Transcranial direct current stimulation to enhance cognition in euthymic bipolar disorder

Area of Science:

• Neuroscience
• Psychiatry
• Cognitive Science

Background:

• Bipolar disorder is often associated with cognitive impairments, including deficits in working memory and sustained attention.
• Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique explored for cognitive enhancement.

Purpose of the Study:

• To evaluate the efficacy of anodal left prefrontal tDCS and fronto-cerebellar tDCS in improving working memory and sustained attention in euthymic bipolar disorder patients.
• To identify potential responders and non-responders to tDCS interventions for cognitive functions in this population.

Main Methods:

• An intra-individual, cross-over, sham-controlled design was employed with 15 euthymic bipolar disorder patients.
• Participants underwent three conditions: prefrontal tDCS, fronto-cerebellar tDCS, and sham tDCS, while performing working memory and sustained attention tasks.
• Exploratory cluster analyses were performed to differentiate responders from non-responders.

Main Results:

• Approximately one-third of patients demonstrated improved working memory performance with both active tDCS conditions.
• A minority of patients (3 out of 15) showed enhanced sustained attention with prefrontal tDCS.
• Individuals who responded to active tDCS for working memory exhibited poorer performance during the sham condition compared to non-responders.

Conclusions:

• A single session of active prefrontal or fronto-cerebellar tDCS did not yield significant improvements in working memory or sustained attention in euthymic bipolar disorder patients.
• The findings suggest that tDCS may not be an effective standalone intervention for cognitive enhancement in this population.
• Further research is warranted to explore optimal parameters and patient characteristics for future tDCS investigations in bipolar disorder.