Acute effects of deep brain stimulation on brain function in obsessive–compulsive disorder

•Theta power and phase-stability may be candidate markers to optimize deep brain stimulation (DBS) dose (voltage) in obsessive–compulsive disorder.•Maximal DBS-induced cortical power increases were seen at the previously defined individual therapeutic dose (voltage).•Within most patients, spectral power density effects lasted beyond stimulation time (pre-vs post-DBS). Deep brain stimulation (DBS) is an effective treatment for refractory obsessive–compulsive disorder (OCD) yet neural markers of optimized stimulation parameters are largely unknown. We aimed to describe (sub-)cortical electrophysiological responses to acute DBS at various voltages in OCD. We explored how DBS doses between 3–5 V delivered to the ventral anterior limb of the internal capsule of five OCD patients affected electroencephalograms and intracranial local field potentials (LFPs). We focused on theta power/ phase-stability, given their previously established role in DBS for OCD. Cortical theta power and theta phase-stability did not increase significantly with DBS voltage. DBS-induced theta power peaks were seen at the previously defined individualized therapeutic voltage. Although LFP power generally increased with DBS voltages, this occurred mostly in frequency peaks that overlapped with stimulation artifacts limiting its interpretability. Though highly idiosyncratic, three subjects showed significant acute DBS effects on electroencephalogram theta power and four subjects showed significant carry-over effects (pre-vs post DBS, unstimulated) on LFP and electroencephalogram theta power. Our findings challenge the presence of a consistent dose–response relationship between stimulation voltage and brain activity. Theta power may be investigated further as a neurophysiological marker to aid personalized DBS voltage optimization in OCD.