PRIMARY OBJECTIVE:

I. To evaluate the feasibility of twice daily memantine started before radiation therapy (RT) and one month after RT.

SECONDARY OBJECTIVE:

I. To evaluate the feasibility of twice daily (BID) memantine started before RT and continued 3 and 6 months after RT.

EXPLORATORY OBJECTIVES:

I. To evaluate the change in neurocognitive function (NCF) as found by formal neurocognitive testing between baseline and 12 months post-RT.

II. To compare the change in NCF between baseline and the end of RT, 3,and 6 months after RT using both neuropsychological testing and the CogState exam.

III. To evaluate changes in quantitative volumetric brain imaging using Neuroquant software analysis of magnetic resonance imaging (MRI) imaging before and 12 months after radiation.

IV. To correlate cognitive changes detected by CogState composite score and formal neuropsychological testing.

V. Disease-free (of primary tumor) and overall survival.

Patients receive memantine orally (PO) BID beginning at the time of study enrollment (no later than 1st day of RT) up to 6 months after completion of standard of care RT in the absence of unacceptable toxicity. Patients also complete CogState cognitive testing at baseline, at completion of RT, and at 3, 6, and 12 months after completion of RT.

After completion of study, patients are followed up periodically.