The goals of the proposed research are to (1) elucidate impairments of fundamental cognitive processes, including working memory, inhibition, and metacognitive skills in relation to the severity of closed head injury (CHI) defined by the Glasgow Coma Scale, focal brain lesions depicted by MRI, and age at injury; (2) evaluate the impact of deficits in working memory, inhibition, and metacognitive skills on outcome domains, including discourse processing, academic achievement, and adaptive behavior; (3) examine the effects of posttraumatic impairments of inhibition and metacognitive skills, CHI severity, and focal brain lesions on development of new psychiatric disorder, and assess the role of family environment, preinjury psychiatric history, and psychological stress as effect modifiers. To accomplish these goals, 332 children will be studied who sustain a CHI of varying severity, including 166 cases currently age 5-15 years who were injured at least 3 years before testing (Study I, cross-sectional/retrospective) and 166 cases, age 5-12 years at time of injury will be recruited during their initial hospitalization and serially study at 3,6,12, and 24 months postinjury (Study II, prospective). In addition, 110 uninjured, healthy children as part of Study I to obtain age-referenced comparison data. Volumetric determination of focal brain lesions and localization in Talairach space will be used to evaluate the contribution of prefrontal injury relative to other cortical and subcortical sites. Working memory is measured by matching letters on rhyme or identity with variable memory load, the Tower of London, and a divided attention task in which single vs dual task skills are compared. Inhibition is measured by Stroop-like and stop signal reaction time tasks. Metacognitive skills are assessed by tasks involving detection and repair of anomalous sentences, and judgement of learning. Measures of processing speed, motor speed, and declarative memory are also given to study interactions of these abilities with working memory, inhibition, and metacognitive skills. Discourse processing will be analyzed for summarization, lesson, and gist, while standardized tests will measure reading, arithmetic, and adaptive behavior. Structured interviews of the parent and child and supplemental measures will evaluate psychiatric status.
The Specific Aims will be addressed by linear models, including the ones designed for the analysis of change. By analyzing the nature of executive function deficits after CHI and later applying the findings to special education and rehabilitation programs, the applicant postulates that it should be possible to improve methods for assessment and design interventions for the cognitive and behavioral sequelae of head injury.
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