This is a 24-week, observational, prospective study to evaluate the effectiveness of improving cognitive function of aripiprazole in treating adolescents and young adults with psychotic disorder in Taiwan. Approximately 120 qualified patients who have clinical diagnosis of DSM-IV of psychotic symptom (e.g. schizophrenia or other psychotic disorders such as schizophreniform disorder, schizoaffective disorder, delusional disorder, shared psychotic disorder, bipolar disorder with psychotic feature or psychotic disorder not otherwise specified.) will be recruited to achieve at least 100 evaluable subjects. After signing the informed consent form, the demographics, medical history and concomitant medication will be recorded. Besides, physical examination, vital sign, BMI, DSM-IV multiaxial examination, CGI-S and menstrual history will be conducted. Laboratory tests and pregnancy test will be optionally conducted. After evaluating all variables obtained, the eligible patients will be enrolled into study. Patients who fulfill the inclusion / exclusion criteria will be performed the CPT, WCST, BPRS and WHOQOL. Afterwards, patients will be given their first medication at this visit (5 mg ~ 30 mg daily by subject). Besides, the switching period is maximum 8 weeks and is depended upon the clinical judgment of investigator. Efficacy will be evaluated by the change from baseline in Continuous Performance Test (CPT), Wisconsin Card Sorting Test (WCST), Clinical Global Impression Scale (CGI), Brief Psychiatric Rating Scale (BPRS) and The World Health Organization Quality of Life questionnaire (WHOQOL). Safety will be evaluated by the frequency of adverse events, abnormal laboratory results, physical examination, vital sign, BMI and menstrual history for female subgroup analysis.