Abstract:
Introduction: An intense discussion continues as to whether pain and depression are causally related or independent of each other. To investigate pain threshold and processing of pain-related word stimuli in subclinically depressed subjects, we designed an event-related potentials study in a group control design.
Methods: Pain threshold was measured in 16 subclinically depressed and 16 control participants. For the event-related potentials study, pain words and neutral words were presented to participants. Behavioral and electrophysiological measures were taken during lexical decision and recognition tasks.
Results: Pain threshold did not differ between depressive subjects and controls. However pain threshold was increased for all participants. In the event-related potentials study, depressive compared to control participants showed enhanced P300 potentials at parietal electrodes triggered by pain-related words during the lexical decision task: presumably a sign of enhanced recollection processes for these word stimuli. In line with this electrophysiological finding, depressed participants also tended to better recall the pain-related words in the subsequent recognition task than did the control participants.
Conclusion: We conclude that subclinically depressed subjects selectively process pain-related stimuli, which could enhance their vulnerability to developing pain symptoms.