Selective processing of pain-related word stimuli in subclinical depression as indicated by event-related brain potentials.

An intense discussion still exists as to whether pain and depression are causally related or independent of each other. To investigate processing of pain-related word stimuli in subclinically depressed individuals, we designed an event-related potentials study in a group control design. Pain words and neutral words were presented to 16 subclinically depressed and 16 control participants. Behavioral and electrophysiological measures were taken during lexical decision and recognition tasks. Depressive compared to control participants showed enhanced P300 amplitudes at parietal electrodes triggered by pain-related words during the lexical decision task, which presumably is a sign of enhanced recollection processes for these word stimuli. In line with these electrophysiological findings, depressed participants also tended to better recall the pain-related words in the later recognition task than control participants. We conclude that subclinically depressed individuals selectively process pain-related stimuli, and this processing bias could enhance their vulnerability to develop pain symptoms.