Can directed activity improve mobility in Huntington's disease?

Rehabilitation training in neural restitution

Over the last decade, neural transplantation has emerged as one of the more promising, albeit highly experimental, potential therapeutics in neurodegenerative disease. Preclinical studies in rat lesion models of Huntington's disease (HD) and Parkinson's disease (PD) have shown that transplanted precursor neuronal tissue from a fetus into the lesioned striatum can survive, integrate, and reconnect circuitry. Importantly, specific training on behavioral tasks that target striatal function is required to encourage functional integration of the graft to the host tissue. Indeed, "learning to use the graft" is a concept recently adopted in preclinical studies to account for unpredicted profiles of recovery posttransplantation and is an emerging strategy for improving graft functionality. Clinical transplant studies in HD and PD have resulted in mixed outcomes. Small sample sizes and nonstandardized experimental procedures from trial to trial may explain some of this variability. However, it is becoming increasingly apparent that simply replacing the lost neurons may not be sufficient to ensure the optimal graft effects. The knowledge gained from preclinical grafting and training studies suggests that lifestyle factors, including physical activity and specific cognitive and/or motor training, may be required to drive the functional integration of grafted cells and to facilitate the development of compensatory neural networks. The clear implications of preclinical studies are that physical activity and cognitive training strategies are likely to be crucial components of clinical cell replacement therapies in the future. In this chapter, we evaluate the role of general activity in mediating the physical ability of cells to survive, sprout, and extend processes following transplantation in the adult mammalian brain, and we consider the impact of general and specific activity at the behavioral level on functional integration at the cellular and physiological level. We then highlight specific research questions related to timing, intensity, and specificity of training in preclinical models and synthesize the current state of knowledge in clinical populations to inform the development of a strategy for neural transplantation rehabilitation training.

Cognitive training modifies disease symptoms in a mouse model of Huntington's disease

Huntington's disease (HD) is an incurable neurodegenerative disorder which causes a triad of motor, cognitive and psychiatric disturbances. Cognitive disruptions are a core feature of the disease, which significantly affect daily activities and quality of life, therefore cognitive training interventions present an exciting therapeutic intervention possibility for HD. We aimed to determine if specific cognitive training, in an operant task of attention, modifies the subsequent behavioural and neuropathological phenotype of the Hdh(Q111) mouse model of HD. Three testing groups comprising both Hdh(Q111) mice and wildtype controls were used. The first group received cognitive training in an operant task of attention at 4months of age. The second group received cognitive training in a comparable non-attentional operant task at 4months of age, and the third group were control animals that did not receive cognitive training. All groups were then tested in an operant task of attention at 12months of age. Relative to naïve untrained mice, both wildtype and Hdh(Q111) mice that received cognitive training in the operant task of attention demonstrated an increased number of trials initiated, greater accuracy, and fewer 'time out' errors. A specific improvement in response time performance was observed in Hdh(Q111) mice, relative to naïve untrained Hdh(Q111) mice. Relative to the group that received comparable training in a non-attentional task, both wildtype and Hdh(Q111) mice that received attentional training demonstrated superior accuracy in the task and made fewer 'time out' errors. Despite significant behavioural change, in both wildtype and Hdh(Q111) mice that had received cognitive training, no significant changes in neuropathology were observed between any of the testing groups. These results demonstrate that attentional cognitive training implemented at a young age significantly improves attentional performance, at an older age, in both wildtype and Hdh(Q111) mice. Attentional cognitive training also improved motor performance in Hdh(Q111) mice, thus leading to the conclusion that cognitive training can improve disease symptoms in a mouse model of HD.

Supporting physical activity engagement in people with Huntington's disease (ENGAGE-HD): study protocol for a randomized controlled feasibility trial

Background

Huntington’s disease (HD) is a complex, single-gene inherited neurodegenerative condition resulting in symptoms that occur across a wide range of neurological domains, including cognitive, behavioral and motor. The benefits of regular physical activity for people with HD are widely recognized. However, a number of factors can prohibit sustained exercise and activity. The purpose of this trial is to explore the feasibility, acceptability and effectiveness of a physical activity intervention program targeted for people with early- to mid-stage HD.

Methods/Design

The proposed trial is a single blind, multisite, exploratory, randomized controlled feasibility trial of a physical activity intervention. A total of 62 participants with genetically confirmed HD will be recruited. Each participant will be involved in the trial for 26 weeks. Participants will be randomized immediately following the baseline assessment into either a physical activity intervention or a social contact control intervention. The physical activity intervention is framed around self-determination theory placed within a broader behaviour change wheel framework. An HD-specific workbook and individual goal setting will be utilized over six 1:1 sessions, with interim telephone calls. All participants will be reassessed at 16 weeks following the baseline assessment, and then again at a final follow-up assessment 26 weeks later. At the end of the study, all participants will be offered a brief version of the alternative intervention, with one home visit and one follow-up telephone call.

Discussion

Engaging and supporting people with HD in a regular physical activity program raises a number of challenges. The physical activity intervention and the comparator social interaction intervention have been developed following consultation with people with HD and their families. Each are individually tailored and determined on individual needs and goals. The results from this trial will provide guidance for the development of definitive trials.

Trial registration

The trial was registered with ISRCTN ( http://www.isrctn.com/ISRCTN65378754) on 13 March 2014.

Gait in Huntington's disease and the stride length-cadence relationship

Background

The progressive deterioration of gait in Huntington’s disease (HD) leads to functional decline and loss of function. To understand the underlying mechanisms responsible for the gait changes in HD, we examined the automatic control of gait by measuring the relationship between stride length and cadence. The relationship is strongly linked in healthy adults during automatic gait but disrupted in pathological gait disorders, such as Parkinson’s disease (PD).

Methods

The stride length cadence relationship was compared between seventeen participants with HD, twenty with PD and twenty one healthy older adults (HOA). Participants had their gait recorded at self-selected preferred, very slow, slow, fast and very fast speeds. Linear regression analysis was used to determine the slope and intercept of the relationship which were compared between groups. The adjustment of stride length and cadence when changing gait speeds was measured and compared within and between groups.

Results

Linearity was strong in all but two participants with HD and one with PD. Slope did not differ between groups (p > 0.05) but intercept was lower in the HD and PD groups compared to HOA (p < 0.05). Stride length was shorter in the HD and PD groups compared to controls at preferred and most adjusted speed conditions (p < 0.05) but cadence did not differ between groups (p > 0.05) regardless of speed. The HD group adjusted stride length and cadence similar to HOA when changing speed. The range of cadence across speed conditions did not differ between groups.

Conclusion

Scaling of stride length but not the regulation of cadence was found to be disrupted in participants with HD.

Adherence to use of a home-based exercise DVD in people with Huntington disease: participants' perspectives

BACKGROUND

Individualized exercise instruction on a regular basis may be desirable for people with Huntington disease (HD). Sustained interventions, however, may not be the most feasible for lifelong disease management. It is critical, therefore, for physical therapists to find ways to facilitate engagement in independent exercise programs. The capabilities of DVD technology can make the DVD a useful format to facilitate engagement for people with HD who have motivational and cognitive problems.

OBJECTIVE

The purpose of this study was to explore how people with HD used a home-based exercise DVD and how it was perceived by the participants and their caregivers.

DESIGN

An exploratory, mixed-method design was used in this study.

METHODS

Fifteen participants with HD were provided with an exercise DVD, developed by the authors, to support their engagement in a home-based exercise program. Exercise diaries were used to record adherence rates. Semistructured interviews were conducted to explore what factors affected the usability of the DVD. Conversations were audio recorded and fully transcribed. Content analysis approach was used to analyze the interviews.

RESULTS

Most of the participants (11/15, 73.3%) adhered well to the use of the DVD. Participants felt that the exercises were suitable. Commitment of the caregiver as a key to the success of the program was the main theme that emerged from the data. Participants identified barriers and facilitators that affected adherence to using the exercise DVD and described management strategies that helped promote adherence to the exercise program.

CONCLUSIONS

The DVD was perceived to be suitable and supportive. The DVD could be appropriate for use in supporting people with HD to engage in exercise at home, either outside of therapy sessions or upon completion of a therapy program.

Role of experience, training, and plasticity in the functional efficacy of striatal transplants

Cell-based treatments of neurodegenerative diseases have been tested clinically with partial success. In the context of Huntington's disease (HD), experimental studies show that the grafted embryonic striatal cells survive, integrate within the host brain, and reverse some functional deficits. Importantly, once transplanted, the grafted striatal neurons retain a significant level of cellular, morphological, and functional plasticity which allows the experimental modification of their character through the manipulation of environmental cues or learning protocols. Using embryonic striatal grafts in the rodent model of HD as the principal example, this chapter summarizes seminal experiments that demonstrate that environmental factors, training, and activity can tap into mechanisms that influence the development of the grafted cells and can change the profile of graft-mediated behavioral recovery. Although currently there is limited understanding of the biological rationale behind the recovery, we put forward experimental data indicating that striatal grafts can express experience-dependent physiological plasticity at the synaptic as well as at the systemic functional level.

Cell-based treatments for huntington's disease

In experimental rats, mice, and monkeys, transplantation of embryonic striatal cells into the striatum can repair the damage and alleviate the functional deficits caused by striatal lesions. Such strategies have been translated to striatal repair by cell transplantation in small numbers of patients with progressive genetic striatal degeneration in Huntington's disease. In spite of some encouraging preliminary data, the clinical results are to date neither as reliable nor as compelling as the broad extend of recovery observed in the animal models across motor, cognitive, and skill and habit learning domains. Strategies to achieve immediate and long-term improvements in the clinical applications include identifying and limiting the causes of complications, standardization and quality control of preparation and delivery, appropriate patient selection to match the cellular repair to specific profiles of cell loss and degeneration in individual patients and different neurodegenerative diseases, and improving the availability of alternative sources of donor cells and tissues.

Client and therapist views on exercise programmes for early-mid stage Parkinson's disease and Huntington's disease

PURPOSE

Physiotherapists frequently prescribe home exercise programmes for individuals with Parkinson's disease (PD) and Huntington's disease (HD); however, little is known about clients' perceptions of such programmes and any barriers that may affect participation and compliance.

METHOD

A qualitative design was used to capture the attitudes and experiences of people with early-mid stage HD and PD, and with physiotherapists who have experience in neurodegenerative diseases. Two focus groups were conducted for physiotherapists (n = 8); individual interviews were conducted for clients with HD and PD (n = 10). Conversations were digitally recorded and transcribed, and transcriptions were analysed using grounded theory and validated through researcher triangulation. Concepts were categorised according to emerging themes and findings were verified by participants.

RESULTS

Both groups cited several barriers to engagement in exercise programmes, which included disease-specific impairments, individual safety and the location at which exercising takes place. Therapists felt that a client's cognition could affect their ability to participate in an exercise programme. Therapists and clients offered a number of strategies to overcome barriers to exercise.

CONCLUSIONS

Therapists should work in collaboration with clients to evaluate their individual considerations, identify barriers to exercise and design a client-specific programme that is acceptable and feasible for the client.

The current clinical management of Huntington's disease

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

The detection and measurement of locomotor deficits in a transgenic mouse model of Huntington's disease are task- and protocol-dependent: influence of non-motor factors on locomotor function

Locomotor performance of transgenic R6/2 mice carrying the Huntington's disease (HD) mutation was assessed using four different tasks, fixed speed rotarod, accelerating rotarod, Digigait and footprint test. The tasks were compared directly in age- and CAG repeat-matched R6/2 mice. Accelerating rotarod was more sensitive than fixed speed rotarod for detecting early motor deficits in R6/2 mice. The sensitivity of accelerating rotarod increased with the acceleration rate and/or the start speed from which the rod accelerated. Differences between tasks were not due to inability of R6/2 mice to maintain balance at high speeds or increased fatigue on accelerating rotarod, but to difficulties in coordinating gait changes required by the constant change in speed on accelerating rotarod. The footprint test was sensitive to gait disturbances. However, surprisingly, R6/2 mice did not show major gait abnormalities on an automated treadmill task (Digigait), even though they showed overt gait deficits in the home cage. The fact that the sensitivity for detecting motor deficits depended strongly on the individual task, and on the protocol used, suggests that non-motor factors were differentially engaged in the different paradigms. We thus recommend that more than one task should be used for detecting and tracking different aspects of motor decay in animal models of HD. Since deficits in non-motor factors such as executive function and motivation may differentially influence motor outcome in each task, our results call for a more thorough investigation of the importance of higher level control of locomotion in animal models of HD.

Physical therapy intervention for people with Huntington disease

BACKGROUND AND PURPOSE

The clinical symptoms of Huntington disease (HD) include progressive movement disorders, cognitive deficits, and behavioral changes, all of which affect an individual's ability to participate in activities of daily living. To date, very few quantitative or qualitative studies have been conducted to guide physical therapists working with people with HD. The objective of this study was to characterize current physical therapist practice for people with HD, thus informing the development of standardized clinical care and future research studies.

SUBJECTS AND METHODS

Consultation with physical therapists working with people with HD was undertaken in the form of mailed questionnaires (n=49) and semistructured interviews (n=8). The development of the interview schedule was aided by consideration of the data obtained from the questionnaires. Themes identified from the interviews were considered in light of published literature and questionnaire responses.

RESULTS

The main issues that emerged from the interviews were classified into 3 subthemes: (1) there is insufficient use of routine physical therapy-related outcome measures at different stages of HD, (2) there is underutilization of physical therapy services in managing HD (particularly in the early stages), and (3) the management of falls and mobility deficit progression is a key treatment aim for people with HD.

DISCUSSION AND CONCLUSION

A conceptual framework for physical therapy intervention in HD was developed on the basis of the themes that emerged from the data in this study. Such a framework has utility for complex, progressive conditions such as HD and may facilitate clinical decision making and standardization of practice and affect the development of future physical therapy trials.