Cognitive dysfunctions in medulloblastoma survivors are common and multifactorial. Craniospinal radiation therapy, surgery-related injuries, and chemotherapy cytotoxicity are the major contributors. Given the long-lasting effects, neurocognitive outcomes should be adequately assessed and a key focus in clinical trials. This methodological review merges data about the mechanisms through which medulloblastoma and its treatment affect cognition and points out how the domains of cognition have been evaluated in observational studies and clinical trial protocols. The main objectives are to sensibilize neuro-oncologists on the theoretical foundations of cognition and its evaluation, emphasizing the importance and feasibility of integrating neurocognitive assessments into clinical trials and practice.