Radiation constitutes an integral component in the management of primary brain tumors in pediatric and young adults like medulloblastoma, ependymoma, low-grade glioma, pituitary tumors, etc. A decline in neurocognitive outcomes is a multifactorial effect occurring from the primary disease as well as associated with treatments, including radiation. Since many of these tumors are highly curable, it is crucial to reduce long-term side effects, including memory loss, to improve the quality of life in these patients, leading to better rehabilitation. Radiation-induced neurocognitive deterioration is postulated to occur from multiple factors like neuroinflammation, vascular damage, and depletion of neural stem cells. The proposed study will prospectively evaluate 200 pediatric and young adults with brain tumors treated with radiotherapy. Biological samples (peripheral blood and cerebrospinal fluid) will be procured during routine investigations (an additional amount will be collected for study purposes without the need for additional investigations). Serial blood markers (whenever available pre-operative and before, during, and after completion of radiation) of neuroinflammation and neural markers will be tested in patients undergoing radiation as part of their standard treatment, and correlate with the neurocognitive outcomes measured by age-appropriate Wechsler intelligence scales. Also, the impact of clinical (e.g. age) and radiotherapy parameters like volume, dose of radiation, and technique (photon versus proton therapy) on acute (during radiotherapy) and late systemic inflammatory markers will be analyzed. The study will even provide the opportunity to know the influence of radiation on systemic neuroinflammatory markers in the human population, providing better biological insights into the neurocognitive decline. If proven successful, these biomarkers can be used in routine clinical practice for early intervention to improve neurocognitive function in patients receiving radiation (even for other histology or other patients receiving radiation like brain metastasis).