Dissertation (Ph.D.)--University of South Florida, 2007. / Title from PDF of title page. Document formatted into pages; contains 194 pages. Includes vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [104]-122).

Thesis (Ph. D.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains vii, 174 p. Includes abstract. Includes bibliographical references (p. 138-152).

Thesis (Ph.D.) -- University of Texas Southwestern Medical Center at Dallas, 2005. / On campus access only. Vita. Bibliography: 124-141.

Thesis (M.S.)--University of North Texas, May, 2007. / Title from title page display. Includes bibliographical references.

Thesis (M.S.)--Uniformed Services University of the Health Sciences, 2006 / Typescript (photocopy)

Thesis (doctoral)--La Salle University, 2002. / ProQuest dissertations and theses ; AAT 3108288. Includes bibliographical references (leaves 97-111).

This study investigates the effects of cumulative concussive and subconcussive mild head injury on the cognitive functioning of professional rugby players. A comprehensive battery of neuropsychological tests was administered to 26 professional rugby players and a noncontact sport control group of 21 professional cricket players. The test performances of the rugby players were compared to those of the cricket players. Within the rugby group, forward and backline players were compared. An analysis of mean score differences between the rugby and cricket group failed to support the presence of brain damage effects in the rugby group. However, there was significantly increased variability of scores for the rugby players compared with the cricket players on tests particularly sensitive to cognitive deficit associated with mild head injury. This invalidates the null indications of average effects, indicating that a notable proportion of rugby players’ performances were falling off relative to the rest of the rugby players on tests vulnerable to the cognitive effects of diffuse brain damage. Mean score comparisons within the rugby group indicated that it was the subgroup of forward players, in particular, whose test performances revealed deficits suggestive of cerebral damage. Specifically, deficits were found in working memory, visuoperceptual tracking, verbal memory and visual memory, a pattern of deficits commensurate with cumulative mild head injury. The theoretical perspectives of Satz’s (1997) Brain Reserve Capacity Theory and Jordan’s (1997) ‘Shuttle’ model of variability are drawn upon in order to elucidate research findings and suggestions for future research are provided.

This study investigates the effects of cumulative mild head injury on the cognitive functioning of elite rugby players. A comprehensive battery of neuropsychological tests was administered to top national (Springbok) rugby players (n=26), national Under 21 rugby players (n= 19), and a non-contact sport control group of national hockey players (n=21). The test results of the Total Rugby group (Springbok Rugby and Under 21 Rugby players), the Under 21 Rugby group, the hockey controls, and the Total Rugby and Under 21 Rugby forward and backline players respectively, were each compared with established normative data. Results showed significant differences in the direction of a poorer performance relative to the norms for the Total Rugby and Under 21 Rugby groups, and for the Total Rugby Forwards and Under 21 Rugby Forwards, on tests sensitive to the effects of diffuse brain damage. On the other hand, the Hockey Control group and the Total Rugby Backs and Under 21 Rugby Backs tended to perform within the normal range or better than the norm on some tests. These results confirm the hypothesis that rugby players, and the forward players in particular, are at risk of adverse cognitive effects consequent on cumulative mild head injury. The theoretical implications are that the aggregate effects of multiple exposures to mild head injuries in the rugby players served to reduce their brain reserve capacities and acted as a threshold-lowering influence associated with symptom onset.

sustained multiple concussions may be at risk of cumulative impairment. The role of neuropsychological testing in the management of sports-related concussion is a contentious and challenging issue which has gained credibility given the lack of clear and well-established guidelines pertaining to the diagnosis, assessment and return-to-play decisions following concussion. Despite various traditional paper and pencil tests being shown to be effective indicators of postconcussive neuropsychological dysfunction, testing has not been widely implemented, due to time- and labour-demands. ImPACT, a computer-based neuropsychological assessment instrument, has been recognised as a valid and reliable tool in the monitoring of athletes' symptoms and neurocognitive functioning preseason and postconcussion. As a part of larger-scale concussion research conducted on top-team university rugby players, this is an in-depth case study conducted on a 20-year old participant with a history of multiple concussions, who was referred following a concussion sustained during the season. The objectives of the study were: (i) to determine the sensitivity of ImPACT versus WAIS-III Digit Span and Trail Making Test during the acute postconcussive phase; and (ii) to examine the sensitivity of ImPACT versus a comprehensive battery of neuropsychological tests to possible residual deficits as a result of the multiple concussions. ImPACT was determined to be more sensitive to acute postconcussive impairment following concussion than Digit Span and Trail Making Test. Furthermore, the ImPACT preseason baseline scores appear to be sensitive to neurocognitive dysfunction, possibly due to cumulative concussive injuries.