The value of neuroimaging for treating depression with brain stimulation
Sarrazin V., O'Shea J.
This chapter evaluates how neuroimaging can advance non-invasive brain stimulation (NIBS) treatment for depression by addressing four questions: (1) Does neuroimaging-guided target localization improve treatment? (2) Has neuroimaging advanced understanding of NIBS treatment action? (3) Can neuroimaging help predict who will respond to treatment? (4) How can neuroimaging help personalize treatment? Since transcranial direct current stimulation (tDCS) is currently for investigational use, this chapter covers both tDCS and clinically approved treatment, transcranial magnetic stimulation, because the concepts and challenges are similar. For tDCS, the current most pressing use of imaging is to test for target engagement - to verify that stimulation is changing physiology within targeted brain circuits. Regarding treatment action, resting-state imaging suggests that stimulation normalizes aberrant fronto-limbic functional connectivity, resulting in improved regulation of negative affect. To date, the most promising predictor of treatment is strong connectivity between the cortical stimulation site and limbic regions. For treatment personalization, current imaging-guided approaches include the following: adjusting the stimulation target location per individual to maximize engagement of fronto-limbic connectivity, or categorizing patients into depression subtypes based on imaging biomarkers and tailoring the cortical target accordingly. A major future challenge will be translating group-level strategies into interventions that work for individuals.