A Study to Investigate JNJ-40411813 in Combination With Levetiracetam or Brivaracetam in Epilepsy

Inclusion Criteria:

• Body mass index (BMI) between 18 and 35 kilogram per meter square (kg/m^2, inclusive (BMI = weight/height^2). Minimum body weight should be 40-kilogram (kg)

• Established diagnosis of focal epilepsy, for at least 1 year using the InternationalLeague Against Epilepsy (ILAE) criteria. Participants should not be enrolled if theyare known to have had fewer than 3 or more than 100 seizures in any monthly periodin the past 6 months. It is preferred that participants have experience inmaintaining a seizure e-diary

• Must have had a neuroimaging procedure within 10 years, including a computedtomography (CT) scan or magnetic resonance imaging (MRI), that excluded aprogressive neurologic disorder; these procedures may be performed within the 8-weekbaseline period

• Cohort 1: Current treatment with at least 1 and up to 4 anti-epileptic drugs (AEDs) (including levetiracetam), administered at stable dosage(s) for at least 1 monthbefore screening, and no new AEDs added for the previous 2 months; these AEDs mustremain unchanged throughout the pretreatment and double-blind treatment periods (with the exception of dosage reductions of concomitant AEDs because of suspectedelevated AED levels or side effects) Cohort 2 and beyond: Current treatment with atleast 1 and up to 4 AEDs (including levetiracetam or brivaracetam), administered atthe appropriate dosage(s) and for a sufficient treatment period before screening.These AEDs must remain unchanged throughout the pretreatment and double-blindtreatment periods (with the exception of dosage reductions of concomitant AEDsbecause of suspected elevated AED levels or side effects). Important note: screeningof participants receiving brivaracetam will start when enrolling for Cohort 2

• Currently showing inadequate response to levetiracetam, administered at theappropriate dosage(s) and for a sufficient treatment period, based on the judgmentof the investigator

• Healthy based on clinical laboratory tests, physical examination, medical history,vital signs, and 12-lead ECG

• Men or women between 18 and 69 years old

Exclusion Criteria:

• Have a generalized epileptic syndrome

• Diagnosis of Lennox-Gastaut Syndrome

• Currently experiencing seizures that cannot be counted accurately

• History of any current or past nonepileptic seizures, including psychogenic seizures

• Known allergies, hypersensitivity, or intolerance to placebo, JNJ-40411813 or itsexcipients

• Current treatment with vagus nerve stimulation, deep brain and cortical stimulationfor 1 year or less

• Planned epilepsy surgery within the next 6 months or completed epilepsy surgery lessthan (<) 6 months ago

• Current treatment with vigabatrin

• History of malignancy within 5 years before screening (exceptions are squamous andbasal cell carcinomas of the skin and carcinoma in situ of the cervix, ormalignancy, which is considered cured with minimal risk of recurrence)

• Current or past (within the past year) major psychotic disorder, such asschizophrenia, bipolar disorder, or other psychotic conditions, recent (within thepast 6 months) interictal psychosis, and major depressive disorder (MDD) withpsychotic features

• Exacerbation of MDD within the past 6 months; antidepressant use is allowed

• Has a current or recent history of clinically significant suicidal ideation withinthe past 6 months, corresponding to a score of 4 (active suicidal ideation with someintent to act, without specific plan) or 5 (active suicidal ideation with specificplan and intent) for ideation on the Columbia Suicide Severity Rating Scale (C-SSRS), or a history of suicidal behavior within the past 1 year, as validated bythe CSSRS at screening

• Has a history of at least mild drug or alcohol use disorder according to Diagnosticand Statistical Manual of Mental Disorders (5th edition) (DSM-5) criteria within 1year before Screening