A Safety, Tolerability and Pharmacokinetics Study of JNJ-54861911 in Healthy Japanese Male Participants

This is a single-center, randomized (study medication assigned to participants by chance), double-blind (neither Investigator nor participant knows which treatment the participant receives), placebo controlled (placebo is an inactive substance that is compared with a drug to test whether the drug has a real effect in a clinical trial), study of a single-ascending dose of JNJ-54861911 in participants between 55 to 75 years of age. The duration of study will be approximately 2 to 6 weeks per participant. The study consists of 3 periods: Screening period (28 to 2 days prior to dose administration); Double-blind Treatment period (participants will receive either a single oral dose of JNJ-54861911 or placebo as tablets under fasted conditions); and a Follow-up visit period (7 to 14 days after dose administration). All the eligible participants will be assigned to any of following 3 cohorts: Cohort A (single oral dose of JNJ-54861911, 25 milligram \[mg\] or placebo); Cohort B (single oral dose of JNJ-54861911, 50 mg or placebo); Cohort C (single oral dose of JNJ-54861911, 100 mg or placebo). Each cohort will include 8 participants. Participants in each cohort will be randomly assigned to receive either a single oral dose of JNJ-54861911 (n = 6) or placebo (n = 2). Blood samples will be collected pre-dose and over 96 hours (that is up to Day 5) after dosing for understanding the PK characteristics of JNJ-54861911. Participants' safety will be monitored throughout the study.