Skin conductance and subjective arousal in anxiety, depression, and comorbidity: Implications for affective reactivity

Skin conductance (SC), an autonomic arousal measure of the sympathetic nervous system, is a sensitive and useful index of physiological arousal. However, SC data does not always align with self-reports of arousal. SC, self-reported arousal, and their association, known as emotion coherence, may be altered with the presence of major psychiatric illness. This study investigated group differences on SC reactivity and self-reported arousal while viewing positive, negative, neutral, and threat images between participants diagnosed with major depression with and without anxiety disorders relative to a healthy comparison group. Additionally, the strength and direction of association between SC reactivity and arousal ratings (emotion coherence) was examined within groups. Unmedicated participants were recruited via online and paper advertisements around Chicago and categorized into one of four groups (Depressed: n = 35, Anxious: n = 44, Comorbid: n = 38, Healthy: n = 29). SC and affect ratings were collected during and after a standardized emotional picture viewing task. SC reactivity was significantly higher during threat images, regardless of group. During threat image presentation, increased SC reactivity occurred during the last few seconds before picture offset; for all other stimulus types, SC reactivity decreased significantly after picture offset. Anxious and comorbid participants rated emotional images as more arousing than healthy participants; there were no observed differences in arousal ratings between depressed and healthy participants. Heightened reactivity in anxiety may manifest in arousal ratings without corresponding increased SC reactivity to emotional images. Results do not suggest underlying altered psychophysiology in this sample of depressed or anxious participants.