 This is a randomized the study drug is assigned by chance, double-blind DB, neither physician nor patient knows the name of the assigned drug, multicenter, placebo-controlled, parallel group each group of patients will be treated at the same time, dose-titration study. This study consists of a screening period, a DB phase titration period and efficacy assessment period, and post-study phase. The study includes a 1 to 2-week screening period for wash-out of prohibited drugs, and screening for eligibility. Eligible patients will be randomly assigned to receive JNS001 or placebo in a ratio of 1:1. The study also includes a 4-week titration period. Patients will be titrated from a starting dose of 18 mgday or matching placebo for 7 days - 2 days, and continue with a weekly - 2 days increment of 18 mg until an individualized dose is achieved. Once an individualized dose is achieved, patients will remain on that dose for the rest of the titration period as far as tolerable. Doses can be tapered down only once during the titration period in the study, and their dose cannot be up-titrated again for the rest of the period. The 4-week titration period will be followed by the 4-week efficacy assessment period. The post-study phase for collection of additional safety data will be scheduled for 1 week after a patients final study treatment. The study drug will be administered with water once daily in the morning at doses of 18 mg, 36 mg, 54 mg, 72 mg per day or the matching placebo. The study treatment period is 8 weeks titration period of 4 weeks and efficacy assessment period of 4 weeks. 