An experimental study on the effect of symptom expectations on mental fatigue and motivation in people with primary biliary cholangitis.

Fatigue is the most common symptom in people with primary biliary cholangitis (PBC) and resistant to current treatment modalities. The aim of this study was to investigate the effect of negative and positive fatigue expectations in people with PBC on experienced fatigue and the motivational urge to stop a cognitive task. A subsample of the SOMA.LIV study of N = 46 people with PBC was randomly assigned to two experimental conditions. They received either fatigue-inducing or fatigue-reducing task instructions for a subsequent cognitive task. Participants rated their fatigue expectations prior to the task and their fatigue and motivational urge to stop after each of five task blocks. The total sample showed an increase in subjective fatigue and urge to stop across all task blocks. Participants receiving fatigue-inducing task instructions reported higher urge to stop compared to the group with fatigue-reducing task instructions. Both groups did not differ significantly in fatigue expectations and subjective fatigue. Our findings suggest that people with PBC may benefit from encouragement to engage in cognitive activities and maintain mental effort by verbal suggestions - an effect that can be of use in clinical practice to reduce potential avoidance behaviour.