A Phase 2, randomized, double-blind, parallel, placebo-controlled study with a 6- or 12-month open-label extension. The study is designed to evaluate the efficacy, safety and tolerability, and pharmacokinetics (PK) of treatment with luvadaxistat when administered orally once daily as an adjunctive treatment on improving symptoms of cognitive impairment associated with schizophrenia (CIAS).