Browsing by Author "Dennis, Maureen"
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Item Attention in spina bifida myelomeningocele: Relations with brain volume and integrity(NeuroImage: Clinical, 2015-03) Kulesz, Paulina A.; Treble-Barna, Amery; Williams, Victoria J.; Juranek, Jenifer; Cirino, Paul T.; Dennis, Maureen; Fletcher, Jack M.This study investigated the relations of tectal volume and superior parietal cortex, as well as alterations in tectocortical white matter connectivity, with the orienting and executive control attention networks in individuals with spina bifida myelomeningocele (SBM). Probabilistic diffusion tractography and quantification of tectal and superior parietal cortical volume were performed on 74 individuals aged 8–29 with SBM and a history of hydrocephalus. Behavioral assessments measured posterior (covert orienting) and anterior (conflict resolution, attentional control) attention network functions. Reduced tectal volume was associated with slower covert orienting; reduced superior parietal cortical volume was associated with slower conflict resolution; and increased axial diffusivity and radial diffusivity along both frontal and parietal tectocortical pathways were associated with reduced attentional control. Results suggest that components of both the orienting and executive control attention networks are impaired in SBM. Neuroanatomical disruption to the orienting network appears more robust and a direct consequence of characteristic midbrain dysmorphology; whereas, executive control difficulties may emerge from parietal cortical anomalies and reduced frontal and parietal cortical–subcortical white matter pathways susceptible to the pathophysiological effects of congenital hydrocephalus.Item Folate metabolism gene 5, 10-methylenetetrahydrofolate reductase (MTHFR) is associated with ADHD in myelomeningocele patients(PLoS ONE, 2012-12) Spellicy, Catherine J.; Northrup, Hope; Fletcher, Jack M.; Cirino, Paul T.; Dennis, Maureen; Morrison, Alanna C.; Martinez, Kit Sing AuThe objective of this study was to examine the relation between the 5, 10-methylenetetrahydrofolate reductase (MTHFR) gene and behaviors related to attention- deficit/hyperactivity disorder (ADHD) in individuals with myelomeningocele. The rationale for the study was twofold: folate metabolizing genes, (e.g. MTHFR), are important not only in the etiology of neural tube defects but are also critical to cognitive function; and individuals with myelomeningocele have an elevated incidence of ADHD. Here, we tested 478 individuals with myelomeningocele for attention-deficit hyperactivity disorder behavior using the Swanson Nolan Achenbach Pelham-IV ADHD rating scale. Myelomeningocele participants in this group for whom DNAs were available were genotyped for seven single nucleotide polymorphisms (SNPs) in the MTHFR gene. The SNPs were evaluated for an association with manifestation of the ADHD phenotype in children with myelomeningocele. The data show that 28.7% of myelomeningocele participants exhibit rating scale elevations consistent with ADHD; of these 70.1% had scores consistent with the predominantly inattentive subtype. In addition, we also show a positive association between the SNP rs4846049 in the 3'-untranslated region of the MTHFR gene and the attention-deficit hyperactivity disorder phenotype in myelomeningocele participants. These results lend further support to the finding that behavior related to ADHD is more prevalent in patients with myelomeningocele than in the general population. These data also indicate the potential importance of the MTHFR gene in the etiology of the ADHD phenotype.Item Neocortical reorganization in spina bifida(NeuroImage, 2008-05) Juranek, Jenifer; Fletcher, Jack M.; Hasan, Khader M.; Breier, Joshua I.; Cirino, Paul T.; Pazo-Alvarez, Paula; Diaz, Javier D.; Ewing-Cobbs, Linda; Dennis, Maureen; Papanicolaou, Andrew C.Normal brain development throughout childhood and adolescence is usually characterized by decreased cortical thickness in the frontal regions as well as region-specific patterns of increased white matter myelination and volume. We investigated total cerebral volumes, neocortical surface area, and neocortical thickness in 16 children with a neural tube defect, spina bifida myelomeningocele (SB), and 16 age-matched typically developing controls using a semi-automated, quantitative approach to MRI-based brain morphometry. The results revealed no significant group differences in total cerebral volume. However, group differences were observed in the global distribution of distinct tissue classes within the cerebrum: the SB group demonstrated a significant 15% reduction in total white matter and a 69% increase in cerebrospinal fluid, with no differences in total gray matter. Group comparisons of neocortical surface area assessments were significantly smaller in the occipital regions for SB, with no significant group differences in the frontal regions. Group comparisons of cortical thickness measurements demonstrated reduced cortical thickness in all regions except the frontal regions, where the SB group exhibited an increase relative to the PC group. Although regional patterns of thinning may be associated with the mechanical effects of hydrocephalus, the overall reduction in white matter and increased neocortical thickness in the frontal regions suggest that SB reflects a long-term disruption of brain development that extends far beyond the neural tube defect in the first weeks of gestation.Item Neurobehavioral outcomes in spina bifida: Processes versus outcomes(Journal of Pediatric Rehabilitation Medicine, 2008-01) Fletcher, Jack M.; Ostermaier, Kathryn K.; Cirino, Paul T.; Dennis, MaureenWe review neurobehavioral outcomes and interventions for children with spina bifida. Focusing on children with spina bifida myelomeningocele, we contrast historical views of outcomes based on comparisons across content domains (e.g., language versus visual perceptual skills) with a view based on overarching processes that underlie strengths and weakness within content domains. Thus, we suggest that children with SBM have strengths when the skill involves the capacity to retrieve information from semantic memory and generate material that has been associatively linked or learned (associative processing) and general difficulties on tasks that require the construction or integration of a response (assembled processing). We use a hypothetical case to illustrate the differences in content domains versus general processes and also identify interventions that may be effective in addressing some of the cognitive and behavioral difficulties experienced variably by people with SBM. We extend these general principles to a discussion of variability in outcomes and use data from a large sample of children with spina bifida to illustrate the basis for this variability.Item Neurocognitive predictors of mathematical processing in school-aged children with spina bifida and their typically developing peers: Attention, working memory, and fine motor skills(Neuropsychology, 2015-11) Raghubar, Kimberly P.; Barnes, Marcia A.; Dennis, Maureen; Cirino, Paul T.; Taylor, Heather; Landry, SusanObjective: Math and attention are related in neurobiological and behavioral models of mathematical cognition. This study employed model-driven assessments of attention and math in children with spina bifida myelomeningocele (SBM), who have known math difficulties and specific attentional deficits, to more directly examine putative relations between attention and mathematical processing. The relation of other domain general abilities and math was also investigated. Method: Participants were 9.5-year-old children with SBM (n = 44) and typically developing children (n = 50). Participants were administered experimental exact and approximate arithmetic tasks, and standardized measures of math fluency and calculation. Cognitive measures included the Attention Network Test (ANT), and standardized measures of fine motor skills, verbal working memory (WM), and visual-spatial WM. Results: Children with SBM performed similarly to peers on exact arithmetic, but more poorly on approximate and standardized arithmetic measures. On the ANT, children with SBM differed from controls on orienting attention, but not on alerting and executive attention. Multiple mediation models showed that fine motor skills and verbal WM mediated the relation of group to approximate arithmetic; fine motor skills and visual-spatial WM mediated the relation of group to math fluency; and verbal and visual-spatial WM mediated the relation of group to math calculation. Attention was not a significant mediator of the effects of group for any aspect of math in this study. Conclusion: Results are discussed with reference to models of attention, WM, and mathematical cognition.Item Neuropsychological profiles of children with aqueductal stenosis and spina bifida myelomeningocele(Journal of the International Neuropsychological Society, 2013-02) Hampton, Lyla E.; Fletcher, Jack M.; Cirino, Paul T.; Blaser, Susan; Kramer, Larry A.; Dennis, MaureenWe compared neuropsychological profiles in children with shunted hydrocephalus secondary to aqueductal stenosis (AS), a rare form of congenital hydrocephalus, and spina bifida myelomeningocele (SBM), a common form of congenital hydrocephalus. Participants were 180 children with shunted hydrocephalus grouped according to etiology: SBM (n = 151), AS (n = 29), and typically developing (TD; n = 60) individuals. The group with AS performed below the TD group on all tasks except for reading, and their overall performance was higher than the group with SBM, who had the lowest performance in the sample. Both clinical groups significantly differed from the TD group on tasks of spatial function, concept formation, motor function, and memory. Performance of the subgroup of AS children with normal cerebellum status approximated that of the TD group, while those with cerebellar anomalies performed lower than others with AS. Cerebellar abnormalities (present in the whole SBM group and in a subset of the AD group) are associated with more compromise of cognitive as well as motor function.Item Prospective and episodic memory in relation to hippocampal volume in adults with spina bifida myelomeningocele(Neuropsychology, 2015-01) Treble-Barna, Amery; Juranek, Jenifer; Stuebing, Karla K.; Cirino, Paul T.; Dennis, Maureen; Fletcher, Jack M.The present study examined prospective and episodic memory in relation to age, functional independence, and hippocampal volume in younger to middle-aged adults with spina bifida myelomeningocele (SBM) and typically developing (TD) adults. Prospective and episodic memory, as well as hippocampal volume, was reduced in adults with SBM relative to TD adults. Neither memory performance nor hippocampal volume showed greater decrements in older adults. Lower hippocampal volume was associated with reduced prospective memory in adults with SBM, and this relation was specific to the hippocampus and not to a contrast structure, the amygdala. Prospective memory mediated the relation between hippocampal volume and functional independence in adults with SBM. The results add to emerging evidence for reduced memory function in adults with SBM and provide quantitative evidence for compromised hippocampal macrostructure as a neural correlate of reduced memory in this population.Item Strong-meter and weak-meter rhythm identification in spina bifida meningomyelocele and volumetric parcellation of rhythm-relevant cerebellar regions(Annals of the New York Academy of Sciences, 2009-07) Dennis, Maureen; Hopyan, Talar; Juranek, Jenifer; Cirino, Paul T.; Hasan, Khader M.; Fletcher, Jack M.Children with spina bifida meningomyelocele (SBM) are impaired relative to controls in terms of discriminating strong-meter and weak-meter rhythms, so congenital cerebellar dysmorphologies that affect rhythmic movements also disrupt rhythm perception. Cerebellar parcellations in children with SBM showed an abnormal configuration of volume fractions in cerebellar regions important for rhythm function: a smaller inferior-posterior lobe, and larger anterior and superior-posterior lobes.Item Sustained attention in children with two etiologies of early hydrocephalus(Neuropsychology, 2008-11) Swartwout, Maegan D.; Cirino, Paul T.; Hampson, Amy W.; Fletcher, Jack M.; Brandt, Michael E.; Dennis, MaureenSeveral studies have shown that children with spina bifida meningomyelocele (SBM) and hydrocephalus have attention problems on parent ratings and difficulties in stimulus orienting associated with a posterior brain attention system. Less is known about response control and inhibition associated with an anterior brain attention system. Using the Gordon Vigilance Task (Gordon, 1983), we studied error rate, reaction time, and performance over time for sustained attention, a key anterior attention function, in 101 children with SBM, 17 with aqueductal stenosis (AS; another condition involving congenital hydrocephalus), and 40 typically developing controls (NC). In SBM, we investigated the relation between cognitive attention and parent ratings of inattention and hyperactivity and explored the impact of medical variables. Children with SBM did not differ from AS or NC groups on measures of sustained attention, but they committed more errors and responded more slowly. Approximately one-third of the SBM group had attention symptoms, although parent attention ratings were not associated with task performance. Hydrocephalus does not account for the attention profile of children with SBM, which also reflects the distinctive brain dysmorphologies associated with this condition.Item The cerebellum in children with spina bifida and Chiari II malformation: Quantitative volumetrics by region(The Cerebellum, 2010-06) Juranek, Jenifer; Dennis, Maureen; Cirino, Paul T.; El-Messidi, Lyla; Fletcher, Jack M.Few volumetric MRI studies of the entire cerebellum have been published; even less quantitative information is available in patients with hindbrain malformations, including the Chiari II malformation which is ubiquitous in patients with spina bifida meningomyelocele (SBM). In the present study, regional volumetric analyses of the cerebellum were conducted in children with SBM/Chiari II and typically developing (TD) children. Total cerebellar volume was significantly reduced in the SBM group relative to the TD group. After correcting for total cerebellum volume, and relative to the TD group, the posterior lobe was significantly reduced in SBM, the corpus medullare was not different, and the anterior lobe was significantly enlarged. Children with thoracic level lesions had smaller cerebellar volumes relative to those with lumbar/sacral lesions, who had smaller volumes compared to TD children. The reduction in cerebellar volume in the group with SBM represents not a change in linear scaling but rather a reconfiguration involving anterior lobe enlargement and posterior lobe reduction.Item Why IQ is not a covariate in cognitive studies of neurodevelopmental disorders(Journal of the International Neuropsychological Society, 2009-05) Dennis, Maureen; Francis, David J.; Cirino, Paul T.; Schachar, Russell; Barnes, Marcia A.; Fletcher, Jack M.IQ scores are volatile indices of global functional outcome, the final common path of an individual's genes, biology, cognition, education, and experiences. In studying neurocognitive outcomes in children with neurodevelopmental disorders, it is commonly assumed that IQ can and should be partialed out of statistical relations or used as a covariate for specific measures of cognitive outcome. We propose that it is misguided and generally unjustified to attempt to control for IQ differences by matching procedures or, more commonly, by using IQ scores as covariates. We offer logical, statistical, and methodological arguments, with examples from three neurodevelopmental disorders (spina bifida meningomyelocele, learning disabilities, and attention deficit hyperactivity disorder) that: (1) a historical reification of general intelligence, g, as a causal construct that measures aptitude and potential rather than achievement and performance has fostered the idea that IQ has special status and that in studying neurocognitive function in neurodevelopmental disorders; (2) IQ does not meet the requirements for a covariate; and (3) using IQ as a matching variable or covariate has produced overcorrected, anomalous, and counterintuitive findings about neurocognitive function.