Reaction time, cerebral blood flow, and heart rate responses in fibromyalgia: Evidence of alterations in attentional control.

The study investigated cerebral blood flow (CBF) and heart rate (HR) responses during a cued reaction time (RT) task in patients with fibromyalgia syndrome (FMS). CBF velocities in the middle (MCA) and anterior (ACA) cerebral arteries of both hemispheres were recorded in 46 patients and 32 healthy control participants using functional transcranial Doppler sonography (fTCD). Patients exhibited markedly longer RT than healthy participants. Group differences in CBF responses were mainly observed for both ACAs, with greater right hemispherical increases but lower left hemispherical increases in FMS patients than in healthy participants. HR deceleration around the imperative stimulus was more pronounced in healthy participants. RT was inversely related to increases in CBF in both right arteries and in the left ACA in the FMS group, but was positively associated with CBF responses in all four arteries in healthy participants. The magnitude of task-induced HR deceleration correlated negatively with RT in both groups. Patients' clinical pain severity was positively associated with RT and CBF responses; trait anxiety and insomnia were secondary negative predictors of CBF responses. The study provided evidence of a deficit in the alertness component of attention in FMS at behavioral, CBF, and autonomic levels. These results may be interpreted in terms of the neural efficiency hypothesis of intelligence (i.e., less efficient brain activation during cognition in FMS) and the interfering effect of clinical factors on cognition. Clinical factors such as pain, anxiety, and sleep disturbances can affect cognition in FMS by interfering with CBF adjustment to cognitive demands.