Comorbid anxiety and depression: Opposing effects on the electrocortical processing of negative imagery in a focal fear sample

Abstract

Background: Anxiety and depression are highly comorbid and share clinical characteristics, such as high levels of negative emotion. Attention toward negative stimuli in anxiety and depression has been studied primarily using negative pictures. Yet, negative mental imagery-that is, mental representations of imagined negative events or stimuli-might more closely mirror patient experience.

Methods: The current study presents the first examination of neural response to negative imagery in 57 adults (39 female) who all shared a common "focal fear" diagnosis (i.e., specific phobia or performance-only social anxiety disorder), but varied in levels of comorbid anxiety and depression. After listening to standardized descriptions of negative and neutral scenes, participants imagined these scenes as vividly as possible. Associations between categorical and continuous measures of depression, generalized anxiety disorder (GAD), and social anxiety disorder with electrocortical and subjective responses to negative imagery were assessed.

Results: Individuals who were more depressed showed reduced electrocortical processing of negative imagery, whereas those with GAD showed increased electrocortical processing of negative imagery-but only when controlling for depression. Furthermore, participants with higher levels of depression rated negative imagery as less negative and those with greater social anxiety symptoms rated negative imagery more negatively.

Conclusions: Depression and GAD are characterized by opposing electrocortical response to negative imagery; moreover, depression may suppress GAD-related increases in the electrocortical processing of negative imagery. Results highlight distinctions between different dimensions of distress-based psychopathology, and reveal the unique and complex contribution of comorbid depression to affective response in anxiety.

Keywords: depression (MDD); event-related potential (ERP); generalized anxiety disorder (GAD); late positive potential (LPP); negative imagery; social anxiety disorder (SAD); transdiagnostic.

Figure 1.

A) Grand-averaged waveforms at the centroparietal pooling where the LPP was scored, shown separately for neutral and negative imagery, for participants without a diagnosis of depression (n=44) and participants diagnosed with depression (n=13); positive is plotted downwards. Headmaps depict the voltage distributions for neutral and negative imagery 10,500 to 20,000 ms after audio clip onset. B) Partial regression plot showing the association between depression symptoms and the LPP to negative imagery, controlling for the LPP to neutral imagery, diffuse anxiety, and social anxiety symptoms.

Figure 2.

Grand-averaged waveforms at the centroparietal pooling where the LPP was scored, shown separately for neutral and negative imagery, for participants without a diagnosis of GAD (n=38) and participants diagnosed with GAD (n=19); positive is plotted downwards. Headmaps depict the voltage distributions for neutral and negative imagery 10,500 to 20,000 ms after audio clip onset. GAD = generalized anxiety disorder.

Figure 3.

A) Partial regression plot showing the association between depression symptoms and valence ratings of negative imagery, controlling for valence ratings of neutral imagery, diffuse anxiety, and social anxiety symptoms. B) Partial regression plot showing the association between social anxiety symptoms and valence ratings of negative imagery, controlling for valence ratings of neutral imagery, depression symptoms, and diffuse anxiety. Higher valence ratings indicate more neutral valence.