There are few systematic data regarding treatment of the predecessors of ATPD. Treatment of the acute episode with electroconvulsive therapy has been advocated for ‘atypical psychoses’ (Kurosawa, 1961) and ‘cycloid psychoses’. A rapid response of cycloid psychoses to ECT has been supported by Kirov (1972), Mattson and Perris (1973) and Perris (1974). Neuroleptic treatment has also been recommended (Neumann and Schulze, 1966). For the long-term prophylaxis of cycloid psychoses, lithium therapy has been described as effective (Mattsson and Perris, 1973; Perris and Smigan, 1984).

Data on medication at the end of the acute episode of ATPD are given by J⊘rgensen and co-workers (1996) in their study on 51 patients. At the time of assessment the patients were non-psychotic; nevertheless most of them (n = 42; 82%) were taking antipsychotics and other psychotropic drugs (n = 27acute episode. Approximately; 53%). Five patients (10%) were drug-free at the time of the interview.

The HASBAP was naturalistic with regard to treatment. It was decided that the treatment of the patients would depend upon the symptomatology according to clinical guidelines, and not to a rigid standardised schedule. The reason for this decision was based on the fact that there is no standardised knowledge on the treatment of Acute and Transient Psychotic Disorders in the literature, in contrast to schizophrenia, and to some extent, also in comparison to Bipolar Schizoaffective Disorders, where treatment guidelines do exist.