Disclosed is a means for improving the symptoms of a cerebral dysfunction. The present inventors made a new discovery that the activity of brain aromatic monoamines increases when sepiapterin is administered peripherally. Disclosed, therefore, is a medicinal agent, which contains at least sepiapterin or a salt thereof, for preventing or improving cerebral dysfunction. Also disclosed is a beverage/food, which contains at least sepiapterin or a salt thereof, for preventing or improving cerebral dysfunction. Unlike tetrahydrobiopterin and the like, sepiapterin can control reductions in the brain neuron levels of brain aromatic monoamines (serotonin, dopamine, noradrenaline, and the like) and increase the activity thereof even when administered peripherally. Therefore, sepiapterin may be effective for cerebral dysfunctions, which are due to reductions in the brain neuron levels of brain aromatic monoamines, such as depression, bulimia, autism, impaired consciousness and concentration, cognitive disorders and other central mental disorders, as well as myotonia, rigidity, tremors, and other central motor disorders.
