In this letter, we hypothesize that efficiency reduction in the entire brain network as a result of destruction of basal ganglia in PD might be the cause of other psychiatric symptoms because, in complex networks, there are tremendous interactions between different parts; thus, if destruction occurs in one area, it can cause malfunctioning in the other parts of the system. To give a clue to this conjecture, we propose to construct the brain structural network graph with available data in a way that nodes represent different functional areas in the brain, and edges represent the connections between these parts.3 However, one of the issues that concerns us with most of the graph studies of the brain, is the lack of using weighted-edges graphs.1 Weights can represent different meanings in structural and functional brain networks.5 We consider dopamine levels in dopaminergic pathways between nodes as weights for edges. This approach gives a realistic meaning to nodal and modular connections of the brain graph in Parkinson modeling. By using this definition, we can determine whether the reduction of dopamine in basal ganglia can affect the function of other parts of the brain. This can lead us to a new explanation about how psychiatric symptoms like depression appear in PD patients. This suggested model should be simulated in future works in order to make its advantages and problems manifest.