EEG-Derived Functional Connectivity Patterns Associated with Mild Cognitive Impairment in Parkinson’s Disease

Abstract

Objective: To evaluate EEG-derived functional connectivity (FC) patterns associated with mild cognitive impairment (MCI) in Parkinson’s disease (PD). METHODS: A sample of 15 patients without cognitive impairment (PD-WCI), 15 with MCI (PD-MCI), and 26 healthy subjects were studied. The EEG was performed in the waking functional state with eyes closed, for the functional analysis it was used the synchronization likelihood (SL) and graph theory (GT). RESULTS: PD-MCI patients showed decreased FC in frequencies alpha, in posterior regions, and delta with a generalized distribution. Patients, compared to the healthy people, presented a decrease in segregation (lower clustering coefficient in alpha p = 0.003 in PD-MCI patients) and increased integration (shorter mean path length in delta (p = 0.004) and theta (p = 0.002) in PD-MCI patients). There were no significant differences in the network topology between the parkinsonian groups. In PD-MCI patients, executive dysfunction correlated positively with global connectivity in beta (r = 0.47) and negatively with the mean path length at beta (r = −0.45); alterations in working memory were negatively correlated with the mean path length at beta r = −0.45. CONCLUSIONS: PD patients present alterations in the FC in all frequencies, those with MCI show less connectivity in the alpha and delta frequencies. The neural networks of the patients show a random topology, with a similar organization between patients with and without MCI. In PD-MCI patients, alterations in executive function and working memory are related to beta integration.

Graph Theory on Brain Cortical Sources in Parkinson’s Disease: The Analysis of ‘Small World’ Organization from EEG

“…In fact, they observed that the SW index in the alpha band increased in the pathological condition rather than the physiological one. In other studies [2,85], the EEG recordings of PD patients were analyzed through several indexes of graph theory, demonstrating evidence of network breakdown that correlates with decreased cognitive performance.…”

EEG-Based Mapping of Resting-State Functional Brain Networks in Patients with Parkinson’s Disease

“…Few studies investigated EEG-derived directed connectivity patterns in patients with PD, showing increased connectivity in the beta frequency band and decreased connectivity in the theta band [ 27 ]. However, these studies measured connectivity between EEG electrodes representing the sum of many underlying components generated from various brain areas (“the superposition problem”) [ 19 , 20 , 27 ]. In addition, these findings do not fully depict the functional changes within the brains’ functional networks.…”

The applied principles of EEG analysis methods in neuroscience and clinical neurology

“…In addition, it can be classified according to the shape of the EEG itself. For example, it can be divided into delta, theta, and alpha based on frequency [ 18 , 19 ] or slow wave, fast wave, sharp wave, and spike wave based on shape.…”