Relationship between apathy and cognitive dysfunctions in multiple sclerosis: A 4-year prospective longitudinal study.

Background: Cognitive dysfunctions are highly prevalent in multiple sclerosis (MS) and negatively impact occupational and social functioning.

Objective: In the present longitudinal study, we aimed at modeling cognitive changes and at assessing whether apathy could be a predictor of cognitive decline in MS.

Methods: We assessed 67 people with MS at two-time points (baseline, T0; 4-year follow-up, T1), by means of several clinical, behavioural, and cognitive measures. We used a delta approach to measure cognitive decline during the follow-up period. We applied a mixed factorial design and a linear regression model to explore factors associated with cognitive changes over time.

Results: A higher level of apathy at baseline predicted the progressive cognitive decline at follow-up, whereas a higher level of depression did not. Among demographic and clinical characteristics, only low education level was significantly associated with cognitive decline over time. Interestingly, participants with persistent apathy (diagnosis of apathy at T0 and T1, A+A+) and those who developed apathy (A-A+) showed poorer inhibitory control and a larger decline in executive functioning during the 4-year follow-up than participants who had never received the diagnosis of apathy (A-A-).

Conclusion: Apathy represents an early marker of cognitive decline in MS. These findings have important clinical and prognostic implications.