This study, conducted by Conti et al., explores the relationship between deficiencies in the blood-brain barrier (BBB) and cortico-cortical functional connectivity (FC) in patients with early-stage Parkinson’s disease by using the Albumin Index (Qalb) to measure BBB permeability. This study utilized high-density electroencephalography (HD-EEG) to record EEG data and network-based statistics (NBS) in combination with machine learning (ML) to analyze data. FC between 68 patients with early-stage Parkinson’s and 62 healthy controls were compared using NBS in combination with optimized non-linear ML, and the Qalb data was analyzed using this novel method as well. In this study, it was found that Qalb had little correlation with neurodegenerative markers, but prior research has found higher Qalb measurements in diseased patients compared to healthy patients. The results showed that FC differences between healthy patients and diseased patients varied by band. In the α band, there was decreased FC in patients with Parkinson’s compared to healthy patients, while in the β band, there was increased FC. Decreased FC in the α band was found to be linked to deficits in motor and cognitive function, while increased FC in the β band was found to be linked to bradykinesia. In the limbic, prefrontal, and temporal regions, a negative correlation was found between higher Qalb values and the EEG-FC in the α band.