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Date of Award


Document Type

Dissertation - NSU Access Only

Degree Name

Doctor of Psychology (PhD)


Center for Psychological Studies

First Advisor

Ed Simco

Second Advisor

Susan Ireland


Brain, TBI, WAIS-IV, Wechsler


Traumatic Brain Injury (TBI) is a major concern for health professionals as it is a leading cause of death and disability in the United States. Patients can experience difficulties that include intellectual impairment, memory impairment, and executive functioning deficits. Psychometric tests have been used to assist in the diagnosis of head injuries. Specifically, the Wechsler scales are recognized in the scientific and medical communities as the most widely utilized measure of general intellectual function in older adolescents and adults. The recently published Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) is a revision of the WAIS-III. No studies have been published to date relevant to the effects of head trauma or other neurological disorders due to the recent introduction of the test. The purpose of the study was to understand the immediate intellectual consequences of head injury in adults along a continuum of severity, evaluate whether new additions to the WAIS-IV provide additional information about the effects of head trauma, and determine if the length of recovery affects the WAIS-IV indices differently. A total of 47 participants between the ages of 18-89 were selected from inpatient and outpatient admissions at a major trauma center. Participants who had sustained a closed-head injury were selected and tested between 1 month and 36 months post-injury (once any post traumatic amnesia had resolved). Patients were administered the Galveston Orientation Amnesia Test, Wechsler Test of Adult Reading, and WAIS-IV. The main question addressed by the current study was the extent to which brain injured adults display intellectual deficits and if these were consistent with those observed on prior versions of the Wechsler scales. An examination of the pattern of intellectual impairments and the effects of demographic corrections on the WAIS-IV was also conducted. Results indicated that the WAIS-IV IQ and indexes were reduced significantly by traumatic brain injury, and that more severe injuries were likely to show the most pronounced effect on the Processing Speed Index. Abnormalities visualized by brain CT or MRI scans were associated with lower IQ's and index scores than were shown by patients with traumatic head injury that had normal CT scans. There was no evidence that corrections for educational level, ethnicity, and gender improved the sensitivity of the WAIS-IV to injury severity beyond that obtained by corrections for age.

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