Biomarkers for nonmotor disease acuteness among individuals with Parkinson disease can be reliably and economically measured using quantitative electroencephalogram (EEG), according to a study recently published in Neurology.

This systematic review included 36 studies, of which 23 dealt with cognition, 13 with motor function, 7 with intervention response, and 10 with other results. Cross-sectional studies revealed EEG slowing to be associated with broad deterioration and global impairment of cognition. Longitudinal studies found EEG slowing through reduced dominant frequency and greater θ power to be a biomarker of individual cognitive decline.

Individuals with normal cognitive function had significantly faster EEG than those with Parkinson disease and dementia. Certain correlations varied with the instrument of measurement used in the study. Researchers found inconsistent results for motor dysfunction and its respective treatment, while longitudinal studies on connectivity and other domains, as well as studies dealing with individual functional connectivity, were low quality.

Investigators found studies using the PubMed, Web of Science, EmCare, Cochrane Library, Academic Search Premier, Embase, and ScienceDirect databases. Inclusion criteria included satisfactory quality of methodology and an investigation of associations between cortical quantitative EEG readings and idiopathic Parkinson disease symptoms.

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The study researchers conclude that “[quantitative EEG] provides inexpensive, reliable, and widely available measures that could serve as biomarkers for nonmotor disease severity in patients with [Parkinson disease]. The availability of objective biomarkers of disease severity and progression in [Parkinson disease] could directly contribute to patient management, potentially providing the opportunity for early diagnosis of nonmotor symptoms, a more reliable prognosis, and an objective monitoring of progression, both in the context of clinical practice and clinical trials.”

This study received a grant from Stichting ParkinsonFonds and the Stichting Alkemade-Keuls. Several authors report associations with pharmaceutical companies. For a full list of disclosures, visit the reference.


Geraedts VJ, Boon LI, Marinus J, et al. Clinical correlates of quantitative EEG in Parkinson disease: a systematic review [published online October 5, 2018]. _Neurology._doi: 10.1212/WNL.0000000000006473