Frontal Cortex Stimulation Modulates Attentional Circuits and Increases Anxiety-Potentiated Startle in Anxious...

Area of Science:

• Neuroscience
• Psychiatry
• Clinical Psychology

Background:

• Major depressive disorder (MDD) with comorbid anxiety poses treatment challenges, often leading to high relapse rates.
• Transcranial direct current stimulation (tDCS) is a non-invasive method targeting neural circuits implicated in anxious depression.
• Understanding tDCS effects on threat sensitivity in anxious depression is crucial for developing effective interventions.

Purpose of the Study:

• To investigate the acute effects of tDCS on neural, behavioral, and physiological measures of threat sensitivity.
• To assess tDCS impact on brain activity, emotional processing, and physiological responses in individuals with anxious depression.

Main Methods:

• A double-blind, randomized trial involving 141 participants with MDD and elevated anxiety.
• Participants received 30-minute active (2mA) or sham tDCS targeting the dorsolateral prefrontal cortex (DLPFC) during fMRI.
• Measures included neural responses to emotional faces, fear-potentiated startle (FPS), and anxiety-potentiated startle (APS).

Main Results:

• Active tDCS enhanced executive functions, improving task accuracy and reaction times with increased frontal cortical activation.
• Unexpectedly, active tDCS heightened amygdala response under low attentional load and increased anxiety-potentiated startle (APS) responses.
• Anxiety ratings also showed a slight increase with active tDCS, contrary to the hypothesis.

Conclusions:

• tDCS demonstrates potential in enhancing executive functions and cognitive engagement in individuals with anxious depression.
• The study did not find evidence for tDCS reducing threat sensitivity as hypothesized.
• Optimizing tDCS efficacy may require contextual interventions or synergistic approaches for treating anxious depression.