Illness intrusiveness: A key part of the cognition-mood link in multiple sclerosis

The current study attempted to expand the literature on cognition and mood in MS by determining if illness intrusiveness may potentially serve as an intermediary factor in the well-established cognition-mood relationship in people with MS.

This study employed a retrospective cross-sectional design to answer this question. Baseline neuropsychological test data and mood questionnaires from 199 participants with clinically definite MS were used in this study. The sample was middle-aged (M = 48.4, SD = 11.8), highly educated (M = 14.6, SD = 2.2), majority female (76.9%) and majority White (74.5%). Assumptions for parametric statistics and ordinary least squares regression were met. Conditional process models evaluated whether illness intrusiveness mediated the relationship between cognitive functioning and psychiatric symptoms.

In total, 33.2% of the sample met criteria for clinically significant anxiety, 41.7% met criteria for depression, and 27.8% of the sample met criteria for processing speed impairment, consistent with other MS samples. Illness intrusiveness was found to mediate the relationship between processing speed and depression, ab = -.07, 95% CI [-.15, -.002], processing speed and anxiety, ab = -.06, 95% CI [-.12, -.02], and processing speed and more general mood disturbance, ab = -.08, 95% CI [-.13, -.0005].

Illness intrusiveness was found to be a potential important intermediary mechanism by which the primary cognitive impairment in MS, processing speed, impacts mood in this disease population. Conclusions, treatment implications, and directions for future research in light of these findings were discussed. (PsycInfo Database Record (c) 2023 APA, all rights reserved).