Complexity of electrocortical activity as potential biomarker in untreated Parkinson’s disease
In Parkinson’s disease (PD), the identification of instrumental biomarkers is crucial to evaluate disease susceptibility and motor stage. We evaluated self-similarity of electrocortical activity as expression of brain signal complexity in untreated PD, to investigate its possible role as a neurophysiological biomarker. We analyzed the data of 34 untreated PD subjects and 18 group-matched controls who underwent standardized electroencephalography. A Welch’s periodogram was applied to site-specific electroencephalographic signal epochs. To investigate self-similarity of electrocortical activity, the power law exponent β was computed for each selected coordinate. In both PD subjects and controls, β values at each coordinate increased with an antero-posterior gradient, changing from values around one in fronto-temporal sites to values around two among parieto-occipital sites. PD subjects presented overall lower β values among different sites compared to controls, with significant differences for the left fronto-temporal sites. Our findings suggest an increased level of fronto-temporal neuronal organization in untreated PD. We hypothesize a possible role of β as a neurophysiological biomarker for early untreated PD.
KeywordsUntreated Parkinson’s disease Electrocortical complexity Power law exponent β Fronto-temporal electrocortical activity Biomarker
Compliance with ethical standards
The study protocol concerning data collection and analysis was approved by the local ethics committee. A written informed consent was obtained by study participants. The study has been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments.
Conflict of interest
The authors have nothing to report.
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