November 5, 2008

MRI Reveals Depression and Pain Link

The brains of individuals with major depressive disorder appear to react more strongly when anticipating pain, U.S. researchers have found.

Irina A. Strigo of the University of California-San Diego and colleagues studied 15 young adults with major depressive disorder, who were not taking medication and 15 individuals who were the same age -- average 24.3 years -- and had the same education level but did not have depression. Patients with depression completed a questionnaire that evaluated their tendencies to magnify, ruminate over or feel helpless in the face of pain.

All participants underwent functional magnetic resonance imaging while their arms were exposed to a thermal device heated to painful levels of hot and cold temperatures and non-painful temperatures. Visual cues -- a green shape for non-painful warmth and a red shape for painful warmth -- were presented before the heat was applied.

The study, published in the Archives of General Psychiatry, found that compared with the controls, patients with depression showed increased activation in certain areas of their brain during the anticipation of painful stimuli. The patients also displayed increased activation in the right amygdala -- part of the brain that deals with memory and emotional reactions -- and decreased activation in other areas, including those responsible for pain modulation -- adjusting sensitivity to pain -- during the painful experience.