If memantine were started 6 weeks after completion of radiation to base of skull, would you expect any potential benefit?

There is currently no credible high-quality data to support the use of memantine in focal brain RT for primary or metastatic brain tumors, regardless of whether the hippocampus is in the radiation field. Therefore, I would not prescribe memantine during or after RT in such a clinical setting. In my experience, I'm yet to see a clinically appreciable neurocognitive deficit in any adult patient treated with focal RT that can be directly attributed to radiation to intact brain parenchyma and not to tumor progression. While memantine is generally safe, it can occasionally cause bothersome side effects such as fatigue, drowsiness, and dizziness. Additionally, the out-of-pocket cost of memantine for 6 months is approximately 1,200 USD, and insura...

I liberally prescribe memantine to patients with cranial radiation (not only WBRT) but I would not start memantine 6 months post-radiation. I believe that the damage is mostly done by then and the evidence for drug treatments once the cognitive effects of radiation have set in are not supportive of treatment.