Several studies have demonstrated a strong link between fibromyalgia, negative affect (NA) and depression. However, it remains unclear why some fibromyalgia patients get depressed while others do not and, primarily, which mechanisms account for this difference. We hypothesize that, besides clinical features, the engagement in dysfunctional strategies like perseverative negative thinking (PNT) followed by an amplification of NA levels may increase the risk of fibromyalgia patients experiencing depressive symptoms.

To explore the serial mediator effect of PNT and NA on the relationship between fibromyalgia symptoms and depressive symptoms.

Hundred and three women with fibromyalgia (mean age 47.32±10.63) completed the Portuguese version of the Revised-Fibromyalgia Impact Questionnaire, Perseverative Thinking Questionnaire, Profile of Mood States and Beck Depression Inventory-II. The association between the variables was investigated via Pearson correlations and serial multiple mediation.

The estimated model was significant [F (3.86)=57.318, P<.001] explaining 66.66% of depressive symptoms variance. The total effect of fibromyalgia symptoms on depressive symptoms was of .4998 (SE=0.0795, P<0.001; CI>0.3417 and<0.6578), with a significant direct effect of 0.1911 (SE=0.0653; CI>0.0614 and<0.3209). The total indirect effects were of 0.3086 (SE=0.0619; CI>0.2033<0.4458). Three significant specific indirect effects were found.

The effect of fibromyalgia symptoms on depressive symptoms is partially operated through cognitive interference/unproductiveness, which in turn influences NA levels. Such findings highlight the crucial role of these constructs in the relationship between fibromyalgia symptoms and depressive symptoms and the urge to address them when treating individuals reporting greater fibromyalgia symptoms.