Interaction of multiple brain networks provides insight into how pain occurs
A recent study from researchers at Massachusetts General Hospital and University of Michigan provides the first direct evidence of linkage between elevated intrinsic (resting-state) brain connectivity and spontaneous pain intensity in patients with fibromyalgia (FM). This research shows an interaction of multiple brain networks, offering greater understanding of how pain arises. Details of the study appear online and in the August issue of Arthritis & Rheumatism, a journal published by Wiley-Blackwell on behalf of the American College of Rheumatology.
Chronic pain syndromes such as FM can cause widespread pain that varies in intensity and fluctuates over time. In addition to pain, FM patients may experience other symptoms such as fatigue, sleep disturbances, memory problems, and temperature sensitivity. The National Institute of Arthritis and Musculoskeletal and Skin Diseases estimates that FM affects 5 million American 18 years of age or older, occurring more often in women (80%-90%).
In the current study, Vitaly Napadow, Ph.D. and colleagues enrolled 36 female subjects -18 FM patients and 18 healthy control subjects with a mean age of 38.9 and 36.1 years of age, respectively. FM study subjects had a disease-duration of at least 1 year, self-reported pain for more than 50% of each day, and were willing to limit introduction of new medications or treatment strategies to control FM symptoms.
As a part of the study, 6 minutes of resting-state functional magnetic resonance imaging (FMRI) data from study subjects were collected. Data were analyzed using dual-regression independent components analysis-a data-driven approach for the identification of independent brain networks. Intrinsic connectivity was evaluated in multiple brain networks: the default mode network (DMN), the executive attention network (EAN), and the medial visual network (MVN), with the MVN serving as a negative control.
Prior to undergoing the MRI scan, participants were asked to rate the intensity of their FM pain on a scale of 0, where 0 is equivalent to "no pain present" and 10 is equivalent to "the worst pain they could imagine." The pain scores ranged widely, from 0 to 8.1.