An experimental paradigm to repeatedly induce somatic symptoms

Experimental research in the field of medically unexplained physical symptoms (MUPS) is rare. We examined a method of script driven imagery in terms of manipulating the intensity of the symptom, the impairment by the symptom and the symptom tolerance. Additionally, we identified relevant predictors for the efficacy of symptom induction.

We assessed the most impairing symptom in 48 subjects suffering from multiple, chronic MUPS and a severe physical illness that 48 age-matched healthy controls suffered from in the past. An individual script including thoughts and sensations accompanying the symptom was recorded. During the experiment, participants were exposed to the script repeatedly and then rated the intensity of, impairment by and tolerance of the symptom on a visual analog scale (VAS).

A mixed model repeated-measures-ANOVA revealed a significant main effect for the factor time (pre- and post-induction assessment; p<.001) but not for group (MUPS- vs. control-groups; p=.159-.314) indicating that the manipulation of all VASs was effective for both groups. The interaction time×group was significant for tolerance and post-hoc analyses showed no significant reduction for tolerance in the MUPS-group. The number of somatic symptoms and endurance behavior predicted higher induction efficacy in the MUPS-group for intensity. For healthy controls, endurance behavior and pain-persistence were associated with lower induction efficacy for all VAS.

Script-driven imagery could be a promising research procedure in the field of MUPS. It could be used to investigate short term effects of psychological interventions as well as physiological and cognitive processes accompanying symptom manipulation.