A Study to Evaluate the Efficacy, Safety, and Tolerability of Brivaracetam as Monotherapy in Patients 2 to 25 Years of Age With Childhood Absence Epilepsy or Juvenile Absence Epilepsy

Inclusion Criteria: * Study participant is 2 to 25 years of age inclusive, at the time of signing the informed consent. No study participants from 2 to \<4 years of age will be included in Stage 1 * Study participant is diagnosed with either childhood absence epilepsy (CAE) or juvenile absence epilepsy (JAE) as defined by the International League Against Epilepsy (ILAE) criteria * Study participants 2 to \<4 years of age and participants who had onset of absence seizures at an age younger than 4 years must have a negative glucose transporter type 1 deficiency syndrome (GLUT1DS) genetic test * Study participant is untreated with antiepileptic drugs (AEDs) or pretreated for absence seizures with a maximum of 2 historical AEDs, but without AED treatment for a period of at least 5 half-lives of the AED before randomization into this study. The UCB study physician should be consulted if in doubt * Study participant has electroencephalogram (EEG) evidence of bilateral synchronous, symmetric generalized paroxysmal spike waves (2.5-6 hertz) with normal background activity and with at least 1 electrographically recorded seizure lasting 3 seconds or more on a 1-hour EEG with hyperventilation (HV) while awake at Visit 1 (V1), or on a historical EEG up to 12 weeks before enrollment * Study participant has a history of clinically evident absence seizures occurring on at least 3 days per week in the 2 weeks prior to enrollment * Study participant is without treatment with psychoactive dru…