Cycloid psychoses (CP) as described by Leonhard comprise the subtypes anxiety-happiness, confusion and motility psychoses. CP presents with an acute onset and have a favourable prognosis. The operational criteria by Perris and Brockington (P&B, 1981) are partly incorporated in ICD-10 as acute polymorphic psychosis (APP). The DSM-IV category Brief Psychotic Disorder (BPD) includes all psychoses with short duration.

Establishing concordance of Leonhard's CP with DSM-IV and ICD-10 categories.

This study was aimed to investigate the clinical characteristics of CP and to determine the prevalence of CP in patients with psychotic disorders.

80 patients with psychotic disorders were assessed by means of CASH, PANSS and CGI at baseline and after six weeks of treatment. CP's were identified according to Leonhard's descriptions. Furthermore, patients were classified using DSM-IV, ICD-10 and P&B criteria.

A diagnosis of Leonhard's CP was present in 12 patients. Overlap between Leonhard's and P&B-CP was modest. ICD-10 and DSM-IV classification showed considerable heterogeneity. Diagnoses of ICD-APP and DSM-BPD were mostly assigned to CP patients. Concordance between Leonhard's CP and these categorical diagnoses was small. Leonhard CP patients showed, compared to non-CP patients, more atypical symptoms like perplexity, pananxiety and psychomotor disturbances.

The estimated prevalence of CP in patients with psychotic disorders is 15 percent. Although identification of CP is of heuristic value, this is not warranted by current classification systems or operational criteria. Thorough clinical evaluation of psychotic disorders is required, especially in patients presenting with perplexity, psychomotor disturbances or severe anxieties.