The design and instrument are identical for two years. This add-on sodium benzoate randomized, double-blinded, placebo-controlled trial which is a two-arm, 6-week follow-up trial. The 90 patients will be 2:1 (SB: placebo) randomly assigned to 1. Treatment with sodium benzoate (A); or 2. placebo (P). The group of sodium benzoate treatment will be divided into two subgroups: 1. Responder (AR), and nonresponder (AN), as illustrated in Figure 4. The response criteria is defined the improvement of 20% total PANSS score after 6-week SB treatment. The participants with TRS will be enrolled in this trail from 3 hospitals(National Cheng Kung University Hospital, Tainan Hospital, Ministry of Health and Welfare, Chia-Yi branch, Taichung Veteran General Hospital).
