Abstract
IntroductionThe microstate analysis is a method to convert the electrical potentials on the multi-channel electrode array to topographical electroencephalography (EEG) data. Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive method that can modulate brain networks. This study explores the pathophysiological changes through microstate analysis in two different neurodegenerative diseases, Alzheimer’s (AD) and Parkinson’s disease (PD), characterized by motor and cognitive symptoms and analysis the effect of rTMS on the impaired cognitive and motor functions.Materials and MethodsWe included 18 AD, 8 PD patients, and 13 age-matched controls. For both groups, we applied 5 Hz rTMS on the left pre-SMA in PD patients while 20 Hz rTMS on the left lateral parietal region in AD patients. Each patient was re-evaluated 1 week after the end of the sessions, which included a detailed clinical evaluation and measurement of EEG microstates.ResultsAt the baseline, the common findings between our AD and PD patients were altered microstate (MS) B, MS D durations and transition frequencies between MS A–MS B, MS C–MS D while global explained variance (GEV) ratio and the extent and frequency of occurrence of MS A, MS B, and MS D were separately altered in AD patients. Although no specific microstate parameter adequately differentiated between AD and PD patients, we observed significant changes in MS B and MS D parameters in PD patients. Further, we observed that Mini-Mental State Examination (MMSE) performances were associated with the transition frequencies between MS A–MS B and MS C–MS D and GEV ratio. After left parietal rTMS application, we have observed significantly increased visual memory recognition and clock drawing scores after left parietal rTMS application associated with improved microstate conditions prominent, especially in the mean duration of MS C in AD patients. Also, pre-SMA rTMS resulted in significant improvement in motor scores and frequency of transitions from MS D to MS C in PD patients.ConclusionThis study shows that PD and AD can cause different and similar microstate changes that can be modulated through rTMS, suggesting the role of MS parameters and rTMS as a possible combination in monitoring the treatment effect in neurodegenerative diseases.
Highlights
The microstate analysis is a method to convert the electrical potentials on the multi-channel electrode array to topographical electroencephalography (EEG) data
To evaluate the significance of these findings to the microstate correlates of the pathophysiological mechanisms, we examined the microstate parameters before and after the Repetitive transcranial magnetic stimulation (rTMS) application
In evaluating the cognitive and motor responses and their relation with microstate parameters we have observed significantly increased visual memory recognition and clock drawing scores after left parietal rTMS application associated with improved microstate conditions prominent, especially in the mean duration of MS C
Summary
The microstate analysis is a method to convert the electrical potentials on the multi-channel electrode array to topographical electroencephalography (EEG) data. This study explores the pathophysiological changes through microstate analysis in two different neurodegenerative diseases, Alzheimer’s (AD) and Parkinson’s disease (PD), characterized by motor and cognitive symptoms and analysis the effect of rTMS on the impaired cognitive and motor functions. Neurodegenerative diseases are devastating conditions with progressive pathologies affecting neurons in both the central and the peripheral nervous systems (Rekatsina et al, 2020). In many neurodegenerative diseases, including Alzheimer’s (AD) and Parkinson’s disease (PD), neuronal networks undergo complex progressive degeneration manifested by both morphological and functional modifications leading to gradual changes in cognitive, behavioral, and motor skill functions (Katsnelson et al, 2016). Neurodegenerative diseases are thought to share common pathophysiological mechanisms highlighted by the aggregation of misfolded proteins and neuroinflammation which leads to progressive central nervous system impairments. There has been sufficient evidence to show cognitive domains that are impaired in patients with AD are memory, attention and executive functions (Spaan et al, 2005, 2010)
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