This study is testing whether a medicine called memantine can help protect the brain during radiation therapy for kids and teens with brain tumors. Memantine might help with cognitive function, which means how well we think, remember, and pay attention, by blocking certain parts of the brain cells. The study compares memantine to a placebo (a fake pill) to see which works better.

Key Points:

• The study lasts up to 48 months, with follow-ups at several points including 12 and 24 months.
• Participants are required to take the study medicine or placebo daily for about 6 months, and undergo cognitive tests and MRIs.
• Eligibility includes ages 4-18, certain health conditions, and no prior radiation therapy. Pregnancy and certain health issues may exclude participants.

If chosen for the study, kids will be randomly assigned to take either memantine or a placebo. They will also have tests to measure their cognitive function at different times over the study period. This will help researchers find out if memantine is effective in helping the brain during radiation treatment.