[Problem] To provide means for improving symptoms of cerebral dysfunction. [Solution Means] The inventor has newly found that peripheral administration of sepiapterin increases the bioavailability of aromatic monoamines in the brain. Accordingly, provided are a drug for preventing or improving cerebral dysfunction, which contains at least one of sepiapterin and its salt and food/drink for preventing or improving cerebral dysfunction, which contains at least one of sepiapterin and its salt. Unlike tetrahydrobiopterin, etc., sepiapterin is able to repress the lowering level of aromatic monoamines (such as serotonin, dopamine and noradrenaline) in neurons in the brain and also increase the bioavailability. Therefore, sepiapterin may be effective against cerebral dysfunction caused by the lowered level of aromatic monoamines in the brain in neurons in the brain, for example, central mental disorders such as depression, hyperphagia, autism, impaired consciousness and concentration, and cognitive disturbance as well as central motor disorders such as myotonia, rigidity and tremor.
