Impacts of dance on non-motor symptoms, participation, and quality of life in Parkinson disease and healthy older adults.

Evidence indicates exercise is beneficial for motor and non-motor function in older adults and people with chronic diseases including Parkinson disease (PD). Dance may be a relevant form of exercise in PD and older adults due to social factors and accessibility. People with PD experience motor and non-motor symptoms, but treatments, interventions, and assessments often focus more on motor symptoms. Similar non-motor symptoms also occur in older adults. While it is well-known that dance may improve motor outcomes, it is less clear how dance affects non-motor symptoms. This review aims to describe the effects of dance interventions on non-motor symptoms in older adults and PD, highlights limitations of the literature, and identifies opportunities for future research. Overall, intervention parameters, study designs, and outcome measures differ widely, limiting comparisons across studies. Results are mixed in both populations, but evidence supports the potential for dance to improve mood, cognition, and quality of life in PD and healthy older adults. Participation and non-motor symptoms like sleep disturbances, pain, and fatigue have not been measured in older adults. Additional well-designed studies comparing dance and exercise interventions are needed to clarify the effects of dance on non-motor function and establish recommendations for these populations.

A comparison of dance interventions in people with Parkinson disease and older adults.

It is important for our aging population to remain active, particularly those with chronic diseases, like Parkinson disease (PD), which limit mobility. Recent studies in older adults and people with PD suggest dance interventions provide various motor benefits. The literature for dance in PD is growing, but many knowledge gaps remain, relative to what is known in older adults. The purpose of this review is to: (1) detail results of dance intervention studies in older adults and in PD, (2) describe limitations of dance research in these populations, and (3) identify directions for future study. Generally, a wide variety of dance styles have been investigated in older adults, while a more limited subset has been evaluated in PD. Measures vary widely across studies and a lack of standardized outcomes measures hinders cross-studies comparisons. Compared to the dance literature in older adults, there is a notable absence of evidence in the PD literature in outcome domains related to cardiovascular health, muscle strength, body composition, flexibility, and proprioception. As a whole, the dance literature supports substantial and wide-ranging benefits in both populations, but additional effort should be dedicated to well-designed comparative studies using standardized outcome measures to identify optimal treatment programs.

Cerebral blood flow responses to dorsal and ventral STN DBS correlate with gait and balance responses in Parkinson's disease.

OBJECTIVES: The effects of subthalamic nucleus (STN) deep brain stimulation (DBS) on gait and balance vary and the underlying mechanisms remain unclear. DBS location may alter motor benefit due to anatomical heterogeneity in STN. The purposes of this study were to (1) compare the effects of DBS of dorsal (D-STN) versus ventral (V-STN) regions on gait, balance and regional cerebral blood flow (rCBF) and (2) examine the relationships between changes in rCBF and changes in gait and balance induced by D-STN or V-STN DBS. METHODS: We used a validated atlas registration to locate and stimulate through electrode contacts in D-STN and V-STN regions of 37 people with Parkinson's disease. In a within-subjects, double-blind and counterbalanced design controlled for DBS settings, we measured PET rCBF responses in a priori regions of interest and quantified gait and balance during DBS Off, unilateral D-STN DBS and unilateral V-STN DBS. RESULTS: DBS of either site increased stride length without producing significant group-level changes in gait velocity, cadence or balance. Both sites increased rCBF in subcortical regions and produced variable changes in cortical and cerebellar regions. DBS-induced changes in gait velocity are related to premotor cortex rCBF changes during V-STN DBS (r=-0.40, p=0.03) and to rCBF changes in the cerebellum anterior lobe during D-STN DBS (r=-0.43, p=0.02). CONCLUSIONS: DBS-induced changes in gait corresponded to rCBF responses in selected cortical and cerebellar regions. These relationships differed during D-STN versus V-STN DBS, suggesting DBS acts through distinct neuronal pathways dependent on DBS location.

Which measures of physical function and motor impairment best predict quality of life in Parkinson's disease?

INTRODUCTION: Our objective was to compare the relative value of elements of the motor system in predicting the physical mobility domain of health related quality of life in patients with Parkinson's disease in order to specify targets for intervention. METHODS: In this cross-sectional study, the Parkinson's disease questionnaire-39 was administered to 263 subjects with Parkinson's disease to assess health related quality of life. Demographics, motor impairments and physical function were assessed using the Unified Parkinson disease rating scale, 10-m walk test, 6-min walk test, Freezing of gait questionnaire, Timed up & go, functional gait assessment, Berg balance test, functional reach and 9-hole peg test. RESULTS: The results revealed that demographic factors accounted for 19.7% of the variance in Parkinson disease questionnaire-39 mobility score. When motor impairments were added to the model, the bradykinesia composite score contributed a significant portion of the variance (R(2) change = 0.12, p < 0.001). The tremor and rigidity composite scores did not contribute significantly. The Freezing of gait questionnaire was the strongest predictor (R(2) change = 0.23, p < 0.001) of the physical function tests followed by Functional gait assessment (R(2) change = 0.06, p < 0.001) and 6-min walk test (R(2) change = 0.01, p = 0.01). Collectively, 61% of the variance in Parkinson disease questionnaire-39 mobility score and 41.5% of the Parkinson disease questionnaire-39(total) score was accounted for. DISCUSSION: These results suggest greater value of physical function tests, and not tests of motor impairments, in predicting health related quality of life.

Effects of deep brain stimulation of dorsal versus ventral subthalamic nucleus regions on gait and balance in Parkinson's disease.

OBJECTIVE: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) improves motor function, including gait and stability, in people with Parkinson's disease (PD) but differences in DBS contact locations within the STN may contribute to variability in the degree of improvement. Based on anatomical connectivity, dorsal STN may be preferentially involved in motor function and ventral STN in cognitive function. METHODS: To determine whether dorsal DBS affects gait and balance more than ventral DBS, a double blind evaluation of 23 PD patients with bilateral STN DBS was conducted. Each participant underwent gait analysis and balance testing off Parkinson's medication under three DBS conditions (unilateral DBS in the dorsal STN region, unilateral DBS in the ventral STN region and both stimulators off) on 1 day. RESULTS: Improvements were seen in Unified Parkinson's Disease Rating Scale (UPDRS)-III scores and velocity in walking trials as fast as possible (Fast gait) and preferred pace (Pref gait), as well as stride length for Fast and Pref gait, with dorsal and ventral stimulation compared with the off condition (post hoc tests, p<0.05). However, there were no differences with dorsal compared to ventral stimulation. Balance, assessed using the multi-item mini-Balance Evaluation Systems Test (mini-BESTest), was similar across conditions. CONCLUSIONS: Absence of differences in gait and balance between the dorsal and ventral conditions suggests motor connections involved in gait and balance may be more diffusely distributed in STN than previously thought, as opposed to neural connections involved in cognitive processes, such as response inhibition, which are more affected by ventral stimulation.

Dance as therapy for individuals with Parkinson disease.

Parkinson disease (PD) is a progressive, neurodegenerative movement disorder that is often accompanied by impaired balance and walking and reduced quality of life (QoL). Recent studies indicate that dance may be an effective alternative to traditional exercise for addressing these areas of concern to individuals with PD. This review summarizes the relatively scant literature on the benefits of dance for those with PD, discusses what is currently known with respect to appropriate dosing of dance interventions, and speculates upon potential mechanisms by which dance may convey benefits. There is a clear need for additional research using larger sample sizes to examine the potential long-term effects of dance for those with PD.

Postural responses to combinations of head and body displacements: vestibular-somatosensory interactions.

Postural responses to head displacements are triggered by the vestibular system; responses to body displacements are triggered by the somatosensory system. We examined the interaction of responses to combinations of head and support surface perturbations. Head displacements were always in the opposite direction of body displacements. The time between head and support surface perturbations was varied. We measured amplitude and latency of gastrocnemius and tibialis anterior EMGs for various head backward/body forward and head forward/body backward displacement combinations. These responses were compared to head-only or body-only displacement trials, which served as controls. Relative to controls, the latency of somatosensory-evoked responses to body displacement was longer and vestibular-evoked responses were absent or of low amplitude for combinations where head and support surface perturbations were presented closely in time (10-50 ms apart). These results illustrate complex integration of vestibular and somatosensory information, suggesting that the vestibulospinal and somatosensory-spinal pathways are not two isolated systems independently driving motor neurons. Rather, these pathways may influence one another at premotoneuronal levels where common circuitry may be shared by both systems.

Forward versus backward walking: transfer of podokinetic adaptation.

We asked whether podokinetic adaptation to walking on a circular treadmill transfers to different forms of locomotion. Subjects were blindfolded and asked to walk straight across the floor, in the forward and backward directions, following podokinetic (PK) stimulation that consisted of 30 min of forward walking-in-place on the perimeter of a disk rotating in the clockwise direction. During both forward and backward walking following forward-walking PK stimulation, subjects involuntarily walked along curved trajectories at angular velocities well above vestibular threshold, although they perceived that they were walking along straight paths. The curved paths of forward and backward walking were indistinguishable from one another. Transfer of PK adaptations acquired during forward walking on the turntable to backward walking trials suggests that the PK system controls general locomotor trajectory. Adaptation of the system thus influences forms of locomotion other than that used during acquisition of the adaptation. This transfer also supports the concept that forward and backward walking are controlled by neural networks that share common elements. An interesting feature of the transfer of PK adaptation is that for both forward and backward walking, subjects turned in a counterclockwise direction. As such, the direction of relative rotation between the trunk and feet was maintained for both forward and backward walking. However, the relationship of the lower extremities to the center of rotation was not preserved. The left limb was the inner leg during PK stimulation and forward walking after adaptation, but the left leg was the outer leg during backward walking. These results suggest that PK adaptation affects general locomotor trajectory via a remodeling of the rotational relationship between the trunk and the feet.

Selection and coordination of human locomotor forms following cerebellar damage.

We have previously shown that control subjects use two distinct temporal strategies when stepping on an inclined surface during walking: one for level and 10 degrees surfaces and another for 20 and 30 degrees surfaces. These two temporal strategies were characterized by systematic shifts in the timing of muscle activity and peak joint angles. We examined whether cerebellar subjects with mild to moderate gait ataxia were impaired in their ability to select these two temporal strategies, adjust peak joint angle amplitudes, and/or adjust one joint appropriately with respect to movements and constraints at another joint. Subjects walked on a level surface and on different wedges (10, 20, and 30 degrees ) presented in the context of level walking. In a single trial, a subject walked on a level surface in approach to a wedge, took a single step on the wedge, and continued walking on an elevated level surface beyond the wedge. Cerebellar subjects used two temporal strategies, one for the level and 10 degrees surfaces and another for 20 and 30 degrees surfaces. Cerebellar strategies were similar to those used by controls except for the timing of ankle-joint movement on the steeper wedges. Cerebellar subjects adjusted the peak amplitudes of individual joint angles normally, with the exception of peak ankle plantarflexion. However, they exhibited greater trial-to-trial variability of peak hip and knee joint angles that increased as a function of wedge inclination. The most substantial deficit noted in the cerebellar group was in the relative movement of multiple joints. Cerebellar subjects demonstrated multijoint coordination deficits in all conditions, although these deficits were most pronounced during stance on the steeper wedges. On the 30 degrees wedge, cerebellar subjects showed abnormal relative movement of hip, knee, and ankle joints and the most substantial decomposition of movement. We speculate that to simplify multijoint control, cerebellar subjects decomposed their movement by fixing the ankle joint in a dorsiflexed position on the steepest wedges. Our results suggest that the cerebellum may not be critical in selecting the basic motor patterns for the two temporal strategies because cerebellar subjects produced appropriate timing shifts at most joints. Instead, our data suggest that the cerebellum is most critical for adjusting the relative movement of multiple joints, especially to accommodate external constraints.

Step, swim, and scratch motor patterns in the turtle.

The turtle generates a variety of coordinated hindlimb movements, including different forms of locomotion and scratching. The intact turtle produces forward step, forward swim, and backpaddle. Following spinal cord transection, rostral, pocket, and caudal scratches can be evoked by mechanical stimulation of the shell. Comparisons of the kinematics and motor patterns of these six behaviors provide insights regarding neuronal mechanisms underlying their production. All six behaviors were characterized by alternating hip flexion and extension and by an event during which force was exerted against a substrate. The portion of the cycle occupied by hip flexion or extension movement varied across behaviors. Hip extension occupied well over half the cycle period in the forward step and the caudal scratch. The cycle was split into approximately half hip flexion and half hip extension for the forward swim, the backpaddle, and the rostral scratch. Hip flexion occupied over half the cycle in the pocket scratch. The swim and scratch forms had curvilinear, crescent-shaped toe trajectories and a single burst of monoarticular knee extensor activity during each cycle. The forward step had a linear toe trajectory and two bursts of knee extensor activity during each cycle, one during swing and one during stance. Timing of monoarticular knee extensor onset was similar for: the forward swim, the rostral scratch, and the swing phase burst of forward step; the pocket scratch and the stance phase burst of forward step; and the backpaddle and the caudal scratch. Amplitudes of muscle activity varied among the six behaviors; high amplitudes of activity were associated with events during which force was exerted against a substrate. These times of force exertion were: stance phase in the forward step, powerstroke in the forward swim and the backpaddle, and rubs of the limb against the shell in the scratch forms. The six behaviors studied represent a range of parameter values, as evidenced by relative durations of hip flexion to hip extension, knee extensor phasing, and electromyogram (EMG) amplitudes. This range of behaviors could be produced by assembling different combinations of neurons from a common pool, with all six behaviors likely sharing some basic circuitry. The extent of shared circuitry may be greater between behaviors with similar timing, e.g., backpaddle and caudal scratch.

Form switching during human locomotion: traversing wedges in a single step.

We examined the neural control strategies used to accommodate discrete alterations in walking surface inclination. Normal subjects were tested walking on a level surface and on different wedges (10 degrees, 15 degrees, 20 degrees, and 30 degrees ) presented in the context of level walking. On a given trial, a subject walked on a level surface in approach to a wedge, took a single step on the wedge, and continued walking on an elevated level surface beyond the wedge. As wedge inclination increased, subjects linearly increased peak joint angles. Changes in timing of peak joint angles and electromyograms were not linear. Subjects used two distinct temporal strategies, or forms, to traverse the wedges. One form was used for walking on a level surface and on the 10 degrees wedge, another form for walking on the 20 degrees and 30 degrees wedges. In the level/10 degrees form, peak hip flexion occurred well before heel strike (HS) and peak dorsiflexion occurred in late stance. In the 20 degrees /30 degrees form, peak hip flexion was delayed by 12% of the stride cycle and peak dorsiflexion was reached 12% earlier. For the level/10 degrees form, onsets of the rectus femoris, gluteus maximus, and vastus lateralis muscles were well before HS and offset of the anterior tibialis was at HS. For the 20 degrees /30 degrees form, onsets of the rectus femoris, gluteus maximus, and vastus lateralis and offset of the anterior tibialis were all delayed by 12% of the stride cycle. Muscles shifted as a group, rather than individually, between the forms. Subjects traversing a 15 degrees wedge switched back and forth between the two forms in consecutive trials, suggesting the presence of a transition zone. Differences between the forms can be explained by the differing biomechanical constraints imposed by the wedges. Steeper wedges necessitate changes in limb orientation to accommodate the surface, altering limb orientation with respect to gravity and making it necessary to pull the body forward over the foot. The use of different forms of behavior is a common theme in neural control and represents an efficient means of coordinating and adapting movement to meet changing environmental demands. The forms of locomotion reported here are likely used on a regular basis in real-world settings.

Scratch-swim hybrids in the spinal turtle: blending of rostral scratch and forward swim.

Turtles with a complete transection of the spinal cord just posterior to the forelimb enlargement at the D2-D3 segmental border produced coordinated rhythmic hindlimb movements. Ipsilateral stimulation of cutaneous afferents in the midbody shell bridge evoked a rostral scratch. Electrical stimulation of the contralateral dorsolateral funiculus (DLF) at the anterior cut face of the D3 segment activated a forward swim. Simultaneous stimulation of the ipsilateral shell bridge and the contralateral DLF elicited a scratch-swim hybrid: a behavior that blended features of both rostral scratch and forward swim into each cycle of rhythmic movement. This is the first demonstration of a scratch-locomotion hybrid in a spinal vertebrate. The rostral scratch and the forward swim shared some characteristics: alternating hip flexion and extension, similar timing of knee extensor activity within the hip cycle, and a behavioral event during which force was exerted against a substrate. During each cycle, each behavior exhibited three sequential stages, preevent, event, and postevent. The rostral scratch event was a rub of the foot against the stimulated shell site. The forward swim event was a powerstroke, a hip extension movement with the foot held in a vertical position with toes and webbing spread. The two behaviors differed with respect to several features: amount of hip flexion and extension, electromyogram (EMG) amplitudes, and EMG duty cycles. Scratch-swim hybrids displayed two events, the scratch rub and the swim powerstroke, within each cycle. Hybrid hip flexion excursion, knee extensor EMGs, and hip flexor EMGs were similar to those of the scratch; hybrid hip extension excursion and hip extensor EMGs were similar to those of the swim. The hybrid also had three sequential stages during each cycle: 1) a combined scratch prerub and swim postpowerstroke, 2) a scratch rub that also served as a swim prepowerstroke, and 3) a swim powerstroke that also served as a scratch postrub. Merging of the rostral scratch with the forward swim was possible because of similarities between the sequential stages of the two forms, making them biomechanically compatible for hybrid formation. Kinematic and myographic similarities between the rostral scratch and the forward swim support the hypothesis that the two behaviors share common neural circuitry. The common features of the sequential stages of each behavior and the production of scratch-swim hybrids provide additional support for the hypothesis of a shared core of spinal cord neurons common to both rostral scratch and forward swim.