Cognitive symptoms play a significant role in the development and maintenance of Major Depressive Disorder (MDD). This is evidenced by the fact that one of the major theories about MDD is the cognitive theory. However, the manner in which cognitive symptoms develop over time after treatment and the influence of these symptoms on other MDD symptoms remain unclear. This thesis will attempt to gain a better understanding of the influence of cognitive symptoms on other MDD symptoms and the development of the cognitive symptoms by using the network analysis approach. The results of this thesis indicates that cognitive symptoms are a significant component of the MDD structure and dynamics, exerting a considerable influence on the core symptoms of MDD.