Both a shortage and an excess of dopamine (DA) in the prefrontal cortex and striatum result in their decreased functions, and the relationship between the DA levels and their functions exhibits an inverted-U shape. Increased DA transmission via dose reduction in the currently used antipsychotics may improve the activation of DA-related symptoms in schizophrenia; these include delusions and auditory hallucinations caused by increased DA release. In this case, reducing the dose of the antipsychotic may be a treatment option for relapse in patients with schizophrenia who are already on high doses of antipsychotics and find it difficult to further increase the dose. A total of 54 inpatients with schizophrenia receiving high-dose antipsychotic therapy were randomly assigned to either the halved-dose group or the high-dose group (symptomatic treatment). The study compared the time from relapse to improvement between the two groups. In the halved-dose group, the period until relapse improvement ranged from 1 to 3 weeks, while the high-dose group experienced improvement in 4 to 9 weeks, and a significant difference was observed between the two groups using Kaplan-Meier survival analysis ( < 0.001).