BackgroundProblematic use of social networks is a widespread problem that may exert deleterious impacts on cognitive functions. Moreover, studies have added an important link between loneliness and its harmful effect on cognitive functions. Other studies have also revealed that problematic use of social networks among teenagers has a pejorative influence on their social interactions, leading to increased social isolation. Therefore, the goal of our research was to investigate the link between problematic use of social networks and cognitive function in a group of Lebanese adolescents while also taking into consideration the indirect role of loneliness in this relationship.MethodsThis cross-sectional study, which was carried out between January and April 2022, included 379 teenagers (aged between 13 and 17 years), from all Lebanese governorates. The PROCESS SPSS Macro version 3.4, model four was used to compute three pathways. Pathway A determined the regression coefficient for the effect of problematic use of social networks on loneliness; Pathway B examined the association between loneliness and cognitive function, and Pathway C’ estimated the direct effect of problematic use of social networks on cognitive function.ResultsHigher negative social comparison, addictive consequences of problematic use of social networks, and loneliness were significantly associated with worse cognitive function. Loneliness mediated the association between negative social comparison and worse cognitive function, as well as between addictive consequences of problematic use of social networks and worse cognitive function. In addition, higher financial burden was significantly correlated with worse cognitive function, whereas higher physical activity was related to better cognitive function.ConclusionIn sum, the current study supports that problematic use of social networks is negatively associated with adolescents’ cognitive function, where loneliness seems to play a pivotal role in this equation. The results thus endorse the importance of helping Lebanese adolescents to overcome problematic use of social networks and recover from their loneliness, to achieve a better cognitive/academic performance.