Profiling cognitive-motor interference in a large sample of persons with progressive multiple sclerosis and impaired processing speed: results from the CogEx study.

BACKGROUND: Performing cognitive-motor dual tasks (DTs) may result in reduced walking speed and cognitive performance. The effect in persons with progressive multiple sclerosis (pwPMS) having cognitive dysfunction is unknown. OBJECTIVE: To profile DT-performance during walking in cognitively impaired pwPMS and examine DT-performance by disability level. METHODS: Secondary analyses were conducted on baseline data from the CogEx-study. Participants, enrolled with Symbol Digit Modalities Test 1.282 standard deviations below normative value, performed a cognitive single task ([ST], alternating alphabet), motor ST (walking) and DT (both). Outcomes were number of correct answers on the alternating alphabet task, walking speed, and DT-cost (DTC: decline in performance relative to the ST). Outcomes were compared between EDSS subgroups (≤ 4, 4.5-5.5, ≥ 6). Spearman correlations were conducted between the DTCmotor with clinical measures. Adjusted significance level was 0.01. RESULTS: Overall, participants (n = 307) walked slower and had fewer correct answers on the DT versus ST (both p < 0.001), with a DTCmotor of 15.8% and DTCcognitive of 2.7%. All three subgroups walked slower during the DT versus ST, with DTCmotor different from zero (p's < 0.001). Only the EDSS ≥ 6 group had fewer correct answers on the DT versus ST (p < 0.001), but the DTCcognitive did not differ from zero for any of the groups (p ≥ 0.039). CONCLUSION: Dual tasking substantially affects walking performance in cognitively impaired pwPMS, to a similar degree for EDSS subgroups.

Dual Task of Fine Motor Skill and Problem Solving in Individuals With Multiple Sclerosis: A Pilot Study.

OBJECTIVES: To (1) examine and compare dual-task performance in patients with multiple sclerosis (MS) and healthy controls (HCs) using mathematical problem-solving questions that included an everyday competence component while performing an upper extremity fine motor task; and (2) examine whether difficulties in dual-task performance are associated with problems in performing an everyday internet task. DESIGN: Pilot study, mixed-design with both a within and between subjects' factor. SETTING: A nonprofit rehabilitation research institution and the community. PARTICIPANTS: Participants (N=38) included persons with MS (n=19) and HCs (n=19) who were recruited from a nonprofit rehabilitation research institution and from the community. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Participant were presented with 2 testing conditions: (1) solving mathematical everyday problems or placing bolts into divots (single-task condition); and (2) solving problems while putting bolts into divots (dual-task condition). Additionally, participants were required to perform a test of everyday internet competence. RESULTS: As expected, dual-task performance was significantly worse than either of the single-task tasks (ie, number of bolts into divots or correct answers, and time to answer the questions). Cognitive but not motor dual-task cost was associated with worse performance in activities of everyday internet tasks. CONCLUSIONS: Cognitive dual-task cost is significantly associated with worse performance of everyday technology. This was not observed in the motor dual-task cost. The implications of dual-task costs on everyday activity are discussed.

Descriptive epidemiology of physical activity rates in multiple sclerosis.

BACKGROUND: Persons with multiple sclerosis (MS) engage in substantially less overall physical activity than healthy controls, but there is little information on public health rates of physical activity necessary for health benefits. PURPOSE: This study examined the rates of insufficient, moderate, and sufficient physical activity in persons with MS compared with healthy controls. METHOD: Secondary analysis of data from participants with MS (n = 1521) and healthy controls (n = 162) who completed the Godin Leisure-Time Exercise Questionnaire (GLTEQ) as part of a questionnaire battery in 14 previous investigations. RESULTS: There were statistically significant differences in overall GLTEQ scores (F1,1666 = 96.8, P < 0.001, d = 0.83) and rates of physical activity (χ(2) (2, N = 1683) = 94.2, P < 0.001) between MS and control groups. The rates of insufficient, moderate, and sufficient physical activity in the MS group were 58.0%, 15.2%, and 26.8%, respectively. Those with MS were 2.5 times more likely to report insufficient physical activity and 2.3 times less likely to report sufficient physical activity than controls. CONCLUSION: The majority of persons with MS were insufficiently physically active, and this segment represents the largest opportunity for successful behavior change and accumulation of associated health benefits.

Mobility and cognitive correlates of dual task cost of walking in persons with multiple sclerosis.

BACKGROUND: Persons with multiple sclerosis (MS) often experience a decrease in walking performance while simultaneously performing a cognitive task. This decrease in walking performance is termed dual task cost (DTC). OBJECTIVE: To examine if mobility and cognitive function are correlates of DTC in persons with MS. METHODS: Participants were 96 persons with MS who had Expanded Disability Status Scale scores that ranged between 2.0 and 6.5. To determine DTC, participants walked at a self-selected pace with and without a cognitive task while gait velocity was recorded. The effect of the cognitive task was quantified as the percent change in walking velocity between conditions. Participants further completed the timed 25-foot walk (T25FW) and Symbol Digit Modalities Test (SDMT). Centered scores for the T25FW and SDMT, and the product of the center scores, were placed into a linear regression to determine the correlates of DTC. RESULTS: DTC averaged 12.5% (SD = 9.3) and ranged between -14.1 and 42.4%. Performance on the T25FW ranged between 3.1 and 24.5 s with an average of 6.8 s (SD = 3.1 s). SDMT scores ranged between 15 and 79 with an average of 45 items (SD = 12). Regression analysis revealed that age, disability, walking and cognitive performance explained 17% of the variance in DTC. The interaction between walking and cognition did not explain additional variance. CONCLUSIONS: Mobility and cognitive impairment were both independent predictors of DTC of walking in persons with MS. This raises the possibility that DTC could be reduced with modifications of either mobility or cognition.

Randomized controlled trial of a behavioral intervention targeting symptoms and physical activity in multiple sclerosis.

BACKGROUND: Exercise training is beneficial, but most persons with multiple sclerosis (MS) are sedentary and physically inactive. This has prompted a new focus on the promotion of lifestyle physical activity in MS. We previously designed, tested, and refined a behavioral intervention delivered through the Internet that successfully increased lifestyle physical activity in MS, but have not evaluated the effects on secondary symptomatic and health-related quality of life (HRQOL) outcomes. OBJECTIVE: We conducted a 6-month randomized controlled trial (RCT) that examined the efficacy of an Internet-delivered, behavioral intervention for improving outcomes of fatigue, depression, anxiety, pain, sleep quality, and HRQOL in 82 ambulatory persons with MS. The secondary aim was to replicate previous results regarding change in free-living physical activity. RESULTS: There was a significant and positive effect of the intervention on fatigue severity (p=.001, η ρ (2)=.15) and its physical impact (p=.008, η ρ (2)=.09), depression (p=.006, η ρ (2)=.10), and anxiety (p=.006, η ρ (2)=.10). There were non-significant improvements in pain (p=.08, η ρ (2)=.04), sleep quality (p=.06, η ρ (2)=.05), and physical HRQOL (p=.06, η ρ (2)=.05). We replicated our previous results by demonstrating an increase in self-reported physical activity (p=.001, η ρ (2)=.13). CONCLUSIONS: Our results support behavioral interventions targeting lifestyle physical activity as an alternative approach for managing symptoms in MS.

Psychometric properties of the Fatigue Severity Scale and the Modified Fatigue Impact Scale.

OBJECTIVE: Fatigue is one of the most common, debilitating and life altering symptoms experienced by those with multiple sclerosis (MS) and has become the focus of therapeutic interventions and clinical rehabilitation. There is limited evidence regarding the psychometric properties and clinical relevance of fatigue outcomes for interpreting the effectiveness of intervention and rehabilitation strategies. This study determined the reliability, precision and clinically important change of the uni-dimensional Fatigue Severity Scale (FSS) and the multi-dimensional Modified Fatigue Impact Scale (MFIS). METHODS: The FSS and MFIS along with physical, psychological and cognitive clinical outcomes were administered to a sample of 82 persons with MS in a clinical research setting on two time points, separated by six months. Intraclass correlation coefficient (ICC) analyses established reliability; standard error of measurement (SEM) and coefficient of variation (CV) determined precision; minimal detectable change (MDC) defined clinically important change. RESULTS: Participants varied in type of MS and disability status, with 77% of participants classified as having substantial fatigue, based on the criteria of a mean FSS score ≥4. The MFIS (ICC=0.863) and the FSS (ICC=0.751) had acceptable reliability over six months. Precision was reasonable for both scales (based on SEM and CV estimates) but better for the FSS. MDC estimates were established and were lower for the FSS. CONCLUSION: Reliability of the FSS and MFIS falls within acceptable ranges, and precision and clinically important change estimates provide guidelines for interpreting change in scores from these outcomes in clinical research of intervention and rehabilitation approaches for managing fatigue.

Symptomatic correlates of six-minute walk performance in persons with multiple sclerosis.

BACKGROUND: The six-minute walk (6MW) test has been identified as a valid, reliable, and reproducible measure of endurance walking performance that differentiates persons with multiple sclerosis (MS) and controls and correlates with disability and walking impairment. AIM: This study examined symptoms of fatigue, pain, and depression as correlates of 6MW performance and the possibility that such symptoms would account for the difference in 6MW distance between persons with MS and controls. DESIGN: Observational. SETTING: Research laboratory. POPULATION: Sixty-six persons, 33 with MS and 33 controls matched on age, sex, height, and weight. METHODS. Participants completed the fatigue severity scale (FSS), short-form of the McGill pain questionnaire (SF-MPQ), and depression items of the hospital anxiety and depression scale (HADS-D) and then performed the six-minute walk (6MW) in a rectangular corridor. RESULTS: There were statistically significant differences between groups in 6MW distance (p = 0.0001) and FSS (P=0.0001) and SF-MPQ (P=0.025), but not HADS-D (P>0.05), scores. 6MW distance was significantly correlated with FSS (P=-0.66), SF-MPQ (P=-0.38), and HADS-D (P=-0.33) scores in the overall sample, but 6MW distance was significantly correlated with only FSS scores in the separate samples of those with MS (P=-0.46) and controls (P=-0.46). Only group (ß=0.32) and FSS scores (ß=-0.53) explained variance in overall 6MW distance in a hierarchical, linear regression analysis. CONCLUSION: This study provides new insight into the symptomatic correlates of 6MW performance and identifies fatigue as a possible target of interventions designed to improve walking endurance in MS. CLINICAL REHABILITATION IMPACT: Clinicians and practitioners might consider targeting fatigue as a method of managing compromised endurance walking in persons with MS.

The dynamics of finger tremor in multiple sclerosis is affected by whole body position.

Multiple sclerosis (MS) is a disease that results in widespread damage to the nervous system. One consequence of this disease is the emergence of enhanced tremor. This study was designed to (1) compare the tremor responses of persons with MS to that of healthy adults and to (2) examine the impact of whole body position (i.e., seated/standing) on tremor. Bilateral postural tremor was recorded using accelerometers attached to each index finger. Results revealed some similarity of tremor between groups in regard to the principal features (e.g., presence of peaks in similar frequency ranges). However, significant differences were observed with tremor for the MS persons being of greater amplitude, more regular (lower ApEn) and more strongly coupled across limbs compared to the elderly. The effects of body position were consistent across all subjects, with tremor increasing significantly from sitting-to-standing. However, the tremor increase for the MS group was greater than the elderly. Overall, the tremor for MS group was negatively affected by both this disease process and the nature of the task being performed. This latter result indicates that tremor does not simply reflect the feed-forward output of the neuromotor system but that it is influenced by the task constraints.

Accelerometry as a measure of walking behavior in multiple sclerosis.

OBJECTIVE: Accelerometry has been identified as a possible ecologically valid and objective approach for measuring community ambulation in multiple sclerosis (MS). This study provides a validation of accelerometer output based on associations with Expanded Disability Status Scale (EDSS), Patient Determined Disease Steps (PDDS) Scale, and Multiple Sclerosis Walking Scale-12 (MSWS-12) scores, timed 25-foot walk (T25FW) and 6-min walk (6MW) performance, oxygen cost (O(2) cost) of walking, and spatial and temporal parameters of gait. MATERIALS AND METHODS: 256 persons with MS completed the PDDS and MSWS-12, underwent an examination for the generation of an EDSS score, undertook two T25FW tests and a 6MW while wearing a portable metabolic unit for measuring the O(2) cost of walking, completed two trials of comfortable walking on a GAITRite electronic walkway for measuring spatial and temporal parameters of gait, and then wore an Actigraph accelerometer during the waking hours of a 7-day period. RESULTS: The accelerometer output was significantly correlated with EDSS (ρ = -0.522), PDDS (ρ = -0.551), and MSWS-12 (ρ = -0.617) scores, T25FW (ρ = -0.595) and 6MW (ρ = 0.630) performance, and O(2) cost of walking (ρ = -0.457). Regarding gait parameters, the accelerometer output was significantly correlated with velocity (ρ = 0.420), cadence (ρ = 0.349), step time (ρ = -0.353), step length (ρ = 0.395), double support (ρ = -0.424), and single support (ρ = 0.400). CONCLUSION: We provide comprehensive evidence from a large sample of persons with MS that further supports accelerometry as a measure of walking behavior.

Falls and physical activity in persons with multiple sclerosis.

Objectives. To examine the association between fall history and physical activity using an objective measure of physical activity (i.e., accelerometry) in persons with multiple sclerosis. Design. A community-based sample of 75 ambulatory persons with multiple sclerosis volunteered for the investigation. Participants self-reported fall history in the last year, underwent a neurological exam to determine Expanded Disability Status Scale (EDSS) score, and wore an accelerometer around the waist for 7 consecutive days to determine physical activity. Results. Overall, 37 persons (49.3% of the sample) reported falling in the last year with 28 of the 37 falling more than once. Persons who fell in the last year had a significantly lower number of steps/day than nonfallers (3510 versus 4940 steps/day; P < .05). However, when controlling for disability status there was no statistically significant difference between fallers and nonfallers (4092 versus 4373 steps/day; P > .05). Conclusions. Collectively, the findings suggest that fall history may have little impact on current physical activity levels in persons with multiple sclerosis.

Physical activity and multiple sclerosis: new insights regarding inactivity.

OBJECTIVES: There is increasing recognition that physical activity has beneficial consequences among persons with multiple sclerosis (MS), but there is concern regarding the current degree of physical inactivity in this population because of limitations with previous research and increased recognition of health behaviors in MS. This study compared physical activity levels between large samples of persons with mild MS and matched controls using validated measures of physical activity. MATERIALS AND METHODS: The sample included 77 cases of MS and 77 controls matched on age, height, weight, and gender. Physical activity was assessed using five measures, namely the Godin Leisure-Time Exercise Questionnaire (GLTEQ), International Physical Activity Questionnaire (IPAQ), and activity counts per day, step counts per day, and time spent in moderate-to-vigorous physical activity (MVPA) per day by accelerometry. RESULTS: There were statistically significant differences between groups in accelerometer activity counts (t = -3.87, P = 0.0001), accelerometer step counts (t = -4.29, P = 0.0001), time spent in MVPA (t = -2.39, P = 0.01), GLTEQ scores (t = -3.83, P = 0.0001), and IPAQ scores (t = -3.42, P = 0.0001). The average effect size across all five measures was d = -0.59 and indicated that persons with MS overall were moderately less physically active than the matched controls. CONCLUSIONS: The primary finding was a moderate reduction in physical activity among those with MS, but the magnitude was substantially smaller than reported in a published meta-analysis. Importantly, the degree of physical inactivity can likely be overcome through the delivery of behavioral interventions for increasing physical activity and this should translate into meaningful consequences for persons with MS.