Table 3.

Summary of the main results of PD studies reported in the present review.

Authors	Recording Type	Graph Parameters	Main Results
Fogelson et al., 2013 [60]	EEG	C PL	C ↑ in theta and alpha bands PL ↑ in theta band for PD vs. Healthy subjects.
Olde Dubbelink et al., 2014 [57]	MEG	C PL	C↓ in delta band for PD vs. Healthy subjects C ↓ in theta and alpha 2 bands, PL ↓ in alpha 2 band for PD subjects
Utianski et al., 2016 [22]	EEG	C PL Divergence Modularity	C and PL ↑ in all frequency bands, Divergence ↑ in theta and beta bands and ↓ in delta and alpha bands, Modularity ↑ in all frequency bands, for normally cognitive PD vs. Healthy subjects. C ↓ in alpha 1 band for PD-MCI vs. normally cognitive PD subjects. C, PL and Divergence ↓ in alpha 1, Modularity ↑ in alpha 1 and 2 frequency bands, for demented PD vs. normally cognitive PD subjects.
Hassan et al., 2017 [26]	EEG	C PL Modularity Strength	PL, C, Modularity and Strength ↓ in alpha frequency band for demented PD vs. normally cognitive PD subjects.
Mehraram et al., 2020 [59]	EEG	Node degree C PL SW Modularity	C and Node degree↓ in alpha band, PL ↑ in alpha band and Modularity↑ in theta and alpha bands, for PD demented vs. Healthy subjects. PL ↑ in alpha band, Modularity↑ in theta and alpha bands and SW ↑in theta band, for PD demented vs. AD subjects.
Bočková et al., 2021 [61]	EEG	Node strength C PL Modularity	Node strength ↓, C ↓ and PL ↑ in 1–8 Hz frequencies band for DBS-ON compared to DBS-OFF for subjects responding faster with DBS-OFF rather than DBS-ON.
Suárez et al., 2021 [58]	EEG	C PL Local efficiency Global connectivity	C and PL ↓ in theta and beta bands for normally cognitive PD vs. Healthy subjects. C ↓ in alpha band, PL ↓ in delta and theta bands in PD-MCI vs. Healthy subjects.
Vecchio et al., 2021 [21]	EEG	SW	SW ↓ in theta band and ↑ in alpha 2 band.
Li et al., 2021 [20]	EEG	C PL Global efficiency Local efficiency	C and Local efficiency ↓ in alpha, beta 1 and beta 2 bands for PD subjects in DBS-OFF and DBS-ON vs. healthy subjects.
Revankar et al., 2021 [23]	EEG	C PL Efficiency Centrality	C and parietal Efficiency ↑ in alpha 1 band, frontal Centrality ↓ for PD with pareidolias vs. normal PD and Healthy subjects.

The arrows refer to an increase (↑) or a decrease (↓) of the indicated parameters. Abbreviations: EEG: electroencephalography; MEG: magnetoencephalography; PL: path length; C: clustering coefficient; SW: small-world index; PD-MCI: Parkinson disease with mild cognitive impairments.