| The intent of this thesis was to explore the relationships between age, processing speed, and brain morphology for 57 to 81 year olds (N = 37). All data used for this thesis were obtained from the International Consortium on Brain Mapping project. Two morphological markers, gyral gray matter (GM) thickness and gyral white matter (WM) span, were assessed and measured via magnetic resonance images. The two morphological markers were assessed in three regions: frontal, parietal, and occipital. Three different tests, Coding, Symbol Digit Modalities Test (SDMT), and Grooved Pegboard, were used to measure processing speed.;Results indicated that age is related to the slowing of processing speed. Age was also associated with gyral thinning and widening. Gyral GM thickness had the strongest relationships with processing speed in the parietal region for SDMT and in the occipital region for Pegboard. Gyral WM span in the frontal region with Pegboard was the only significant effect by region. Regression analyses indicated that the morphology markers did not account for any significant variance beyond what age already accounted for. Overall it was found that age is related to cognitive slowing and gyral thinning and widening. The hypothesized regional effects were not found nor were the hypothesized mediational effects of morphology found between age and processing speed. |
