As I understand it, delusions are included as a feature of psychosis. While many of the psychotic symptoms are greatly reduced or stopped with AP's, the delusions can be a little to a lot more resistant depending on the nature of them and how long you have had them. From what I have read about, it seems delusions are helped as much by behavioral therapy as they they are by medication. Some long standing delusions may persist still, and the treatment becomes learning effective coping mechanisms to keep a resistant delusion from causing as much problems.