Altered habenular and whole brain functional connectivity in early Parkinson's disease using 7 T MRI.

Parkinson's disease (PD) is traditionally linked to basal ganglia dysfunction, yet evidence highlights broader network disruptions. Habenula, involved in regulating mood, reward, and motor functions, remains underexplored in PD. This study investigated whole-brain and habenular functional connectivity and their clinical correlates in early-stage PD using 7 T MRI. Functional connectivity was analyzed in 104 early-stage PD and 45 healthy controls. Whole-brain analysis revealed increased connectivity in two clusters in PD: the first involved paracentral lobule, middle frontal gyrus, orbital middle frontal gyrus, precentral gyrus, angular gyrus, middle cingulate gyrus, supplementary motor area; the second included middle cingulate gyrus and cerebellum Crus I. Left habenula showed increased connectivity with right middle temporal and angular gyri (p-FDR = 0.011). Levodopa equivalent daily dose positively correlated with connectivity between postcentral gyrus and cerebellum (p-FDR = 0.020). These findings highlight early motor and cognitive network disruptions and suggest these regions may serve as potential markers of PD-related neurobiological changes.