AGE-RELATED WHITE MATTER CHANGES MEDIATE THE RELATIONSHIP BETWEEN AGE AND SPEED OF PROCESSING

Open Access
Author:
Ryan, Casey Aileen
Area of Honors:
Kinesiology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Dr. Nancy Dennis, Thesis Supervisor
  • Dr. Mary Jane De Souza, Honors Advisor
Keywords:
  • Aging
  • Speed of Processing
  • DTI
  • Mediation
Abstract:
Aging is associated with changes in cognitive processing and changes in white matter. Decreasing white matter integrity disrupts networks in the brain which can be a potential mediator of the age-related cognitive decline. Diffusion Tensor Imaging (DTI) is a neuroimaging technique that is capable of extracting and investigating specific white matter tracts and their respective integrity by measuring the diffusion of water molecules in the brain by a value called FA. In this current DTI study, white matter tracts were investigated for their relationship with age and speed of processing cognitive domain in a data driven analysis in a study that included 45 older adults screened to be representative of healthy aging. Our results showed that correlations between age and cognitive function, age and tract integrity, as well as cognitive function and tracts of interest existed. As age increased, decreases in FA values and cognitive performance were observed for posterior corona radiata, anterior corona radiata, posterior thalamic radiation, external capsule, cingulum, and superior longitudinal fasciculus. Additionally, follow-up mediation analysis suggested that white matter tracts of interests were found to be significant mediators in the relationship between aging and the speed of processing cognitive domain. Our results suggest that the age-related changes in the white matter tracts play a significant role in the age-related decline in performance for speed of processing.