Cognitive impairment is a core symptom of pediatric-onset multiple sclerosis (MS), although relat... more Cognitive impairment is a core symptom of pediatric-onset multiple sclerosis (MS), although relatively little is known regarding the rate of cognitive decline. This study examined the extent, pattern, and correlates of change in cognitive functioning in youth with MS. Changes in cognitive performance in 28 patients with pediatric-onset MS and 26 age-matched controls were ascertained through repeat comprehensive neuropsychological assessment conducted over a 1-year period. Change was evaluated by using a mixed factorial design with repeated measures to determine the interaction between group and time and using the Reliable Change Index (RCI) to determine individual differences on test scores over time. Participants were classified as showing "decline" or "improvement" if change scores exceeded the RCI on three or more tests. The pattern of change over time differed by group. At the group level, healthy controls were more likely to show improvement across multiple domains of function relative to the MS group. Using the RCI, 7 of 28 patients (25%) showed cognitive deterioration compared with only 1 of 26 controls (3.8%; p < .05). Performance on measures of attention and processing speed, visuomotor integration, verbal fluency, visual memory, and calculation and spelling ability were most responsive to deterioration in functioning over time. Longer disease duration was associated with greater deterioration in visuomotor integration. Increased lesion volume was associated with slower psychomotor speed over time. Lower rates of improvement in the pediatric MS group may be suggestive of a lack of age-appropriate cognitive development and warrant further evaluation over time.
Fluoride, which may be toxic to the developing brain, is added to salt in Mexico and drinking wat... more Fluoride, which may be toxic to the developing brain, is added to salt in Mexico and drinking water in Canada to prevent dental caries. We compared childhood urinary fluoride (CUF) concentrations in Mexico City and Canada to characterize patterns of fluoride exposure in these two populations. We also examined associations of CUF with dietary and water fluoride levels in Mexico City and Canada respectively. We included 561 children (ages 4–6; mean age 4.8 years) from the Programming Research in Obesity, Growth, Environment, and Social Stress (PROGRESS) cohort in Mexico City, and 645 children (ages 2–6; mean age 3.7 years) from the Maternal–Infant Research on Environmental Chemicals (MIREC) cohort in Canada. We applied Spearman correlations, T-tests, ANOVA or covariate-adjusted linear regression to examine associations of CUF (mg/L; adjusted for specific gravity) with demographics and dietary or water fluoride concentrations. We used Welch equivalence testing to compare means across c...
Background: Exposure to fluoride has been linked with increased prevalence of attention deficit h... more Background: Exposure to fluoride has been linked with increased prevalence of attention deficit hyperactivity disorder (ADHD) in the United States and symptoms of inattention in Mexican children. We examined the association between fluoride exposure and attention outcomes among youth living in Canada. Method: We used cross-sectional data collected from youth 6 to 17 years of age from the Canadian Health Measures Survey (Cycles 2 and 3). Urinary fluoride concentration adjusted for specific gravity (UFSG) was available for 1877 participants. Water fluoride concentration measured in tap water samples was available for 980 participants. Community water fluoridation (CWF) status was determined by viewing reports on each city's website or contacting the water treatment plant. We used logistic regression to test the association between the three measures of fluoride exposure and ADHD diagnosis. Linear regression was used to examine the relationship between the three measures of fluoride exposure and the hyperactivity/inattention score on the Strengths and Difficulties Questionnaire (SDQ). Results: UF SG did not significantly predict ADHD diagnosis or hyperactive/inattentive symptoms. A 1 mg/L increase in tap water fluoride level was associated with a 6.1 times higher odds of an ADHD diagnosis (95% CI = 1.60, 22.8). A significant interaction between age and tap water fluoride level (p = .03) indicated a stronger association between tap water fluoride and hyperactivity/inattention symptoms among older youth. A 1 mg/L increase in water fluoride level was associated with a 1.5 SDQ score increase (95% CI: 0.23, 2.68, p = .02) for youth at the 75th percentile of age (14 years old). Similarly, there was a significant interaction between age and CWF. At the 75th percentile of age (14 years old), those living in a fluoridated region had a 0.7-point higher SDQ score (95% CI = 0.34, 1.06, p < .01) and the predicted odds of an ADHD diagnosis was 2.8 times greater compared with youth in a non-fluoridated region (aOR = 2.84, 95% CI: 1.40, 5.76, p < .01). Discussion: Exposure to higher levels of fluoride in tap water is associated with an increased risk of ADHD symptoms and diagnosis of ADHD among Canadian youth, particularly among adolescents. Prospective studies are needed to confirm these results.
Journal of the International Neuropsychological Society
Objectives: Youth and young adults with pediatric-onset multiple sclerosis (MS) are vulnerable to... more Objectives: Youth and young adults with pediatric-onset multiple sclerosis (MS) are vulnerable to executive dysfunction; however, some patients do not demonstrate functional deficits despite showing abnormalities on structural magnetic resonance imaging (MRI). Cognitively intact adults with MS have shown enhanced activation patterns relative to healthy controls on working memory tasks. We aim to evaluate whether cognitively preserved pediatric-onset MS patients engage compensatory recruitment strategies to facilitate age-normative performance on a task of working memory. Methods: Twenty cognitively preserved patients (mean age=18.7±2.7 years; 15 female) and 20 age- and sex-matched controls (mean age=18.5±2.9 years; 15 female) underwent neuropsychological testing and 3.0 Tesla MRI, including structural and functional acquisitions. Patterns of activation during the Alphaspan task, a working memory paradigm with two levels of executive control demand, were examined via whole-brain and ...
Youth with multiple sclerosis (MS) often experience cognitive impairment and psychosocial disturb... more Youth with multiple sclerosis (MS) often experience cognitive impairment and psychosocial disturbances. We describe the relationship between memory function, psychosocial skills, and brain volume in 32 patients with pediatric-onset MS and 30 controls. Amygdala volume was significantly lower in patients compared with controls. In general, poorer memory was associated with reduced functional communication skills and reduced amygdala volume. Greater amygdala volume in patients correlated with parent-reported functional communication and social skills. Adjusting for whole-brain volume, right amygdala volume was positively associated with visual memory; left amygdala volume was a stronger predictor of parent-reported social skills.
Journal of clinical and experimental neuropsychology, Jan 18, 2018
The Cambridge Neuropsychological Test Automated Battery (CANTAB) is a computerized tool used to m... more The Cambridge Neuropsychological Test Automated Battery (CANTAB) is a computerized tool used to measure cognitive function in diverse populations and is sensitive for assessing developmental changes in children. Although CANTAB has been used in several countries, its applicability in a Mexican child population is unknown. This study examined developmental trends on CANTAB in a large sample of urban Mexico City youth and tested the hypothesis that their performance would be similar to a large US normative sample. As part of a birth cohort, Early Life Exposures in Mexico to Environmental Toxicants, 826 children, ages 5-15 years, completed CANTAB. Subtests measured planning (Stockings of Cambridge; SOC), short-term memory (Delayed Matching to Sample; DMS), sustained attention (Rapid Visual Information Processing; RVP), ability to match visual stimuli (Match to Sample Visual Search; MTS), flexibility (Intra-extra Dimensional Set Shift; IED), and response inhibition (Stop Signal Task; SS...
To determine the frequency of cortical lesions (CLs) in patients with pediatric-onset multiple sc... more To determine the frequency of cortical lesions (CLs) in patients with pediatric-onset multiple sclerosis (POMS) using multi-contrast magnetic resonance imaging (MRI), and the relationship between frontal CL load and upper limb dexterity assessed with the Nine-Hole Peg Test (9-HPT). Participants completed the 9-HPT and were imaged on a 3T MRI scanner to collect T1-weighted three-dimensional (3D) magnetization prepared rapid gradient echo (MPRAGE), proton density-weighted, T2-weighted and fluid-attenuated inversion recovery (FLAIR) images. CLs were manually segmented using all MRI contrasts. We enrolled 24 participants with POMS (mean (standard deviation) age at first symptom: 13.3 (±2.7) years; mean age at scan: 18.8 (±3) years; mean disease duration of 5 (±3.2) years). A total of 391 CLs (mean, 16.3 ± 27.2; median, 7) were identified in 19 of 24 POMS patients (79%). The total number of CLs was positively associated with white matter lesion volume ( p = 0.04) but not with thalamic vo...
Processing speed is a frequently affected cognitive domain in pediatric multiple sclerosis (MS) a... more Processing speed is a frequently affected cognitive domain in pediatric multiple sclerosis (MS) and is commonly assessed using the Symbol Digit Modalities Test (SDMT). The objective of this study was to determine maturational trajectories in SDMT performance and baseline factors affecting trajectories in a sample of 82 pediatric MS individuals. Performance on the SDMT increased with age in patients with pediatric MS followed by a subsequent decline. Furthermore, patients who were older at disease onset and had a higher IQ showed greater gains with age, suggesting that these factors may be protective with respect to cognitive maturation in pediatric MS.
To investigate physical activity levels in youth with multiple sclerosis and monophasic acquired ... more To investigate physical activity levels in youth with multiple sclerosis and monophasic acquired demyelinating syndromes ([mono-ADS], ie, children without relapsing disease) compared with healthy controls and to determine factors that contribute to engagement in physical activity. We hypothesized that greater physical activity goal setting and physical activity self-efficacy would be associated with greater levels of vigorous physical activity in youth with multiple sclerosis. A total of 68 consecutive patients (27 multiple sclerosis, 41 mono-ADS) and 37 healthy controls completed fatigue, depression, Physical Activity Self-Efficacy Scale, perceived disability, Exercise Goal-Setting scale, and physical activity questionnaires, and wore an accelerometer for 7 days. All patients had no ambulatory limitations (Expanded Disability Status Scale, scores all <4). Youth with multiple sclerosis engaged in fewer minutes per day of vigorous (P = .009) and moderate and vigorous physical acti...
Journal of Clinical and Experimental Neuropsychology, Jan 17, 2014
Impairments in visuospatial abilities are commonly reported in children and adolescents with mult... more Impairments in visuospatial abilities are commonly reported in children and adolescents with multiple sclerosis (MS). Corpus callosum (CC) pathology occurs in patients with MS and may contribute to impairment in visuospatial perception, particularly when interhemispheric information transfer is required. This study used a global-local hierarchical letter paradigm to examine the relationship between interhemispheric information transfer and white matter integrity in the CC assessed using diffusion tensor imaging. Thirteen cognitively preserved pediatric-onset MS patients and 15 age-matched healthy controls were asked to determine whether a target letter E appeared at the attended level of the stimulus. As expected, both groups processed global and local information more slowly under divided than selective attention conditions. The MS group performed similarly to the control group with respect to reaction time and accuracy on selective and divided attention conditions, with one exception. Specifically, the presence of a global target when attending to a local target caused greater response conflict in the MS group than in controls (p = .01). Pooling both the patient and control data, greater response conflict was associated with reduced white matter integrity as indicated by lower fractional anisotropy in the anterior body of the CC (r = -.33, p &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .05). Results suggest that reduced white matter integrity in anterior regions of the CC may lead to less efficient inhibition of task-irrelevant global information in the hierarchal processing of visual information.
Journal of clinical and experimental neuropsychology, Jan 22, 2015
This study aimed to determine the extent and pattern of brain activation elicited by a functional... more This study aimed to determine the extent and pattern of brain activation elicited by a functional magnetic resonance imaging version of the Symbol Digit Modalities Test (fMRI-SDMT), a task of information processing speed, in pediatric-onset multiple sclerosis (MS) patients as compared to sex- and age-matched non-MS self-reported healthy individuals. Participants included 20 right-handed individuals aged 13-24 years with pediatric-onset MS (mean age = 19 years, 15 female) and 16 non-MS self-reported healthy individuals. All participants underwent a 3.0-tesla MRI scan with structural (T1; T2; proton density, PD; fluid-attenuated inversion recovery, FLAIR) and fMRI-SDMT acquisition. Participants were instructed to indicate with a button press whether a single pairing of a symbol to a number matched any of those shown in a key that displays nine possible pairings. Response time (p = .909) and accuracy (p = .832) on the fMRI-SDMT did not differ between groups. However, the MS group demon...
Reduced white matter (WM) integrity is a fundamental aspect of pediatric multiple sclerosis (MS),... more Reduced white matter (WM) integrity is a fundamental aspect of pediatric multiple sclerosis (MS), though relations to resting-state functional MRI (fMRI) connectivity remain unknown. The objective of this study was to relate diffusion-tensor imaging (DTI) measures of WM microstructural integrity to resting-state network (RSN) functional connectivity in pediatric-onset MS to test the hypothesis that abnormalities in RSN reflects changes in structural integrity. This study enrolled 19 patients with pediatric-onset MS (mean age = 19, range 13-24 years, 14 female, mean disease duration = 65 months, mean age of disease years) and 16 age- and sex-matched healthy controls (HC). All subjects underwent 3.0T anatomical and functional MRI which included DTI and resting-state acquisitions. DTI processing was performed using Tract-Based Spatial Statistics (TBSS). RSNs were identified using Independent Components Analysis, and a dual regression technique was used to detect between-grou...
Cognitive impairment is a core symptom of pediatric-onset multiple sclerosis (MS), although relat... more Cognitive impairment is a core symptom of pediatric-onset multiple sclerosis (MS), although relatively little is known regarding the rate of cognitive decline. This study examined the extent, pattern, and correlates of change in cognitive functioning in youth with MS. Changes in cognitive performance in 28 patients with pediatric-onset MS and 26 age-matched controls were ascertained through repeat comprehensive neuropsychological assessment conducted over a 1-year period. Change was evaluated by using a mixed factorial design with repeated measures to determine the interaction between group and time and using the Reliable Change Index (RCI) to determine individual differences on test scores over time. Participants were classified as showing &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;decline&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; or &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;improvement&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; if change scores exceeded the RCI on three or more tests. The pattern of change over time differed by group. At the group level, healthy controls were more likely to show improvement across multiple domains of function relative to the MS group. Using the RCI, 7 of 28 patients (25%) showed cognitive deterioration compared with only 1 of 26 controls (3.8%; p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .05). Performance on measures of attention and processing speed, visuomotor integration, verbal fluency, visual memory, and calculation and spelling ability were most responsive to deterioration in functioning over time. Longer disease duration was associated with greater deterioration in visuomotor integration. Increased lesion volume was associated with slower psychomotor speed over time. Lower rates of improvement in the pediatric MS group may be suggestive of a lack of age-appropriate cognitive development and warrant further evaluation over time.
Fluoride, which may be toxic to the developing brain, is added to salt in Mexico and drinking wat... more Fluoride, which may be toxic to the developing brain, is added to salt in Mexico and drinking water in Canada to prevent dental caries. We compared childhood urinary fluoride (CUF) concentrations in Mexico City and Canada to characterize patterns of fluoride exposure in these two populations. We also examined associations of CUF with dietary and water fluoride levels in Mexico City and Canada respectively. We included 561 children (ages 4–6; mean age 4.8 years) from the Programming Research in Obesity, Growth, Environment, and Social Stress (PROGRESS) cohort in Mexico City, and 645 children (ages 2–6; mean age 3.7 years) from the Maternal–Infant Research on Environmental Chemicals (MIREC) cohort in Canada. We applied Spearman correlations, T-tests, ANOVA or covariate-adjusted linear regression to examine associations of CUF (mg/L; adjusted for specific gravity) with demographics and dietary or water fluoride concentrations. We used Welch equivalence testing to compare means across c...
Background: Exposure to fluoride has been linked with increased prevalence of attention deficit h... more Background: Exposure to fluoride has been linked with increased prevalence of attention deficit hyperactivity disorder (ADHD) in the United States and symptoms of inattention in Mexican children. We examined the association between fluoride exposure and attention outcomes among youth living in Canada. Method: We used cross-sectional data collected from youth 6 to 17 years of age from the Canadian Health Measures Survey (Cycles 2 and 3). Urinary fluoride concentration adjusted for specific gravity (UFSG) was available for 1877 participants. Water fluoride concentration measured in tap water samples was available for 980 participants. Community water fluoridation (CWF) status was determined by viewing reports on each city&#39;s website or contacting the water treatment plant. We used logistic regression to test the association between the three measures of fluoride exposure and ADHD diagnosis. Linear regression was used to examine the relationship between the three measures of fluoride exposure and the hyperactivity/inattention score on the Strengths and Difficulties Questionnaire (SDQ). Results: UF SG did not significantly predict ADHD diagnosis or hyperactive/inattentive symptoms. A 1 mg/L increase in tap water fluoride level was associated with a 6.1 times higher odds of an ADHD diagnosis (95% CI = 1.60, 22.8). A significant interaction between age and tap water fluoride level (p = .03) indicated a stronger association between tap water fluoride and hyperactivity/inattention symptoms among older youth. A 1 mg/L increase in water fluoride level was associated with a 1.5 SDQ score increase (95% CI: 0.23, 2.68, p = .02) for youth at the 75th percentile of age (14 years old). Similarly, there was a significant interaction between age and CWF. At the 75th percentile of age (14 years old), those living in a fluoridated region had a 0.7-point higher SDQ score (95% CI = 0.34, 1.06, p &lt; .01) and the predicted odds of an ADHD diagnosis was 2.8 times greater compared with youth in a non-fluoridated region (aOR = 2.84, 95% CI: 1.40, 5.76, p &lt; .01). Discussion: Exposure to higher levels of fluoride in tap water is associated with an increased risk of ADHD symptoms and diagnosis of ADHD among Canadian youth, particularly among adolescents. Prospective studies are needed to confirm these results.
Journal of the International Neuropsychological Society
Objectives: Youth and young adults with pediatric-onset multiple sclerosis (MS) are vulnerable to... more Objectives: Youth and young adults with pediatric-onset multiple sclerosis (MS) are vulnerable to executive dysfunction; however, some patients do not demonstrate functional deficits despite showing abnormalities on structural magnetic resonance imaging (MRI). Cognitively intact adults with MS have shown enhanced activation patterns relative to healthy controls on working memory tasks. We aim to evaluate whether cognitively preserved pediatric-onset MS patients engage compensatory recruitment strategies to facilitate age-normative performance on a task of working memory. Methods: Twenty cognitively preserved patients (mean age=18.7±2.7 years; 15 female) and 20 age- and sex-matched controls (mean age=18.5±2.9 years; 15 female) underwent neuropsychological testing and 3.0 Tesla MRI, including structural and functional acquisitions. Patterns of activation during the Alphaspan task, a working memory paradigm with two levels of executive control demand, were examined via whole-brain and ...
Youth with multiple sclerosis (MS) often experience cognitive impairment and psychosocial disturb... more Youth with multiple sclerosis (MS) often experience cognitive impairment and psychosocial disturbances. We describe the relationship between memory function, psychosocial skills, and brain volume in 32 patients with pediatric-onset MS and 30 controls. Amygdala volume was significantly lower in patients compared with controls. In general, poorer memory was associated with reduced functional communication skills and reduced amygdala volume. Greater amygdala volume in patients correlated with parent-reported functional communication and social skills. Adjusting for whole-brain volume, right amygdala volume was positively associated with visual memory; left amygdala volume was a stronger predictor of parent-reported social skills.
Journal of clinical and experimental neuropsychology, Jan 18, 2018
The Cambridge Neuropsychological Test Automated Battery (CANTAB) is a computerized tool used to m... more The Cambridge Neuropsychological Test Automated Battery (CANTAB) is a computerized tool used to measure cognitive function in diverse populations and is sensitive for assessing developmental changes in children. Although CANTAB has been used in several countries, its applicability in a Mexican child population is unknown. This study examined developmental trends on CANTAB in a large sample of urban Mexico City youth and tested the hypothesis that their performance would be similar to a large US normative sample. As part of a birth cohort, Early Life Exposures in Mexico to Environmental Toxicants, 826 children, ages 5-15 years, completed CANTAB. Subtests measured planning (Stockings of Cambridge; SOC), short-term memory (Delayed Matching to Sample; DMS), sustained attention (Rapid Visual Information Processing; RVP), ability to match visual stimuli (Match to Sample Visual Search; MTS), flexibility (Intra-extra Dimensional Set Shift; IED), and response inhibition (Stop Signal Task; SS...
To determine the frequency of cortical lesions (CLs) in patients with pediatric-onset multiple sc... more To determine the frequency of cortical lesions (CLs) in patients with pediatric-onset multiple sclerosis (POMS) using multi-contrast magnetic resonance imaging (MRI), and the relationship between frontal CL load and upper limb dexterity assessed with the Nine-Hole Peg Test (9-HPT). Participants completed the 9-HPT and were imaged on a 3T MRI scanner to collect T1-weighted three-dimensional (3D) magnetization prepared rapid gradient echo (MPRAGE), proton density-weighted, T2-weighted and fluid-attenuated inversion recovery (FLAIR) images. CLs were manually segmented using all MRI contrasts. We enrolled 24 participants with POMS (mean (standard deviation) age at first symptom: 13.3 (±2.7) years; mean age at scan: 18.8 (±3) years; mean disease duration of 5 (±3.2) years). A total of 391 CLs (mean, 16.3 ± 27.2; median, 7) were identified in 19 of 24 POMS patients (79%). The total number of CLs was positively associated with white matter lesion volume ( p = 0.04) but not with thalamic vo...
Processing speed is a frequently affected cognitive domain in pediatric multiple sclerosis (MS) a... more Processing speed is a frequently affected cognitive domain in pediatric multiple sclerosis (MS) and is commonly assessed using the Symbol Digit Modalities Test (SDMT). The objective of this study was to determine maturational trajectories in SDMT performance and baseline factors affecting trajectories in a sample of 82 pediatric MS individuals. Performance on the SDMT increased with age in patients with pediatric MS followed by a subsequent decline. Furthermore, patients who were older at disease onset and had a higher IQ showed greater gains with age, suggesting that these factors may be protective with respect to cognitive maturation in pediatric MS.
To investigate physical activity levels in youth with multiple sclerosis and monophasic acquired ... more To investigate physical activity levels in youth with multiple sclerosis and monophasic acquired demyelinating syndromes ([mono-ADS], ie, children without relapsing disease) compared with healthy controls and to determine factors that contribute to engagement in physical activity. We hypothesized that greater physical activity goal setting and physical activity self-efficacy would be associated with greater levels of vigorous physical activity in youth with multiple sclerosis. A total of 68 consecutive patients (27 multiple sclerosis, 41 mono-ADS) and 37 healthy controls completed fatigue, depression, Physical Activity Self-Efficacy Scale, perceived disability, Exercise Goal-Setting scale, and physical activity questionnaires, and wore an accelerometer for 7 days. All patients had no ambulatory limitations (Expanded Disability Status Scale, scores all <4). Youth with multiple sclerosis engaged in fewer minutes per day of vigorous (P = .009) and moderate and vigorous physical acti...
Journal of Clinical and Experimental Neuropsychology, Jan 17, 2014
Impairments in visuospatial abilities are commonly reported in children and adolescents with mult... more Impairments in visuospatial abilities are commonly reported in children and adolescents with multiple sclerosis (MS). Corpus callosum (CC) pathology occurs in patients with MS and may contribute to impairment in visuospatial perception, particularly when interhemispheric information transfer is required. This study used a global-local hierarchical letter paradigm to examine the relationship between interhemispheric information transfer and white matter integrity in the CC assessed using diffusion tensor imaging. Thirteen cognitively preserved pediatric-onset MS patients and 15 age-matched healthy controls were asked to determine whether a target letter E appeared at the attended level of the stimulus. As expected, both groups processed global and local information more slowly under divided than selective attention conditions. The MS group performed similarly to the control group with respect to reaction time and accuracy on selective and divided attention conditions, with one exception. Specifically, the presence of a global target when attending to a local target caused greater response conflict in the MS group than in controls (p = .01). Pooling both the patient and control data, greater response conflict was associated with reduced white matter integrity as indicated by lower fractional anisotropy in the anterior body of the CC (r = -.33, p &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .05). Results suggest that reduced white matter integrity in anterior regions of the CC may lead to less efficient inhibition of task-irrelevant global information in the hierarchal processing of visual information.
Journal of clinical and experimental neuropsychology, Jan 22, 2015
This study aimed to determine the extent and pattern of brain activation elicited by a functional... more This study aimed to determine the extent and pattern of brain activation elicited by a functional magnetic resonance imaging version of the Symbol Digit Modalities Test (fMRI-SDMT), a task of information processing speed, in pediatric-onset multiple sclerosis (MS) patients as compared to sex- and age-matched non-MS self-reported healthy individuals. Participants included 20 right-handed individuals aged 13-24 years with pediatric-onset MS (mean age = 19 years, 15 female) and 16 non-MS self-reported healthy individuals. All participants underwent a 3.0-tesla MRI scan with structural (T1; T2; proton density, PD; fluid-attenuated inversion recovery, FLAIR) and fMRI-SDMT acquisition. Participants were instructed to indicate with a button press whether a single pairing of a symbol to a number matched any of those shown in a key that displays nine possible pairings. Response time (p = .909) and accuracy (p = .832) on the fMRI-SDMT did not differ between groups. However, the MS group demon...
Reduced white matter (WM) integrity is a fundamental aspect of pediatric multiple sclerosis (MS),... more Reduced white matter (WM) integrity is a fundamental aspect of pediatric multiple sclerosis (MS), though relations to resting-state functional MRI (fMRI) connectivity remain unknown. The objective of this study was to relate diffusion-tensor imaging (DTI) measures of WM microstructural integrity to resting-state network (RSN) functional connectivity in pediatric-onset MS to test the hypothesis that abnormalities in RSN reflects changes in structural integrity. This study enrolled 19 patients with pediatric-onset MS (mean age = 19, range 13-24 years, 14 female, mean disease duration = 65 months, mean age of disease years) and 16 age- and sex-matched healthy controls (HC). All subjects underwent 3.0T anatomical and functional MRI which included DTI and resting-state acquisitions. DTI processing was performed using Tract-Based Spatial Statistics (TBSS). RSNs were identified using Independent Components Analysis, and a dual regression technique was used to detect between-grou...
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