Donepezil in Treating Patients Who Have Undergone Radiation Therapy for Brain Tumors

INCLUSION CRITERIA: * Adults \>18 years old. * Life expectancy of at least \> 30 weeks. * Must have received a prior course of at least 30 Gy fractionated whole or partial brain irradiation for treatment of a primary brain tumor or metastatic disease to the brain. * Must have completed radiation \> 6 months prior to enrollment and have no radiographic evidence of brain disease, or stable brain disease defined as no evidence of tumor progression in the 3 months prior to enrollment. * Patients who have undergone one or more treatments with single fraction stereotactic radiosurgery (SRS) in addition to whole or partial brain irradiation are eligible, as long as the SRS was completed \> 6 months prior to registration if NED or stable disease. * Radiation treatment records must be available for all prior radiation treatments (external beam and/or SRS). * Patients who have received PCI (prophylactic cranial irradiation) are eligible. * Karnofsky Performance Status must be \> 60 or ECOG 0-2. * Treatment with steroids, anti-cholinergics, anti-epileptics, anti-depressants, and /or sedatives/benzodiazepines is acceptable, but the patient must be on a stable or decreasing dose at the time of study entry. * Patients using narcotic analgesics on a stable dose and/or prn basis are eligible. * Patients currently on a stable dose of Methylphenidate or Dextramphetamine are eligible. * For patients with brain metastases, if extracranial primary or metastatic disease is present, it must have r…