Increased aperiodic offset and heightened alpha power characterize resting-state EEG activity in Parkinson’s disease

Background Parkinson’s disease (PD) is characterized by widespread neurodegeneration across neuromodulatory systems, profoundly affecting cortico–basal ganglia–thalamic loops. The resulting cortical alterations can be detected with electroencephalography (EEG). Emerging evidence shows that aperiodic EEG components provide biologically meaningful information that complements the periodic features traditionally examined. Therefore, dissociating periodic and aperiodic components may yield sensitive and specific pathophysiological markers of PD.

Objectives To characterize aperiodic and periodic EEG signatures in PD during OFF-medication resting-state and examine their relationships with age, disease duration, and levodopa-induced dyskinesias.

Methods Resting-state EEG was recorded from forty patients with PD OFF-medication and twenty-six age- and sex-matched healthy controls. Twenty-five patients and ten controls returned for a second visit. Power spectra were parametrized to extract aperiodic exponent, offset and power in the alpha and beta frequency bands. Bayesian ANCOVAs were used to assess between-group differences and associations with clinical and demographic variables.

Results Aperiodic offset and alpha power were higher in patients than controls across all channels (BF10=72.41; BF10=20.45) and when restricting analysis to pericentral sensorimotor channels (BF10=63.01; BF10=12.06). These differences were expressed in patients with and without levodopa-induced dyskinesias and replicated at follow-up. In patients, aperiodic offset and exponent, but not periodic alpha or beta power, scaled positively with age and disease duration (BF10=2.16–9.76).

Conclusions PD is associated with changes in resting-state brain activity, reflected in both aperiodic and periodic EEG activity. The finding that aperiodic parameters scale with age and disease duration suggests that aperiodic EEG features may serve as markers of disease progression, complementing traditional periodic measures.