Emotion-modulated startle in anxiety disorders is blunted by co-morbid depressive episodes.

BACKGROUND While anxiety has been associated with exaggerated emotional reactivity, depression has been associated with blunted, or context insensitive, emotional responding. Although anxiety and depressive disorders are frequently co-morbid, surprisingly little is known about emotional reactivity when the two disorders co-occur. METHOD We utilized the emotion-modulated startle (EMS) paradigm to examine the effects of a concurrent depressive episode on emotional reactivity in young adults with anxiety disorders. Using an archival dataset from a multi-disciplinary project on risk factors in childhood-onset depression, we examined eye-blink startle reactions to late-onset auditory startle probes while participants viewed pictures with affectively pleasant, unpleasant and neutral content. EMS response patterns were analyzed in 33 individuals with a current anxiety (but no depressive) disorder, 24 individuals with a current anxiety disorder and co-morbid depressive episode and 96 healthy controls. RESULTS Control participants and those with a current anxiety disorder (but no depression) displayed normative linearity in startle responses, including potentiation by unpleasant pictures. By contrast, individuals with concurrent anxiety and depression displayed blunted EMS. CONCLUSIONS An anxiety disorder concurrent with a depressive episode is associated with reactivity that more closely resembles the pattern of emotional responding that is typical of depression (i.e. context insensitive) rather than the pattern that is typical for anxiety (i.e. exaggerated).