Startle Habituation in Individuals with Depression and/or Panic Disorder

Depression and anxiety, although traditionally classified as distinct psychological disorders, often co-occur and have been shown to have overlapping affective and behavioral characteristics (Watson, Clark, Lee & Harkness, 1994). Despite their commonalities, some studies have indicated that the two diagnostic constructs vary in their emotional responses to aversive events, as measured by the startle response. Specifically, anxious individuals often have a heightened startle response, whereas the association between depression and startle are more mixed, with some studies showing blunted startle in depressed individuals. One reason for these mixed findings may be because emotional responses to aversive events may change over time. For example, there may be different patterns of habituation of the startle response (Harris, 1943) in depression vs. anxiety. The present study examined the habituation of the startle response in a sample of depressed individuals without a history of anxiety (n = 40), individuals with panic disorder without a history of depression (n = 28), those with comorbid depression and panic disorder (n = 56), and healthy controls (n = 65). Results indicate that depressed-only individuals habituate at quicker rates than control participants, but no other significant differences were found in rates of startle habituation between other diagnostic groups. Theoretical and clinical implications are discussed.