This chapter longitudinally compares patients diagnosed as having acute and transient psychotic disorder (ATPD) from the Halle Study on Brief and Acute Psychotic Disorder (HASBAP) with patients diagnosed as having affective or schizoaffective mixed states belonging to the Halle Bipolarity Longitudinal Study (HABILOS) group. The distinction between "abrupt" and "acute" onset is recommended because there is some evidence that the prognosis of ATPD with abrupt onset could be more favorable. The most essential predecessors of ATPD are cycloid psychosis and bouffée délirante, which show relevant similarities to the subgroup of ATPD "acute polymorphic psychotic disorders". The anxiety-happiness psychosis is characterized by continuous changing between severe all-pervasive anxiety and ecstatic happiness. Anxiety is often associated with delusions and hallucinations. The main characteristic of the hyperkinetic-akinetic motility psychosis is a disturbance of motility. Cycloid psychoses are bipolar disorders, but differ from manic-depressive illness.