Biomedical subjects

Linda Ewing-Cobbs

Publications and source records attributed to Linda Ewing-Cobbs.

16 recordsLinked to original sources

PubMed2006

Diffusion tensor imaging-based tissue segmentation: validation and application to the developing child and adolescent brain.

We present and validate a novel diffusion tensor imaging (DTI) approach for segmenting the human whole-brain into partitions representing grey matter (GM), white matter (WM) and cerebrospinal fluid (CSF). The approach utilizes the contrast among tissue types in the DTI anisotropy vs. diffusivity rotational invariant space. The DTI-based whole-brain GM and WM fractions (GMf and WMf) are contrasted with the fractions obtained from conventional magnetic resonance imaging (cMRI) tissue segmentation (or clustering) methods that utilized dual echo (proton density-weighted (PDw)), and spin-spin relaxation-weighted (T2w) contrast, in addition to spin-lattice relaxation weighted (T1w) contrasts acquired in the same imaging session and covering the same volume. In addition to good correspondence with cMRI estimates of brain volume, the DTI-based segmentation approach accurately depicts expected age vs. WM and GM volume-to-total intracranial brain volume percentage trends on the rapidly developing brains of a cohort of 29 children (6-18 years). This approach promises to extend DTI utility to both micro and macrostructural aspects of tissue organization.

Adolescent↗

PubMed2006

Evaluation of the errorless learning technique in children with traumatic brain injury.

OBJECTIVE: To compare errorless learning with trial-and-error (T&E) learning of declarative facts in children with memory disorders secondary to traumatic brain injury (TBI). DESIGN: Retrospective within-subjects concurrent treatment design. SETTING: Participants' school or home. PARTICIPANTS: Thirty-four children, ages 6 to 18 years, with mild, moderate, or severe postacute TBI who met criteria for memory impairment. INTERVENTION: Conditions consisted of an errorless learning method and a T&E method. Within a session, half the items were taught with the errorless learning method and half with the T&E method. Each child received two 1-hour sessions a week for 7 weeks. MAIN OUTCOME MEASURES: Relative effectiveness of errorless learning and T&E methods for (1) initial learning and (2) retention over time for learned items. RESULTS: There was an advantage for T&E on initial learning. In children with mild, but not moderate or severe TBI, 2-day retention was better with the errorless learning technique; 7-day retention was better with errorless learning in young children with mild TBI. Seventy-seven-day retention revealed an advantage for errorless learning in younger children with severe TBI. CONCLUSIONS: Findings did not support errorless learning as a generalized intervention for learning difficulties after TBI or identify specific age- or injury-severity groups that benefited from this technique.

Adolescent↗

PubMed2006

Predictors of personality change due to traumatic brain injury in children and adolescents six to twenty-four months after injury.

Phenomenology and predictive factors of personality change due to traumatic brain injury (TBI) 6 to 24 months after injury was investigated in children, ages 5 to 14 years, enrolled from consecutive admissions and followed prospectively for 2 years. Injury and preinjury psychosocial variables were assessed. Personality change occurred in 13% of participants between 6 and 12 months after injury and 12% in the second year after injury. Severity of injury consistently predicted personality change, and preinjury adaptive function predicted personality change only in the second year postinjury. Lesions of the superior frontal gyrus were associated with personality change between 6 and 12 months following injury, after controlling for severity of injury and the presence of other brain lesions. Only lesions in the frontal lobe white matter were significantly related to personality change in the second year after injury. After childhood TBI, neural correlates of personality change evolve between 6 and 12 months and 12 to 24 months after injury. The data implicate the dorsal prefrontal cortex and frontal lobe white matter in the emergence of personality change involving the effortful or conscious regulation of affective states.

Adolescent↗

PubMed2005

Predictors of personality change due to traumatic brain injury in children and adolescents in the first six months after injury.

OBJECTIVE: To assess the phenomenology and predictive factors of personality change due to traumatic brain injury. METHOD: Children (N = 177), aged 5 to 14 years with traumatic brain injury from consecutive admissions to five trauma centers, were followed prospectively at baseline and 6 months with semistructured psychiatric interviews. Injury severity, lesion characteristics, and preinjury variables including psychiatric disorder, family psychiatric history, family function, socioeconomic status, psychosocial adversity, and adaptive function were assessed with standardized instruments. RESULTS: Personality change occurred in 22% of participants in the first 6 months after injury. Severity of injury predicted personality change, whereas none of the psychosocial variables predicted personality change. Lesions of the dorsal prefrontal cortex, specifically the superior frontal gyrus, were associated with personality change after controlling for severity of injury or the presence of other lesions. CONCLUSIONS: These findings are consistent with models of affective dysregulation that implicate a dorsal prefrontal cortex system important for effortful regulation of affective states.

Adolescent↗

PubMed2005

Predictors of secondary attention-deficit/hyperactivity disorder in children and adolescents 6 to 24 months after traumatic brain injury.

OBJECTIVE: To assess the phenomenology and predictive factors of attention-deficit/hyperactivity disorder (ADHD) after traumatic brain injury (TBI), also called secondary ADHD (SADHD). METHOD: Children without preinjury ADHD 5-14 years old with TBI from consecutive admissions (n = 143) to five trauma centers were observed prospectively from 6 to 12 months (12-month assessment) and from 12 to 24 months (24-month assessment) postinjury with semistructured psychiatric interviews. Injury and preinjury psychosocial variables were assessed. RESULTS: SADHD occurred in 15 of 103 (15%) of participants between 6 and 12 months after injury and 17 of 82 (21%) in the second year after injury. SADHD was significantly (p < .05) comorbid with personality change due to TBI and new-onset disruptive behavior disorders. Preinjury adaptive function was a consistent predictor of SADHD. Regression analyses revealed that preinjury psychosocial adversity was an independent predictor of SADHD in the second year after injury. Neither severity of injury nor lesion location predicted SADHD from 6 to 24 months postinjury. CONCLUSIONS: Determination of preinjury psychosocial adversity and the child's preinjury functioning during the index hospitalization would improve identification of children at highest risk of development of SADHD.

Adolescent↗

PubMed2005

Predictors of attention-deficit/hyperactivity disorder within 6 months after pediatric traumatic brain injury.

OBJECTIVE: To assess the phenomenology and predictive factors of attention-deficit/hyperactivity disorder (ADHD) after traumatic brain injury (TBI), also called secondary ADHD (SADHD). METHOD: Children without preinjury ADHD 5-14 years old with TBI from consecutive admissions (n = 143) to five trauma centers were observed prospectively for 6 months (baseline and 6 months), with semistructured psychiatric interviews. Injury severity, lesion characteristics, and preinjury variables including psychiatric disorder, family psychiatric history, family psychiatric history of ADHD, family function, socioeconomic status, psychosocial adversity, and adaptive function were assessed with standardized instruments. RESULTS: SADHD in the first 6 months after injury occurred in 18 of 115 (16%) of returning participants. All subtypes of ADHD occurred. Socioeconomic status (p = .041) and orbitofrontal gyrus lesions (p = .005) independently significantly predicted SADHD. CONCLUSIONS: These findings are consistent with research on developmental ADHD that implicate psychosocial factors and prefrontal structural and functional differences between those with and without the disorder.

Adolescent↗

PubMed2005

Response inhibition after traumatic brain injury (TBI) in children: impairment and recovery.

Children who experience traumatic brain injury (TBI) often show cognitive impairments postinjury, some of which recover over time. We examined the recovery of motor response inhibition immediately following TBI and over 2 years. We assessed the role of injury severity, age at injury, and lesion characteristics on initial impairment and recovery while considering the role of pre-injury psychiatric disorder. Participants were 136 children with TBI aged 5-16 years. Latency of motor response inhibition was measured with the stop-signal task within 1 month of the injury and again at 3, 6, 12, and 24 months. The performance of the TBI participants at each measurement occasion was standardized with 117 children of similar age, but without injury. Residualized latency scores were calculated. Growth curve analyses showed an initial impairment in response inhibition and improvement over the 2 years following injury. Younger TBI patients were initially more impaired although they exhibited greater recovery of response inhibition than did older TBI patients. Longer duration of coma, but not reactivity of pupils or Glasgow Coma Scale score, predicted initial deficit. Lesion characteristics or pre-injury attention deficit hyperactivity disorder did not predict initial impairment or recovery. Replication with longitudinal testing of a comparison group of children sustaining extracranial injury is necessary to confirm our findings.

Adolescent↗

PubMed2004

Psychosocial outcome of TBI in children with unilateral frontal lesions.

To evaluate effects of unilateral frontal lesions on psychosocial and global outcome of traumatic brain injury (TBI) in children, Study 1 compared matched groups of 22 school aged children who had sustained TBI either with or without unilateral frontal lesions. Study 2 evaluated effects of unilateral extrafrontal lesions in 18 TBI patients as compared with 18 nonlesional TBI patients. Communication, Daily Living, and Socialization domains and the Maladaptive Behavior Scale of the Vineland Adaptive Behavior Scales (VABS) were used to assess psychosocial outcome, and the Glasgow Outcome Scale (GOS) measured global outcome. All patients underwent magnetic resonance imaging at least 3 months post injury. Children with frontal lesions had worse scores on the Daily Living and Socialization domains and a higher frequency of maladaptive behavior than those without frontal lesions, but there was no difference in cognitive function. Disability was twice as common in the frontal lesion group relative to children without frontal lesions. Volume of frontal lesion was related to the Socialization domain. Side of lesion had no effect, nor did presence of an extrafrontal lesion (Study 2). Unilateral frontal lesions adversely affect late psychosocial outcome of TBI in children.

Activities of Daily Living↗

PubMed2004

Changes in working memory after traumatic brain injury in children.

The impact of traumatic brain injury (TBI) on working memory (WM) was studied in 144 children (79 with mild, 23 with moderate, and 42 with severe injuries) who underwent magnetic resonance imaging (MRI) at 3 months and were tested at baseline and at 3, 6, 12, and 24 months postinjury. An n-back WM task for letter identity was administered with memory load ranging from 1- to 3-back and a 0-back condition. A TBI Severity x Quadratic Tune interaction showed that net percentage correct (correct detections of targets minus false alarms) was significantly lower in severe than in mild TBI groups. The Left Frontal Lesions x Age interaction approached significance. Mechanisms mediating late decline in WM and the effects of left frontal lesions are discussed.

Adolescent↗

PubMed2004

Modeling of longitudinal academic achievement scores after pediatric traumatic brain injury.

In a prospective longitudinal study, academic achievement scores were obtained from youth 5 to 15 years of age who sustained mild-moderate (n = 34) or severe (n = 43) traumatic brain injuries (TBI). Achievement scores were collected from baseline to 5 years following TBI and were subjected to individual growth curve analysis. The models fitted age at injury, years since injury, duration of impaired consciousness, and interaction effects to Reading Decoding, Reading Comprehension, Spelling, and Arithmetic standard scores. Although scores improved significantly over the follow-up relative to normative data from the standardization sample of the tests, children with severe TBI showed persistent deficits on all achievement scores in comparison to children with mild-moderate TBI. Interactions of the slope and age parameters for the Arithmetic and Reading Decoding scores indicated greater increases over time in achievement scores of the children injured at an older age, but deceleration in growth curves for the younger children with both mild-moderate and severe TBI. These results are compatible with the hypothesis that early brain injuries disrupt the acquisition of some academic skills. Hierarchical regression models revealed that indexes of academic achievement obtained 2 years following TBI had weak relations with the duration of impaired consciousness and socioeconomic status. In contrast, concurrent cognitive variables such as phonological processing and verbal memory accounted for more variability in academic scores. Given the significant and persistent decrement in basic academic skills in youth with severe TBI, it is clear that head-injured youth require intensive, long-term remediation and intervention not only of the academic skills themselves, but also of those cognitive abilities that support the development and maintenance of reading and math.

Achievement↗

PubMed2004

Executive functions following traumatic brain injury in young children: a preliminary analysis.

To examine executive processes in young children with traumatic brain injury (TBI), we evaluated performance of 44 children who sustained moderate-to-severe TBI prior to age 6 and to 39 comparison children on delayed response (DR), stationary boxes, and spatial reversal (SR) tasks. The tasks have different requirements for holding mental representations in working memory (WM) over a delay, inhibiting prepotent responses, and shifting response set. Age at the time of testing was divided into 10- to 35- and 36- to 85-month ranges. In relation to the community comparison group, children with moderate-to-severe TBI scored significantly lower on indexes of WM/inhibitory control (IC) on DR and stationary boxes tasks. On the latter task, the Age x Group interaction indicated that performance efficiency was significantly reduced in the older children with TBI relative to the older comparison group; performance was similar in younger children irrespective of injury status. The TBI and comparison groups did not differ on the SR task, suggesting that shifting response set was not significantly altered by TBI. In both the TBI and comparison groups, performance improved with age on the DR and stationary boxes tasks. Age at testing was not significantly related to scores on the SR task. The rate of acquisition of working memory (WM) and IC increases steeply during preschool years, but the abilities involved in shifting response set show less increase across age groups (Espy, Kaufmann, & Glisky, 2001; Luciana & Nelson, 1998). The findings of our study are consistent with the rapid development hypothesis, which predicts that skills in a rapid stage of development will be vulnerable to disruption by brain injury.

Attention↗

PubMed2004

Social competence in young children with inflicted traumatic brain injury.

As infants develop skills that allow for increasing independence in social and cognitive domains, they acquire the ability to identify goals, sequence behaviors to carry out goals, and to flexibly use strategies for attaining goals in both social and independent play contexts. Little is known about how brain injury in young children may disrupt the precursors to such executive processes. In this study, we examined social and cognitive competence in 25 infants ages 3 to 23 months who sustained moderate to severe traumatic brain injury (TBI) secondary to physical abuse and in 22 healthy community comparison children. Children with TBI were evaluated an average of 1.6 months after the injury. A toy-centered activity with the examiner was used to capture joint attention and social behavior and an exploratory toy play situation was used to measure independent goal-directed play. The inflicted TBI group showed significant reduction in both social and cognitive domains relative to the comparison group. Canonical correlation analyses disclosed that inflicted TBI was associated with reduction in (a) initiation of social interactions, (b) responsiveness to interactions initiated by the examiner, (c) positive affect, and (d) compliance. The groups performed comparably on indexes of gestural and verbal communication and for the occurrence of negative affect. Joint attention was an area of vulnerability for the TBI group in both social initiation and response contexts. Although general cognitive and motor scores were lower in the inflicted TBI group, the complexity of independent toy play did not differ across groups. Early brain injury causes significant disruption in behaviors regulating initiation and responsiveness in social contexts. Longitudinal follow-up will characterize the long-term consequences of early disruption in joint attention and other behaviors on the development of social and cognitive precursors to executive processes.

Analysis of Variance↗

PubMed2003

Early brain injury in children: development and reorganization of cognitive function.

Children who sustain congenital or acquired brain injury typically experience a diffuse insult that impacts many areas of the brain. Yet research has only recently begun to examine the development of these children, who often provide excellent examples of the presence or absence of neural plasticity. Development and recovery after such injuries reflects both restoration and reorganization of cognitive functions. To understand these processes, research should focus on questions and assessment paradigms oriented toward the acquisition (rather than the recovery) of cognitive functions. Outcomes may appear similar across types of insults, even when the sources of difficulties and their neural correlates are different. Comparisons of outcomes involving intellectual functions, memory and learning, reading, and language/discourse in children who sustain congenital injury (spina bifida meningomyelocele) and acquired injury (traumatic brain injury) illustrate these principles and the value of research on diffuse brain injury in children.

Brain Injuries↗

PubMed2002

Working memory after traumatic brain injury in children.

To investigate the effects of traumatic brain injury on working memory in children, we administered semantic (letter identity) and phonological (letter rhyme) N-back tasks to children who were on average 5 years post-mild (n = 54) or -severe (n = 26) traumatic brain injury and 44 typically developing children who were comparable in age. The correct detection of targets and false alarms were measured for each task. Memory load (which varied from 0 to 3 letters back) and age significantly affected the detection of targets and false alarms in both tasks. The severity of traumatic brain injury affected the correct detection of letters on the identity task and false alarms on the rhyme task. Traumatic brain injury severity also interacted with memory load in its effect on false alarms on the rhyme task. Traumatic brain injury results in impaired working memory and diminished inhibition in children. The N-back working memory task is feasible for administration to brain-injured children and potentially could be useful for studying brain activation associated with working memory and effects of drug therapy in this group of patients.

Adolescent↗

PubMed2002

Linguistic outcomes following traumatic brain injury in children.

Recent studies of outcome after traumatic brain injury (TBI) emphasize the adverse effect of diffuse brain injury on linguistic development. This article reviews studies of lexical development, discourse processes, and reading in children and adolescents with TBI. The child's developmental level at the time of injury is related to the pattern of deficits. Young children who sustain severe TBI are particularly vulnerable to linguistic deficits at both lexical and discourse levels. TBI in older children and adolescents preferentially disrupts higher-order discourse functions. The contribution of deficits in fundamental processes, such as working memory and processing speed, to linguistic outcomes requires further investigation.

Adolescent↗

PubMed2002

Predictors of outcome following traumatic brain injury in young children.

The relationship between clinical and neuroimaging variables and multiple outcome measures was examined in a longitudinal, prospective study of 60 children less than 6 years of age who sustained either inflicted or noninflicted traumatic brain injury. Hierarchical multiple regression indicated that the modified Glasgow Coma Scale score, the duration of impaired consciousness and the number of intracranial lesions visualized on CT/MRI accounted for a significant amount of the variance in the Glasgow Outcome Scale (GOS), cognitive and motor scores at baseline, 3- and 12-month evaluations. Inflicted brain injury adversely affected both GOS and cognitive outcomes. Pupillary abnormalities were associated with poorer motor outcome. Neither age at injury nor the Injury Severity Score accounted for significant variability in outcomes.

Brain Injury, Chronic↗