Apathy, a decline in goal-directed motivated behavior, is a common non-motor symptom in Parkinson's disease (PD). The dynamic information interaction between multiple brain functional networks, crucial for goal-directed behavior, remains unknown in patients with PD and pure apathy (PD-PA). This study thus used the dynamic functional network connectivity (dFNC) analysis to explore the dynamic brain networks changes of apathy in PD.

Thirty patients with PD-PA, 37 patients with PD but not pure apathy (PD-NPA), and 37 healthy controls (HCs) were studied using dFNC analysis to explore dynamic functional connectivity (FC) patterns of brain networks in PD-PA.

Seven brain networks were finally identified and configured into four states. Patients with PD-PA showed longer mean dwell time in State 1 when compared to patients with PD-NPA. Furthermore, the mean dwell time of State 1 positively correlated with apathy severity in patients with PD-PA. Generally, State 1 is hypo-connected than other states. In State 1, intra-network FC within the default mode network (DMN) in patients with PD-PA was decreased compared to patients with PD-NPA. Specifically, the FC of the left precuneus and the left medial superior frontal gyrus (SFGmed) within the DMN was decreased.

Apathy in PD may be related with prolonged low connectivity in brain networks, particularly the disconnection between the precuneus and SFGmed within the DMN, highlighting impaired information transmission within and between networks as a key mechanism of apathy in PD.