The objective was to investigate the time-varying functional connectivity (FC) patterns of Parkinson’s disease (PD) patients with depressive symptomatology.

Depression is frequently observed in PD and is related to quality of life deterioration. Previous studies have shown relationships between static FC alterations and depressive symptoms in PD, but to date, no study has evaluated the temporal properties of connectivity in PD patients with depressive symptomatology.

Seventy-nine PD patients and 63 healthy controls (HC) underwent a clinical, cognitive and depression assessment evaluated by Geriatric Depression Scale.  Resting-state fMRI and T1-weighted MRI were also acquired. Dynamic FC analyses were performed in GIFT toolbox. The temporal properties of connectivity were analyzed: fractional time window (i.e. total time spent in one dynamic state); mean dwell time (i.e. mean time spent in one state before switching to another); and state transitions (i.e. number of changes between states). MANCOVA analyses were performed to test differences between groups.

Fifty-six PD patients with depression, 23 PD patients without depression and 63 HC were analyzed. Dynamic FC analyses revealed two dynamic connectivity States. State I showed intra-network connectivity and State II revealed stronger between-network connectivity.  PD patients with depression showed reduced fractional time window in State I compared to PD patients without depression and HC, while State II occurred at a higher rate (p<.05). Similar changes were found in mean dwell time. Also, PD patients with depressive symptoms increased the number of changes between states (p<.001).

Findings suggest that presence of depressive symptoms in PD patients was related to alterations in the dynamic FC, showing a shorter time spent in the state with intra-network connectivity and proportionally remained longer in the state with stronger connectivity. In addition, PD patients with depressive symptoms showed a less stable pattern connectivity. Instead, PD patients without depressive symptomatology showed no dynamic FC alterations.