Brain activity, regional gray matter loss, and decision-making in multiple sclerosis.

BACKGROUND

Decision-making (DM) abilities deteriorate with multiple sclerosis (MS) disease progression which impairs everyday life and is thus clinically important.

OBJECTIVE

To investigate the underlying neurocognitive processes and their relation to regional gray matter (GM) loss induced by MS.

METHODS

We used a functional magnetic resonance imaging (fMRI) Iowa Gambling Task to measure DM-related brain activity in 36 MS patients and 21 healthy controls (HC). From this activity, we determined neural parameters of two cognitive stages, a deliberation ("choice") period preceding a choice and a post-choice ("feedback") stage reporting decision outcomes. These measures were related to DM separately in intact and damaged GM areas as determined by a voxel-based morphometry analysis.

RESULTS

Severely affected patients (with high lesion burden) showed worse DM-learning than HC ( t = -1.75, p = 0.045), moderately affected (low lesion burden) did not. Activity in the choice stage in intact insular ( t = 4.60, p = 0.034), anterior cingulate ( t = 4.50, p = 0.044), and dorsolateral prefrontal areas ( t = 4.43, p = 0.049) and in insular areas with GM loss ( t = 3.78, p = 0.011) was positively linked to DM performance across patients with severe tissue damage and HC. Furthermore, activity in intact orbitofrontal areas was positively linked to DM-learning during the feedback stage across these participants ( t = 4.49, p = 0.032). During none of the stages, moderately affected patients showed higher activity than HC, which might have indicated preserved DM due to compensatory activity.

CONCLUSION

We identified dysregulated activity linked to impairment in specific cognitive stages of reward-related DM. The link of brain activity and impaired DM in areas with MS-induced GM loss suggests that this deficit might be tightly coupled to MS neuropathology.