Depression-Pain Relationship Seen with MRI

According to study results published in the October issue of Archives of General Psychiatry, functional MRI (fMRI) shows that reactions in the brain to anticipatory pain are stronger among persons with major depressive disorder compared with counterparts without depression, with altered functioning of the neural network that modifies pain sensitivity seen in the former group as well.

For the study—conducted “because the presence of comorbid pain contributes significantly to poorer outcomes and increased cost of treatment in major depressive disorder”—15 young adults with major depressive disorder who were not on medication and 15 young adults of the same education level who did not have depression underwent fMRI while their arms were exposed to painful levels of heat (115-116° F) and non-painful levels of heat, with visual cues presented before application of the heat. Participants with depression were also asked to evaluate their tendencies to magnify, ruminate over, or feel helpless when faced with pain.

In certain parts of the brain, including the right amygdala, patients with depression displayed increased activation, compared with controls, when anticipating painful stimuli, which continued during the painful experience. Also during the painful experience, those with depression showed decreased activation in the parts of the brain that control pain modulation.

When comparing questionnaire answers of those with depression to these findings, the researchers found significant positive correlation “between greater helplessness scores and greater activity in the right amygdala during the anticipation of pain."

They concluded that the “anticipatory brain response may indicate hypervigilance to impending threat, which may lead to increased helplessness and maladaptative modulation during the experience of heat pain. This mechanism could in part explain the high comorbidity of pain and depression when these conditions become chronic."