Not only being the mainstay of treatment for schizophrenia spectrum psychotic disorders, antipsychotics, especially the second-generation antipsychotics (SGAs) have also been recommended as augmenting agents for treating depression. Dopaminergic agents, including both dopamine D2/D3 antagonists and dopamine partial D2 agonists, have been effective for treating psychosis and schizophrenia. Amongst all SGAs, those with partial D2 agonistic property are generally acknowledged to have better side-effect profiles with lower incidence of extrapyramidal side-effects, prolactin increase, weight gain, QTc prolongation, and metabolic syndrome, as well as more efficacious in alleviating depressive symptoms. Up-to-date, three SGAs, namely aripiprazole, brexpiprazole and cariprazine, are known to possess such partial D2 agonism. ReSD-HK study is part of the ReSD Asian Study aiming to carefully evaluate a cohort of patients prescribed with brexpiprazole on its efficacy and tolerability as treatment for schizophrenia and/or depression in a real-life clinical setting.

This is a 6-month, non-interventional, prospective naturalist study that adult patients (18-65 years old) receiving brexpiprazole for treatment of psychosis and/or as adjunctive treatment for major depressive disorder are eligible to participate. Minimal exclusion criteria are employed to fit the usual real-life setting.

Inclusion Criteria:

• Age: 18- 65 years old at the time of enrollment
• Able to read and communicate in English and/or Chinese
• Able to give informed consent
• Has been diagnosed according to Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5), or International Statistical Classification of Diseases and Related Health Problems 10th revision (ICD-10) to have either Psychotic Disorders (F10-F19.5, F20-23, F25, F32-F33)
• is receiving brexpiprazole as treatment for less than 4 weeks at the time of recruitment

Exclusion Criteria:

• Age <18 years old
• Unable to read English or Chinese
• Unable to give informed consent
• Had been diagnosed to have Intellectual Disabilities (DSM-5) or Mental Retardation (ICD-10 F70-73)

Subjects suffering from psychosis or depressive disorders who are treated with the oral medication, brexpiprazole

To be shared within the ReSD Asian Study Group

Five year after the study period upon the last subject recruitments in the respective study sites.

For those named investigator who are engaged in the ReSD Asian Study with agreement signed.