Adults who possess relative pitch but do not already have absolute pitch can learn "pseudo-absolute pitch" and become able to identify notes in a way that superficially resembles absolute pitch. Certain people who train to name notes may indeed become able to identify all 12 notes of the scale with 90% accuracy or above, and valproate, a medication used to treat epilepsy and severe depression, may re-open the "critical period" of learning, making the acquisition of absolute pitch, as well as languages, potentially as efficient for adults as for children. Even so, this form of pitch training can require considerable motivation, time, and effort, and it is not retained without constant practice and reinforcement.