Acute effects of aerobic exercise on corticomotor plasticity in individuals with and without depression.

BACKGROUND: Although complex in nature, the pathophysiology of depression involves reduced or impaired neuroplastic capabilities. Restoring or enhancing neuroplasticity may serve as a treatment target for developing therapies for depression. Aerobic exercise (AEx) has antidepressant benefits and may enhance neuroplasticity in depression although the latter has yet to be substantiated. Therefore, we sought to examine the acute effect of AEx on neuroplasticity in depression. METHODS: Sixteen individuals with (DEP; 13 female; age = 28.5 ± 7.3; Montgomery-Äsberg Depression Rating Scale [MADRS] = 21.3 ± 5.2) and without depression (HC; 13 female; age 27.2 ± 7.5; MADRS = 0.8 ± 1.2) completed three experimental visits consisting of 15 min of low intensity AEx (LO) at 35% heart rate reserve (HRR), high intensity AEx (HI) at 70% HRR, or sitting (CON). Following AEx, excitatory paired associative stimulation (PAS25ms) was employed to probe neuroplasticity. Motor evoked potentials (MEP) were assessed via transcranial magnetic stimulation before and after PAS25ms to indicate acute changes in neuroplasticity. RESULTS: PAS25ms primed with HI AEx led to significant increases in MEP amplitude compared to LO and CON. HI AEx elicited enhanced PAS25ms-induced neuroplasticity for up to 1-h post-PAS. There were no significant between-group differences. CONCLUSION: HI AEx enhances PAS measured neuroplasticity in individuals with and without depression. HI AEx may have a potent influence on the brain and serve as an effective primer, or adjunct, to therapies that seek to harness neuroplasticity.

Relative handgrip strength as a vitality measure in US stroke survivors.

PURPOSE: Stroke is a leading cause of long-term disability in the US, yet a feasible assessment measure with predictive value for components of the International Classification of Functioning, Disability, and Health (ICF) Core Set for Stroke is lacking. The purpose of the present study was to explore the predictive value of potential assessment measures on factors within each ICF component in stroke survivors. MATERIALS AND METHODS: Demographic, anthropometric, blood-based biomarker, physical functioning, and Global Physical Activity Questionnaire data were collected on stroke survivors in the 2011-2018 NHANES cycles. Potential predictors (handgrip strength relative to weight, age, sex, race, education level, marital status, poverty ratio, stroke chronicity) of physical function, activities of daily living (ADLs), participation in social activities, metabolic syndrome, and meeting physical activity recommendations were evaluated using weighted linear and ordinal logistic regression. RESULTS: Relative handgrip strength was a significant predictor of physical function, difficulty participating in ADLs and social activities, and odds of meeting physical activity recommendations. As relative handgrip strength increased, these factors improved among stroke survivors. CONCLUSIONS: To decrease disability rates and optimize function among stroke survivors, the use of assessment measures like relative handgrip strength that may predict multiple ICF components is warranted.

Handgrip strength relative to weight may be a significant predictor of multiple components of the International Classification of Functioning, Disability, and Health (ICF) Core Set for Stroke, including physical function, difficulty completing activities of daily living, difficulty participating in social activities, and the odds of meeting physical activity recommendations.Environmental and personal factors, such as income and education, may influence outcomes; thus, education and appropriate resources may need to be included as an aspect of stroke rehabilitation.The heterogenous and pervasive effects of chronic stroke highlight the need to identify outcome measures, like relative handgrip strength, that can influence multiple domains of stroke recovery.

Association of Brain Age, Lesion Volume, and Functional Outcome in Patients With Stroke.

BACKGROUND AND OBJECTIVES: Functional outcomes after stroke are strongly related to focal injury measures. However, the role of global brain health is less clear. In this study, we examined the impact of brain age, a measure of neurobiological aging derived from whole-brain structural neuroimaging, on poststroke outcomes, with a focus on sensorimotor performance. We hypothesized that more lesion damage would result in older brain age, which would in turn be associated with poorer outcomes. Related, we expected that brain age would mediate the relationship between lesion damage and outcomes. Finally, we hypothesized that structural brain resilience, which we define in the context of stroke as younger brain age given matched lesion damage, would differentiate people with good vs poor outcomes. METHODS: We conducted a cross-sectional observational study using a multisite dataset of 3-dimensional brain structural MRIs and clinical measures from the ENIGMA Stroke Recovery. Brain age was calculated from 77 neuroanatomical features using a ridge regression model trained and validated on 4,314 healthy controls. We performed a 3-step mediation analysis with robust mixed-effects linear regression models to examine relationships between brain age, lesion damage, and stroke outcomes. We used propensity score matching and logistic regression to examine whether brain resilience predicts good vs poor outcomes in patients with matched lesion damage. RESULTS: We examined 963 patients across 38 cohorts. Greater lesion damage was associated with older brain age (ß = 0.21; 95% CI 0.04-0.38, p = 0.015), which in turn was associated with poorer outcomes, both in the sensorimotor domain (ß = -0.28; 95% CI -0.41 to -0.15, p < 0.001) and across multiple domains of function (ß = -0.14; 95% CI -0.22 to -0.06, p < 0.001). Brain age mediated 15% of the impact of lesion damage on sensorimotor performance (95% CI 3%-58%, p = 0.01). Greater brain resilience explained why people have better outcomes, given matched lesion damage (odds ratio 1.04, 95% CI 1.01-1.08, p = 0.004). DISCUSSION: We provide evidence that younger brain age is associated with superior poststroke outcomes and modifies the impact of focal damage. The inclusion of imaging-based assessments of brain age and brain resilience may improve the prediction of poststroke outcomes compared with focal injury measures alone, opening new possibilities for potential therapeutic targets.

Effect of power training on rate of torque development and spatiotemporal gait parameters post stroke.

BACKGROUND: Maximizing independence and function post-stroke are two common therapy goals. Rate of torque development in lower-extremity muscles was recently reported to be associated with walking speed; however, trainability and subsequent effect on gait is unknown. This study aimed to determine effect of power training on paretic and non-paretic limb torque parameters, spatiotemporal gait parameters, and walking speed in chronic stroke survivors. METHODS: Individuals with chronic stroke (n = 22; 7 females; 62.7 ± 8.8 yrs) completed 24 progressive power-training sessions over 8 weeks with pre and post assessments. Knee extensor strength was assessed via dynamometry with torque parameters measured from maximal voluntary isometric contractions. Gait speed and spatiotemporal gait parameters were assessed via an instrumented gait mat, and a 6-min walk test was performed. FINDINGS: Rate of torque development at 200 ms and peak torque improved 58.6% and 14.1%, respectively, in the quadricep of the paretic limb (p < 0.05); conversely the non-paretic limb was unchanged. On average, self-selected walking speed, fastest-comfortable walking speed, and 6-min walk test improved 21.7%, 21.1%, and 19.5%, respectively (all p < 0.05). Change in torque development at 100 ms in the quadricep of the non-paretic limb was positively associated with improvements in self-selected and fastest-comfortable walking speeds (both r = 0.70, p < 0.05) and 6-min walk (r = 0.78, p < 0.001). INTERPRETATIONS: These findings suggest power training may be an effective intervention for improving torque development in the quadricep of the paretic limb in individuals with chronic stroke. Further research to explore utility and mechanistic aspects of force development for gait function in chronic stroke survivors is warranted.

Combined Aerobic Exercise and Virtual Reality-Based Upper Extremity Rehabilitation Intervention for Chronic Stroke: Feasibility and Preliminary Effects on Physical Function and Quality of Life.

Objectives: To (1) examine the feasibility of combining lower extremity aerobic exercise (AEx) with a virtual reality (VR) upper extremity (UE) rehabilitation intervention and (2) provide an estimate of effect size for the combined intervention on UE function, aerobic capacity, and health-related quality of life. Design: Single-group feasibility trial. Setting: Research laboratory. Participants: Community-dwelling individuals with mild to moderate impairment of the UE at least 6 months post stroke (N=10; male, n=6; female n=4; mean age, 54 years). Intervention: All participants received 18 sessions over a nominal 2-3 sessions per week schedule of a combined AEx and VR-UE rehabilitation intervention. During each session, participants completed 15 minutes of lower extremity AEx followed by playing a VR-UE rehabilitation game for approximately 20 minutes. Main Outcome Measures: Feasibility was evaluated by metrics of adherence, retention, treatment acceptability, data completeness, and adverse events. UE function, aerobic capacity (peak oxygen consumption [Vo2peak]), and quality of life were assessed with the Fugl-Meyer Assessment of Upper Extremity (FMA-UE), expired gas exchange analysis, and Stroke Impact Scale (SIS), respectively. Results: Adherence was 100%, and there were no withdrawals or losses to follow-up to report. Participants completed the intervention in 49±14 days. Cohen's dz effect size calculations indicated the intervention elicited medium effects on FMA-UE (dz =0.50) and SIS memory domain (dz =0.46) and large effects on absolute Vo2peak (dz =1.46), relative Vo2peak (dz =1.21), SIS strength (dz =1.18), and SIS overall recovery domains (dz =0.81). Conclusions: Combining lower extremity AEx and VR-UE rehabilitation appears feasible in the clinical research setting. Fifteen minutes of lower extremity AEx performed at vigorous intensity appears to elicit clinically meaningful benefits in chronic stroke. Further examination of the combination of lower extremity AEx and VR-UE rehabilitation and its effects on physical function and quality of life is warranted.

Interhemispheric Asymmetries in Intracortical Facilitation Correlate With Fatigue Severity in Individuals With Poststroke Fatigue.

PURPOSE: Poststroke fatigue (PSF) contributes to increased mortality and reduces participation in rehabilitative therapy. Although PSF's negative influences are well known, there are currently no effective evidence-based treatments for PSF. The lack of treatments is in part because of a dearth of PSF pathophysiological knowledge. Increasing our understanding of PSF's causes may facilitate and aid the development of effective therapies. METHODS: Twenty individuals, >6 months post stroke, participated in this cross-sectional study. Fourteen participants had clinically relevant pathological PSF, based on fatigue severity scale (FSS) scores (total score ≥36). Single-pulse and paired-pulse transcranial magnetic stimulation were used to measure hemispheric asymmetries in resting motor threshold, motor evoked potential amplitude, and intracortical facilitation (ICF). Asymmetry scores were calculated as the ratios between lesioned and nonlesioned hemispheres. The asymmetries were then correlated (Spearman rho) to FSS scores. RESULTS: In individuals with pathological PSF (N = 14, range of total FSS scores 39-63), a strong positive correlation (rs = 0.77, P = 0.001) between FSS scores and ICF asymmetries was calculated. CONCLUSIONS: As the ratio of ICF between the lesioned and nonlesioned hemispheres increased so did self-reported fatigue severity in individuals with clinically relevant pathological PSF. This finding may implicate adaptive/maladaptive plasticity of the glutamatergic system/tone as a contributor to PSF. This finding also suggests that future PSF studies should incorporate measuring facilitatory activity and behavior in addition to the more commonly studied inhibitory mechanisms. Further investigations are required to replicate this finding and identify the causes of ICF asymmetries.

Feasibility of performing a multi-arm clinical trial examining the novel combination of repetitive transcranial magnetic stimulation and aerobic exercise for post-stroke depression.

BACKGROUND: Post-stroke depression (PSD) occurs in approximately one-third of chronic stroke survivors. Although pharmacotherapy reduces depressive symptoms, side effects are common and stroke survivors have increased likelihood of multimorbidity and subsequent polypharmacy. Thus, alternative non-pharmacological treatments are needed. Combining two non-pharmacological anti-depressant treatments, aerobic exercise (AEx) and repetitive transcranial magnetic stimulation (rTMS), has been demonstrated to be feasible and well-tolerated in chronic stroke survivors. OBJECTIVES: The purpose of this trial was to determine the feasibility of conducting a multi-arm combinatorial trial of rTMS and AEx and to provide an estimate of effect size of rTMS+AEx on PSD symptoms. METHODS: Twenty-four participants were allocated to one of four treatment arms AEx, rTMS, rTMS+AEx, or non-depressed Control receiving AEx. All participants received a total of 24 treatment sessions. Participant adherence was the primary outcome measure for feasibility and within group effect sizes in Patient Health Questionnaire-9 (PHQ-9) score was the primary outcome for preliminary efficacy. RESULTS: Mean adherence rates to the exercise intervention for AEx, rTMS+AEx, and Control subjects were 83%, 98%, and 95%, respectively. Mean adherence rates for rTMS and rTMS+AEx subjects were 97% and 99%, respectively. The rTMS and rTMS+AEx treatment groups demonstrated clinically significant reductions of 10.5 and 6.2 points in PHQ-9 scores, respectively. CONCLUSION: Performing a multi-arm combinatorial trial examining the effect of rTMS+AEx on PSD appears feasible. All treatment arms demonstrated strong adherence to their respective interventions and were well received. rTMS and the combination of AEx with rTMS may be alternative treatments for PSD.

Weight Loss and Exercise Effects on Rate of Torque Development and Physical Function in Overweight Older Women.

Exercise training (EX) and weight loss (WL) improve lower extremity physical function (LEPF) in older overweight women; however, effects on rate of torque development (RTD) are unknown. This study aimed to determine the effects of WL + EX or WL alone on RTD, and relatedly LEPF, in overweight older women. Leg strength was assessed using isokinetic dynamometry, and RTD was calculated (RTD200 = RTD at 200 ms, RTDPeak = peak RTD, T2P = time to 1st peak). LEPF was determined via clinical functional tasks. Women (n = 44, 69.1 ± 3.6 years, 30.6 ± 4.3 kg/m2) completed a 6-month trial in EX + WL or WL groups with similar weight loss (-9.8 ± 4.2%, p > .95). EX + WL had greater improvements in (a) most LEPF tasks (p < .001) and (b) RTD200, compared with WL (36% vs. -16%, p = .031); no other RTD parameters differed. Changes in RTD parameters and LEPF were not related (all p > .05). RTD is responsive to EX but is not associated with LEPF in older women.

The role of exercise in the treatment of depression: biological underpinnings and clinical outcomes.

Globally, depression is a leading cause of disability and has remained so for decades. Antidepressant medications have suboptimal outcomes and are too frequently associated with side effects, highlighting the need for alternative treatment options. Although primarily known for its robust physical health benefits, exercise is increasingly recognized for its mental health and antidepressant benefits. Empirical evidence indicates that exercise is effective in treating individuals with depression; however, the mechanisms by which exercise exerts anti-depressant effects are not fully understood. Acute bouts of exercise have been shown to transiently modulate circulating levels of serotonin and norepinephrine, brain-derived neurotrophic factor, and a variety of immuno-inflammatory mechanisms in clinical cohorts with depression. However, exercise training has not been demonstrated to consistently modulate such mechanisms, and evidence linking these putative mechanisms and reductions in depression is lacking. The complexity of the biological underpinnings of depression coupled with the intricate molecular cascade induced by exercise are significant obstacles in the attempt to disentangle exercise's effects on depression. Notwithstanding our limited understanding of these effects, clinical evidence uniformly argues for the use of exercise to treat depression. Regrettably, exercise remains underutilized despite being an accessible, low-cost alternative/adjunctive intervention that can simultaneously reduce depression and improve overall health. To address the gaps in our understanding of the clinical and molecular effects of exercise on depression, we propose a model that leverages systems biology and multidisciplinary team science with a large-scale public health investment. Until the science matches the scale of complexity and burden posed by depression, our ability to advance knowledge and treatment will continue to be plagued by fragmented, irreproducible mechanistic findings and no guidelines for standards of care.

The relationship between motor pathway damage and flexion-extension patterns of muscle co-excitation during walking.

Background: Mass flexion-extension co-excitation patterns during walking are often seen as a consequence of stroke, but there is limited understanding of the specific contributions of different descending motor pathways toward their control. The corticospinal tract is a major descending motor pathway influencing the production of normal sequential muscle coactivation patterns for skilled movements. However, control of walking is also influenced by non-corticospinal pathways such as the corticoreticulospinal pathway that possibly contribute toward mass flexion-extension co-excitation patterns during walking. The current study sought to investigate the associations between damage to corticospinal (CST) and corticoreticular (CRP) motor pathways following stroke and the presence of mass flexion-extension patterns during walking as evaluated using module analysis. Methods: Seventeen healthy controls and 44 stroke survivors were included in the study. We used non-negative matrix factorization for module analysis of paretic leg electromyographic activity. We typically have observed four modules during walking in healthy individuals. Stroke survivors often have less independently timed modules, for example two-modules presented as mass flexion-extension pattern. We used diffusion tensor imaging-based analysis where streamlines connecting regions of interest between the cortex and brainstem were computed to evaluate CST and CRP integrity. We also used a coarse classification tree analysis to evaluate the relative CST and CRP contribution toward module control. Results: Interhemispheric CST asymmetry was associated with worse lower extremity Fugl-Meyer score (p = 0.023), propulsion symmetry (p = 0.016), and fewer modules (p = 0.028). Interhemispheric CRP asymmetry was associated with worse lower extremity Fugl-Meyer score (p = 0.009), Dynamic gait index (p = 0.035), Six-minute walk test (p = 0.020), Berg balance scale (p = 0.048), self-selected walking speed (p = 0.041), and propulsion symmetry (p = 0.001). The classification tree model reveled that substantial ipsilesional CRP or CST damage leads to a two-module pattern and poor walking ability with a trend toward increased compensatory contralesional CRP based control. Conclusion: Both CST and CRP are involved with control of modules during walking and damage to both may lead to greater reliance on the contralesional CRP, which may contribute to a two-module pattern and be associated with worse walking performance.

A large, curated, open-source stroke neuroimaging dataset to improve lesion segmentation algorithms.

Accurate lesion segmentation is critical in stroke rehabilitation research for the quantification of lesion burden and accurate image processing. Current automated lesion segmentation methods for T1-weighted (T1w) MRIs, commonly used in stroke research, lack accuracy and reliability. Manual segmentation remains the gold standard, but it is time-consuming, subjective, and requires neuroanatomical expertise. We previously released an open-source dataset of stroke T1w MRIs and manually-segmented lesion masks (ATLAS v1.2, N = 304) to encourage the development of better algorithms. However, many methods developed with ATLAS v1.2 report low accuracy, are not publicly accessible or are improperly validated, limiting their utility to the field. Here we present ATLAS v2.0 (N = 1271), a larger dataset of T1w MRIs and manually segmented lesion masks that includes training (n = 655), test (hidden masks, n = 300), and generalizability (hidden MRIs and masks, n = 316) datasets. Algorithm development using this larger sample should lead to more robust solutions; the hidden datasets allow for unbiased performance evaluation via segmentation challenges. We anticipate that ATLAS v2.0 will lead to improved algorithms, facilitating large-scale stroke research.

Contributions of social determinants of health to systolic blood pressure in United States adult immigrants: Use of path analysis to validate a conceptual framework.

OBJECTIVE: Validate a conceptual framework and identify pathways between antecedent (life-course socioeconomic status (L-SES)), predisposing (age, sex, married, homeless as a child), enabling (health literacy, acculturation), and need (disability) social determinants of health (SDoH) and systolic blood pressure (SBP) in US immigrants. METHODS: 181 immigrants were enrolled in the study. Path analysis was used to identify paths by which SDoH influence SBP and to determine if antecedents, predisposing, enabling, and need factors have direct and indirect relationships with SBP. RESULTS: The final model(chi2(5)=14.88, p = 0.011, RMSEA = 0.070, pclose = 0.17, CFI = 0.96) showed L-SES was directly associated with age (0.12, p = 0.019) and disability(0.17, p = 0.001); and indirectly associated with disability (0.29, p < 0.001) and SBP (0.31, p < 0.001). Age (0.31, p < 0.001) and sex(0.25, p < 0.001) were directly associated with SBP, and age was directly associated with disability (0.29, p < 0.001) and indirectly associated with SBP(0.14, p = 0.018). Other predisposing factors such as being married (-0.32, p < 0.001) and being homeless as a child alone (0.16, p < 0.001) were directly associated with disability and indirectly associated (0.14, p = 0.018) with SBP. Enabling factor of health literacy (0.16, p = 0.001) was directly associated with disability and indirectly associated (0.14, p = 0.018) with SBP. Need factor of disability (0.14, p = 0.018) was directly associated with SBP. CONCLUSIONS: This study provides the first validation of a conceptual model for the relationship between SDoH and SBP among immigrants and identifies potential targets for focused interventions.

The ENIGMA Stroke Recovery Working Group: Big data neuroimaging to study brain-behavior relationships after stroke.

The goal of the Enhancing Neuroimaging Genetics through Meta-Analysis (ENIGMA) Stroke Recovery working group is to understand brain and behavior relationships using well-powered meta- and mega-analytic approaches. ENIGMA Stroke Recovery has data from over 2,100 stroke patients collected across 39 research studies and 10 countries around the world, comprising the largest multisite retrospective stroke data collaboration to date. This article outlines the efforts taken by the ENIGMA Stroke Recovery working group to develop neuroinformatics protocols and methods to manage multisite stroke brain magnetic resonance imaging, behavioral and demographics data. Specifically, the processes for scalable data intake and preprocessing, multisite data harmonization, and large-scale stroke lesion analysis are described, and challenges unique to this type of big data collaboration in stroke research are discussed. Finally, future directions and limitations, as well as recommendations for improved data harmonization through prospective data collection and data management, are provided.

Smaller spared subcortical nuclei are associated with worse post-stroke sensorimotor outcomes in 28 cohorts worldwide.

Up to two-thirds of stroke survivors experience persistent sensorimotor impairments. Recovery relies on the integrity of spared brain areas to compensate for damaged tissue. Deep grey matter structures play a critical role in the control and regulation of sensorimotor circuits. The goal of this work is to identify associations between volumes of spared subcortical nuclei and sensorimotor behaviour at different timepoints after stroke. We pooled high-resolution T1-weighted MRI brain scans and behavioural data in 828 individuals with unilateral stroke from 28 cohorts worldwide. Cross-sectional analyses using linear mixed-effects models related post-stroke sensorimotor behaviour to non-lesioned subcortical volumes (Bonferroni-corrected, P < 0.004). We tested subacute (≤90 days) and chronic (≥180 days) stroke subgroups separately, with exploratory analyses in early stroke (≤21 days) and across all time. Sub-analyses in chronic stroke were also performed based on class of sensorimotor deficits (impairment, activity limitations) and side of lesioned hemisphere. Worse sensorimotor behaviour was associated with a smaller ipsilesional thalamic volume in both early (n = 179; d = 0.68) and subacute (n = 274, d = 0.46) stroke. In chronic stroke (n = 404), worse sensorimotor behaviour was associated with smaller ipsilesional putamen (d = 0.52) and nucleus accumbens (d = 0.39) volumes, and a larger ipsilesional lateral ventricle (d = -0.42). Worse chronic sensorimotor impairment specifically (measured by the Fugl-Meyer Assessment; n = 256) was associated with smaller ipsilesional putamen (d = 0.72) and larger lateral ventricle (d = -0.41) volumes, while several measures of activity limitations (n = 116) showed no significant relationships. In the full cohort across all time (n = 828), sensorimotor behaviour was associated with the volumes of the ipsilesional nucleus accumbens (d = 0.23), putamen (d = 0.33), thalamus (d = 0.33) and lateral ventricle (d = -0.23). We demonstrate significant relationships between post-stroke sensorimotor behaviour and reduced volumes of deep grey matter structures that were spared by stroke, which differ by time and class of sensorimotor measure. These findings provide additional insight into how different cortico-thalamo-striatal circuits support post-stroke sensorimotor outcomes.

Quantifying direct effects of social determinants of health on systolic blood pressure in United States adult immigrants.

Identify the pathway by which social determinants of health (SDoH) variables impact systolic blood pressure (SBP) in immigrants. Latent variables were used to assess the relationship between SDoH and SBP. Latent variables were identified using confirmatory factor analysis (CFA) for (1) global socioeconomic status (SES) (education, income, number of hours worked per week), (2) stressors of immigration (life-course SES, immigration stress, immigration demand), (3) adaptation to immigration (perceived discrimination, perceived stress, health literacy), and (4) burden of disease (disability, comorbidities, chronic pain). Structural equation modeling (SEM) was used to investigate the relationship between immigrant specific latent variables and SBP. The study included 181 adult immigrants. The initial model (chi2 (77, n = 181) = 302.40, p < 0.001, RMSEA = 0.086, CFI = 0.84, TLI = 0.78, CD = 0.91) showed that stressors of immigration had a direct relationship with SBP (-0.35, p = 0.033); global (SES) had a direct relationship with burden of disease (-0.70, p = 0.007) and an indirect relationship with SBP by way of burden of disease (0.24, p = 0.015). The final model (chi2 (69, n = 181) = 149.98, p < 0.001, RMSEA = 0.054, CFI = 0.94, TLI = 0.91, CD = 0.96) maintained that global SES had a direct relationship with burden of disease (-0.40, p < 0.001) and an indirect relationship with SBP by way burden of disease (0.34, p < 0.001). This study suggests a direct relationship between burden of disease and SBP, and an indirect relationship between SES and SBP. Development of interventions should take burden of disease into account as a direct driver of blood pressure in immigrants, and address factors related to SES.

Evaluating a novel MR-compatible foot pedal device for unipedal and bipedal motion: Test-retest reliability of evoked brain activity.

The purpose of this study was to develop and evaluate a new, open-source MR-compatible device capable of assessing unipedal and bipedal lower extremity movement with minimal head motion and high test-retest reliability. To evaluate the prototype, 20 healthy adults participated in two magnetic resonance imaging (MRI) visits, separated by 2-6 months, in which they performed a visually guided dorsiflexion/plantar flexion task with their left foot, right foot, and alternating feet. Dependent measures included: evoked blood oxygen level-dependent (BOLD) signal in the motor network, head movement associated with dorsiflexion/plantar flexion, the test-retest reliability of these measurements. Left and right unipedal movement led to a significant increase in BOLD signal compared to rest in the medial portion of the right and left primary motor cortex (respectively), and the ipsilateral cerebellum (FWE corrected, p < .001). Average head motion was 0.10 ± 0.02 mm. The test-retest reliability was high for the functional MRI data (intraclass correlation coefficients [ICCs]: >0.75) and the angular displacement of the ankle joint (ICC: 0.842). This bipedal device can robustly isolate activity in the motor network during alternating plantarflexion and dorsiflexion with minimal head movement, while providing high test-retest reliability. Ultimately, these data and open-source building instructions will provide a new, economical tool for investigators interested in evaluating brain function resulting from lower extremity movement.

The effect of time since stroke, gender, age, and lesion size on thalamus volume in chronic stroke: a pilot study.

Recent stroke studies have shown that the ipsi-lesional thalamus longitudinally and significantly decreases after stroke in the acute and subacute stages. However, additional considerations in the chronic stages of stroke require exploration including time since stroke, gender, intracortical volume, aging, and lesion volume to better characterize thalamic differences after cortical infarct. This cross-sectional retrospective study quantified the ipsilesional and contralesional thalamus volume from 69 chronic stroke subjects' anatomical MRI data (age 35-92) and related the thalamus volume to time since stroke, gender, intracortical volume, age, and lesion volume. The ipsi-lesional thalamus volume was significantly smaller than the contra-lesional thalamus volume (t(68) = 13.89, p < 0.0001). In the ipsilesional thalamus, significant effect for intracortical volume (t(68) = 2.76, p = 0.008), age (t(68) = 2.47, p = 0.02), lesion volume (t(68) = - 3.54, p = 0.0008), and age*time since stroke (t(68) = 2.46, p = 0.02) were identified. In the contralesional thalamus, significant effect for intracortical volume (t(68) = 3.2, p = 0.002) and age (t = - 3.17, p = 0.002) were identified. Clinical factors age and intracortical volume influence both ipsi- and contralesional thalamus volume and lesion volume influences the ipsilesional thalamus. Due to the cross-sectional nature of this study, additional research is warranted to understand differences in the neural circuitry and subsequent influence on volumetrics after stroke.

Examination of the Association Between Latent Variables for Social Determinants of Health and Blood Pressure Control in Immigrants using Structural Equation Modeling.

BACKGROUND: Hypertension is responsible for about 12.8% of deaths around the world. Immigrants' risk of developing hypertension increases with length of residency. There is limited work on the role of social determinants of health and blood pressure control in immigrants. We created a theory-based conceptual model for immigrant-specific and general social determinants variables and their relationship to blood pressure. PURPOSE: Use a theory-based model to identify latent variables for immigrant-specific social determinants using confirmatory factor analysis (CFA) and structural equation modeling (SEM) to test theoretical validity and relationship with blood pressure (BP). METHODS: CFA was used to identify latent variables for global socioeconomic status, stressors of immigration, adaptation to immigration, acculturation, and burden of disease. SEM was used to test the structural relationships between latent variables and BP. RESULTS: 181 immigrants were included in the analysis. The final model (chi2 (68, n = 181) = 149.87, p < 0.001, RMSEA = 0.055, CFI = 0.94, TLI = 0.91, CD = 0.99) found burden of disease was significantly related to BP (r = 0.35, p < 0.001). CONCLUSIONS: One latent variable measuring need was significantly associated with BP in an immigrant sample. This suggests that interventions targeting burden of disease are likely to be effective in controlling blood pressure in immigrants.

Associations Between Doing Planned Exercise and Probable Major Depressive Disorder in Individuals Following Spinal Cord Injury.

Background: In neurologically healthy individuals, exercise positively impacts depressive symptoms, but there is limited knowledge regarding the association between exercise behaviors and depression after spinal cord injury (SCI). Objective: To examine associations between doing planned exercise and probable major depressive disorder (PMDD) after SCI. Methods: Community-dwelling adults, who were one or more years post traumatic SCI, completed self-report assessments at baseline (Time 1) and an average of 3.29 years later (Time 2). Patient Health Questionnaire-9 was used to assess depressive symptoms. Participants self-reported frequency of doing planned exercise. There were 1,790 participants who responded at both Time 1 and 2. Associations were analyzed using logistic regression. Results: Prevalence of PMDD was 10% at Time 1 and 12% at Time 2. Only 34% of participants at Time 1 and 29% at Time 2 reported doing planned exercise three or more times per week. The majority of participants (47%) reported no change in frequency of doing planned exercise between Times 1 and 2. Significant risk factors for PMDD at Time 2 included low household income (p = .0085), poor to fair self-perceived health (p < .0001), and doing less planned exercise at Time 2 (p = .0005). Meanwhile, number of years post injury (p = .04), doing planned exercise three or more times per week at Time 1 (p = .0042), and doing more planned exercise at Time 2 (p = .0005) were associated with decreased odds of PMDD at Time 2. Conclusion: These results demonstrate that a negative association exists between doing planned exercise and PMDD post SCI. Future longitudinal studies are needed to further explain these findings.

Using Inferred Mobility Status to Estimate the Time to Major Depressive Disorder Diagnosis Post-Spinal Cord Injury.

OBJECTIVE: Estimate (1) prevalence of major depressive disorder (MDD) diagnosis; (2) risk factors associated with MDD diagnosis; (3) time at which MDD is diagnosed post-spinal cord injury (SCI); and (4) interaction of inferred mobility status (IMS) in a commercially insured population over 3 years. DESIGN: Retrospective longitudinal cohort design. SETTING: A commercial insurance claims database from January 1, 2010 to December 31, 2013. PARTICIPANTS: Individuals with an index cervical or thoracic SCI in 2011 or 2012, without history of MDD ≤30 days pre-SCI (N=1409). INTERVENTION: Not applicable. MAIN OUTCOME MEASURES: Prevalence of, risk factors associated with, and time to MDD diagnosis post-SCI. A stratified survival analysis using IMS, based upon durable medical equipment (DME) claims, was also completed. RESULTS: Post-SCI, 294 out of 1409 (20.87%) were diagnosed with new-onset MDD. Significant (P<.05) risk factors included: employment, length of index hospitalization, discharge from index hospitalization with healthcare services, rehabilitation services post-SCI, and 2 of 5 IMS comparisons. Median time to MDD was 86 days. Survival analysis demonstrated a significant difference between 6 of 10 IMS comparisons. Regarding new-onset or recurring MDD, 432 out of 1409 (30.66%) were diagnosed post-SCI. Significant risk factors included: female, employment, length of index hospitalization, discharge from index hospitalization with healthcare services, rehabilitation services post-SCI, MDD>30 days pre-SCI, catheter claims, and 2 of 5 IMS comparisons. Median time to MDD was 74 days. Survival analysis demonstrated a significant difference between 4 of 10 IMS comparisons. CONCLUSIONS: Prevalence of MDD post-SCI is greater than the general population. Stratification by IMS illustrated that individuals with greater inferred reliance on DME are at a greater risk for MDD and have shorter time to MDD diagnosis post-SCI.