Effect of levodopa on electroencephalographic biomarkers of the parkinsonian state.

Abstract

OBJECTIVE\nTo evaluate proposed electroencephalographic biomarkers of Parkinson disease (PD) and test their correlation with motor impairment, in a new well-characterized cohort of PD patients and controls.\n\n\nMETHODS\n64-channel electroencephalography was recorded from 14 rigid-akinetic PD patients with minimal tremor, and 14 age-matched healthy controls at rest and during voluntary movement. Patients were tested off and on medication during a single session. Recordings were analyzed for phase-amplitude coupling over sensorimotor cortex, and for pairwise coherence from all electrode pairs in the recording montage (distributed coherence).\n\n\nRESULTS\nPhase-amplitude coupling and distributed coherence were found to be elevated off compared to on levodopa and their reduction was correlated with motor improvement. In the off medication state, phase-amplitude coupling was greater in sensorimotor contacts contralateral to the most affected body part, and reduced by voluntary movement.\n\n\nCONCLUSIONS\nPhase-amplitude coupling and distributed coherence are cortical biomarkers of the Parkinsonian state that are detectable noninvasively, and may be useful as objective aids for management of dopaminergic therapy.\n\n\nSIGNIFICANCE\nSeveral analytic methods may be used for noninvasive measurement of abnormal brain synchronization in PD. Calculation of phase-amplitude coupling requires only a single electrode over motor cortex.