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The purpose of this thesis is to investigate: whether cross sectional MRI can help to discriminate progressive supranuclear palsy (PSP), multiple system atrophy (Parkinsonian subtype, MSA-P) and Parkinson's disease (PD) whether established methods of serial volumetric MRI analysis can be applied to measure in-vivo rates of brain atrophy in PSP and whether cross sectional MRI and MRI-derived atrophy rates have a clinical correlate. Volumetric and diffusion-weighted MRI (DWI) scans were performed in 24 patients with PSP, 11 with MSA-P, 12 with PD and 18 healthy controls. Detailed clinical and neuropsychological assessments were undertaken, and results at the time of initial assessment and follow-up compared. Whole brain and regional brain volumes were measured on positionally matched (registered) baseline and follow up MR images. The boundary shift integral (BSI), an image analysis technique for assessing volume differences from registered MR scans was applied to whole brain, and hypothesis-driven regions of interest in order to allow quantification of atrophy rates. PSP can be reliably discriminated from MSA-P with quantitative regional volume measurements of the superior cerebellar peduncle, midbrain, pons and cerebellum (p<0.001). DWI may help to identify regional pathological change in-vivo, discriminating MSA-P and PSP using apparent diffusion coefficients in the middle cerebellar peduncle (p0.001). The mean (SD) brain atrophy rate in PSP, 1.2 (1.0) %year_1 was greater than in healthy controls 0.4(0.5)%year"1 (p=0.04) but similar to MSA-P 1.0(l.l)%year'1. In PSP, the mean midbrain atrophy rate was most significantly different from controls (p<0.001). Ponto-cerebellar atrophy rates discriminated MSA-P and PSP (p<0.05). The distinct patterns and rates of atrophy in these diseases have a meaningful clinical correlate and power calculations confirm that in PSP, regional atrophy rates are quantifiable and feasible markers of disease progression that have utility in clinical trials as a marker for evaluating disease-modifying treatments in PSP.

The aims of this study were to assess neuropsychological function and change in participants with mild cognitive impairment (MCI).Further aims were to determine if platelet membrane secretase activity was higher in MCI participants compared to controls and to assess FOG-PET CT brain changes in MCI participants. METHODS Participants with MCI were recruited through a memory clinic. Controls with no evidence of cognitive impairment were also recruited. Participants undertook a neuropsychological test battery. MCI participants were reassessed through the memory clinic and a subset returned for in-depth neuropsychological testing on a yearly basis. Blood samples were collected for measurement of platelet membrane secretase activity and APOE genotyping. FOG-PET CT Brain scans were carried out on 36 MCI participants. Statistical analysis was performed using SPSS Version 17 for Windows. RESULTS 237 participants were recruited over a 2.5 year period; 139 MCI and 98 control participants. The MCI participants performed significantly worse than the controls on all cognitive tests, except one test of memory. Most MCI participants were categorised as amnestic multidomain; this was the group most likely to convert to dementia on follow-up. Age had the most significant effect on conversion, however. Conversion rate was 15.7% per year overall. There was no significant difference in platelet membrane secretase activity between the MCI and control groups. FOGPET CT Brain activity changes were seen in MCI participants and most changes correlated with previous literature of brain imaging. CONCLUSIONS MCI is a heterogeneous condition with most participants having multiple cognitive deficits on full assessment at baseline. Older participants with amnestic multidomain MCI are most likely to convert to dementia. Platelet membrane secretase activity cannot be advocated as a useful biomarker of MCI from the results of this study. Changes in FDG-PET and cognition produced some interesting associations that would need verified in larger studies.

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Neuropsychologists are becoming increasingly aware that there is a complex interplay of cognitive, personality, and sociocultural factors that affect an individual's performance on neuropsychological tests. The current study investigated the effect of one aspect of the sociocultural environment, that is, quality of education, on performance on neuropsychological tests of executive function. The sample included 40 high school learners: Group A comprised learners with a high quality of education and Group B comprised learners with a low quality of education. Four tests of executive function were administered: the Verbal Fluency Test, the Design Fluency Test, the Stroop Test and the Wisconsin Card Sorting Test. Results indicated that quality of education significantly affected the participants' performance with Group A performing significantly better than Group B on all the tests of executive function. These findings have implications for the interpretation of neuropsychological test performance in cross-cultural research and practice. / Psychology / M.A. (Clinical Psychology)

Thesis (M.A. (Clinical Psychology)) --University of Limpopo (Turfloop Campus), 2005 / The aim of this study was to establish whether children with Attention-Deficit/Hyperactivity show deficits in cognitive impulsiveness and motor functions, caused by a hypofunctioning dopamine system. A group of 84 primary school children, 42 classified as ADHD and 42 controls, matched for age, gender and SES, with children without ADHD symptomatology, were compared on their performance on neuropsychological tests which test the functions of the cortical areas supplied by two dopamine branches, the meso-cortical and nigrostriatal branches. The battery consisted of the Wisconsin Card Sorting Test, the Grooved Pegboard, and the Maze Coordination Task. The results of the tests were analysed as a function of gender and ADHD-subtypes. In the majority of tests the clinical groups performed worse than the control groups. This was the case for both genders. The Hyperactive/Impulsive and Combined subtypes consistently performed poorer than the other groups. The results indicate that children with ADHD are more impulsive (deficient executive functions) and have poorer motor control than their control counterparts, which may be an indication of dopamine dysfunction.

Neuropsychologists are becoming increasingly aware that there is a complex interplay of cognitive, personality, and sociocultural factors that affect an individual's performance on neuropsychological tests. The current study investigated the effect of one aspect of the sociocultural environment, that is, quality of education, on performance on neuropsychological tests of executive function. The sample included 40 high school learners: Group A comprised learners with a high quality of education and Group B comprised learners with a low quality of education. Four tests of executive function were administered: the Verbal Fluency Test, the Design Fluency Test, the Stroop Test and the Wisconsin Card Sorting Test. Results indicated that quality of education significantly affected the participants' performance with Group A performing significantly better than Group B on all the tests of executive function. These findings have implications for the interpretation of neuropsychological test performance in cross-cultural research and practice. / Psychology / M.A. (Clinical Psychology)