A systematic review of diabetes prevention programs adapted to include family members.

Objectives: Family-based programs may be a strategy to prevent health conditions with hereditary risk such as diabetes. This review examined the state of the science regarding interventions that adapted the Diabetes Prevention Program (DPP) lifestyle change curriculum to include family members. Methods: CINAHL, Cochrane Central, PsycINFO, PubMed, and Scopus were searched for reports that were peer reviewed, written in English, evaluated interventions that adapted the DPP lifestyle change curriculum to be family-based, reported diabetes risk related outcomes, and published between 2002 and August 2023. Records were reviewed, data extracted, and quality assessed by two researchers working independently. A narrative synthesis was completed. Meta-analysis was not completed due to the small number of studies and the heterogeneity of the study characteristics. Results: 2177 records were identified with four meeting inclusion criteria. Primary participants for three studies were adults and one study focused on youth. Family participants were adult family members, children of the primary participant, or caregivers of the enrolled youth. For primary participants, two studies found significant intervention effects on weight-related outcomes. Of the studies with no intervention effects, one was a pilot feasibility study that was not powered to detect changes in weight outcomes. Three studies assessed outcomes in family participants with one finding significant intervention effects on weight. Conclusions: While DPP interventions adapted to include family showed promising or similar results as individual-based DPP interventions, additional studies are needed to better understand the mechanisms of action and the most effective methods to engage family members in the programs.

An exploratory study of mothers engaging in physical activity in rural communities.

Gender gaps in physical activity (PA) exist with women being less active than men. Multiple cultural and psychosocial factors influence women's ability to successfully negotiate barriers to PA and other health promoting behaviors. The goal of this exploratory descriptive study was to better understand the daily experiences of mothers in making health promoting decisions for themselves and their families. Semi-structured interviews (N = 17) were conducted with rural dwelling mothers who were the primary caregivers of children in the home. Participants were asked to share their experiences with PA and other health behaviors, focusing on their motivators, barriers, and facilitators. Interviews were audio-recorded, transcribed verbatim, and analyzed using thematic content analysis. Emerging themes focused on 1) feeling internal and external pressures to prioritize family's needs over one's health, 2) family exerting both positive and negative influences on health choices, and 3) living in a rural community often resulting in a lack of opportunities to engage in physical activity and feelings of being isolated from social networks. To close the gender gap in PA, interventions should support mothers in navigating their multiple roles and competing demands while engaging in health promoting behaviors such as physical activity.

Proprioceptive and olfactory deficits in individuals with Parkinson disease and mild cognitive impairment.

BACKGROUND: Individuals with neurodegenerative diseases such as Parkinson disease (PD) and Alzheimer's (AD) disease often present with perceptual impairments at an early clinical stage. Therefore, early identification and quantification of these impairments could facilitate diagnosis and early intervention. OBJECTIVES: This study aimed to compare proprioceptive and olfactory sensitivities in individuals diagnosed with PD and mild cognitive impairment (MCI). METHODS: Proprioception in the forearm and olfactory function were measured in neurotypical older adults, individuals with PD, and individuals with MCI. Position and passive motion senses were assessed using a passive motion apparatus. The traditional Chinese version of the University of Pennsylvania smell identification test (UPSIT-TC) and the smell threshold test (STT) were used to identify and discriminate smell, respectively. RESULTS: Position sense threshold between the groups differed significantly (p < 0.001), with the PD (p < 0.001) and MCI (p = 0.004) groups showing significantly higher than the control group. The control group had significantly higher mean UPSIT-TC scores than the PD (p < 0.001) and MCI (p = 0.006) groups. The control group had a significantly lower mean STT threshold than the PD and MCI groups (p < 0.001 and p = 0.008, respectively). UPSIT-TC scores significantly correlated with disease progression in PD (r = - 0.50, p = 0.008) and MCI (r = 0.44, p = 0.04). CONCLUSIONS: Proprioceptive and olfactory sensitivities were reduced in individuals with PD and MCI, and these deficits were related to disease severity. These findings support previous findings indicating that perceptual loss may be a potential biomarker for diagnosing and monitoring disease progression in individuals with neurodegenerative diseases.

Quantification of early gait development: Expanding the application of Catwalk technology to an infant rhesus macaque model.

BACKGROUND: Understanding gait development is essential for identifying motor impairments in neurodevelopmental disorders. Defining typical gait development in a rhesus macaque model is critical prior to characterizing abnormal gait. The goal of this study was to 1) explore the feasibility of using the Noldus Catwalk to assess gait in infant rhesus macaques and 2) provide preliminary normative data of gait development during the first month of life. NEW METHOD: The Noldus Catwalk was used to assess gait speed, dynamic and static paw measurements, and interlimb coordination in twelve infant rhesus macaques at 14, 21, and 28 days of age. All macaque runs were labeled as a diagonal or non-diagonal walking pattern. RESULTS: Infant rhesus macaques primarily used a diagonal (mature) walking pattern as early as 14 days of life. Ten infant rhesus macaques (83.3%) were able to successfully walk across the Noldus Catwalk at 28 days of life. Limited differences in gait parameters were observed between timepoints because of the variability within the group at 14, 21, and 28 days. COMPARISON WITH EXISTING METHODS: No prior gait analysis system has been used to provide objective quantification of gait parameters for infant macaques. CONCLUSIONS: The Catwalk system can be utilized to quantify gait in infant rhesus macaques less than 28 days old. Future applications to infant rhesus macaques could provide a better understanding of gait development and early differences within various neurodevelopmental disorders.

Keeping Pace With 21st Century Healthcare: A Framework for Telehealth Research, Practice, and Program Evaluation in Occupational Therapy.

The use of telehealth to deliver occupational therapy services rapidly expanded during the COVID-19 pandemic. There are frameworks to evaluate services delivered through telehealth; however, none are specific to occupational therapy. Therefore, occupational therapy would benefit from a framework to systematically evaluate components of telehealth service delivery and build evidence to demonstrate the distinct value of occupational therapy. The PACE Framework outlines four priority domains to address areas of need: (1) Population and Health Outcomes; (2) Access for All Clients; (3) Costs and Cost Effectiveness; and (4) Experiences of Clients and Occupational Therapy Practitioners. This article describes the development and expert reviewer evaluation of the PACE Framework. In addition, the PACE Framework's domains, subdomains, and outcome measure examples are described along with future directions for implementation in occupational therapy research, practice, and program evaluation.

Resting-state functional connectivity associated with gait characteristics in people with Parkinson's disease.

INTRODUCTION: Parkinson's disease (PD) is a movement disorder caused by dysfunction in the basal ganglia (BG). Clinically relevant gait deficits, such as decreased velocity and increased variability, may be caused by underlying neural dysfunction. Reductions in resting-state functional connectivity (rs-FC) between networks have been identified in PD compared to controls; however, the association between gait characteristics and rs-FC of brain networks in people with PD has not yet been explored. The present study aimed to investigate these associations. METHODS: Gait characteristics and rs-FC MRI data were collected for participants with PD (N = 50). Brain networks were identified from a set of seeds representing cortical, subcortical, and cerebellar regions. Gait outcomes were correlated with the strength of rs-FC within and between networks of interest. A stepwise regression analysis was also conducted to determine whether the rs-FC strength of brain networks, along with clinical motor scores, were predictive of gait characteristics. RESULTS: Gait velocity was associated with rs-FC within the visual network and between motor and cognitive networks, most notably BG-thalamus internetwork rs-FC. The stepwise regression analysis showed strength of BG-thalamus internetwork rs-FC and clinical motor scores were predictive of gait velocity. CONCLUSION: The results of the present study demonstrate gait characteristics are associated with functional organization of the brain at the network level, providing insight into the neural mechanisms of clinically relevant gait characteristics. This knowledge could be used to optimize the design of gait rehabilitation interventions for people with neurological conditions.

Stimulating Research to Advance Evidence-Based Applications of Telehealth in Occupational Therapy.

Occupational therapy focuses on therapeutic means to address participation in meaningful everyday tasks across the lifespan. No single setting is more conducive to this pursuit than individuals' authentic contexts. Occupational therapists are therefore uniquely suited to lead the charge toward stimulating research and advancing evidence-based application of telehealth. To this end, the American Occupational Therapy Foundation digitally convened their 2020 Planning Grant Collective to focus on the topic of Telehealth. Participants of the interdisciplinary collective collaboratively identified four themes: (1) Using technology to assess and intervene in the everyday context, (2) Partnerships with caregivers, (3) Telehealth delivery, and (4) Uniform data collection. Subgroups explored potential research and funding opportunities in their specialty area while also addressing the centralizing concepts of equity and diversity of telehealth delivery and COVID-19. Here, we provide a summary of the key concepts and recommendations from the 3 days of collaboration.

Systematic Review of Exercise for Caregiver-Care Recipient Dyads: What Is Best for Spousal Caregivers-Exercising Together or Not at All?

BACKGROUND AND OBJECTIVES: Though exercise for care recipients receives considerable emphasis, few dyadic studies focus on caregivers. This systematic review identified dyadic exercise interventions, which measured outcomes for older adult caregivers. Studies that met inclusion criteria were examined to better understand whether caregivers derived greater benefit from exercising with care recipients, or not exercising at all. RESEARCH DESIGN AND METHODS: PRISMA guidelines were followed to identify quantitative studies of dyadic exercise interventions in which caregivers enrolled with care recipients, and either coparticipated in exercise; or while their care recipients exercised independently, caregivers received a separate, nonexercise intervention or usual care (UC). To be included, studies had to measure physical or psychosocial outcomes for caregivers. Study quality was assessed via the Downs and Black checklist. RESULTS: Eleven studies met inclusion criteria. In six, the dyad exercised; in five, care recipients exercised while caregivers received a separate program, or UC. Results suggest that caregivers may improve both psychosocial and physical health when exercising together with care recipients. Caregivers who did not exercise but received a separate, nonexercise intervention, such as support, education, or respite, showed psychosocial benefits. Those who received UC were less likely to derive physical or psychosocial benefits. Included studies were fair to good quality with moderate to high risk of bias. DISCUSSION AND IMPLICATIONS: Often examined secondarily, caregivers are overlooked for participation in interventions with care recipients. This analysis suggests that caregivers may benefit from dyadic interventions in which they either exercise together with their care recipients or receive a separate nonexercise intervention or respite.

The Effects of Systematic Environmental Manipulation on Gait of Older Adults.

Quantification of gait changes in response to altered environmental stimuli may allow for improved understanding of the mechanisms that influence gait changes and fall occurrence in older adults. This study explored how systematic manipulation of a single dimension of one's environment affects spatiotemporal gait parameters. A total of 20 older adult participants walked at a self-selected pace in a constructed research hallway featuring a mobile wall, which allowed manipulation of the hallway width between three conditions: 1.14 m, 1.31 m, and 1.48 m. Spatiotemporal data from participants' walks were captured using an instrumented GAITRite mat. A repeated measures ANOVA revealed older adults spent significantly more time in double support in the narrowest hallway width compared to the widest, but did not significantly alter other spatiotemporal measures. Small-scale manipulations of a single dimension of the environment led to subtle, yet in some cases significant changes in gait, suggesting that small or even imperceptible environmental changes may contribute to altered gait patterns for older adults.

Interlimb Coordination During a Combined Gait and Prehension Task.

Reaching and grasping are often completed while walking, yet the interlimb coordination required for such a combined task is not fully understood. Previous studies have produced contradictory evidence regarding preference for support of the lower limb ipsilateral or contralateral to the upper limb when performing a reaching task. This coordinative aspect of the combined task provides insight into whether the two tasks are mutually modified or if the reach is superimposed upon normal arm swinging. Collectively, 18 right-handed young adults walked slower, took shorter steps, and spent more time in double support during the combined task compared with walking alone. The peak grasp aperture was larger in walking reach-to-grasp trials compared with standing trials. There was not a strong trend for lower limb support preferences at the reach initiation or object contact. The participants could begin walking with either foot and demonstrated variability of preferred gait initiation patterns. There was a range of interlimb coordination patterns, none of which could be generalized to all young adults. The variability with which healthy right-handed young adults execute a combined walking reach-to-grasp task suggests that the cyclical (walking) and discrete (prehension) motor tasks may have separate motor control mechanisms, as proposed in the two primitives theory.

Spatiotemporal quantification of gait in common marmosets.

BACKGROUND: Objective gait evaluation in humans is used as a predictive disability outcome measure as well as an indicator for intervention effectiveness. Parallel methods of gait analysis in nonhuman primate models are essential for clinical translation. The goal of this study was to first assess whether marmosets' gait data could be reliably collected in a Noldus CatWalk XT10.6 and second, establish a testing protocol to assess gait and the intraindividual variability during repeated testing. NEW METHOD: The CatWalk, originally developed for rodents, was modified and used to assess gait in eight adult common marmoset monkeys across multiple days and trials. Data was first analyzed to identify valid runs. Repeated measures ANOVA was completed for the following gait measures: mean base of support, average stride length, average swing time, and average stance time. RESULTS: Raters had a high level of concurrence of usable data across all trials with successful trials including four consecutive hindfoot footfalls, during a continuous, uninterrupted segment of walking. A significant main effect of time (p < 0.000) but not rater (p = 0.98) was present with significant interactions for time by subject (p < 0.000), but not rater per subject (p = 0.538), time (p = 0.186), or three-way interaction (p = 0.297). COMPARISON WITH EXISTING METHOD(S): Gait has been assessed using force-plate and video data. The CatWalk allowed reproducible, automated and translational locomotor data to be collected at multiple time points with detailed analyses that identified a diagonal gait pattern. CONCLUSIONS: The CatWalk system, similar to those used in humans, can be effectively used to quantify spatiotemporal characteristics of gait in the common marmoset.

Balance and the brain: A review of structural brain correlates of postural balance and balance training in humans.

BACKGROUND: Balance challenges are associated with not only the aging process but also a wide variety of psychiatric and neurological disorders. However, relatively little is known regarding the neural basis of balance and the effects of balance interventions on the brain. RESEARCH QUESTION: This review synthesizes the existing literature to answer the question: What are the key brain structures associated with balance? METHODS: This review examined 37 studies that assessed brain structures in relation to balance assessment or intervention. These studies provided 234 findings implicating 71 brain structures. The frequency of implication for each structure was examined based upon specific methodological parameters, including study design (assessment/intervention), type of balance measured (static/dynamic), population (clinical/non-clinical), and imaging analysis technique (region of interest [ROI]/voxel-based morphometry [VBM]). RESULTS: Although a number of structures were associated with balance across the brain, the most frequently implicated structures included the cerebellum, basal ganglia, thalamus, hippocampus, inferior parietal cortex, and frontal lobe regions. Findings in the cerebellum and brainstem were most common in studies with clinical populations, studies that used an ROI approach, and studies that measured dynamic balance. Findings in the frontal, occipital, and parietal regions were also more common in studies that measured dynamic compared to static balance. SIGNIFICANCE: While balance appears to be a whole-brain phenomenon, a subset of structures appear to play a key role in balance and are likely implicated in balance disorders. Some of these structures (i.e., the cerebellum, basal ganglia and thalamus) have a well-appreciated role in balance, whereas other regions (i.e., hippocampus and inferior parietal cortex) are not commonly thought to be associated with balance and therefore may provide alternative explanations for the neural basis of balance. Key avenues for future research include understanding the roles of all regions involved in balance across the lifespan and in different clinical populations.

Exercise and Parkinson Disease: Comparing Tango, Treadmill, and Stretching.

BACKGROUND AND PURPOSE: Impaired gait, balance, and motor function are common in Parkinson disease (PD) and may lead to falls and injuries. Different forms of exercise improve motor function in persons with PD, but determining which form of exercise is most effective requires a direct comparison of various approaches. In this prospective, controlled trial, we evaluated the impact of tango, treadmill walking, and stretching on gait, balance, motor function, and quality of life. We hypothesized tango and treadmill would improve forward walking and motor symptom severity, and tango would also improve backward walking, balance, and quality of life. METHODS: Ninety-six participants (age: 67.2 ± 8.9 years, 42% female) with mild to moderate idiopathic PD were serially assigned to tango, treadmill walking, or stretching (active control group) and attended 1-hour classes twice weekly for 12 weeks. Assessments occurred OFF anti-PD medication before and after the intervention and at follow-up 12 weeks after the intervention. RESULTS: Forward velocity and backward velocity improved for the treadmill group from baseline to posttest and improvements persisted at follow-up. Backward velocity and motor functioning improved for the stretching group from baseline to posttest, but results did not persist at follow-up. There were no significant changes in the tango group across time points. DISCUSSION AND CONCLUSIONS: Contrary to our hypotheses, only treadmill improved forward walking, while backward walking improved with treadmill and stretching. Future research should examine combinations of exercises with a focus on optimizing dosing and examining whether specific characteristics of people with PD correlate with different types of exercise.Video Abstract available for more insights from the authors (see Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A237).

Effects of exercise on gait and motor imagery in people with Parkinson disease and freezing of gait.

INTRODUCTION: Exercise improves gait in Parkinson disease (PD), but whether exercise differentially affects people with PD with (freezers) and without freezing of gait (non-freezers) remains unclear. This study examines exercise's effects on gait performance, neural correlates related to these effects, and potential neural activation differences between freezers and non-freezers during motor imagery (MI) of gait. METHODS: Thirty-seven participants from a larger exercise intervention completed behavioral assessments and functional magnetic resonance imaging (fMRI) scans before and after a 12-week exercise intervention. Gait performance was characterized using gait velocity and stride length, and a region of interest (ROI) fMRI analysis examined task-based blood oxygen-level dependent (BOLD) signal changes of the somatomotor network (SMN) during MI of forward (IMG-FWD) and backward (IMG-BWD) gait. RESULTS: Velocity (F(1,34) = 55.04, p < 0.001) and stride length (F(1,34) = 77.58, p < 0.001) were significantly lower for backward versus forward walking in all participants. The ROI analysis showed freezers had lower BOLD signal compared to non-freezers in the cerebellum (F(1,32) = 7.01, p = 0.01), primary motor (left: F(1,32) = 7.09, p = 0.01; right: F(1,32) = 7.45, p = 0.01), and primary sensory (left: F(1,32) = 9.59, p = 0.004; right: F(1,32) = 8.18, p = 0.007) cortices during IMG-BWD only. The evidence suggests the exercise intervention did not affect gait or BOLD signal during MI. CONCLUSION: While all participants had significantly slower and shorter backward velocity and stride length, respectively, the exercise intervention had no effect. Similarly, BOLD signal during MI did not change with exercise; however, freezers had significantly lower BOLD signal during IMG-BWD compared to non-freezers. This suggests potential decreased recruitment of the SMN during MI of gait in freezers.

Greater fear of reinjury is related to stiffened jump-landing biomechanics and muscle activation in women after ACL reconstruction.

PURPOSE: Fear of reinjury is an important factor in determining who returns to sport following anterior cruciate ligament reconstruction (ACLR). Evidence from other musculoskeletal injuries indicates fear of reinjury may be related to stiffened movement patterns observed in individuals following ACLR. The relationship between fear of reinjury and performance on dynamic tasks, however, has not been investigated. Therefore, the purpose of this study was to investigate the relationship between fear of reinjury and jump-landing biomechanics. METHODS: Thirty-six females (height = 168.7 ± 6.5 cm, body mass = 67.2 ± 10.0 kg, age = 18.9 ± 1.5 years) with a history of ACLR (time from surgery = 26.1 ± 13.3 months) participated in the study. Each participant performed five trials of a standard jump-landing task. 3D motion capture and surface electromyography was used to record peak kinematics and lower extremity muscle activation on the injured limb during the jump landings. Spearman's rank correlations established the relationship between TSK-11 scores and each biomechanical variable of interest. RESULTS: There was a significant, negative relationship between fear of reinjury (TSK-11: 19.9 ± 4.5) and knee (p = 0.006), hip (p = 0.003), and trunk flexion (p = 0.013). There was also a significant, positive relationship between hip adduction (p = 0.007), and gluteus maximus preparatory activation (p = 0.001). CONCLUSIONS: The results of this study indicate that higher fear of reinjury is associated with stiffened movement patterns that are associated with increased risk of a second ACL injury. Similar movement patterns have been observed in patients with low back pain. Clinicians should evaluate psychological and emotional consequences of injury in addition to the physical consequences as they appear to be related. LEVEL OF EVIDENCE: III.

Monitoring Motor Symptoms During Activities of Daily Living in Individuals With Parkinson's Disease.

This literature review addressed wearable sensor systems to monitor motor symptoms in individuals with Parkinson's disease (PD) during activities of daily living (ADLs). Specifically, progress in monitoring tremor, freezing of gait, dyskinesia, bradykinesia, and hypokinesia was reviewed. Twenty-seven studies were found that met the criteria of measuring symptoms in a home or home-like setting, with some studies examining multiple motor disorders. Accelerometers, gyroscopes, and electromyography sensors were included, with some studies using more than one type of sensor. Five studies measured tremor, five studies examined bradykinesia or hypokinesia, thirteen studies included devices to measure dyskinesia or motor fluctuations, and ten studies measured akinesia or freezing of gait. Current sensor technology can detect the presence and severity of each of these symptoms; however, most systems require sensors on multiple body parts, which is challenging for remote or ecologically valid observation. Different symptoms are detected by different sensor placement, suggesting that the goal of detecting all symptoms with a reduced set of sensors may not be achievable. For the goal of monitoring motor symptoms during ADLs in a home setting, the measurement system should be simple to use, unobtrusive to the wearer and easy for an individual with PD to put on and take off. Machine learning algorithms such as neural networks appear to be the most promising way to detect symptoms using a small number of sensors. More work should be done validating the systems during unscripted and unconstrained ADLs rather than in scripted motions.

The Effect of Dopaminergic Medication on Joint Kinematics during Haptic Movements in Individuals with Parkinson's Disease.

This study examined whether altered joint angular motion during haptic exploration could account for a decline in haptic sensitivity in individuals with PD by analyzing joint position data during haptic exploration of a curved contour. Each participant's hand was passively moved by a robotic arm along the edges of a virtual box (5 cm × 15 cm) with a curved left wall. After each trial, participants indicated whether the contour was curved or straight. Visual, auditory, and tactile cues were occluded, and an electrogoniometer recorded shoulder and elbow joint angles during each trial. The PD group in the OFF state had a higher mean detection threshold (4.67 m-1) than the control group (3.06 m-1). Individuals with PD in the OFF state also had a significantly greater magnitude of shoulder abduction than those in the ON state (p = 0.003) and a smaller magnitude of elbow flexion than those in the ON state or compared to the control group (both p < 0.001). These findings suggest that individuals with PD employ joint configurations that may contribute to haptic insensitivity. Dopamine replacement therapy improved joint configurations during haptic exploration in patients with PD, suggesting a role for dopaminergic dysfunction in PD-related haptic insensitivity.

Star Excursion Balance Test Anterior Asymmetry Is Associated With Injury Status in Division I Collegiate Athletes.

Study Design Retrospective cohort. Background Star Excursion Balance Test (SEBT) performance differs by sport in healthy collegiate athletes, and lower extremity injury rates also vary by sport, sex, and athletic exposure. The relationship between SEBT performance and injury risk has not been evaluated with consideration of these additional variables, which may be necessary to fully describe the relationship between SEBT performance and injury risk. Objectives To assess the association between preseason SEBT performance and noncontact injury occurrence to the knee or ankle in Division I collegiate athletes when controlling for sport, sex, and athletic exposure. Methods Star Excursion Balance Test performance, starting status, and injury status were reviewed retrospectively in National Collegiate Athletic Association Division I collegiate athletes from a single institution. A total of 147 athletes were healthy at the time of preseason SEBT testing and either remained healthy (n = 118) or sustained a noncontact injury to the knee or ankle (n = 29) during their sport's subsequent competitive season. Side-to-side asymmetries were calculated in each direction as the absolute difference in reach distance between limbs. Star Excursion Balance Test reach distances and asymmetries were compared between groups using multivariable regression, controlling for sport, sex, and athletic exposure (starter, nonstarter). Receiver operating characteristic curves were used to determine optimal sensitivity and specificity for significant models. Results When controlling for sport, sex, and athletic exposure, SEBT side-to-side asymmetry in the anterior direction, expressed as an absolute or normalized to limb length, discriminated between injured and noninjured athletes (area under the curve greater than 0.82). Conclusion Assessing side-to-side reach asymmetry in the anterior direction of the SEBT may assist in identifying collegiate athletes who are at risk for sustaining noncontact injuries to the knee or ankle. Level of Evidence Prognosis, level 2b. J Orthop Sports Phys Ther 2017;47(5):339-346. Epub 29 Mar 2017. doi:10.2519/jospt.2017.6974.

The Effect of Dopaminergic Medication on Beat-Based Auditory Timing in Parkinson's Disease.

Parkinson's disease (PD) adversely affects timing abilities. Beat-based timing is a mechanism that times events relative to a regular interval, such as the "beat" in musical rhythm, and is impaired in PD. It is unknown if dopaminergic medication influences beat-based timing in PD. Here, we tested beat-based timing over two sessions in participants with PD (OFF then ON dopaminergic medication) and in unmedicated control participants. People with PD and control participants completed two tasks. The first was a discrimination task in which participants compared two rhythms and determined whether they were the same or different. Rhythms either had a beat structure (metric simple rhythms) or did not (metric complex rhythms), as in previous studies. Discrimination accuracy was analyzed to test for the effects of beat structure, as well as differences between participants with PD and controls, and effects of medication (PD group only). The second task was the Beat Alignment Test (BAT), in which participants listened to music with regular tones superimposed, and responded as to whether the tones were "ON" or "OFF" the beat of the music. Accuracy was analyzed to test for differences between participants with PD and controls, and for an effect of medication in patients. Both patients and controls discriminated metric simple rhythms better than metric complex rhythms. Controls also improved at the discrimination task in the second vs. first session, whereas people with PD did not. For participants with PD, the difference in performance between metric simple and metric complex rhythms was greater (sensitivity to changes in simple rhythms increased and sensitivity to changes in complex rhythms decreased) when ON vs. OFF medication. Performance also worsened with disease severity. For the BAT, no group differences or effects of medication were found. Overall, these findings suggest that timing is impaired in PD, and that dopaminergic medication influences beat-based and non-beat-based timing differently. Judging the beat in music does not appear to be affected by PD or by dopaminergic medication.

Impact of limiting visual input on gait: Individuals with Parkinson disease, age-matched controls, and healthy young participants.

Normal and limited vision gait was investigated in individuals with Parkinson disease (PD), healthy older and healthy young individuals. Participants walked a GAITRite mat with normal vision or vision of lower limbs occluded. Results indicate individuals with PD walked more slowly, with shorter and wider steps, and spent more time in double support with limited vision as compared to full vision. Healthy young and old individuals took shorter steps but were otherwise unchanged between conditions.