Objectives:
Fibromyalgia (FM) is often comorbid with psychiatric disorders. Moreover, several studies show that psychiatric disorders may be linked to the severity and impact of FM. Therefore, the study described in the article had two main goals: (1) to explore various psychopathological symptom dimensions in patients with fibromyalgia and secondly, (2) to examine the links between psychopathology and response to treatment with serotonin and norepinephrine reuptake inhibitors (SNRI).

Methods:
This cross-sectional study was performed between December 2020 and November 2022. The definition of resistance to SNRI was <30% reduction of pain after ≥8 weeks of treatment. 30 FM subjects responsive to SNRI (FM T[+]), 32 patients non-responsive to SNRI (FM T[–]) and 30 healthy controls were enrolled. Participants were examined by physicians and completed self-report tools to evaluate levels of depression (Quick Inventory of Depressive Symptomatology, Hospital Anxiety and Depression Scale), anxiety (State and Trait Anxiety Inventory), anhedonia (Snaith-Hamilton Pleasure Scale), bipolar symptoms (Mood Disorder Questionnaire, Hypomania Checklist), and dissociation (Dissociative Experiences Scale – Revised). ANOVA analysis and a series of simple logistic regressions were used to examine the associations between psychopathological variables and response to SNRI.

Results:
FM T[–] vs. FM T[+] showed higher levels of: depression, state and trait anxiety and anhedonia as well as higher proportion of scores indicating the presence of anxiety disorder. Increased severity of depression, anxiety and anhedonia were predictors of resistance to SNRI.

Conclusions:
Modifiable psychopathological symptoms vary in FM T[+] vs. FM T[–] and are predictors of resistance to SNRI. Psychological assessment should be integrated into standard care for FM patients.