The presence of attentional and interpretation biases in patients with severe MS-related fatigue

Objective: Severe fatigue is a prevalent and disabling symptom in multiple sclerosis (MS). This study tested if a fatigue- and physical activity-related attentional bias (AB) and a somatic interpretation bias (IB) are present in severely fatigued patients with MS. Biases were compared to healthy controls and patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Method: Severely fatigued patients with MS or ME/CFS and healthy controls completed a Visual Probe Task (VPT) assessing fatigue- and physical activity-related AB and an IB task that assesses the tendency to interpret ambiguous information in either a somatically threatening way or in a more neutral manner. The VPT was completed by 38 MS patients, 44 ME/CFS patients, and 46 healthy controls; the IB task was completed by 156, 40 and 46 participants respectively. Results: ANOVA showed no statistically significant group differences in a fatigue-related AB or physical activity-related AB (omnibus test of interaction between topic × condition: F_2,125 = 1.87; p =.159). Both patient groups showed a tendency to interpret ambiguous information in a somatically threatening way compared to healthy controls (F_1,2 = 27.61, p <.001). This IB was significantly stronger in MS patients compared to ME/CFS patients. IB was significantly correlated with cognitive responses to symptoms in MS patients. Conclusion: MS patients tend to interpret ambiguous information in a somatically threatening way. This may feed into unhelpful ways of dealing with symptoms, possibly contributing to the perpetuation of severe fatigue in MS.