is the best time for therapeutic interventions.

OBJECTIVES

Our study aimed to test whether cognitive scores in prodromal ENROLL-HD mutation carriers show the potential to predict the severity of motor and behavioral changes once HD became fully manifested.

METHODS

From the global ENROLL-HD cohort of 21,343 participants, we first selected a premanifest Cohort#1 (ie, subjects with Total Motor Score (TMS) <10 and Diagnostic Confidence Level (DCL) <4, N = 1.222). From this cohort, we then focused on a prodromal Cohort#2 of subjects who were ascertained to phenoconvert into manifest HD at follow-up visits (ie, subjects from 6 ≤ TMS≤9 and DCL <4 to TMS≥10 and DCL = 4, n = 206).

RESULTS

The main results of our study showed that low IPS before phenoconversion in Cohort#2 predicted the severity of motor and behavioral manifestations. By combining the four IPS cognitive measures (eg, the Categorical Verbal Fluency Test; Stroop Color Naming Test; Stroop Word Reading; Symbol Digit Modalities Test), we generated a Composite Cognition Score (CCS). The lower the CCS score the higher the TMS and the apathy scores in the same longitudinally followed-up patients after phenoconversion.

CONCLUSIONS

CCS might represent a clinical instrument to predict the prognosis of mutation carriers who are close to manifesting HD.

Systematic Review and Meta-Analyses of Word Production Abilities in Dysfunction of the Basal Ganglia: Stroke, Small Vessel Disease, Parkinson's Disease, and Huntington's Disease

Clinical populations with basal ganglia pathologies may present with language production impairments, which are often described in combination with comprehension measures or attributed to motor, memory, or processing-speed problems. In this systematic review and meta-analysis, we studied word production in four (vascular and non-vascular) pathologies of the basal ganglia: stroke affecting the basal ganglia, small vessel disease, Parkinson's disease, and Huntington's disease. We compared scores of these clinical populations with those of matched cognitively unimpaired adults on four well-established production tasks, namely picture naming, category fluency, letter fluency, and past-tense verb inflection. We conducted a systematic search in PubMed and PsycINFO with terms for basal ganglia structures, basal ganglia disorders and language production tasks. A total of 114 studies were included, containing results for one or more of the tasks of interest. For each pathology and task combination, effect sizes (Hedges' g) were extracted comparing patient versus control groups. For all four populations, performance was consistently worse than that of cognitively unimpaired adults across the four language production tasks (p-values < 0.010). Given that performance in picture naming and verb inflection across all pathologies was quantified in terms of accuracy, our results suggest that production impairments cannot be fully explained by motor or processing-speed deficits. Our review shows that while language production difficulties in these clinical populations are not negligible, more evidence is necessary to determine the exact mechanism that leads to these deficits and whether this mechanism is the same across different pathologies.

Feasibility of Identifying Factors Related to Alzheimer's Disease and Related Dementia in Real-World Data

A comprehensive view of factors associated with AD/ADRD will significantly aid in studies to develop new treatments for AD/ADRD and identify high-risk populations and patients for prevention efforts. In our study, we summarized the risk factors for AD/ADRD by reviewing existing meta-analyses and review articles on risk and preventive factors for AD/ADRD. In total, we extracted 477 risk factors in 10 categories from 537 studies. We constructed an interactive knowledge map to disseminate our study results. Most of the risk factors are accessible from structured Electronic Health Records (EHRs), and clinical narratives show promise as information sources. However, evaluating genomic risk factors using RWD remains a challenge, as genetic testing for AD/ADRD is still not a common practice and is poorly documented in both structured and unstructured EHRs. Considering the constantly evolving research on AD/ADRD risk factors, literature mining via NLP methods offers a solution to automatically update our knowledge map.

Pearls & Oy-sters: Huntington Disease Presenting as Primary Progressive Aphasia: A Case of Semantics

We present a case of semantic variant primary progressive aphasia as the presenting feature in a patient with Huntington disease (HD). The patient initially developed progressive language impairment including impaired naming and object knowledge and single-word comprehension and then developed chorea and behavioral changes. An MRI of the brain showed left anterior temporal lobe and hippocampal atrophy. A neurologic FDG PET/CT showed reduced metabolism in the head of the left caudate nucleus. Huntingtin gene testing revealed an expansion of 39 CAG repeats in 1 allele. This case outlines the substantial overlap between the clinical presentation of HD and frontotemporal lobar degeneration syndromes and provides commentary on the investigation of these neurodegenerative diseases.

Subtyping monogenic disorders: Huntington disease

Huntington disease is a highly disabling neurodegenerative disease characterized by psychiatric, cognitive, and motor deficits. The causal genetic mutation in huntingtin (Htt, also known as IT15), located on chromosome 4p16.3, leads to an expansion of a triplet coding for polyglutamine. The expansion is invariably associated with the disease when >39 repeats. Htt encodes for the protein huntingtin (HTT), which carries out many essential biological functions in the cell, in particular in the nervous system. The precise mechanism of toxicity is not known. Based on a one-gene-one-disease framework, the prevailing hypothesis ascribes toxicity to the universal aggregation of HTT. However, the aggregation process into mutant huntingtin (mHTT) is associated with a reduction of the levels of wild-type HTT. A loss of wild-type HTT may plausibly be pathogenic, contributing to the disease onset and progressive neurodegeneration. Moreover, many other biological pathways are altered in Huntington disease, such as in the autophagic system, mitochondria, and essential proteins beyond HTT, potentially explaining biological and clinical differences among affected individuals. As one gene does not mean one disease, future efforts at identifying specific Huntington subtypes are important to design biologically tailored therapeutic approaches that correct the corresponding biological pathways-rather than continuing to exclusively target the common denominator of HTT aggregation for elimination.

Comorbidities and clinical outcomes in adult- and juvenile-onset Huntington's disease: a study of linked Swedish National Registries (2002-2019)

BACKGROUND

Huntington's disease (HD) is a rare, neurodegenerative disease and its complex motor, cognitive and psychiatric symptoms exert a lifelong clinical burden on both patients and their families.

OBJECTIVE

To describe the clinical burden and natural history of HD.

METHODS

This longitudinal cohort study used data from the linked Swedish national registries to describe the occurrence of comorbidities (acute and chronic), symptomatic treatments and mortality in an incident cohort of individuals who either received the first diagnosis of HD above (adult onset HD; AoHD) or below (juvenile-onset HD; JoHD) 20 years of age, compared with a matched cohort without HD from the general population. Disease burden of all individuals alive in Sweden was described during a single calendar year (2018), including the occurrence of key symptoms, treatments and hospitalizations.

RESULTS

The prevalence of HD in 2018 was approximately 10.2 per 100,000. Of 1492 individuals with a diagnosis of HD during 2002 and 2018, 1447 had AoHD and 45 had JoHD. Individuals with AoHD suffered a higher incidence of obsessive-compulsive disorder, acute psychotic episodes, pneumonia, constipation and fractures compared with matched controls. Individuals with JoHD had higher incidence rates of epilepsy, constipation and acute respiratory symptoms. Median time to all-cause mortality in AoHD was 12.1 years from diagnosis. Patients alive with HD in Sweden in 2018 displayed a pattern of increased clinical burden for a number of years since diagnosis.

CONCLUSIONS

This study demonstrates the significant and progressive clinical burden in individuals with HD and presents novel insights into the natural history of JoHD.

Linguistic feature of anorexia nervosa: a prospective case-control pilot study

PURPOSE

Attention has recently been paid to Clinical Linguistics for the detection and support of clinical conditions. Many works have been published on the "linguistic profile" of various clinical populations, but very few papers have been devoted to linguistic changes in patients with eating disorders. Patients with Anorexia Nervosa (AN) share similar psychological features such as disturbances in self-perceived body image, inflexible and obsessive thinking and anxious or depressive traits. We hypothesize that these characteristics can result in altered linguistic patterns and be detected using the Natural Language Processing tools.

METHODS

We enrolled 51 young participants from December 2019 to February 2020 (age range: 14-18): 17 girls with a clinical diagnosis of AN, and 34 normal-weighted peers, matched by gender, age and educational level. Participants in each group were asked to produce three written texts (around 10-15 lines long). A rich set of linguistic features was extracted from the text samples and the statistical significance in pinpointing the pathological process was measured.

RESULTS

Comparison between the two groups showed several linguistics indexes as statistically significant, with syntactic reduction as the most relevant trait of AN productions. In particular, the following features emerge as statistically significant in distinguishing AN girls and their normal-weighted peers: the length of the sentences, the complexity of the noun phrase, and the global syntactic complexity. This peculiar pattern of linguistic erosion may be due to the severe metabolic impairment also affecting the central nervous system in AN.

CONCLUSION

These preliminary data showed the existence of linguistic parameters as probable linguistic markers of AN. However, the analysis of a bigger cohort, still ongoing, is needed to consolidate this assumption.

LEVEL OF EVIDENCE III

Evidence obtained from case-control analytic studies.

Neurobiological and Psychosocial Correlates of Communication Between Huntington's Disease Patients and Their Offspring

OBJECTIVE

Huntington's disease (HD) is an autosomal dominant neurodegenerative disease that presents significant challenges to family communication. The investigators examined observations of communication between parents with HD and their offspring talking about the challenges of HD and explored potential correlates of their communication.

METHODS

The sample included parents with HD and their adolescent and young-adult offspring (N=64). Parent communication and chorea were independently coded from video recordings. Parents and offspring completed working memory assessments and self-reports of neuropsychiatric symptoms, stress, and coping.

RESULTS

Evidence was found for the association of observed parent-offspring communication with disease markers, psychosocial characteristics, and neurocognitive function. For parents, disease markers and working memory were correlates of communication, whereas offspring's psychiatric symptoms, stress, and coping were associated with their communication.

CONCLUSIONS

These findings have potential implications for clinical interventions to enhance communication and quality of life for HD families.

Speech and language difficulties in Huntington's disease: A qualitative study of patients' and professional caregivers' experiences

BACKGROUND

Huntington's disease (HD) is a neurodegenerative disease characterized by a triad of motor, cognitive and psychological symptoms, leading to a gradual breakdown of communication skills. Few studies have investigated how people affected by HD and their professional caregivers, for example, medical doctors, physiotherapists and nurses, experience the patients' gradual loss of speech and language.

AIMS

To examine communication-related experiences of patients and professional caregivers. Experiences with speech therapy and the use of augmentative and alternative communication aids (AAC) were also investigated.

METHODS & PROCEDURES

Seven individuals with HD and seven professional caregivers were interviewed individually, using a semi-structured interview guide. Transcripts were analysed using a conventional content analysis, and the results presented in three main categories.

OUTCOMES & RESULTS

Most individuals with HD were aware of having communication difficulties, struggling with understanding others as well as being understood. This was confirmed by professional caregivers, who also raised ethical issues encountered when patients struggled with communication. Both groups talked about external factors (such as noise or crowded social settings) as disrupting communication, and shared recommendations on how people in general, and speech and language therapists (SLTs) in particular, could optimize communication. Very few patients had received information about communication aids, and none was using AACs. Professional caregivers underlined the importance of interdisciplinary collaborations, including SLTs, in order to optimize care.

CONCLUSIONS & IMPLICATIONS

Findings shed a light on everyday communication challenges faced by people with HD and their professional caregivers, and the lack of implementation of communication aids in this group. The dramatic impact of HD on patients' communication skills underscores the need to include SLTs in the follow-up of this patient group, ideally from the early stages of the disease, while the patient is still capable of voicing his/her own wishes and thoughts. Future research that explores how to optimize communication and implement the use of AACs for individuals with HD is needed. What this paper adds What is already known on this subject Although the ability to communicate gradually deteriorates in individuals affected by Huntington's disease (HD), there is little knowledge about how affected individuals experience the loss of speech and language skills. Interdisciplinary care is recognised as essential for this patient group. However, professional caregivers' thoughts and experiences of communicating with their patients have not been fully explored. Recent years have seen a rapid growth of available communication supporting technologies that could potentially be helpful for individuals with HD, but limited attention has been given to this subject. What this paper adds to existing knowledge What do we now know as a result of this study that we did not know before the results highlight that patients are aware of problems with speech and language even in early phases of the disease, and include patients' personal outlook on problems with communication. Professional caregivers raised ethical issues encountered when patients struggled with communication. Both groups described specific strategies that could facilitate communication. There was a significant lack of experience and knowledge about augmentative and alternative communication aids (AACs). What are the potential or actual clinical implications of this work? Clinical implications of this study. The introduction of communication aids in the follow-up of patients with HD needs to be discussed with the patients in the early phases of the disease, and implemented while the individual still has the capacity to learn and take advantage of alternative communication support. Results underline the importance of including speech and language therapists (SLTs) into multidisciplinary care of patients with HD. SLTs should be available also for professional caregivers who need advice on how to facilitate conversations and social interactions, in order to optimise care of patients with HD.

Understanding speech and swallowing difficulties in individuals with Huntington disease: Validation of the HDQLIFE Speech Difficulties and Swallowing Difficulties Item Banks

PURPOSE

As Huntington disease (HD) progresses, speech and swallowing difficulties become more profound. These difficulties have an adverse effect on health-related quality of life (HRQOL), thus psychometrically robust measures of speech and swallowing are needed to better understand the impact of these domains across the course of the disease. Therefore, the purpose of this study is to establish the clinical utility of two new patient-reported outcome measures (PROs), HDQLIFE Speech Difficulties and HDQLIFE Swallowing Difficulties.

METHODS

Thirty-one participants with premanifest or manifest HD, and 31 age- and sex-matched healthy control participants were recruited for this study. Participants completed several PROs [HDQLIFE Speech Difficulties, HDQLIFE Swallowing Difficulties, Communication Participation Item Bank (CPIB)], as well as several clinician-rated assessments of speech and functioning. A computational algorithm designed to detect features of spoken discourse was also examined. Analyses were focused on establishing the reliability and validity of these new measures.

RESULTS

Internal consistency was good for Swallowing (Cronbach's alpha = 0.89) and excellent for Speech and the CPIB (both Cronbach's alpha ≥ 0.94), and convergent/discriminant validity was supported. Known groups validity for the PROs was supported by significant group differences among control participants and persons with different stages of HD (all p < 0.0001). All PROs were able to distinguish those with and without clinician-rated dysarthria (likelihood ratios far exceeded the threshold for clinical decision making [all ≥ 3.28]).

CONCLUSIONS

Findings support the clinical utility of the HDQLIFE Speech and Swallowing PROs and the CPIB for use across the HD disease spectrum. These PROs also have the potential to be clinically useful in other populations.

Language disintegration in spontaneous speech in Huntington's disease: a more fine-grained analysis

Huntington's disease (HD) is a neurodegenerative disease causing motor symptoms along with cognitive and affective problems. Recent evidence suggests that HD also affects language across core levels of linguistic organization, including at stages of the disease when standardized neuropsychological test profiles are still normal and motor symptoms do not yet reach clinical thresholds ('pre-manifest HD'). The present study aimed to subject spontaneous speech to a more fine-grained linguistic analysis in a sample of 20 identified HD gene-carriers, 10 with pre-manifest and 10 with early manifest HD. We further explored how language performance related to non-linguistic cognitive impairment, using standardized neuropsychological measures. A distinctive pattern of linguistic impairments marked off participants with both pre-manifest and manifest HD from healthy controls and each other. Fluency patterns in premanifest HD were marked by prolongations, filled pauses, and repetitions, which shifted to a pattern marked by empty (unfilled) pauses, re-phrasings, and truncations in manifest HD. Both HD groups also significantly differed from controls and each other in how they grammatically connected clauses and used noun phrases referentially. Functional deficits in language occurred in pre-manifest HD in the absence of any non-linguistic neuropsychological impairment and did largely not correlate with standardized neuropsychological measures in manifest HD. These results further corroborate that language can act as a fine-grained clinical marker in HD, which can track disease progression from the pre-manifest stage, define critical remediation targets, and inform the role of the basal ganglia in language processing.