Commercial use is a long way off, but research with mice offers hope for a ‘smart drug’ that doesn’t have the sort of nasty side-effects that, for example, amphetamines have. The mice, genetically engineered to produce dramatically less (70%) kynurenic acid, had markedly better cognitive abilities. The acid, unusually, is produced not in neurons but in glia, and abnormally high levels are produced in the brains of people with disorders such as schizophrenia, Alzheimer's and Huntington's. More acid is also typically produced as we get older.
The acid is produced in our brains after we’ve eaten food containing the amino acid tryptophan, which helps us produce serotonin (turkey is a food well-known for its high tryptophan levels). But serotonin helps us feel good (low serotonin levels are linked to depression), so the trick is to block the production of kynurenic acid without reducing the levels of serotonin. The next step is therefore to find a chemical that blocks production of the acid in the glia, and can safely be used in humans. Although no human tests have yet been performed, several major pharmaceutical companies are believed to be following up on this research.
(2010). Reduction of Endogenous Kynurenic Acid Formation Enhances Extracellular Glutamate, Hippocampal Plasticity, and Cognitive Behavior.
Neuropsychopharmacology. 35(8), 1734 - 1742.