Study Investigating the Effects of JNJ-54861911 on Amyloid-beta Processing in Cerebrospinal Fluid (CSF) and Plasma in Japanese Participants Asymptomatic at Risk for Alzheimer Dementia

Inclusion Criteria: * Participant must have had sufficient education or work experience to exclude mental retardation based on Diagnostic and Statistical Manual of Mental Disorders 4th edition, Text Revision (DSM-IV-TR) and must be able to read and write and must have adequate hearing and visual acuity to complete the required psychometric tests * Participant must have a Clinical Dementia Rating Scale- Japanese version (CDR-J) score of '0' and as such rated as normal * Participant must have evidence of amyloid deposition as demonstrated by low Cerebrospinal Fluid (CSF) Amyloid (A)-beta 1-42 levels at Screening * Participant must have a body mass index between 18 and 35 kilogram per square meter, inclusive, at Screening * Participant must be otherwise healthy for their age group or medically stable with or without medication on the basis of physical examination, medical history, vital signs, and 12-lead electrocardiogram (ECG) performed at Screening or at Baseline Exclusion Criteria: * Participant has evidence of any brain disease other than potential very early signs of Alzheimer's disease (AD) or typical age related changes, or any other abnormality that could explain a possible cognitive deficit * Participant has been diagnosed with dementia due to AD, due to other diseases, or with AD and contribution of other disorders (mixed dementia) * Participant has evidence of familial autosomal dominant AD * Participant has any contra-indications for Magnetic Resonance Imaging (MRI) (for example, prostheses, implants, claustrophobia, pacemakers, and others) * Participant has a clinically significant abnormal physical- or neurological examination, vital signs or 12-lead ECG (including QTc greater than 450 millisecond for males and females, left bundle branch block, atrio-ventricular \[AV\] block second degree or higher, permanent pacemaker or implantable cardioverter defibrillator \[ICD\]) at Screening or Baseline, which in the opinion of the investigator is not appropriate and reasonable for the population under study