Neurocognitive outcomes following pediatric brain injury: A developmental approach

Developmental neuropsychologists postulate that “immaturity” of the cerebral cortex should no longer be perceived as a protective factor. They argue that injury to the young brain may affect new learning by disrupting the skills in the midst of being acquired and skills that are yet to be developed. Cognitive deficits or weaknesses that are not detectable in the acute phase following a traumatic brain injury (TBI) may emerge over development as more complex skills are needed, thereby creating a developmental lag between children who sustained a pediatric TBI and typical age peers. This literature review was conducted to evaluate the developmental perspective on neurocognitive recovery/development following a TBI. Overall, the described findings support a developmental view and suggest that predictions of prognosis should be based on the child's remaining ability to learn.     

Plasticity of nonneuronal brain tissue: roles in developmental disorders

Neuronal and nonneuronal plasticity are both affected by environmental and experiential factors. Remodeling of existing neurons induced by such factors has been observed throughout the brain, and includes alterations in dendritic field dimensions, synaptogenesis, and synaptic morphology. The brain loci affected by these plastic neuronal changes are dependent on the type of experience and learning. Increased neurogenesis in the hippocampal dentate gyrus is a well-documented response to environmental complexity ("enrichment") and learning. Exposure to challenging experiences and learning opportunities also alters existing glial cells (i.e., astrocytes and oligodendrocytes), and up-regulates gliogenesis, in the cerebral cortex and cerebellum. Such glial plasticity often parallels neuronal remodeling in both time and place, and this enhanced morphological synergism may be important for optimizing the functional interaction between glial cells and neurons. Aberrant structural plasticity of nonneuronal elements is a contributing factor, as is aberrant neuron plasticity, to neurological and developmental disorders such as epilepsy, autism, and mental retardation (i.e., fragile X syndrome). Some of these nonneuronal pathologies include abnormal cerebral and cerebellar white matter and myelin-related proteins in autism; abnormal myelin basic protein in fragile X syndrome (FXS); and abnormal astrocytes in autism, FXS, and epilepsy. A number of recent studies demonstrate the possibility of using environmental and experiential intervention to reduce or ameliorate some of the neuronal and nonneuronal abnormalities, as well as behavioral deficits, present in these neurological and developmental disorders.     

Gender and education impact on brain aging: a general cognitive factor approach

In cognitive aging research, the study of a general cognitive factor has been shown to have a substantial explanatory power over the study of isolated tests. The authors aimed at differentiating the impact of gender and education on global cognitive change with age from their differential impact on 4 psychometric tests using a new latent process approach, which intermediates between a single-factor longitudinal model for sum scores and an item-response theory approach for longitudinal data. The analysis was conducted on a sample of 2,228 subjects from PAQUID, a population-based cohort of older adults followed for 13 years with repeated measures of cognition. Adjusted for vascular factors, the analysis confirmed that women performed better in tests involving verbal components, while men performed better in tests involving visuospatial skills. In addition, the model suggested that women had a slightly steeper global cognitive decline with oldest age than men, even after excluding incident dementia or death. Subjects with higher education exhibited a better mean score for the 4 tests, but this difference tended to attenuate with age for tests involving a speed component.     

The impact of developmental speech and language impairments on the acquisition of literacy skills

Children with developmental speech/language impairments are at higher risk for reading disability than typical peers with no history of speech/language impairment. This article reviews the literacy outcomes of children with speech/language impairments, clarifying the differential risk for three groups of children: speech production impairments alone, oral language impairments alone, and speech production and oral language impairments. Children at greatest risk for reading and writing disabilities are children with language impairments alone and children with comorbid speech impairments and language impairments. For children with speech impairments alone, there is limited risk for literacy difficulties. However, even when reading skills are within the average range, children with speech impairments may have difficulties in spelling. Children with language impairments are likely to display reading deficits in word decoding and reading comprehension. It is not clear what role early literacy interventions play in the amelioration of reading difficulties in these populations.     

Confidence judgments in event recall: developmental progression in the impact of question format

Two studies were conducted to examine developmental progression in children's and adults' ability to adequately monitor their own attempts to recall event details as well as the dependence of such metamemorial competencies on question formats. Eight and 10-year-old children as well as adults (Study 1, N=116; Study 2, N=60) rated their confidence when responding to specific questions about an observed event. Confirming most recent results, children and adults gave higher confidence ratings after correct than after incorrect answers. This ability, however, was limited to an unbiased question format. When being asked misleading questions, children's ability to differentiate was undermined, as reflected in equally high confidence judgments after correct and incorrect answers, even when the interview contained a mix of misleading and unbiased questions. When the interviewer "bombarded" the children with an uninterrupted series of misleading questions, children's difficulties appeared to be even more pronounced. These findings highlight the importance of the way in which questions are asked, and point to age-related progression in the relative impact of questioning style.     

Mental retardation genes in drosophila: New approaches to understanding and treating developmental brain disorders

Drosophila melanogaster is emerging as a valuable genetic model system for the study of mental retardation (MR). MR genes are remarkably similar between humans and fruit flies. Cognitive behavioral assays can detect reductions in learning and memory in flies with mutations in MR genes. Neuroanatomical methods, including some at single-neuron resolution, are helping to reveal the cellular bases of faulty brain development caused by MR gene mutations. Drosophila fragile X mental retardation 1 (dfmr1) is the fly counterpart of the human gene whose malfunction causes fragile X syndrome. Research on the fly gene is leading the field in molecular mechanisms of the gene product's biological function and in pharmacological rescue of brain and behavioral phenotypes. Future work holds the promise of using genetic pathway analysis and primary neuronal culture methods in Drosophila as tools for drug discovery for a wide range of MR and related disorders.     

The impact of group psychotherapy on social development in children with pervasive developmental disorders

Thirty-nine children with a diagnosed pervasive developmental disorder (PDD) participated in homogeneous psychotherapy groups. Their social development was assessed at home and at school both before and after treatment. Significant improvements in social functioning were observed in both settings, and these gains were not attributable to demographic variables or cognitive development. This research provides psychometric validation for the Vineland Adaptive Behavior Scale (VABS; Sparrow, Balla, & Cicchetti, 1984) and the Tyminski Social Skills Checklist (SSC), a new index designed to assess children's social functioning in educational settings. The results suggest that group therapy may be an important modality for better understanding and developing crucial social skills among the growing number of children diagnosed with a pervasive developmental disorder.     

Social outcomes in childhood brain disorder: a heuristic integration of social neuroscience and developmental psychology

The authors propose a heuristic model of the social outcomes of childhood brain disorder that draws on models and methods from both the emerging field of social cognitive neuroscience and the study of social competence in developmental psychology/psychopathology. The heuristic model characterizes the relationships between social adjustment, peer interactions and relationships, social problem solving and communication, social-affective and cognitive-executive processes, and their neural substrates. The model is illustrated by research on a specific form of childhood brain disorder, traumatic brain injury. The heuristic model may promote research regarding the neural and cognitive-affective substrates of children's social development. It also may engender more precise methods of measuring impairments and disabilities in children with brain disorder and suggest ways to promote their social adaptation.     

Variant BDNF (Val66Met) impact on brain structure and function

Neurotrophins, such as brain-derived neurotrophic factor (BDNF), are a unique family of polypeptide growth factors that influence differentiation and survival of neurons in the developing nervous system. In adults, BDNF is important in regulating synaptic plasticity and connectivity in the brain. Recently, a common single-nucleotide polymorphism in the human BDNF gene, resulting in a valine to methionine substitution in the prodomain (Val66Met), has been shown to lead to memory impairment and susceptibility to neuropsychiatric disorders. An understanding of how this naturally occurring polymorphism affects behavior, anatomy, and cognition in adults is an important first step in linking genetic alterations in the neurotrophin system to definable biological outcomes in humans. We review the recent literature linking this BDNF polymorphism to cognitive impairment in the context of in vitro and transgenic animal studies that have established BDNF’s central role in neuronal functioning in the adult brain.     

The impact of parental divorce on the attainment of the developmental tasks of young adulthood

The purpose of this study was to assess the impact of parental divorce on young adult development. One hundred twenty-five participants provided demographic information and completed the PAFS-Q (college version) and the conflict subscale of the Family Environment Scale. Results indicate that parental divorce and family conflict significantly affect developmental task attainment. The interactions between sex and age and family structure (i.e., single-parent or stepfamily) were also significant predictors of post-divorce task attainment. Implications of these results for therapists as well as recommendations for future research are provided.This is a revised version of a paper presented at the annual conference of the American Psychological Association, Los Angles, California, August 1994.     

Measuring functional outcomes after prematurity: developmental impact of very low birth weight and extremely low birth weight status on childhood disability

Our purpose was to describe functional outcomes in essential activities in preschool, school-age, and adolescent children who were born very (<32 weeks gestation) and extremely (<28 weeks gestation) prematurely. Very low birth weight (VLBW; 1000-1499 g), or extremely low birth weight (ELBW;<1000 g) populations are the focus of our analysis. We describe models of disablement and enablement for specifying the complexity of childhood outcomes using a framework of pathophysiology, impairment, functional limitation and functional strengths, disability in social roles and social participation, societal limitations and environmental facilitators. Representative early childhood, preschool, school-age, and adolescent studies were examined in terms of describing children's functional strengths and challenges after VLBW and ELBW survival. In early childhood, disability was assessed by diagnosing neurosensory impairments and delays on developmental testing. Instruments for measuring functional status in essential activities of self-care, mobility, communication and learning are described. Rates of neurosensory disability in the first three years among recent ELBW survivors ranged from 9-26% for cerebral palsy, 1-15% for blindness, 0-9% for deafness, and 6-42% for evolving cognitive disability (MDI <70). Rates of preschool functional limitation were 5-27% motor, 5-30% self-care, and 5-22% communicative. Rates of school-age functional educational disabilities exceeded 50%. Rates of adolescent activity limitation were 13-32% and vocational limitations were 27-71%. By examining the functional strengths and challenges of children with major neurodevelopmental impairments after very or extremely preterm birth, we can examine causal pathways that lessen the risk of severe functional disability. Among children with mild to moderate disability, we can enhance functional outcomes, optimize community participation, and provide quality family supports. In order to assess the changing outcomes of this vulnerable population of survivors, combinations of clinical and survey based methodologies are required.     

The impact of school connectedness on violent behavior, transport risk-taking behavior, and associated injuries in adolescence

Adolescents engage in many risk-taking behaviors that have the potential to lead to injury. The school environment has a significant role in shaping adolescent behavior, and this study aimed to provide additional information about the benefits associated with connectedness to school. Early adolescents aged 13 to 15 years (N = 509, 49% boys) were surveyed about school connectedness, engagement in transport and violence risk-taking, and injury experiences. Significant relations were found between school connectedness and reduced engagement in both transport and violence risk-taking, as well as fewer associated injuries. This study has implications for the area of risk-taking and injury prevention, as it suggests the potential for reducing adolescents' injury through school based interventions targeting school connectedness.     

Prevalence and correlates of depressive symptoms following traumatic brain injuries in children.

The prevalence and correlates of depressive symptoms following childhood traumatic brain injuries (TBI) were examined using data drawn from a prospective longitudinal study. Participants included 38 children with severe TBI, 51 with moderate TBI, and 55 with orthopedic injuries (OI). Assessments occurred shortly after injury (baseline) and at 6- and 12-month follow-ups. Children completed the Child Depression Inventory (CDI). Parents rated depressive symptoms using the Child Behavior Checklist (CBC), with baseline ratings reflecting premorbid status. Assessments also included measures of children's neurocognitive functioning and the family environment. The three groups did not differ overall in self-reported symptoms on the CDI, but did display different trends over time. The three groups did not differ on parent ratings of premorbid depressive symptoms on the CBC, but parents reported more depressive symptoms in the TBI groups than in the OI group at 6- and 12-month follow-ups. Child and parent reports were correlated for children in the TBI groups, but not for those in the OI group. Depressive symptoms were related to socioeconomic status in all groups. Socioeconomic status also was a significant moderator of group differences, such that the effects of TBI were exacerbated in children from more disadvantaged homes. Although self-reports of depressive symptoms were related inconsistently to children's verbal memory, parent reports of depressive symptoms were unrelated to IQ or verbal memory. The findings suggest that TBI increases the risk of depressive symptoms, especially among more socially disadvantaged children, and that depressive symptoms are not strongly related to post-injury neurocognitive deficits.     

Loneliness and life satisfaction of boys with developmental coordination disorder: the impact of leisure participation and perceived freedom in leisure

A theoretical model linking motor ability with perceived freedom in leisure, participation in team sports, loneliness, and global life satisfaction was tested using linear confirmatory path analysis. Participants were 173 boys aged 10-13 years who filled in self-report questionnaires about perceived freedom in leisure, loneliness, and global life satisfaction. Parents of boys completed 7-day diaries and 12-month retrospective recall questionnaires about their son's leisure-time activity participation. Results of path analyses confirmed that the fit of the hypothetical model was consistent with predictions. The inferred direct pathways of influence between both total loneliness and global life satisfaction on motor ability were in the expected directions (i.e., inverse and positive relationships, respectively). Perceived Freedom in Leisure (PFL) and participation in team sports were two intermediate variables indirectly influencing these relationships. Although PFL was identified as a motivational process influencing participation levels in team sports it was noted that other psychological and environmental factors must also be considered when evaluating child-activity-environment fit for boys with developmental coordination disorder.     

帕金森病发病与小胶质细胞老化关系的探讨

帕金森病(PD)是一种中老年常见的神经退行性病变.其发病机制可能与小胶质细胞(MI)的慢性炎症反应有关.老化的M1通过释放炎症介质导致多巴胺(DA)神经元大量死亡,帕金森病临床发病.因此澄清MI老化的原因对于了解PD发病及防治策略具有重要意义.