This is a multi-center (when more than one hospital or medical school team work on a medical research study), open-label (all people know the identity of the intervention), prospective (study following participants forward in time), non-comparative study. The total study duration will be 12 weeks for each participant and will include following visits: Screening, Week 2, 4, 8, and 12 (end of treatment or early withdrawal). The effectiveness of paliperidone ER will be evaluated at Week 12 by the proportion of responders who are evaluated as "very much improved" or "much improved" on the Clinical Global Impression improvement (CGI-I) Scale. Participants' safety will also be monitored throughout the study.