Differential Associations of Mobility With Fronto-Striatal Integrity and Lesion Load in Older Adults With and Without Multiple Sclerosis

Perceived physical and mental fatigability in older adults with and without multiple sclerosis

BACKGROUND

Fatigue stands out as a prevalent and debilitating symptom in both Multiple Sclerosis (MS) and the aging population. Traditional methods for measuring perceived fatigue may not adequately account for individual activity differences, leading to varied prevalence rates. Perceived fatigability anchors fatigue to specific activities with predetermined intensity and duration, thereby mitigating self-pacing bias. Despite its potential, perceived fatigability is poorly understood in older adults, particularly those with neurological conditions, including MS. This study thus aimed to (1) investigate whether, among older adults, MS was associated with worse perceived physical and mental fatigability; (2) evaluate whether, among older adults with MS (OAMS), greater patient-reported disease-related disability was associated with worse perceived physical and mental fatigability.

METHODS

Participants were 96 older adults with a physician-confirmed diagnosis of MS (mean age: 64.6 ± 4.2) and 110 healthy controls (mean age: 68.2 ± 7.2), all confirmed to be dementia-free through established case conference procedures. Physical and mental fatigability were measured using the Pittsburgh Fatigability Scale, a 10-item questionnaire (score range: 0 to 50) designed to assess fatigue levels that individuals expect to feel after engaging in a range of typical activities for older adults. MS disease-related disability was assessed with the Patient Determined Disease Steps scale, which ranges from 0 (normal) to 8 (bedridden), with scores ≥ 2 indicating worse MS-related disability after a median split. Separate linear regression models were performed to investigate associations between group status (MS vs. Control) as the predictor and perceived physical and mental fatigability scores as the outcome variables. Within the MS group, additional linear regression models were performed to explore the relationship between disease-related disability and fatigability levels. All models adjusted for age, sex, race, education, global health, general cognitive function, and depressive symptoms levels.

RESULTS

The fully adjusted models yielded the following key findings: OAMS reported significantly higher levels of perceived physical fatigability (M = 25.11 ± 9.67) compared to controls (M = 17.95 ± 8.35) (p = 0.003). Similarly, the perceived mental fatigability in OAMS (M = 16.82 ± 11.79) was significantly greater than that in controls (M = 9.15 ± 7.12) (p = 0.003). Within the MS group, individuals with greater disease-related disability reported significantly greater levels of both physical (M = 30.13 ± 7.71 vs. 18.67 ± 8.00, p < 0.001) and mental fatigability (M = 20.31 ± 12.18 vs. 12.33 ± 9.69, p = 0.009) compared to those with lower MS-related disability. Of note, the significance of these findings persisted in models that adjusted for depressive symptoms.

CONCLUSION

Our study provides compelling evidence that OAMS exhibit significantly higher perceived physical and mental fatigability compared to healthy controls. Additionally, worse MS-related disability correlates with worse physical and mental fatigability. These results persist after adjusting for confounders including depressive symptoms. Our findings underscore the necessity of holistic management strategies that cater to both physical and psychological aspects of MS, laying a foundation for future studies to uncover the pathophysiological mechanisms of fatigability in older adults with and without MS.

Disability Moderates Dual Task Walking Performance and Neural Efficiency in Older Adults With Multiple Sclerosis

BACKGROUND

Mobility and cognitive impairment are prevalent and co-occurring in older adults with multiple sclerosis (OAMS), yet there is limited research concerning the role of disability status in the cognitive control of gait among OAMS.

OBJECTIVE

We investigated the levels of prefrontal cortex (PFC) activation, using oxygenated hemoglobin (HbO2), during cognitively-demanding tasks in OAMS with lower and higher disability using functional near-infrared spectroscopy (fNIRS) to: (1) identify PFC activation differences in single task walk and cognitively-demanding tasks in OAMS with different levels of disability; and (2) evaluate if disability may moderate practice-related changes in neural efficiency in OAMS.

METHODS

We gathered data from OAMS with lower (n = 51, age = 65 ± 4 years) or higher disability (n = 48, age = 65 ± 5 years), using a cutoff of 3 or more, in the Patient Determined Disease Steps, for higher disability, under 3 different conditions (single-task walk, Single-Task-Alpha, and Dual-Task-Walk [DTW]) administered over 3 counterbalanced, repeated trials.

RESULTS

OAMS who had a lower disability level exhibited decreased PFC activation levels during Single-Task-Walk (STW) and larger increases in PFC activation levels, when going from STW to a cognitively-demanding task, such as a DTW, than those with higher disability. OAMS with a lower disability level exhibited greater declines in PFC activation levels with additional within session practice than those with a higher disability level.

CONCLUSIONS

These findings suggest that disability moderates brain adaptability to cognitively-demanding tasks and demonstrate the potential for fNIRS-derived outcome measures to complement neurorehabilitation outcomes.

Initial validation of the university of Alabama Birmingham study of aging life-space assessment in older adults with multiple sclerosis

BACKGROUND

Older adults with multiple sclerosis (OAMS) have declines in walking and physical performance that may erode community mobility defined as the spatial extent of mobility in one's daily life and environment.

OBJECTIVE

This study provided the first application and validation of the University of Alabama Birmingham Study of Aging Life-Space Assessment (UAB LSA) as a measure of community mobility in OAMS.

METHODS

The sample included 97 OAMS and 108 healthy controls (HCs) who completed baseline assessments as part of an ongoing, longitudinal study. The primary assessments included the UAB LSA and timed 25-foot walk (T25FW), short physical performance battery (SPPB), global health score (GHS), and geriatric depression scale (GDS) in both OAMS and HCs, and patient determined disease steps (PDDS) scale in only OAMS.

RESULTS

OAMS had significantly lower UAB LSA scores than HCs (p < .001). UAB LSA scores had strong correlations with T25FW(rs = -.641) and SPPB(rs = 0.507) in OAMS, and moderate correlations in HCs (rs = -.300 & rs = 0.384). The correlations between UAB LSA and GHS and GDS scores were significant, but small in OAMS (rs = -.239 & rs = -.231), and not statistically significant in HCs (rs = -.009 & rs = -.166). There was a strong correlation between UAB LSA and PDDS scores in the OAMS sample (rs = -.605).

CONCLUSION

We provided initial evidence for UAB LSA scores as a measure of community mobility in OAMS.