EEG Oscillations Response To Dual-Target rTMS Therapy of Parkinson Disease and Co-Occuring Depression

Abstract

The approach intended evaluating neurophysiological concomitants of treatment response to dual-target navigated TMS in patients with Parkinson’s disease and co-occuring depression. Patients with PD (n=46) were initially enrolled for a placebo-controlled study and randomly assigned to either an actively treated (rTMS, n = 23) or a sham-stimulation (sTMS, n=23) groups. Every TMS session was performed sequentially over the primary motor cortex (20 min) followed by the DLPFC (20 min). The patients received a total of 20 sessions on 20 consecutive days. For every participant the main outcome measure included the MDS-UPDRS Motor Examination Part (Part 3) scale score, BDI-II and DASS depression scores as well as spectral parameters of the resting EEG (the last ones were available for fewer patients - rTMS, n=15; sTMS, n=16). After the stimulation course the Part 3 scale scores demonstrated clinically meaningful improvement which was larger in the rTMS group (GROUP by TIME: F1,88= 44,06 p<.001). The BDI-2 and DASS scores showed significantly attenuated negative affect for both groups (TIME: BDI-2 - F1,44=4.48, p <.040; DASS - F1,44=15.34, p <.000). According to sLORETA, beneficial treatment response to the TMS course was accounted by selective EEG power increase over the theta, high beta and gamma frequency bands and significantly locked only to the rTMS group. Using source analysis, the generators of this power difference were localized to somatosensory and visual functional networks, as well as to separate nodes of the salience and default mode networks. There was an increased frontal lobe activation (the 9thand 10thBrodman areas). The main EEG power differences were locked to the ranges of 18-30 Hz and 30-45 Hz (sLORETA statistics at p < .05).The findings demonstrate the beneficial effects of the dual-target TMS in PD and hints to some EEG oscillatory signatures as putative predictors of the treatment response.