PAIN RESPONSIVITY IN MAJOR DEPRESSION AND BIPOLAR DISORDER

Signal detection theory measures of thermal pain responsivity were exa mined in patients with major depression and bipolar disorder and in co ntrol subjects. Patients with major depression had significantly poore r sensory discrimination of painful thermal stimuli than control subje cts, but they did not differ from the control subjects in their sensor y discrimination of warm thermal stimuli of lower intensity. Patients with bipolar disorder did not differ significantly in sensory discrimi nation from either the patients with major depression or the control s ubjects. Patients with major depression had significantly higher (i.e. , more stoical) response criteria than the control subjects for the pa inful thermal stimuli and also for the lower intensity stimuli; patien ts with bipolar disorder had significantly higher criteria than contro l subjects for only the lower intensity stimuli. The results suggest t hat reduced responsivity to pain in major depression may reflect senso ry as well as affective abnormalities. Complaints of pain are very com mon in mood disorders, and continued examination of experimental pain in individuals with these disorders has the potential to enhance our u nderstanding of this phenomenon.