 The study period will consist of a 28-week trial period. The participants who fulfill the inclusion criteria and do not meeting any of the exclusion criteria will be enrolled, and randomized in a 1:1:1 ratio to the 0.5 mg of TVP-1012, the 1 mg of TVP-1012, or the placebo group. In each treatment group, participants will receive 0.5 mg of TVP-1012, 1 mg of TVP-1012, or placebo once daily in a double-blinded manner. 