Worry, the presence of intrusive and uncontrollable negative thoughts, is regulated by top-down control mechanisms. When these cognitive control mechanisms are ineffective, they lead to excessive worry, a core symptom in emotional disorders such as depression. Depressive symptoms are often comorbid in fibromyalgia syndrome (FMS). The present study explored the relationship between cognitive control, parasympathetic cardiovascular regulation, and worry in patients with FMS.

Forty-one patients with FMS and seventeen healthy controls completed the Breathing Focus Task (BFT), a task consisting of an induced-worry phase, presented between two phases assessing the ability to focus on breathing. Meanwhile, an electrocardiogram recording and continuous blood pressure measurements were performed. Heart rate variability and baroreflex sensitivity indexes were then computed.

Compared to controls, during the entire procedure, patients reported higher levels of worry and lower HRV, as well as reduced ability to concentrate on breathing, higher frequency of intrusive negative thoughts, and worse mood ratings. These difficulties were more marked after the induced-worry phase, increasing the deficit in attentional focus and the number of intrusive negative thoughts reported.

These results are an indication of decreased parasympathetic cardiovascular regulation in patients with FMS, evidenced by reduced HRV. Given the association between the prefrontal cortex and cardiovascular regulation, low HRV would indicate reduced functional capacity of the prefrontal cortex and impaired cognitive control. These findings suggest that this cognitive dysregulation may be exacerbating worry and contributing to the maintenance of negative emotional states in FMS.