| dc.description.abstract | Cognitive deficits are highly prevalent in multiple sclerosis (MS). Impaired cognitive functions, such as attention abilities, can be among the most limiting changes in individuals rated as having low neurologic disability. Attention is a fundamental cognitive function which plays a role in many tasks conceptualized as assessing other cognitive domains. The Dalhousie Computerized Attention Battery (DalCAB) is a novel computerized assessment, not yet used in MS, that includes 8 tasks. These tasks measure the functioning of three attention networks (executive control, orienting, and vigilance). Slowed response times (RT) and intra-individual variability (IIV) in RT are sensitive indicators of cognitive change in MS and can be calculated for each DalCAB task.
This thesis aimed: To demonstrate validity of the DalCAB tasks as measures of attention network functioning in persons with MS (Aim 1), to examine whether differences in mean-level RT or IIV on the DalCAB tasks are seen in those without clinical evidence of cognitive impairment (Aim 2), to examine whether symptoms of anxiety, depression, pain, and fatigue account for variation in attention network performance and IIV (Aim 3), and to examine whether MRI measures of brain structure and damage are associated with attention network performance or IIV (Aim 4).
Persons with relapsing-remitting MS [Expanded Disability Status Scale (EDSS) ≤ 4.5] were recruited. MS participants (n = 104; M age = 46.0) were mainly female (87.5%) with varying years of education (11-19 years). Median EDSS was 1.9 (interquartile range = 1.5 - 2.5). Control participants matched on age, gender, and years of education were also recruited (n = 43). Participants completed the DalCAB, standard neuropsychological tests, and self-report questionnaires. A sub-set of MS and control participants completed an MRI.
Aim 1: MS participants differed from controls on DalCAB measures reflecting all three attention networks (executive control, orienting, and vigilance) even after accounting for baseline RT differences between groups. Analyses demonstrated initial validity of the DalCAB in this MS sample with regard to known groups validity, ecological validity, and concurrent validity. Aim 2: MS participants unimpaired on standard neuropsychological tests (n = 65) differed from controls in executive control and vigilance network performance, but not orienting. Of the two measures of IIV examined, individual standard deviation (ISD) was better able to distinguish between groups than coefficient of variation. ISD differed between MS participants who were unimpaired on standard neuropsychological tests and controls. Aim 3: Symptoms of anxiety, depression, pain, and fatigue did not explain variability in attention network performance but did explain variability in ISD. Aim 4: MRI measures of brain structure and damage differed between MS and control participants, however, a measure of brain atrophy (i.e., brain parenchymal fraction) did not. MRI measures were not associated with attention network performance. There were limited associations between ISD on some tasks and MRI measures.
The knowledge generated from the thesis has contributed to understanding attention network performance in persons with MS considered to have low neurologic disability. | en_US |
