An exploratory analysis of the influence of personality and emotional factors on cerebral blood flow responses during painful stimulation in Fibromyalgia.

This study explored the influence of certain personality traits (neuroticism, extraversion, psychoticism, alexithymia), emotional variables (depression, catastrophizing), and insomnia on cerebral blood flow (CBF) responses to painful stimulation in fibromyalgia, using functional transcranial Doppler sonography. CBF velocities were recorded bilaterally in the anterior cerebral arteries (ACA) and middle cerebral arteries (MCA) of 24 fibromyalgia patients during exposure to two painful pressure conditions: (1) fixed pressure (2.4 kg) and (2) an individually calibrated pressure to produce an equal-moderate subjective pain intensity in all participants (average, 3.5 kg). Psychological factors were assessed by means of questionnaires. Neuroticism, and the externally-oriented thinking dimension of alexithymia were positively, and extraversion was inversely, associated with specific components of ACA and MCA CBF responses. Regarding catastrophizing and depression, correlations were positive for the fixed pressure condition and negative for the equal subjective intensity condition. The findings suggest that alterations in central nervous pain processing in fibromyalgia vary according to psychological factors. While most of the observed associations reflect a linear increase in nociceptive processing with the magnitude of negative cognitive and emotional states, the inverse associations for catastrophizing and depression during more intense painful stimulation may be ascribed to anti-nociceptive effects due to activation of the defense reflex.