Psychological Variables Associated with Resistance to Treatment with Serotonin and Noradrenaline Reuptake Inhibitors in Fibromyalgia

Objective: The treatment of fibromyalgia (FM) often offers only partial pain relief. Among the most effective drugs for FM pain are serotonin and noradrenalin reuptake inhibitors (SNRI). Few studies investigated the affective temperaments and personality features in FM. Our objective was to explore the associations between the affective temperaments, personality traits, schizotypy and response to SNRI treatment in FM.

Methods: 60 FM patients: 30 responsive to SNRI (FM T[+]), 30 non-responsive to SNRI (FM T[-] and 30 healthy controls were recruited. Resistance to SNRI was defined as <30% pain reduction during at least 8-week treatment. Subjects were assessed by physician and filled self-report questionnaires: Temperament Scale of Memphis, Pisa and San Diego- autoquestionnaire, Ten Item Personality Inventory, Oxford-Liverpool Inventory of Feelings and Experiences and Fibromyalgia Impact Questionnaire (FIQ). ANOVA analysis and simple logistic regressions were used to examine the links between psychological variables and lack of response to SNRI.

Results: FM T[-] presented higher scores in total FIQ and in physical, work, well-being, pain, fatigue/sleep, stiffness domains than FM T[+]. FM T[-] showed higher levels of: irritable and anxious temperaments, neuroticism, schizotypy than FM T[+]. The levels of depressive, irritable and anxious temperaments, introversion, neuroticism and schizotypy were linked to lack of response to SNRI.

Conclusions: FM T[+] and FM T[-] differ in clinical presentation and psychological features. The levels of affective temperaments, personality and schizotypal traits are associated with lack response to SNRI in FM.