Objectives: The current study examined neuropsychological performance among children with spina bifida (SB) to determine biological and functional correlates of distinct “profiles” of cognitive functioning. Methods: A total of 95 children with SB myelomeningocele (ages, 8–15 years) completed a neuropsychological assessment battery. Hierarchical and non-hierarchical cluster analyses were used to identify and confirm a cluster solution. Hypothesized predictors of cluster membership included lesion level, number of shunt surgeries, history of seizures, age, ethnicity, socio-economic status, and family stress. Outcomes included independence, academic success, expectations for the future, and quality of life. Results: Ward’s cluster method indicated a three-cluster solution, and was replicated with two other cluster analytic methods. The following labels were applied to the clusters: “average to low average” (n=39), “extremely low to borderline” (n=27), and “broadly average with verbal strength” (n=29). Socio-econimc status, lesion level, and seizure history significantly predicted group membership. Cluster membership significantly predicted independence, academic success, parent expectations for the future, and child reported physical quality of life. Conclusions: Findings from this study suggest qualitatively different cognitive profiles exist among children with SB, and the relevance of neuropsychological functioning for day-to-day adaptive functioning and quality of life. Clinical implications and future research are discussed. (JINS, 2016, 22, 804–815)

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. (JINS, 2009, 15, 331–343.)

Adolescents with spina bifida (SB) vary in their ability to adapt to the disease, and it is likely that numerous risk and protective factors affect adaptation outcomes. The primary aim was to test neuropsychological impairment, exemplified herein by executive dysfunction, as a risk factor in the Ecological Model of Adaptation for Adolescents with SB. Specific hypotheses were that: (1) executive functioning predicts the adaptation outcome of functional independence in adolescents with SB; (2) executive functioning mediates the impact of neurological severity on functional independence; and (3) family and adolescent protective factors are related to functional independence and moderate the relationship between executive functioning and functional independence. Forty-three adolescents aged 12–21 years completed neuropsychological measures and an interview that assessed risk, adolescent and family protective factors, and functional independence. Age, level of lesion, executive functioning, and the protective factor adolescent activities were significantly correlated with the functional independence outcome. In hierarchical regression analysis, the model accounted for 61% of the variance in functional independence outcomes. Executive functioning mediated the impact of neurological severity on functional independence. (JINS, 2008, 14, 793–804.)

We investigated verb generation in children with spina bifida meningomyelocele (SBM; n = 55) and in typically developing controls (n = 32). Participants completed 6 blocks (40 trials each) of a task requiring them to produce a semantically related verb in response to a target noun and an additional 40 trials on which they were simply required to read target nouns aloud. After controlling for reading response time, groups did not differ significantly in verb generation response time or learning. Children with SBM produced more non-verb errors than controls and tended to repeat their mistakes over blocks. Verb generation performance was associated with brain volume measures in participants with SBM. Congenital cerebellar dysmorphology is associated with impaired performance in verb generation accuracy, although not with increased response times to produce verbs.(JINS, 2008, 14, 181–191.)

Learning and performance on a ballistic task were investigated in children with spina bifida meningomyelocele (SBM), with either upper level spinal lesions (n = 21) or lower level spinal lesions (n = 81), and in typically developing controls (n = 35). Participants completed three phases (20 trials each) of an elbow goniometer task that required a ballistic arm movement to move a cursor to one of two target positions on a screen, including (1) an initial learning phase, (2) an adaptation phase with a gain change such that recalibration of the ballistic arm movement was required, and (3) a learning reactivation phase under the original gain condition. Initial error rate, asymptotic error rate, and learning rate did not differ significantly between the SBM and control groups. Relative to controls, the SBM group had reduced volumes in the cerebellar hemispheres and pericallosal gray matter (the region including the basal ganglia), although only the pericallosal gray matter was significantly correlated with motor adaptation. Congenital cerebellar dysmorphology is associated with preserved motor skill learning on voluntary, nonreflexive tasks in children with SBM, in whom the relative roles of the cerebellum and basal ganglia may differ from those in the adult brain. (JINS, 2006, 12, 598–608.)