Abstract: This invention provides methods of preserving, improving, or restoring cognitive function in mammal having one or more mutations in the FMR1 gene (e.g. at risk for or having fragile x syndrome), where the methods involve the brain derived neurotrophic factor (BDNF) level or activity in the brain of said mammal. In certain embodiments the methods involve administering one or more AMPA potentiators (e.g., ampakines) to the mammal in an amount sufficient to increase BDNF levels in the brain of the mammal.