Cognitive interventions to enhance neural compensation in Huntington's disease

Diagnostic properties of the Frontal Assessment Battery (FAB) in Huntington's disease

BACKGROUND

This study aimed at assessing the diagnostic properties of the Frontal Assessment Battery (FAB) as to its capability to (1) discriminate healthy controls (HCs) from patients with Huntington's disease (HD) and (2) identify cognitive impairment in this population.

MATERIALS

Thirty-eight consecutive HD patients were compared to 73 HCs on the FAB. Patients further underwent the Montreal Cognitive Assessment (MoCA) and the Unified Huntington's Disease Rating Scale (UHDRS). Receiver-operating characteristics (ROC) analyses were run to assess both intrinsic-i.e., sensitivity (Se) and specificity (Sp), and post-test diagnostics, positive and negative predictive values (PPV; NPV) and likelihood ratios (LR+; LR-), of the FAB both in a case-control setting and to identify, within the patient cohort, cognitive impairment (operationalized as a below-cut-off MoCA score). In patients, its diagnostic accuracy was also compared to that of the cognitive section of the UHDRS (UHDRS-II).

RESULTS

The FAB and UHDRS-II were completed by 100 and 89.5% of patients, respectively. The FAB showed optimal case-control discrimination accuracy (AUC = 0.86-0.88) and diagnostic properties (Se = 0.68-0.74; Sp = 0.88-0.9; PPV = 0.74-0.8; NPV = 0.84-0.87; LR+ = 5.6-7.68; LR- = 0.36-0.29), performing even better (AUC = 0.9-0.91) at identifying cognitive impairment among patients (Se = 0.73-1; Sp = 0.86-0.71; PPV = 0.79-0.71; NPV = 0.82-1; LR+ =5.13-3.5; LR- = 0.31-0) and comparably to the UHDRS-II (89% vs. 85% of accuracy, respectively; p = 0.46).

DISCUSSION

In HD patients, the FAB is highly feasible for cognitive screening aims, being also featured by optimal intrinsic/post-test diagnostics within both case-control and case-finding settings.

Immediate and Long-Term Effects of a Computerized Cognitive Rehabilitation Therapy on Cognitive Function in People Living with HIV in Iran: A Single-Blind Two-Arm Parallel Randomized Controlled Trial

ABSTRACT

Up to 50% of people with HIV (PWH) experience neurocognitive impairments (NCIs) that can interfere with everyday functioning and reduce quality of life. To address this problem, this study examined the immediate and long-term efficacy of computerized cognitive rehabilitation therapy (CCRT) on cognitive function in PWH in Tehran, Iran. Thirty PWH with NCI engaged in 24 biweekly 90-min CCRT sessions. A control group of 30 PWH and NCI received treatment-as-usual, but no CCRT. The cognitive rehabilitation protocol focused on attention, visual memory, nonverbal learning, and planning. Pretest, posttest, and follow-up cognitive measurements showed that the designed CCRT protocol was effective in improving performance in selected cognitive domains along with the global neurocognitive performance scores of PWH. These findings suggest that this CCRT protocol be considered as part of a treatment plan to address cognitive impairment for PWH. Implications for clinical practice and research are provided.

Cognitive Reserve in Early Manifest Huntington Disease Patients: Leisure Time Is Associated with Lower Cognitive and Functional Impairment

We focused on Cognitive Reserve (CR) in patients with early Huntington Disease (HD) and investigated whether clinical outcomes might be influenced by lifetime intellectual enrichment over time. CR was evaluated by means of the Cognitive Reserve Index questionnaire (CRIq), an internationally validated scale which includes three sections: education, working activity, and leisure time. The clinical HD variables were quantified at three different time points (baseline-t0, 1 year follow up-t1 and 2 years follow up-t2) as per the Unified Huntington’s Disease Rating Scale (UHDRS), an internationally standardized and validated scale including motor, cognitive, functional and behavioral assays. Our sample consisted of 75 early manifest patients, withclinical stage scored according to the Total Functional Capacity (TFC) scale. Our correlational analysis highlighted a significant inverse association between CRIq leisure time (CRIq_LA) and longitudinal functional impairment (namely, the differential TFC score between t2 and t0 or ΔTFC) (p < 0.05), and the multidimensional progression of HD as measured by the composite UHDRS (cUHDRS, p < 0.01). CRIq_LA was significantly and positively associated with better cognitive performances at all time points (p < 0.05). Our results suggest that higher is the CRIq_LA, milder is the progression of HD in terms of functional, multidimensional and cognitive outcome.

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

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

Multi-compartment analysis of the complex gradient-echo signal quantifies myelin breakdown in premanifest Huntington's disease

White matter (WM) alterations have been identified as a relevant pathological feature of Huntington's disease (HD). Increasing evidence suggests that WM changes in this disorder are due to alterations in myelin-associated biological processes. Multi-compartmental analysis of the complex gradient-echo MRI signal evolution in WM has been shown to quantify myelin in vivo, therefore pointing to the potential of this technique for the study of WM myelin changes in health and disease. This study first characterized the reproducibility of metrics derived from the complex multi-echo gradient-recalled echo (mGRE) signal across the corpus callosum in healthy participants, finding highest reproducibility in the posterior callosal segment. Subsequently, the same analysis pipeline was applied in this callosal region in a sample of premanifest HD patients (n = 19) and age, sex and education matched healthy controls (n = 21). In particular, we focused on two myelin-associated derivatives: i. the myelin water signal fraction (fm), a parameter dependent on myelin content; and ii. The difference in frequency between myelin and intra-axonal water pools (Δω), a parameter dependent on the ratio between the inner and the outer axonal radii. fm was found to be lower in HD patients (β = -0.13, p = 0.03), while Δω did not show a group effect. Performance in tests of working memory, executive function, social cognition and movement was also assessed, and a greater age-related decline in executive function was detected in HD patients (β = -0.06, p = 0.006), replicating previous evidence of executive dysfunction in HD. Finally, the correlation between fm, executive function, and proximity to disease onset was explored in patients, and a positive correlation between executive function and fm was detected (r = 0.542; p = 0.02). This study emphasises the potential of complex mGRE signal analysis for aiding understanding of HD pathogenesis and progression. Moreover, expanding on evidence from pathology and animal studies, it provides novel in vivo evidence supporting myelin breakdown as an early feature of HD.

Beyond Alzheimer's disease: Can bilingualism be a more generalized protective factor in neurodegeneration?

Bilingualism has been argued to have an impact on cognition and brain structure. Effects have been reported across the lifespan: from healthy children to ageing adults, including clinical (ageing) populations. It has been argued that active bilingualism may significantly contribute to the delaying of the expression of Alzheimer's disease symptoms. If bilingualism plays an ameliorative role against the expression of neurodegeneration in dementia, it is possible that it could have similar effects for other neurodegenerative disorders, including Multiple Sclerosis, Parkinson's and Huntington's Diseases. To date, however, direct relevant evidence remains limited, not least because the necessary scientific motivations for investigating this with greater depth have not yet been fully articulated. Herein, we provide a roadmap that reviews the relevant literatures, highlighting potential links across neurodegenerative disorders and bilingualism more generally.

The effects of multidisciplinary rehabilitation on neuroimaging, biological, cognitive and motor outcomes in individuals with premanifest Huntington's disease

BACKGROUND

Huntington's disease (HD) is a chronic, progressive neurodegenerative condition for which there are currently no proven disease-modifying therapies. Lifestyle factors have been shown to impact on the age of disease onset and progression of disease features. We therefore investigated the effects of a nine-month multidisciplinary rehabilitation intervention on neuroimaging, biological and clinical disease outcomes in individuals with premanifest HD.

METHODS

31 individuals with premanifest HD participated in the study. Eighteen participants underwent a nine-month multidisciplinary rehabilitation intervention comprising aerobic and resistance exercise, computerised cognitive training, dual-task training and sleep hygiene and nutritional guidance. The remaining 13 participants were allocated to a standard care control group. Neuroimaging, biological, cognitive, motor and cardiorespiratory fitness data was collected.

RESULTS

Participants displayed good adherence (87%) and compliance (85%) to the intervention. Maintenance of the shape of the right putamen was observed in the intervention group when compared to the control group. The intervention group displayed significant improvements in verbal learning and memory, attention, cognitive flexibility and processing speed following the intervention when compared to the control group. Performance on the mini-social cognition and emotional assessment (mini-SEA) was maintained in the intervention group, but decreased in the control group. No changes were observed in serum neurofilament light protein levels, postural stability outcomes or cardiorespiratory fitness.

CONCLUSION

This study adds to the accumulating body of literature to suggest that multidisciplinary rehabilitation is of clinical benefit for individuals with HD. Large randomised controlled trials are necessary to determine the extent to which benefits occur across the spectrum of the disease.

Brain compensation during response inhibition in premanifest Huntington's disease

Premanifest Huntington's disease (pre-HD) individuals typically show increased task-related functional magnetic resonance imaging (fMRI), suggested to reflect compensatory strategies. Despite the evidence, no study has attempted to understand the compensatory process in light of 'formal' models of compensation. We used a quantitative model of compensation - the Compensation-Related Utilization of Neural Circuits Hypothesis (CRUNCH), to characterise compensation in pre-HD using fMRI. Pre-HD individuals (n = 15) and controls (n = 15) performed a modified stop-signal task that incremented in four levels of stop difficulty. Our results did not support the critical assumption of the CRUNCH model - controls did not show increased fMRI activity with increased level of stop difficulty; however, controls showed decreased fMRI activity with increased stop difficulty in right inferior frontal gyrus and right caudate nucleus. Relative to controls, pre-HD individuals showed increased fMRI activity in right inferior frontal gyrus and in right caudate nucleus at higher levels of stop difficulty, which is the opposite effect to that predicted by the model. Our findings suggest a compensatory process of the response inhibition network in pre-HD; however, the pattern of fMRI activity was not in the manner expected by CRUNCH.

Ancillary Service Utilization and Impact in Huntington's Disease

BACKGROUND

Prior Huntington's disease (HD) studies suggest ancillary services improve motor symptoms, cognition, mood, and quality of life but frequency of use and clinicalcharacteristics are unclear.

OBJECTIVE

Describe ancillary service utilization in a cohort of individuals with HD and determine which participant characteristics are associated with ancillary service utilization.

METHODS

Retrospective cross-sectional analysis of Enroll-HD database. Participants were grouped by therapy: physical and/or occupational (PT/OT), psychotherapy and/or counseling (PC), speech and/or swallowing (ST). We performed bivariate comparisons analysis of demographic and disease characteristics between those with/without each therapy and to analyze one-year mean change in assessment scores.

RESULTS

Of 4751 participants, 1537 (32.35%) utilized therapies (11.82% PT/OT, 5.33% PC, 3.01% ST, 1.98% all three, 10.21% two therapies). PT/OT participants had worse motor and functional scores: mean UHDRS motor score (41.17 vs. 38.05, p = 0.002), median total functional capacity score (TFC) (8.00 vs. 9.00, p < 0.001). PC participants had worse mood but better cognitive and functional scores: median depression score (7.00 vs. 2.00, p < 0.001), median MMSE (28.00 vs. 26.00, p < 0.001), median TFC (10.00 vs. 8.00, p < 0.001). ST participants had more dysarthria, and worse cognitive and functional scores: dysarthria (32.2% vs. 20.1% p < 0.001), mean correct Symbol Digit Modality Test (16.79 vs. 23.27, p < 0.001), median TFC (6.00 vs. 9.00, p < 0.001). Over one year, PC participants' depression scores improved compared to untreated (- 1.24 vs. - 0.11, p = 0.040). ST participants' depression scores worsened (1.14 vs. - 0.23, p = 0.044). Mean change in TFC was not significant for any therapies.

CONCLUSIONS

Only 32% of Enroll-HD site participants received ancillary services. Use correlated with expected clinical characteristics, though impact of use remains unclear.

Cognitive Performance After a One-Year Multidisciplinary Intensive Rehabilitation Program for Huntington's Disease: An Observational Study

BACKGROUND

Studies of physical therapy and multidisciplinary rehabilitation programs for Huntington's disease (HD) have shown improvements in gait function, balance, and physical quality of life. There is a gap in the literature on effects of cognitive interventions and the potential to improve cognitive performance.

OBJECTIVE

To assess changes in cognitive performance among patients with early to middle stage HD as secondary analyses from a one-year multidisciplinary rehabilitation program. The program included cognitive stimulation as a non-specific cognitive intervention in addition to physical interventions.

METHODS

A one-year rehabilitation program that included comprehensive neuropsychological assessments was completed by 31 out 37 participants with early to middle stages of HD. Socio-demographic and clinical information was recorded. A battery of neuropsychological tests was used to measure cognitive functions before and after the intervention. Descriptive statistics was used for sample characteristics. Paired sample t-tests and nonparametric Wilcoxon Signed ranked tests were used to compare cognitive measures at both time points.

RESULTS

Scores on the Symbol Digit Modalities Test (SDMT) were significantly lower post intervention. There were no significant differences in all other measures. Scores on the Stroop color naming and California Verbal Learning Test-II (CVLT-II) long-term delayed recall tasks showed tendencies towards lower scores post intervention.

CONCLUSIONS

An intensive multidisciplinary rehabilitation program for patients with HD was generally well tolerated and feasible, with no indication of negative effects on cognition. Neuropsychological measures overall remained stable following an intensive multidisciplinary rehabilitation program, however continued progression of cognitive impairment was evident on the SDMT, suggesting that disease progression is not halted. Randomized controlled trials are needed to verify these findings.

The Neuropsychology of Huntington's Disease

Huntington's disease is an inherited, degenerative brain disease, characterized by involuntary movements, cognitive disorder and neuropsychiatric change. Men and women are affected equally. Symptoms emerge at around 40 years, although there is wide variation. A rare juvenile form has onset in childhood or adolescence. The evolution of disease is insidious and structural and functional brain changes may be present more than a decade before symptoms and signs become manifest. The earliest site of pathology is the striatum and neuroimaging measures of striatal change correlate with neurological and cognitive markers of disease. Chorea and other aspects of the movement disorder are the most visible aspect of the disease. However, non-motor features have greatest affect on functional independence and quality of life, so require recognition and management. The evidence-base for non-pharmacological treatments in Huntington's disease is currently limited, but recent intervention studies are encouraging.

Assistive Technology for Cognition and Health-related Quality of Life in Huntington's Disease

Background: Assistive technology for cognition (ATC) can be defined as external devices aimed at supporting cognitive function. Studies in neurological populations suggest that use of ATC is a promising strategy to ameliorate negative effects of cognitive impairment and improve Health-related Quality of Life (HRQoL). There is a lack of studies on the effects of ATC in HD.

Objective: This study aimed to describe the use of ATC in patients with HD, and to investigate the association between ATC and HRQoL.

Methods: A cross-sectional population-based study, including eighty-four patients with a clinical HD diagnosis (stages I–V). Socio-demographic and clinical data were collected, including information regarding various aspects of ATC use and an evaluation of cognitive impairment was performed. The Unified Huntington’s Disease Rating Scale (UHDRS) Total Functional Capacity scale (TFC) and the EQ-5D Visual Analogue Scale were used to evaluate functional ability and HRQoL. Descriptive analyses were conducted to describe ATC use and regression analyses to investigate associations between ATC and HRQoL.

Results: Thirty-seven percent of the patients had ATC, and ATC was used most frequently in stages I-III. Information about ATC, needs evaluation and training was provided to 44%, 32.1% and 20.2% respectively. The regression analysis showed a significant association between TFC and HRQoL (β value = –0.564, p = 0.001), but there was no association between ATC and HRQoL.

Conclusions: One-third of all patients used ATC, mainly those with mild to moderate cognitive impairment (stage I –III). No association between ATC and HRQoL was found. More research is needed to investigate effects of ATC in HD.

Transcranial direct current stimulation can enhance working memory in Huntington's disease

Transcranial direct current stimulation (tDCS) combined with a cognitive task can enhance targeted aspects of cognitive functioning in clinical populations. The movement disorder Huntington's disease (HD) is associated with progressive cognitive impairment. Deficits in working memory (WM) can be apparent early in the disease and impact functional capacity. We investigated whether tDCS combined with cognitive training could improve WM in patients with HD, and if baseline clinical or cognitive measures may predict efficacy. Twenty participants with HD completed this crossover trial, undergoing 1.5mA anodal tDCS over left dorsolateral prefrontal cortex and sham stimulation on separate visits. Participants and assessor were blinded to condition order, which was randomised across participants. All participants completed baseline clinical and cognitive assessments. Pre- and post-stimulation tasks included digit reordering, computerised n-back tests and a Stroop task. During 15min of tDCS/sham stimulation, participants practiced 1- and 2-back WM tasks. Participants exhibited an increase in WM span on the digit re-ordering span task from pre- to post-stimulation after tDCS, but not after sham stimulation. Gains in WM were positively related to motor symptom ratings and negatively associated with verbal fluency scores. Patients with more severe motor symptoms showed greatest improvement, suggesting that motor symptom ratings may help identify patients who are most likely to benefit from tDCS.

CONCLUSIONS

Dorsolateral prefrontal tDCS appears well tolerated in HD and enhances WM span compared to sham stimulation. Our findings strongly encourage further investigation of the extent to which tDCS combined with cognitive training could enhance everyday function in HD. ClinicalTrials.gov; NCT02216474 Brain stimulation in Movement Disorders; https://clinicaltrials.gov/ct2/show/NCT02216474.

Myelin Breakdown in Human Huntington's Disease: Multi-Modal Evidence from Diffusion MRI and Quantitative Magnetization Transfer

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The macromolecular proton fraction (MMPF), an MRI marker of myelin, was reduced in Huntington’s disease (HD).

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MMPF reductions in white matter suggest myelin breakdown.

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HD was associated with reductions in basal ganglia volume.

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HD was associated with poor executive functioning but preserved working memory capacity.

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Axial and radial diffusivities as unspecific metrics of white matter changes correlated with clinical markers of disease.

Huntington’s disease (HD) leads to white matter (WM) degeneration that may be due to an early breakdown in axon myelination but in vivo imaging correlates of demyelination remain relatively unexplored in HD compared to other neurodegenerative diseases. This study investigated HD-related effects on a putative marker of myelin, the macromolecular proton fraction (MMPF) from quantitative magnetization transfer and on fractional anisotropy, axial and radial diffusivity from diffusion tensor MR-imaging. Microstructural differences were studied in WM pathways of the basal ganglia and motor systems known to be impaired in HD: the corpus callosum, the cortico-spinal tract, the anterior thalamic radiation, fibers between prefrontal cortex and caudate and between supplementary motor area and putamen. Principal component analysis was employed for dimensionality reduction. Patients showed reductions in a component with high loadings on MMPF in all WM pathways and a trend for increases in a component loading on axial and radial diffusivities but no differences in a component loading on fractional anisotropy. While patients’ performance in executive functioning was impaired, their working memory span was preserved. Inter-individual differences in the diffusivity component correlated with patients’ performance in clinical measures of the United Huntington Disease Rating Scale. In summary, HD-related reductions in MMPF suggest that myelin breakdown contributes to WM impairment in human HD and emphasize the potential of quantitative MRI metrics to inform about disease pathogenesis. Disease severity in manifest HD, however, was best captured by non-specific diffusivity metrics sensitive to multiple disease and age-related changes.

Feasibility and Efficacy of Brief Computerized Training to Improve Emotion Recognition in Premanifest and Early-Symptomatic Huntington's Disease

OBJECTIVES

Deficits in the recognition of negative emotions emerge before clinical diagnosis in Huntington's disease (HD). To address emotion recognition deficits, which have been shown in schizophrenia to be improved by computerized training, we conducted a study of the feasibility and efficacy of computerized training of emotion recognition in HD.

METHODS

We randomly assigned 22 individuals with premanifest or early symptomatic HD to the training or control group. The training group used a self-guided online training program, MicroExpression Training Tool (METT), twice weekly for 4 weeks. All participants completed measures of emotion recognition at baseline and post-training time-points. Participants in the training group also completed training adherence measures.

RESULTS

Participants in the training group completed seven of the eight sessions on average. Results showed a significant group by time interaction, indicating that METT training was associated with improved accuracy in emotion recognition.

CONCLUSIONS

Although sample size was small, our study demonstrates that emotion recognition remediation using the METT is feasible in terms of training adherence. The evidence also suggests METT may be effective in premanifest or early-symptomatic HD, opening up a potential new avenue for intervention. Further study with a larger sample size is needed to replicate these findings, and to characterize the durability and generalizability of these improvements, and their impact on functional outcomes in HD. (JINS, 2017, 23, 314-321).

Revisiting the neuropsychiatry of Huntington's disease

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