Complex sentence: Sinason has helped pioneer the treatment of psychosis with psychodynamic methods with emphasis on treatment of multiple personality disorder renamed in 1994 as dissociated identity disorder (DID) in the Diagnostic and Statistical Manual of the American Psychiatric Association.
Split into simpler sentences: Sinason has helped pioneer the treatment of severe psychopathology including psychosis and multiple personality disorder (MPD) with psychodynamic methods. MPD was renamed in 1994 as dissociated identity disorder (DID) in the Diagnostic and Statistical Manual of the American Psychiatric Association.