Neural basis of dysexecutive and visuospatial impairments in Parkinson’s disease with MCI: a task-based fNIRS study

Parkinson’s disease with mild cognitive impairment (PD-MCI) includes various cognitive deficits, classified into two subtypes based on the “dual syndrome hypothesis”: the executive-dominant dopamine pathway dysfunction impairing executive and language functions (PD-EL subtype), and the visuospatial-dominant non-dopaminergic dysfunction affecting visuospatial perception, attention, and memory (PD-VAM subtype). This study involved 182 participants (122 PD, 60 controls) undergoing cognitive assessments. Using PD-MCI Level II criteria, patients were categorized as PD with normal cognition (PD-NC, 48), PD-EL (34), or PD-VAM (40). Functional near-infrared spectroscopy measured brain activation during verbal fluency (executive) and line orientation (visuospatial) tasks. PD-EL showed lower word accuracy and reduced activation in dorsolateral/ventrolateral prefrontal cortices, supplementary motor area, and orbitofrontal cortex compared to PD-NC. PD-VAM had lower line orientation scores and reduced ventrolateral prefrontal activation. These findings suggest that PD-MCI subtypes may exhibit differential neural activation patterns reflecting their cognitive deficits, underscoring the need for targeted interventions and mechanistic research.