Fibromyalgia syndrome is a disease of unknown pathogenesis characterised by widespread chronic musculoskeletal pain. Fibromyalgia has been associated with dysregulation of the stress systems, but results are inconsistent.
To investigate autonomic nervous system activity (urinary noradrenaline, adrenaline, dopamine, and heart rate) of fibromyalgia patients and healthy controls.
Urinary catecholamines and heart rate were assessed for a 24-hour period in a controlled hospital setting (including relaxation, a test with prolonged mental stress, and sleep), and during daily activity in 29 female fibromyalgia patients and 29 age-matched female healthy controls.
With repeated measures ANOVAs, catecholamine levels were lower in patients than controls (P=.035 for noradrenaline; P=.005 for adrenaline; P=.001 for dopamine). One-way ANOVAs for the single periods showed that patients compared to controls had significantly lower adrenaline levels during the night (P=.010) and the second day (P=.010), significantly lower dopamine levels during the first day (P=.008), the night (P=.001), and the second day (P=.004). However, single time point noradrenaline levels were not significantly different between the groups. Overall, heart rate was significantly higher in patients than controls (P=.014). Specifically, significant differences emerged during relaxation (P=.016) and sleep (P=.011), but not during stress provocation or daily activities.
The results indicate an altered regulation of the autonomic nervous system in fibromyalgia patients, with attenuated activity of both the sympathetic (adrenal medulla component) and the parasympathetic branch.