Cognitive theory predicts that depression is associated with a bias to interpret ambiguous information in a mood-congruent fashion. This negative interpretative bias may serve as a maintenance factor for the continuation of a depressed mood state. The majority of studies investigating such interpretative biases suffer from a variety of methodological problems. This research has utilized an objective physiological measure involving the affective modulation of the human eye blink reflex in 25 depressed and 25 control subjects by depressive, depressive-ambiguous, and distorted stimuli. Almost half of the depressed subjects suffered from a comorbid anxiety disorder. In contrast to previous research utilizing the same methodology, depressed participants did not react differently to non-depressed participants in terms of their blink reflex response to the various stimuli types. This outcome is ascribed to the exclusion of anxiety-related stimuli in the current study. Depression-related stimuli failed to augment blink amplitudes in both subject groups. Therefore, affective modulation of the startle reflex is an ineffective methodology for the detection of depression-linked interpretative biases, as there is no difference to how individuals react to depressive and neutral stimuli. In this study, patients diagnosed with social anxiety disorder reacted to difficult-to-identify stimuli with augmented blink amplitudes, interpreted as an anxiety response.
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