Common and specific effects in oscillations and motor symptoms of tDCS and tACS in Parkinson disease
Poster No:
144
Submission Type:
Abstract Submission
Authors:
Junjie Bu1, Ying Zhu1, Qiujian Meng1, Jiafang Liu1
Institutions:
1Anhui Medical University, Hefei, Anhui
First Author:
Co-Author(s):
Introduction:
Parkinson's disease (PD) is a prototypical oscillation-related neurodegenerative disorder, and these aberrant neural oscillations lead to the pathophysiology of various motor phenotypes specific to patients [1]. Recently, transcranial direct/alternating current stimulation (tDCS/tACS) are widely utilized for non-invasive modulation and restoration of brain neural oscillations, and have been demonstrated to have potential to ameliorate motor symptoms in PD patients. However, it is unclear whether tDCS and tACS improve motor symptoms in PD patients through a consistent oscillatory modulation mechanism. Here, we conducted the first randomized controlled trial (RCT) to compare the modulation in PD patients by tDCS and tACS.
Methods:
To observe abnormal baseline brain oscillations in PD patients, we first analyzed 41 PD patients and 41 healthy controls (HC) from two external open-source datasets. Then, we conducted a double-blind RCT (NCT05678725) with 60 idiopathic PD patients randomly assigned to the tDCS, beta tACS (20Hz), or sham stimulation groups, applying stimulation to left primary motor cortex. Participants completed a 15-minute simple reaction task (sRT) during and after stimulation to assess changes in motor function. Before and after stimulation, we collected 5-minute eyes-open resting-state electroencephalogram (EEG), the unified Parkinson's disease rating scale part III (UPDRS III), and the Montreal cognitive assessment (MoCA) to assess changes in brain oscillations, motor functions, and global cognitive function respectively.
Results:
In external datasets, PD patients displayed abnormal cortical oscillations compared to HC, marked by significantly increased cortical theta power and decreased cortical beta power.
In the RCT, for brain oscillations, both tDCS and tACS induced a common and significant increase in beta power compared to the sham. However, reduced theta power was specific to the tDCS group. The alterations in theta and beta power induced by tDCS or tACS were moving toward a more 'normal' level. Furthermore, for motor symptoms, both tDCS and tACS significantly ameliorated rigidity-bradykinesia symptoms, which were associated with changes in beta power induced by tDCS and tACS. Interestingly, tDCS exhibited specific improvements in tremor and cognition, with tremor improvement being linked to tDCS-induced specific reduction in theta power. Exploratory analyses uncovered that tDCS significantly also decreased theta/beta ratio, and that tDCS-induced tremor-specific change could be more effectively fully mediated and predicted by theta/beta ratio than theta alone, supporting the theta and beta independently together roles in tremor.
In the RCT, for brain oscillations, both tDCS and tACS induced a common and significant increase in beta power compared to the sham. However, reduced theta power was specific to the tDCS group. The alterations in theta and beta power induced by tDCS or tACS were moving toward a more 'normal' level. Furthermore, for motor symptoms, both tDCS and tACS significantly ameliorated rigidity-bradykinesia symptoms, which were associated with changes in beta power induced by tDCS and tACS. Interestingly, tDCS exhibited specific improvements in tremor and cognition, with tremor improvement being linked to tDCS-induced specific reduction in theta power. Exploratory analyses uncovered that tDCS significantly also decreased theta/beta ratio, and that tDCS-induced tremor-specific change could be more effectively fully mediated and predicted by theta/beta ratio than theta alone, supporting the theta and beta independently together roles in tremor.
Conclusions:
This RCT represents the first attempt to compare changes in cortical oscillations and symptom improvements following tDCS or tACS modulation in PD patients, thereby highlighting both their common and specific effects. tDCS exerts a broad-spectrum modulatory effect on oscillations, resulting in the improvement of multiple symptoms in PD patients, while tACS provides specific modulation by targeting single oscillation to impact specific symptom. These findings elucidate the different oscillatory mechanisms underlying symptom improvements in PD, underscoring the pivotal role of aberrant oscillations in the pathophysiology of PD tremor and rigidity-bradykinesia.
Brain Stimulation:
Non-invasive Electrical/tDCS/tACS/tRNS 2
Disorders of the Nervous System:
Neurodegenerative/ Late Life (eg. Parkinson’s, Alzheimer’s) 1
Keywords:
Electroencephaolography (EEG)
Movement Disorder
Treatment
Other - non-invasive transcranial electrical stimulation
1|2Indicates the priority used for review