Previous researchers indicate that impaired cognitive flexibility was the primary factor distinguishing patients with from those without tardive dyskinesia (TD)1, and cognitive dysfunction correlates positively with the severity of TD2. Longitudinal data raised the possibility that the association between cognitive dysfunction and TD may reflect not organic vulnerability to but rather a state marker for this movement disorder as "tardive dementia"3. Atypical antipsychotic had been reported to alleviate the severity of TD4 and improved neurocognitive function separately5. But no researchers ever investigated the correlation of the two effects simultaneously. This randomized, single-blind and controlled study compared the effect of atypical antipsychotic on TD, neurocognitive function and associated factors for these changes.