Objective
To examine the temporal associations, within-day and day-to-day, between pain, fatigue, depressed mood, and cognitive function in multiple sclerosis (MS).
Design
Repeated-measures study involving seven days of ecological momentary assessment (EMA) of symptoms five times a day. Multilevel mixed models were used to analyze data.
Setting
Community.
Participants
Ambulatory adults (N=107) with MS.
Interventions
Not applicable.
Main Outcome Measure(s)
EMA of pain, fatigue, depressed mood, and cognitive function rated on a 0–10 scale.
Results
Fatigue and pain were linked within-day such that higher pain was associated with higher subsequent fatigue (B=0.09, p=0.04; likewise, higher fatigue was associated with higher pain in the following time frame (B=0.05, p=0.04). Poorer perceived cognitive function preceded increased subsequent pain (B=0.08, p=0.007) and fatigue (B=0.10, p=0.01) within-day. Depressed mood was not temporally linked with other symptoms. In terms of day-to-day effects, a day of higher fatigue related to decreased next day fatigue (B=−0.16, p=0.01), and a day of higher depressed mood related to increased depressed mood the next day (B=0.17, p=0.01). There were no cross-symptom associations from one day to the next.
Conclusions
Findings provide new insights on how common symptoms in MS relate to each other and vary within and over days. Pain and fatigue show evidence of a dynamic bidirectional relation over the course of a day, and worsening of perceived cognitive function preceded worsening of both pain and fatigue. Most temporal associations between symptoms occur within the course of a day, with relatively little carry-over from one day to the next.