Verbal Fluency and DTI in Multiple Sclerosis

Open Access
Author:
Insetta, Kathleen Louise
Area of Honors:
Elective Area of Honors - Neurosciences
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Peter Andrew Arnett, Thesis Supervisor
  • Ping Li, Honors Advisor
Keywords:
  • Verbal Fluency
  • Diffusion Tensor Imaging
  • Multiple Sclerosis
Abstract:
Verbal fluency is a common area of cognitive functioning studied in Multiple Sclerosis (MS); approximately 20-25% of MS patients experience verbal fluency deficits (Rao et al., 1991). The present study provides an examination of the relationship between verbal fluency and neural fiber tract integrity (as measured by Diffusion Tensor Imaging - DTI) in 31 MS patients. It may be that disruption in these fiber tracts underlies verbal fluency problems in these patients. Exploration of the relationship between verbal fluency and DTI score in MS patients helps to enhance our understanding of the factors that contribute to verbal fluency deficits in patients with MS. The Maximum Repetition Rate test (MRR), Controlled Oral Word Association task (COWAT), along with the Animal Naming test were used to measure verbal fluency. Magnetic Resonance Imaging (MRI) of the brain was conducted for the 31 MS participants and DTI score was derived. More specifically, the Apparent Diffusion Coefficient (ADC), Fractional Anisotropy (FA), and Relative Anisotropy (RA) were all used to measure the neural fiber integrity in the MS patients. It was hypothesized that all three verbal fluency measures would be correlated with DTI, with effect sizes varying between the three verbal fluency tests. More specifically, it was expected that the highest correlation would be found between the COWAT and DTI measures, as the COWAT is the most cognitively demanding of the three tasks. Pearson’s correlations revealed that the MRR and COWAT were significantly correlated with DTI whereas the Animal Naming measure was not. This difference in correlation could be due to the greater cognitive demands required for the COWAT compared with the Animal Naming tasks, with these greater cognitive demands mediated by the need for greater neural fiber tract integrity. Additional implications of these findings are discussed.