Altered attention and visuospatial abnormalities in Parkinson's disease: links to attention networks and basal ganglia

Background: Attentional and visuospatial deficits in Parkinson's disease (PD) are linked to disrupted attention networks (AN), yet specific neural mechanisms remain unclear. This study aims to elucidate the relationship between these dysfunctions and aberrant AN circuits in PD. Methods: Sixty-two PD patients stratified by cognitive status [cognitively normal (PDCN), mild cognitive impairment (PDMCI), and dementia (PDD)] and 53 matched healthy controls (HC) underwent resting state functional MRI. We performed amplitude of low-frequency fluctuation (ALFF) and seed-based functional connectivity (FC) analyses. Relationships with cognitive functions were evaluated via partial correlation and mediation models. A support vector machine (SVM) classifier incorporating AN features was established for diagnostic validation. Results: Compared to HCs, PD patients showed increased ALFF in the right caudate nucleus (CAU) and left insular cortex (Ins), but reduced ALFF in the left middle occipital gyrus (MOG). FC analysis revealed decreased coupling in the right CAU-left cerebellum VI (CVI), left Ins-left middle cingulate gyrus (MCG), and left Ins-right superior temporal gyrus (STG), alongside enhanced left MOG-left inferior parietal lobule (IPL) connectivity. These alterations correlated significantly with cognitive performance. Mediation analysis identified left Ins ALFF and left Ins-left MCG FC as independent mediators of impairments. The SVM classifier achieved 92.2% accuracy (AUC = 0.944). Subgroup comparisons revealed increased ALFF in the left triangular inferior frontal gyrus (IFGtri) and angular gyrus (AG) in PDMCI vs. PDCN. PDD patients displayed decreased left supramarginal gyrus (SMG) ALFF compared to PDCN. Notably, left SMG-related alterations distinguished PDMCI from PDD and correlated with attention deficits. Conclusion: PD-related attention and visuospatial dysfunctions are closely linked to AN abnormalities. The Ins serves as a key regulatory node, while the SMG emerges as a potential neuroimaging marker for tracking cognitive decline from PDMCI to PDD.