2. Conditions other than HAND associated with cognitive impairment or dementia such as Alzheimer s, Parkinson s disease, head injury with loss of consciousness >30 minutes, untreated sleep apnea with day-time sleepiness, or seizure disorders. Subjects with a history of seizure disorder with no seizure activity that are on a stable, non-sedating anti-seizure regimen for >6 months may be enrolled.