Faculty Bibliography

Diffusion tensor imaging (DTI) is a sensitive tool for detecting microstructural tissue damage in vivo. In this study, we investigated DTI abnormalities in individuals with relapsing remitting multiple sclerosis (RRMS) and examined the relations between imaging-based measures of white matter injury and cognitive impairment. DTI-derived metrics using tract-based spatial statistics (TBSS) were compared between 37 individuals with RRMS and 20 healthy controls. Cognitive impairment was assessed with three standard tests: the Symbol Digit Modalities Test (SDMT), which measures cognitive processing speed and visual working memory, the Rey Auditory Verbal Learning Test (RAVLT), which examines verbal memory, and the Paced Auditory Serial Addition Test (PASAT), which assesses sustained attention and working memory. Correlations between DTI-metrics and cognition were explored in regions demonstrating significant differences between the RRMS patients and the control group. Lower fractional anisotropy (FA) was found in RRMS participants compared to controls across the tract skeleton (0.40 +/- 0.03 vs. 0.43 +/- 0.01, p<0.01). In areas of reduced FA, mean diffusivity was increased and was dominated by increased radial diffusivity with no significant change in axial diffusivity, an indication of the role of damage to CNS myelin in MS pathology. In the RRMS group, voxelwise correlations were found between FA reduction and cognitive impairment in cognitively-relevant tracts, predominantly in the posterior thalamic radiation, the sagittal stratum, and the corpus callosum; the strongest correlations were with SDMT measures, with contributions to these associations from both lesion and normal-appearing white matter. Moreover, results using threshold-free cluster enhancement (TFCE) showed more widespread white matter involvement compared to cluster-based thresholding. These findings indicate the important role for DTI in delineating mechanisms underlying MS-associated cognitive impairment and suggest that DTI could play a critical role in monitoring the clinical and cognitive effects of the disease.

BACKGROUND: Multiple sclerosis (MS) is the leading cause of neurological disability among young and middle-aged adults. One of the most devastating consequences of MS in this relatively young population group is unemployment. Although certain demographic and disease factors have been associated with employment, few studies have examined the contribution of person-specific factors, such as personality. OBJECTIVE: The goal of this study was to determine the extent to which personality, demographics, and clinical measures contribute to unemployment in MS. METHOD: A total of 101 individuals with MS who were enrolled in a clinical trial on cognition underwent a brief neuropsychological battery and completed questionnaires related to vocation, mood, fatigue, and personality. Neurological impairment was measured with the Expanded Disability Status Scale (EDSS). RESULTS: Employment status was related with disease duration, MS subtype, level of neurological impairment, fatigue, performance on measures assessing information processing speed (Symbol Digit Modalities Test (SDMT)), learning and memory (Selective Reminding Test), and the personality characteristic of persistence. Based on a forward logistic regression analysis, EDSS, SDMT, and persistence were the strongest predictors of employment status. CONCLUSIONS: These findings underscore the importance of personality on outcomes in MS and point to the need for more clinical attention and research in this area.