Stimulation of neuronal excitatory amino acid receptors is an important step in the formation of memory. It is unknown whether stimulation of these receptors in patients with Alzheimer's disease and dementing disorders will improve cognitive function. To determine whether positive modulation of AMPA receptors, active in animal models of dementia, can improve cognitive function in demented patients, CX516, at a dose of 900mg TID, will be administered orally for 12 weeks in patients with dementia. In this randomized, controlled proof-of-principle study, drug-induced alterations in intellectual function will be measured by standardized neuropsychological tests. Safety will be monitored by frequent clinical assessments and laboratory tests.