Magnetoencephalography in Parkinson's disease: diagnostic potential and barriers to clinical translation

Parkinson's disease (PD) is a heterogeneous neurodegenerative disorder with motor and nonmotor manifestations. Diagnosis remains primarily clinical, and validated markers of early disease and subsequent progression are still needed. Magnetoencephalography (MEG) measures neuronal magnetic fields with millisecond temporal resolution and provides a means of characterizing cortical dysfunction. This narrative review critically synthesizes MEG evidence on periodic and aperiodic spectral activity, functional connectivity, network topology, and individual brain fingerprinting, with emphasis on diagnostic relevance and barriers to clinical translation. Recurring findings include spectral slowing and cognitive-network disruption, whereas resting β power, burst dynamics, and coupling depend on clinical phenotype, treatment state, and analytical choices. Evidence from electroencephalogram (EEG), functional magnetic resonance imaging (fMRI), and invasive recordings is distinguished from direct MEG findings. Internally validated classification of established PD and healthy controls is promising, but does not establish performance in prodromal disease or clinically uncertain parkinsonism. Optically pumped magnetometers may improve recording flexibility while retaining requirements for environmental interference control. Prospective clinical cohorts, standardized acquisition and analysis, reproducibility studies, independent validation, and comparison with clinical assessment are needed to establish incremental diagnostic and prognostic utility.