Tamara D. Warner

Diffusion Tensor Imaging of Frontal White Matter and Executive Functioning in Cocaine-Exposed Children

BACKGROUND. Although animal studies have demonstrated frontal white matter and behavioral changes resulting from prenatal cocaine exposure, no human studies have associated neuropsychological deficits in attention and inhibition with brain structure. We used diffusion tensor imaging to investigate frontal white matter integrity and executive functioning in cocaine-exposed children. METHODS. Six direction diffusion tensor images were acquired using a Siemens 3T scanner with a spin-echo echo-planar imaging pulse sequence on right-handed cocaine-exposed (n = 28) and sociodemographically similar non-exposed children (n = 25; mean age: 10.6 years) drawn from a prospective, longitudinal study. Average diffusion and fractional anisotropy were measured in the left and right frontal callosal and frontal projection fibers. Executive functioning was assessed using two well-validated neuropsychological tests (Stroop color-word test and Trail Making Test). RESULTS. Cocaine-exposed children showed significantly higher average diffusion in the left frontal callosal and right frontal projection fibers. Cocaine-exposed children were also significantly slower on a visual-motor set-shifting task with a trend toward lower scores on a verbal inhibition task. Controlling for gender and intelligence, average diffusion in the left frontal callosal fibers was related to prenatal exposure to alcohol and marijuana and an interaction between cocaine and marijuana exposure. Performance on the visual-motor set-shifting task was related to prenatal cocaine exposure and an interaction between cocaine and tobacco exposure. Significant correlations were found between test performance and fractional anisotropy in areas of the frontal white matter. CONCLUSIONS. Prenatal cocaine exposure, alone and in combination with exposure to other drugs, is associated with slightly poorer executive functioning and subtle microstructural changes suggesting less mature development of frontal white matter pathways. The relative contribution of postnatal environmental factors, including characteristics of the caregiving environment and stressors associated with poverty and out-of-home placement, on brain development and behavioral functioning in polydrug-exposed children awaits further research.

One Size Still Does Not Fit All in Specific Learning Disability Assessment Across Ethnic Groups

The use of IQ scores and discrepancy formulas for identifying specific learning disabilities (SLD) has been widely discredited by prominent researchers for more than a decade. Nevertheless, the overwhelming majority of state policies still specify the use of discrepancy formulas, including the simple difference method, which is psychometrically inferior to regression-based methods. This study compares the use of a minimum IQ cutoff score and a simple difference method versus a regression-based method for identifying SLD in a sample of African American and European American full-time college students (N = 117). Replicating the findings from previous studies using typically achieving children, typically achieving adults, and school-age children with SLD, this study adds to the chorus of voices criticizing the use of outdated assessment practices that can have deleterious effects for individuals with SLD. The implications for legislative policy are discussed in the context of the historical overrepresentation of African Americans in all special education categories except SLD and the increased access to higher education that students with SLD have gained during the past decade.

Executive functioning at ages 5 and 7 years in children with prenatal cocaine exposure.

This prospective longitudinal study evaluated the effect of prenatal cocaine exposure (PCE) on executive functioning in 5- and 7-year-old children. In total, 154 pregnant cocaine users, identified by urine toxicology and structured interviews, were matched to 154 nonusers. Children were assessed by certified masked evaluators, and caregivers were interviewed by experienced staff during home visits. In approximately 90% of the surviving sample tested at ages 5 and 7 years, structural equation modeling demonstrated that an increased head circumference at birth (adjusted for gestation) significantly predicted better performance on executive functioning, and that PCE was indirectly related to executive functioning through its significant negative effect on head circumference at birth. At age 5 years, quality of environment also predicted executive functioning, and the R2 for the total model was 0.24. At 7 years, caregiver functioning predicted quality of environment, which in turn was positively related to executive functioning, and girls had better executive functioning. The total model at age 7 years accounted for 30% of the variance in executive functioning.

White matter microstructure abnormalities and executive function in adolescents with prenatal cocaine exposure

Children with prenatal exposure to cocaine are at higher risk for negative behavioral function and attention difficulties, and have demonstrated brain diffusion abnormalities in frontal white matter regions. However, brain regions beyond frontal and callosal areas have not been investigated using diffusion tensor imaging (DTI). DTI data were collected on 42 youth aged 14-16 years; subjects were divided into three groups based on detailed exposure histories: those with prenatal exposure to cocaine but not alcohol (prenatal cocaine exposure (PCE), n=12), prenatal exposure to cocaine and alcohol (cocaine and alcohol exposure (CAE), n=17), and controls (n=13). Tractography was performed and along-tract diffusion parameters were examined for group differences and correlations with executive function measures. In the right arcuate fasciculus and cingulum, the CAE group had higher fractional anisotropy (FA) and/or lower mean diffusivity (MD) than the other two groups. The PCE group demonstrated lower FA in the right arcuate and higher MD in the splenium of the corpus callosum than controls. Diffusion parameters in tracts with group differences correlated with measures of executive function. In conclusion, these diffusion differences in adolescents with prenatal cocaine exposure suggest localized, long-term structural brain alterations that may underlie attention and response-inhibition difficulties.

Executive function and cortical thickness in youths prenatally exposed to cocaine, alcohol and tobacco

Highlights • 14–16 yo youth with prenatal cocaine exposure (27) and socio-demographically matched controls (15) were given MRI.• Executive function was similar between groups but cortical thickness differences observed in those with PCE.• Children with PCE could have subtle but persistent brain cortical differences until mid-to-late adolescence.

Adolescents with prenatal cocaine exposure show subtle alterations in striatal surface morphology and frontal cortical volumes

BackgroundPublished structural neuroimaging studies of prenatal cocaine exposure (PCE) in humans have yielded somewhat inconsistent results, with several studies reporting no significant differences in brain structure between exposed subjects and controls. Here, we sought to clarify some of these discrepancies by applying methodologies that allow for the detection of subtle alterations in brain structure.MethodsWe applied surface-based anatomical modeling methods to magnetic resonance imaging (MRI) data to examine regional changes in the shape and volume of the caudate and putamen in adolescents with prenatal cocaine exposure (n = 40, including 28 exposed participants and 12 unexposed controls, age range 14 to 16 years). We also sought to determine whether changes in regional brain volumes in frontal and subcortical regions occurred in adolescents with PCE compared to control participants.ResultsThe overall volumes of the caudate and putamen did not significantly differ between PCE participants and controls. However, we found significant (P <0.05, uncorrected) effects of levels of prenatal exposure to cocaine on regional patterns of striatal morphology. Higher levels of prenatal cocaine exposure were associated with expansion of certain striatal subregions and with contraction in others. Volumetric analyses revealed no significant changes in the volume of any subcortical region of interest, but there were subtle group differences in the volumes of some frontal cortical regions, in particular reduced volumes of caudal middle frontal cortices and left lateral orbitofrontal cortex in exposed participants compared to controls.ConclusionsPrenatal cocaine exposure may lead to subtle and regionally specific patterns of regional dysmorphology in the striatum and volumetric changes in the frontal lobes. The localized and bidirectional nature of effects may explain in part the contradictions in the existing literature.

Knowledge and Awareness of Sickle Cell Trait Among Young African American Adults.

Sickle cell trait (SCT) places individuals at risk of passing an abnormal hemoglobin gene to biological children and is associated with rare but serious complications. The present study sought to examine knowledge of SCT and awareness of personal trait status among 258 young African American adults. Participants were surveyed regarding demographics, medical history, and sources of sickle cell information before completing a trait knowledge questionnaire. Overall, participants possessed significant misinformation about the condition. Women and those who had learned about sickle cell from families displayed higher levels of knowledge. Most participants were uncertain of personal trait status, and many did not wish to be informed of it. Health care providers should be alert that individuals with SCT may be unaware of their condition and potential reproductive and health implications. Screening and reporting procedures should be examined to ensure individuals have access to and control of this vital health information.

Experiences of Pediatric Patients With Sickle Cell Disease in Rural Emergency Departments.

Background: The aims of this study were to describe guardian perceptions of the experiences of a sample of youth with sickle cell disease (SCD) in rural emergency departments (EDs) with a focus on overall patient satisfaction and characteristics of care. Procedure: Guardians of 139 children with SCD (0 to 17 y) seen at a rural pediatric SCD clinic completed a survey concerning their children’s ED experiences in the past 6 months, including information about ED wait times, quality of communications and interactions with the ED health care providers, pain management, perceptions of speed of care, and overall satisfaction. Results: About 41% of guardians reported that their child visited the ED in the past 6 months. Guardians reported moderate satisfaction with ED care. About 25% of those who visited the ED indicated that health care providers did not spend enough time with them and their children did not receive speedy care. Shorter ED wait times and higher ratings of speed of care predicted higher satisfaction. Conclusions: Families of youth with SCD are experiencing longer wait times in rural EDs which contribute to dissatisfaction with care. Efforts are needed to develop strategies to reduce ED wait times and improve speed of care which may improve outcomes following ED care.