Valproic Acid in Subjects With Intact Cognition - Proof of Concept Study

Inclusion Criteria: 1. Men or women aged 65-90, inclusive. 2. English-speaking, to ensure compliance with cognitive testing and study visit procedures. 3. Female participants must not be pregnant or of childbearing potential, i.e. either surgically sterile or postmenopausal for \> 1 year. 4. Stable medical condition for three months prior to screening visit, with no clinically significant abnormalities of hepatic, renal, and hematologic function defined as follows: * Platelets \> 100,000 * Serum creatinine ≤ 1.6 mg/dL * Liver function tests ≤ 1.5 upper limit of normal * No clinically significant abnormalities of other laboratory studies (blood counts, chemistry panel, urinalysis) as determined by the study physician 5. Stable medications for 4 weeks prior to screening visit. 6. Able to ingest oral medications. 7. No history of adverse drug reactions to VPA or similar agents. 8. Physically acceptable for this study as confirmed by medical history, physical exam, neurological exam and clinical tests in the opinion of the study physician. 9. Not demented by Hachinski Ischemic Index (\< 4). Exclusion Criteria: 1. Significant neurologic disease such as Parkinson's disease, stroke, brain tumor, multiple sclerosis or seizure disorder. 2. Major depression in past 12 months (DSM-IV criteria), major mental illness such as schizophrenia, or recent (in past 12 months) alcohol or substance abuse by history. 3. History of invasive cancer within the past two years (excluding non-melanoma skin cancer). 4. Contra-indications to lumbar puncture (bleeding disorder, platelet count \< 100,000, anticoagulant treatment, major structural abnormality or sepsis in the area of the lumbosacral spine that would make spinal fluid collection technically difficult). 5. Clinically significant MRI abnormalities that contraindicate lumber or suggest central nervous system disease processes that could influence study outcomes in the opinion of the PI. 6. Use of any investigational agents within 30 days prior to screening. 7. Major surgery within eight weeks prior to the Baseline Visit. 8. Severe unstable medical illnesses, including uncontrolled cardiac conditions or heart failure (New York Heart Association Class III or IV) . 9. Antiretroviral therapy for human immunodeficiency virus (HIV). 10. Residence in a skilled nursing facility. 11. Blindness, deafness, language difficulties or any other disability which may prevent the participant from participating or cooperating in the protocol. Excluded Medications 1. Experimental drugs 2. Lamictal 3. Tricyclic antidepressants (amitriptyline/nortryptiline) 4. Carbamazepine/ oxcarbazepine 5. Benzodiazepines 6. Phenobarbital 7. Phenytoin 8. Tolbutamide 9. Topiramate 10. Warfarin 11. Zidovudine