Prior clinical studies have documented that high blood pressure is one of the prominent risk factors leading to cerebrovascular disease and subsequent cognitive impairment. The present study aims to examine the relationship between blood pressure and brain and cognitive function in a community sample. This study recruited 41 elderly persons aged 60–70. Multiple imaging modalities were adopted to assess white matter microstructure, regional brain volume, and resting-state neural activity while a set of neuropsychological tests was used to assess cognitive function. With blood pressure measured at clinical interview, correlation and regression analyses were performed. Results showed reduced white matter integrity with increased systolic blood pressure in the splenium of the corpus callosum and inferior longitudinal fasciculus in the absence of change in brain volume or neural activity. Also, increased systolic blood pressure was found to be correlated with poorer cognitive performance in information processing speed. The results held significant after controlling age, sex, and education. These observations of the subclinical sample suggest that high blood pressure relates to subtle changes in the brain and cognitive deficits. Blood pressure control, as a relatively modifiable factor, should be taken seriously in community-dwelling elderly. / published_or_final_version / Clinical Psychology / Doctoral / Doctor of Psychology

The aim of this thesis was to investigate cognitive recovery following closed head injury within an information processing approach. Reasons why Clinical Neuropsychology has neglected the potential contribution from experimental psychology were outlined. Relevant head injury variables were reviewed. including the cognitive deficits often associated with such damage and their recovery. A pilot study confirmed that head-injured people, even soon after injury can attempt tasks with a high information processing load. The study covered the first six months post-injury using mild/moderate and severe head-injured subjects (total n=12). the findings indicating slower performance in severe subjects and their greater susceptibility to interference from irrelevant information. The central focus of the thesis was Sternberg's Memory Scanning Paradigm and this was described in detail. The relevant literature was discussed in depth including both general and clinically-relevant studies. Although pertinent studies are scarce, brain damage appears to slow memory scanning speed, differential effects being suggested according to severity of damage. In the main study a sample of head-injured subjects (n=42) was followed-up longitudinally at 1, 3, 6, 12, 24 and 36 months post-trauma. A second patient sample (n=10) was also tested at 24 and 36 months after injury. to allow a long-term follow-up "back-up" in case of excessive drop-out. A control sample (n=10) of normal volunteers was also tested. In addition to memory scanning performance patient subjects were also tested on a number of other clinical memory tests (Rey AVLT, digit span, WMS) and subjective memory questionnaire data were also obtained. Findings pointed to a slowing of memory scanning ability after head injury, the degree of dysfunction being most marked in subjects who had sustained an extremely severe head injury. Evidence of cognitive recovery was noted in some patients beyond 12-24 month post-injury. Significant associations between memory scanning performance and other memory measures were observed and a number of clinical variables were also examained. The findings were discussed in detail and a (primarily attentional) model was proposed to describe memory scanning and its dysfunction in head injury.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI/Dissertation Abstracts International.

published_or_final_version / Clinical Psychology / Master / Master of Social Sciences

Thesis (Ph.D.)--University of Adelaide, Dept. of Psychology, 2002. / "July 2002" Includes bibliographical references (leaves 324-342).

published_or_final_version / Psychiatry / Master / Master of Philosophy

In this thesis I investigate blood oxygen level-dependent (BOLD) MRI methods of imaging the cerebral blood volume (CBV), mean vessel radius and oxygen extraction fraction (OEF). Through the investigation of these individual techniques a new framework is proposed for the simultaneous measurement of all three parameters, providing a comprehensive assay of the cerebral mesostructure. A new method for the segmentation of blood filled voxels from the sagittal sinus is presented. The implemented method is completely automated and thus removes user bias in voxel selection. The segmentation method is used in a volunteer study to calculate CBV from a hyperoxic challenge according to an existing technique. CBV measurements from this study are found to be significantly overestimated. However, a new derivation of the hyperoxic CBV equation is presented that reveals significant errors in the original method, corresponding to the observed overestimates in CBV. Modelling studies are presented that investigate the discrepancy in reported BOLD MRI measurement of mean vessel size. A significant degree of the variation in the results is found to arise from the noise sensitivity of the analysis methods. This finding is confirmed with experimental data from healthy volunteers that show good agreement with the modelling studies. Comprehensive modelling of the BOLD response to hyperoxia and hypercapnia is used to develop a new framework for OEF calculation. The new method is based on the calibration of the BOLD signal response against a change in intravascular susceptibility. The OEF calculation is extended by introducing a spin-echo readout into the acquisition scheme. This extension of the acquisition scheme provides a further independent probe of the BOLD signal, enabling the simultaneous calculation of the mean vessel size and CBV. The new framework is shown to provide OEF and vessel size estimates over a wider range of physiological parameters, providing greater scope for the clinical implementation of these techniques.

Much of the practice is clinical neuropsychology is performed in the role of consultant and although the neuropsychologist is dependent upon referrals made from outside sources, relatively little attention has been devoted to the investigation of the referral process. Surveys of clinicians and referral sources have reported breakdowns of referral sources by discipline and general topics of referral questions based on recollection, but direct analysis of referral patterns across the same period has not been undertaken. The purpose of the study is to document the advancement of neuropsychology from providing psychological testing to establishing itself as a multifaceted discipline with a significant diagnostic purview that is regularly relied upon to contribute to important decisions in the lives of patients. By examining the referral questions rather than neuropsychologists' or referral sources' recollection of referrals, this study expands what is known about referral content and patterns. In an effort to explain question content without relying upon recollection, a coding rubric was designed to capture the breadth of presenting problems and requests seen in the original referral questions. Two-thousand-six-hundred referral questions were selected from the odd year over the 25 year period from 1983 to 2007, yielding a total of 2600 referral questions. Cochran's Kappa was used to conduct interrater reliability analyses in three stages across the entire rating process. Content analysis showed that 79.1% of all questions had at more than minimal content. The most common request was for assistance with diagnostic considerations, which was present in 66.4% of all cases. Assistance with differential diagnoses was requested in 27.4% of all cases with the majority of these composed of requests for assistance in differentiating between psychiatric and neurological or other medical considerations. There was evidence for a trend over time in the gradual decline of requests for assistance with psychiatric differential diagnosis and requests for the MMPI from 1993 to the present. Memory problems and dementia are the most common presenting problems, although there is evidence of a slight decline in these evaluations beginning in 1997. Requests for specific recommendations, particularly those related to making recommendations regarding treatment planning were found to steadily increase across the sampling period. Limitations and implications for practice were discussed.

"July 2002" Includes bibliographical references (leaves 324-342)

"July 2002" / Includes bibliographical references (leaves 324-342) / xiii, 342 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Psychology, 2002