Driving Automation for Older Adults with Preclinical Alzheimer's Disease.

INTRODUCTION: Older adults with preclinical Alzheimer's disease (AD) show changes in on-road driving performance. The impact of preclinical AD on using automated vehicle (AV) technology is unknown. The aim was to evaluate safety and cognitive workload while operating AV technology in drivers with preclinical AD. INTRODUCTION: This cross-sectional study included 40 participants: 19 older adults (age 74.16 ± 4.78; MOCA scores 26.42 ± 2.52) with preclinical AD, evidenced by elevated cortical beta-amyloid; and 21 controls (age 73.81 ± 5.62; MOCA scores 28.24 ± 1.67). All participants completed two scenarios in a driving simulator. Scenario 1 included conditional automation with an emergency event that required a manual take-over maneuver. Scenario 2 was identical but with a cognitive distractor task. Emergency response time was the main safety outcome measure. Cognitive workload was calculated using moment-to-moment changes in pupillary size and converted into an Index of Cognitive Activity (ICA). Mann-Whitney U and independent t tests were used to compare group differences. RESULTS: Emergency response times were similar between drivers with preclinical AD and controls in scenario 1 (20.85 s ± 1.08 vs. 20.52 s ± 3.18; p = 0.83) and scenario 2 (14.83 s ± 7.37 vs. 13.45 s ± 10.43; p = 0.92). Likewise, no differences were found in ICA between drivers with preclinical AD and controls in scenario 1 (0.34 ± 0.08 vs. 0.33 ± 0.17; p = 0.74) or scenario 2 (0.30 ± 0.07 vs. 0.29 ± 0.17; p = 0.93). CONCLUSIONS: Older drivers with preclinical AD may safely operate AV technology, without increased response times or cognitive workload. Future on-road studies with AV technology should confirm these preliminary results in drivers with preclinical AD.

Frailty and Falls in People Living With Multiple Sclerosis.

OBJECTIVE: To explore the association between frailty and history of falls in people living with multiple sclerosis (MS). DESIGN: Secondary analysis. SETTING: University research laboratories in the United States and Israel. PARTICIPANTS: A total of 118 people (N=118) with relapsing-remitting MS (mean age, 48.9±10.0 years; 74.6% female; Expanded Disability Status Scale [EDSS] range, 1.0-6.0) were studied in this cross-sectional analysis. INTERVENTION: Not applicable. MAIN OUTCOME MEASURES: A frailty index was calculated from 40 health deficits by following standard validated procedures. The number of falls (12-month history) was recorded. RESULTS: Overall, 33.9%, 29.7%, and 36.4% of participants were classified as nonfrail, moderately frail, and severely frail, respectively. The frailty index was significantly correlated (ρ=0.37, P<.001) with higher scores on the EDSS. In univariable negative binomial regression analysis, the frailty index was associated with a higher number of falls (incidence rate ratio [IRR]=3.33; 95% CI, 1.85-5.99; P<.001). After adjustment for age, sex, and EDSS, frailty remained strongly associated with history of falls (IRR=2.78; 95% CI, 1.51-5.10; P=.001). CONCLUSIONS: The current study identifies a significant relationship between frailty and history of falls in MS, independent of age, sex, and disease severity. These findings support the notion that frailty is a syndrome related to but independent of disability in MS.

Cortical Correlates of Increased Postural Task Difficulty in Young Adults: A Combined Pupillometry and EEG Study.

The pupillary response reflects mental effort (or cognitive workload) during cognitive and/or motor tasks including standing postural control. EEG has been shown to be a non-invasive measure to assess the cortical involvement of postural control. The purpose of this study was to understand the effect of increasing postural task difficulty on the pupillary response and EEG outcomes and their relationship in young adults. Fifteen adults completed multiple trials of standing: eyes open, eyes open while performing a dual-task (auditory two-back), eyes occluded, and eyes occluded with a dual-task. Participants stood on a force plate and wore an eye tracker and 256-channel EEG cap during the conditions. The power spectrum was analyzed for absolute theta (4−7 Hz), alpha (8−13 Hz), and beta (13−30 Hz) frequency bands. Increased postural task difficulty was associated with greater pupillary response (p < 0.001) and increased posterior region alpha power (p = 0.001) and fronto-central region theta/beta power ratio (p = 0.01). Greater pupillary response correlated with lower posterior EEG alpha power during eyes-occluded standing with (r = −0.67, p = 0.01) and without (r = −0.69, p = 0.01) dual-task. A greater pupillary response was associated with lower CoP displacement in the anterior−posterior direction during dual-task eyes-occluded standing (r = −0.60, p = 0.04). The pupillary response and EEG alpha power appear to capture similar cortical processes that are increasingly utilized during progressively more challenging postural task conditions. As the pupillary response also correlated with task performance, this measurement may serve as a valuable stand-alone or adjunct tool to understand the underlying neurophysiological mechanisms of postural control.

Reliability and Validity of Pupillary Response During Dual-Task Balance in Parkinson Disease.

OBJECTIVE: To investigate the reliability and validity of pupillary response during dual-task balance conditions in individuals with Parkinson disease (PD). DESIGN: Cross-sectional study. SETTING: University of Kansas Medical Center Parkinson's Disease and Movement Disorder Center. PARTICIPANTS: Participants (N=68) included individuals with PD (n=33) and healthy controls (n=35). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Pupillary response was the main outcome measure that was measured during the following conditions: single-task balance eyes open, single-task balance eyes occluded, dual-task eyes open, and dual-task eyes occluded. After each condition, the National Aeronautics and Space Administration-Task Load Index (NASA-TLX) was administered to assess self-reported cognitive workload. To examine the test-retest reliability of the pupillary response, the conditions were administered twice for each individual within 2 hours. Intraclass correlation coefficients (ICC) were used to analyze the test-retest reliability of pupillary response in each condition for both groups. Pearson's r correlation was used to assess the convergent validity of pupillary response against the NASA-TLX. RESULTS: The test-retest reliability was excellent for both groups in almost all conditions (ICC>0.75). There were no correlations between pupillary response and the NASA-TLX. However, increased mental demand (a subitem of the NASA-TLX) significantly correlated with increased pupillary response in individuals with PD (r=0.38; P=.03). CONCLUSIONS: Pupillary response showed excellent test-retest reliability and validity during dual-task balance for individuals with PD and healthy controls. Overall, these results suggest that pupillary response represents a stable index of cognitive workload during dual-task balance in individuals with PD.

Cognitive workload during verbal abstract reasoning in Parkinson's disease: a pilot study.

BACKGROUND: Pupillary response reflects cognitive workload during processing speed, working memory, and arithmetic tasks in Parkinson's disease (PD). Abstract reasoning, a higher-order cognitive function that relates different objects, events, or thoughts in a similar manner, may also be compromised in PD. The aim of this study was to compare pupillary response as a measure of cognitive workload while completing a verbal abstract reasoning test between patients with PD and age-matched controls. METHODS: Nineteen non-demented individuals with PD (66.6 ± 8.9 years) and 10 healthy controls (65.3 ± 7.3 years) were recruited. A remote eye tracker recorded the pupillary response at 60 Hz, while the participants were performing the Similarities test of Wechsler Adult Intelligence Scale-IV. Outcome measures included pupillary response, evaluated by the Index of Cognitive Activity (ICA), and behavioral responses of the Similarities test. RESULTS: The PD group (scaled scores = 8.9 ± 2.2) did not show impairment in behavioral performance on Similarities test compared with healthy controls (scaled scores = 8.8 ± 2.3; p = .91). However, the PD group (ICA = .32 ± .09) demonstrated significantly greater cognitive workload during the Similarities test compared to controls (ICA = .24 ± .08; p = .03). CONCLUSIONS: Non-demented individuals with PD exerted greater cognitive workload to complete a verbal abstract reasoning task despite similar behavioral performance compared to healthy controls. Clinical utilities of pupillary response to detect and monitor early impairment in higher-order executive function will be the subject of further study in the PD population.

Classification of Parkinson's disease and essential tremor based on balance and gait characteristics from wearable motion sensors via machine learning techniques: a data-driven approach.

BACKGROUND: Parkinson's disease (PD) and essential tremor (ET) are movement disorders that can have similar clinical characteristics including tremor and gait difficulty. These disorders can be misdiagnosed leading to delay in appropriate treatment. The aim of the study was to determine whether balance and gait variables obtained with wearable inertial motion sensors can be utilized to differentiate between PD and ET using machine learning. Additionally, we compared classification performances of several machine learning models. METHODS: This retrospective study included balance and gait variables collected during the instrumented stand and walk test from people with PD (n = 524) and with ET (n = 43). Performance of several machine learning techniques including neural networks, support vector machine, k-nearest neighbor, decision tree, random forest, and gradient boosting, were compared with a dummy model or logistic regression using F1-scores. RESULTS: Machine learning models classified PD and ET based on balance and gait characteristics better than the dummy model (F1-score = 0.48) or logistic regression (F1-score = 0.53). The highest F1-score was 0.61 of neural network, followed by 0.59 of gradient boosting, 0.56 of random forest, 0.55 of support vector machine, 0.53 of decision tree, and 0.49 of k-nearest neighbor. CONCLUSIONS: This study demonstrated the utility of machine learning models to classify different movement disorders based on balance and gait characteristics collected from wearable sensors. Future studies using a well-balanced data set are needed to confirm the potential clinical utility of machine learning models to discern between PD and ET.

Determinants of On-Road Driving in Multiple Sclerosis.

OBJECTIVE: To investigate the cognitive, visual, and motor deficits underlying poor performance on different dimensions of on-road driving in individuals with multiple sclerosis (MS). DESIGN: Prospective cross-sectional study. SETTING: MS clinic and driving simulator lab. PARTICIPANTS: Active drivers (N=102) with various types of MS. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Off-road cognitive, visual, and motor functions, as well as 13 specific driving skills. These skills were categorized into hierarchic clusters of operational, tactical, visuo-integrative, and mixed driving. Stepwise regression analysis was used to determine the off-road functions influencing performance on the on-road test and each cluster. RESULTS: Visuospatial function (P=.002), inhibition (P=.008), binocular acuity (P=.04), vertical visual field (P=.02), and stereopsis (P=.03) best determined variance in total on-road score (unadjusted R2=.37). Attentional shift (P=.0004), stereopsis (P=.007), glare recovery (P=.047), and use of assistive devices (P=.03) best predicted the operational cluster (unadjusted R2=.28). Visuospatial function (P=.002), inhibition (P=.002), reasoning (P=.003), binocular acuity (P=.04), and stereopsis (P=.005) best determined the tactical cluster (unadjusted R2=.41). The visuo-integrative model (unadjusted R2=.12) comprised binocular acuity (P=.007) and stereopsis (P=.045). Inhibition (P=.0001) and binocular acuity (P=.001) provided the best model of the mixed cluster (unadjusted R2=.25). CONCLUSIONS: Our results provide more insights into the specific impairments that influence different dimensions of on-road driving and may be used as a framework for targeted driving intervention programs in MS.

Left ventricular hypertrophy in acute stroke patients with known hypertension.

BACKGROUND: Despite effective treatments, hypertension remains uncontrolled in nearly half of the people with hypertension in the United States. Uncontrolled hypertension leads to end organ damage, such as left ventricular hypertrophy (LVH). To identify reasons for uncontrolled hypertension, we interviewed acute stroke patients with a history of hypertension and evaluated for LVH. METHODS: Using a standardized questionnaire, we collected demographic, socioeconomic, and health-care data in 300 acute ischemic and hemorrhagic stroke patients in one hospital. We also collected relevant clinical data from medical records. We analyzed factors associated with echocardiographic LVH as a marker of uncontrolled hypertension in 190 acute stroke patients with a history of hypertension. RESULTS: Overall, 46% (88/190) of patients had LVH. In univariate analysis, lower household income and self-reported poor adherence to hypertension treatment were significantly associated with increased risk of LVH. In multiple logit modeling, only poor adherence to hypertension treatment remained significantly associated with LVH, odds ratio 1.77 (95% CI: 1.01-3.11), p < 0.05. CONCLUSIONS: In acute stroke patients, poor adherence to hypertension treatment is a significant independent predictor of LVH. A clear reason for poor adherence to treatment is elusive in a large proportion of these patients in our study. Further research is needed to identify and develop strategies to combat the key factors responsible for poor adherence to hypertension treatment.

Use of a driving simulator to improve on-road driving performance and cognition in persons with Parkinson's disease: A pilot study.

BACKGROUND/AIM: The use of simulators as an assessment and intervention tool for driving is an emerging field in occupational therapy. We investigated the potential usefulness of a driving simulator to improve on-road skills and cognitive functions in drivers with Parkinson's disease (PD). METHOD: Fifteen participants with PD, and Hoehn and Yahr stages between 2 and 3 participated in this pre-post comparison study. Twelve of the 15 individuals (median age (Q1-Q3), 68 (63.5-72.5); 10 men) completed 10 hours of training in a high-fidelity driving simulator. A practical road test as well as off-road cognitive and simulator tests were administered at pre-training and post-training. RESULTS: Nine participants, who passed the road test before training, passed at post-training. Furthermore, all three participants who initially failed the on-road test passed after training. Participants' performance improved significantly from pre- to post-training on two cognitive tests: (i) the Montreal Cognitive Assessment and (ii) Dot Cancellation test. CONCLUSION: This pilot study demonstrates the potential usefulness of a simulator to improve on-road driving and driving-related cognitive skills in PD. Adequately powered randomized controlled trials are needed to further expand this field of study.

On-road driving impairments and associated cognitive deficits after stroke.

BACKGROUND: Little is known about the critical on-road driving skills that get affected after a stroke. The purpose of this study was to investigate the key on-road driving impairments and their associated cognitive deficits after a stroke. A second aim was to investigate if lateralization of stroke impacts results of the cognitive and on-road driving tests. METHODS: In this cross-sectional study, 99 participants with a first-ever stroke who were actively driving prior to stroke underwent a cognitive battery and a standardized road test that evaluated 13 specific on-road driving skills. These on-road driving skills were mapped onto an existing, theoretical framework that categorized the on-road items into hierarchic clusters of operational, tactical, visuo-integrative, and mixed driving skills. The total score on the road test and the on-road decision, made by a certified fitness-to-drive expert, decided the main outcome. The critical on-road driving skills predicting the on-road decision were identified using logistic regression analysis. Linear regression analysis was employed to determine the cognitive impairments leading to poor total on-road scores. Analyses were repeated for right- and left-sided strokes. RESULTS: In all, 37 persons scored poorly on the road test. These participants performed worse in all hierarchic clusters of on-road driving. Performances on the operational cluster and the visuo-integrative cluster best predicted on-road decisions (R(2) = 0.60). 'Lane changing' and 'understanding, insight, and quality of traffic participation' were the critical skill deficits leading to poor performance on the road test (R(2) = 0.65). Divided attention was the main determinant of on-road scores in the total group (R(2) = 0.06). Participants with right-sided stroke performed worse on visual field, visual neglect, visual scanning, visuo-constructive skills, and divided attention compared with those with left-sided stroke. Divided attention was the main determinant of total on-road scores in the right-sided stroke group (R(2) = 0.10). A combination of visual scanning, speed of processing, and executive dysfunction yielded the best model to predict on-road scores in left-sided strokes (R(2) = 0.46). CONCLUSIONS: Poor performance in the road test after stroke is determined by critical operational and visuo-integrative driving impairments. Specific and different driving evaluation and training programs are needed for right- and left-sided strokes.

Driving and off-road impairments underlying failure on road testing in Parkinson's disease.

Parkinson's disease (PD) affects driving ability. We aimed to determine the most critical impairments in specific road skills and in clinical characteristics leading to failure on a road test in PD. In this cross-sectional study, certified driving assessment experts evaluated specific driving skills in 104 active, licensed drivers with PD using a standardized, on-road checklist and issued a global decision of pass/fail. Participants also completed an off-road evaluation assessing demographic features, disease characteristics, motor function, vision, and cognition. The most important driving skills and off-road predictors of the pass/fail outcome were identified using multivariate stepwise regression analyses. Eighty-six (65%) passed and 36 (35%) failed the on-road driving evaluation. Persons who failed performed worse on all on-road items. When adjusted for age and gender, poor performances on lateral positioning at low speed, speed adaptations at high speed, and left turning maneuvers yielded the best model that determined the pass/fail decision (R(2) = 0.56). The fail group performed poorer on all motor, visual, and cognitive tests. Measures of visual scanning, motor severity, PD subtype, visual acuity, executive functions, and divided attention were independent predictors of pass/fail decisions in the multivariate model (R(2) = 0.60). Our study demonstrated that failure on a road test in PD is determined by impairments in specific driving skills and associated with deficits in motor, visual, executive, and visuospatial functions. These findings point to specific driving and off-road impairments that can be targeted in multimodal rehabilitation programs for drivers with PD.

Simplified modified Rankin Scale questionnaire correlates with stroke severity.

OBJECTIVE: To further validate the simplified modified Rankin Scale questionnaire (smRSq), we compare it here to a well-established predictor of functional outcome after stroke, the initial stroke severity. DESIGN: Retrospective correlation analysis. PARTICIPANTS: Forty patients identified from a registry of stroke patients treated with intravenous tissue plasminogen activator. SETTING: Community and 17 hospital Emergency Departments within a web-based telestroke network throughout the state of Georgia, USA. MEASURES: Five certified raters assessed the initial stroke severities with the National Institutes of Health Stroke Scale (NIHSS) via the telestroke system. Over a 20 month period, one certified rater, unaware of the NIHSS scores, attempted to contact each patient in the registry to assess their functional outcomes with the smRSq via telephone. We analyzed patients who had the smRSq assessment at least three months after stroke. RESULTS: Forty of 120 registered patients were contacted and qualified for this study. The baseline clinical characteristics of the 40 analyzed and the 80 disqualified patients were similar. The correlation between the initial NIHSS and the smRSq was good (r = 0.69, R(2) = 0.47, P < 0.001). CONCLUSIONS: The good correlation of the smRSq with the initial stroke severity further confirms the smRSq validity in assessing functional outcome after stroke.

Stroke size correlates with functional outcome on the simplified modified Rankin Scale questionnaire.

BACKGROUND: Acute stroke size is one of the factors impacting functional outcome. To further validate the simplified modified Rankin Scale questionnaire (smRSq), we tested its correlation with stroke size. METHODS: We screened 60 ischemic stroke patients with acute brain images available for stroke volume measurement who were enrolled in 2 smRSq reliability studies. Inclusion criteria were acute ischemic stroke visible on computed tomography (CT) or magnetic resonance imaging (MRI) and the smRSq scored at least 3 months after stroke. We excluded patients with disabilities from a previous stroke. One investigator who was blinded to the functional outcomes measured stroke volumes with a specialized computer program (Analyze). We used MRI when both MRI and CT were available. We classified strokes into 2 size categories: lacunar type measuring ≤ 6.28 cm(3), which corresponds to a cylinder with a maximum diameter and height of 2.00 cm, or strokes >6.28 cm(3). The Spearman correlation analysis compared the smRSq between the lacunar type and the larger strokes. RESULTS: Thirty-two patients qualified for this analysis with a mean age of 59 ± 15 years, and 17 (53%) were men. Lacunar stroke volumes (n = 17) ranged from 0.03 to 4.58 cm(3), and the larger stroke volumes (n = 15) ranged from 11.52 to 250.02 cm(3). Lacunar strokes were associated with lower smRSq scores (median 1) than the larger strokes (median 4; r = 0.68; R(2) = 0.46; P < .001). CONCLUSIONS: Acute stroke size correlates well with the smRSq, supporting its validity in assessing functional outcome after stroke.

Association Between Frailty and Free-Living Walking Performance in People With Multiple Sclerosis.

OBJECTIVE: The purpose of this study was to examine the association between frailty and the quantity and quality of free-living walking and the mediating effect of frailty on the relationship between disability and walking performance in people with multiple sclerosis (MS). METHODS: Ninety-nine people with relapsing-remitting MS (mean age = 49.3 [SD = 9.8] years; 73.7% women; Expanded Disability Status Scale [EDSS] score range = 2.0-6.0) wore a triaxial accelerometer for 7 days. Recorded measures reflected the quantity (daily step counts, number of 30-second walking bouts, and signal vector magnitude [SVM]) and quality (gait speed, step cadence, step and stride regularity, and sample entropy) of walking. For each walking quality measure, the typical (median), best (90th percentile), and worst (10th percentile) values were calculated. Frailty was evaluated through a 38-item frailty index. RESULTS: Participants were classified as not frail (n = 31), moderately frail (n = 34), and severely frail (n = 34) on the basis of established procedures. Patients who were moderately and severely frail exhibited poorer performance in all measures of walking quantity and quality, except for sample entropy, than individuals who were not frail. No differences in free-living walking performance were observed between the moderately and severely frail groups. Frailty did not mediate the relationship between disability (EDSS) and measures of walking quality. Conversely, frailty had a significant mediating effect on the relationship between disability and measures of walking quantity, such as daily step counts (indirect effect: b = -220.42, 95% CI = -452.03 to -19.65) and SVM (indirect effect: b = -1.00, 95% CI = -1.86 to -0.30). CONCLUSION: Frailty is associated with poorer free-living walking performance in people with MS. The study findings suggest that frailty, rather than disability, may be primarily responsible for the lower amount of physical activity performed by people with MS in the real world. IMPACT: The observation that frailty and disability are differently related to measures of walking quality and quantity underscores the importance of a targeted approach to rehabilitation in people with MS.

Measured neurological improvements correlate with self-perceived improvements after stroke.

BACKGROUND: Important advantages of neurologic impairment scales after stroke include measurements of within-subject changes over time starting at baseline. We compared percent improvement on the National Institutes of Health stroke scale (NIHSS) to stroke outcome that seems tangible to patients and caregivers: their perceived percent improvement. METHODS: We prospectively measured improvement on the NIHSS between baseline and 3 to 6 months in consecutive patients with acute stroke presenting within 48 hours after onset. Unaware of the measured result, patients and caregivers were asked to estimate their perceived overall improvement since baseline assessment at the time of enrollment. We excluded patients with baseline NIHSS <3, clear improvement before screening, coma, brain herniation, or intraventricular hemorrhage. RESULTS: Of 40 enrolled patients, 9 died, 5 could not return for reevaluation, and the remaining 26 were reevaluated and analyzed. Median time from stroke onset to enrollment was 19.5 hours (range 2-45) and the median baseline NIHSS score was 8 (range 3-31). The measured improvements on the NIHSS ranged between 12.5% and 100% and correlated moderately (Spearman rank coefficient 0.54) and significantly (P = .005) with the patient- and caregiver-perceived percent improvement. CONCLUSIONS: Percent improvement on the NIHSS after stroke correlates moderately and significantly with patient and caregiver perceived overall improvement and appears to be a useful addition to the current functional outcome measures.

Simplified modified rankin scale questionnaire: reproducibility over the telephone and validation with quality of life.

BACKGROUND AND PURPOSE: The simplified modified Rankin Scale questionnaire (smRSq) enables a reliable and rapid determination of the modified Rankin Scale score after stroke. We test the reliability and validity of a slightly revised smRSq. METHODS: Fifty consecutive outpatients 4.83 ± 3.00 months after stroke were scored with a slightly revised smRSq by 3 raters selected consecutively from a list of 10: 4 stroke faculty, 3 neurology residents, 2 medial students, and 1 stroke research coordinator. Two ratings were in person within 20 minutes of each other and 1 was by telephone 1 to 3 days later. The telephone rating also included a quality of life scale, the Short-Form-12v2. Each rater was blinded to the other raters' scores. RESULTS: The average estimated time to administer the smRSq was 1.29 minutes (range, 0.50 to 2.25 minutes). The in-person raters agreed 78% (κ=0.71; CI, 0.57 to 0.86 and weighted κ [κ(w)]=0.86; CI, 0.79 to 0.94). The first in-person and telephone raters agreed 82% (κ=0.76; CI, 0.63 to 0.90 and κ(w)=0.87; CI, 0.79 to 0.95). The second in-person and telephone rates agreed 82% (κ=0.77; CI, 0.63 to 0.90 and κ(w)=0.89; CI, 0.82 to 0.96). The smRSq correlated with the physical (r=-0.50, P=0.005) than the mental (r=-0.36, P=0.048) components of the Short-Form-12v2. CONCLUSIONS: The slightly revised smRSq appears to be useful in clinical stroke; it has excellent reliability in person and by telephone, can usually be administered in <1.5 minutes by a wide variety of raters, and correlates with quality of life.

Proof-of-Concept of the Virtual Reality Comprehensive Balance Assessment and Training for Sensory Organization of Dynamic Postural Control.

Accurate quantification of the impact of visual, somatosensory, and vestibular systems on postural control may inform tailor-made balance intervention strategies. The aim of this proof-of-concept study was to determine the safety, sense of presence, system usability, and face validity of a newly developed Virtual Reality Comprehensive Balance Assessment and Training (VR-ComBAT) in healthy young individuals. The VR-ComBAT included six balance condition: (1) stable surface with fixed virtual reality (VR) surroundings; (2) stable surface with blacked out VR surroundings; (3) stable surface with VR visual conflict; (4) unstable surface with fixed VR surroundings; (5) unstable surface with blacked out VR surroundings; and (6) unstable surface with VR visual conflict. Safety was evaluated using the number of adverse events, including scores on the Simulator Sickness Questionnaire. Sense of presence was evaluated using the igroup Presence Questionnaire (iPQ). System usability was assessed using the Systems Usability Scale (SUS). Friedman analyses with post hoc Wilcoxon Signed Rank tests were employed to demonstrate face validity by quantifying center of pressure (COP) changes in mean distance, mean velocity, and mean frequency in the anteroposterior (AP) and mediolateral (ML) direction across the six conditions. Twenty-three participants (27.4 ± 8.0 years old; 13 women) reported no adverse events. Participants scores on average 44.9 ± 9.6 on the iPQ and 79.7 ± 9.9 on the SUS. Post hoc analyses showed significant changes in COP-based measures when compared to baseline. The mean frequency change of COP showed direction-dependence in which increased frequency change in AP was observed while decreased change in ML was noted. The VR-ComBAT provides a safe, feasible, and cost-effective VR environment that demonstrates consistent sensory re-weighting between visual, somatosensory, and vestibular systems. Future studies should investigate whether VR-ComBAT can be used to inform precision rehabilitation of balance and fall prevention in older adults without and with neurological conditions.

Pupillary Response to Postural Demand in Parkinson's Disease.

Background: Individuals with Parkinson's disease (PD) may need to spend more mental and physical effort (i.e., cognitive workload) to maintain postural control. Pupillary response reflects cognitive workload during postural control tasks in healthy controls but has not been investigated as a measure of postural demand in PD. Objectives: To compare pupillary response during increased postural demand using vision occlusion and dual tasking between individuals with PD and healthy controls. Methods: Thirty-three individuals with PD and thirty-five healthy controls were recruited. The four conditions lasted 60 s and involved single balance task with eyes open; single balance task with eyes occluded; dual task with eyes open; dual task with eyes occluded. The dual task comprised the Auditory Stroop test. Pupillary response was recorded using an eye tracker. The balance was assessed by using a force plate. Two-way Repeated Measures ANOVA and LSD post-hoc tests were employed to compare pupillary response and Center of Pressure (CoP) displacement across the four conditions and between individuals with PD and healthy controls. Results: Pupillary response was higher in individuals with PD compared to healthy controls (p = 0.009) and increased with more challenging postural conditions in both groups (p < 0.001). The post-hoc analysis demonstrated increased pupillary response in the single balance eyes occluded (p < 0.001), dual task eyes open (p = 0.01), and dual task eyes occluded (p < 0.001) conditions compared to single task eyes open condition. Conclusion: Overall, the PD group had increased pupillary response with increased postural demand compared to the healthy controls. In the future, pupillary response can be a potential tool to understand the neurophysiological underpinnings of falls risk in the PD population.

Real-time assessment of daytime sleepiness in drivers with multiple sclerosis.

BACKGROUND: Daytime sleepiness is a common symptom of multiple sclerosis (MS) that may jeopardize safe driving. Our aim was to compare daytime sleepiness, recorded in real-time through eyelid tracking, in a simulated drive between individuals with MS (iwMS) and healthy controls. METHODS: Fifteen iwMS (age = median (Q1 - Q3), 55 (50 - 55); EDSS = 2.5 (2 - 3.5); 12 (80%) female) were matched for age, sex, education, and cognitive status with 15 controls. Participants completed self-reported fatigue and sleepiness scales including the Modified Fatigue Impact Scale (MFIS), Pittsburg Sleep Quality Inventory (PSQI), and Epworth Sleepiness Scale (ESS). Percentage of eyelid closure (PERCLOS) was extracted from a remote eye tracker while completing a simulated drive of 25 min. RESULTS: Although iwMS reported more symptoms of fatigue (MFIS, p = 0.003) and poorer sleep quality (PSQI, p = 0.008), they did not report more daytime sleepiness (ESS, p = 0.45). Likewise, there were no differences between groups in real-time daytime sleepiness, indexed by PERCLOS (p = 0.82). Both groups exhibited more real-time daytime sleepiness as they progressed through the drive (time effect, p < 0.0001). The interaction effect of group*time (p = 0.05) demonstrated increased symptoms of daytime sleepiness towards the end of the drive in iwMS compared to controls. PERCLOS correlated strongly (Spearman ρ = 0.76, p = 0.001) with distance out of lane in iwMS. CONCLUSION: IwMS show exacerbated symptoms of daytime sleepiness during a monotonous, simulate drive. Future studies should investigate the effect of MS on daytime sleepiness during real-world driving.