Family study of acute and transient psychotic disorders: comparison with schizophrenia

Background: Acute non-organic psychoses, as often described in European and Indian literature, and categorized as `Acute and transient psychotic disorders' in ICD-10, lack a clear nosological distinction from schizophrenia. Methods: A family study of psychiatric disorders in first-degree relatives (FDRs) of 40 ICD-10-diagnosed probands of acute and transient psychotic disorders (ATP) was carried out using a semi-structured interview schedule. The results were compared with those of 40 schizophrenic probands. Results: FDRs of ATP probands had a higher prevalence of ATP than those of schizophrenic probands. FDRs of schizophrenic probands had significantly higher prevalence of schizophrenia than those of ATP probands. ATP subtypes with schizophrenic symptomatology (ICD-10 codes F 23.1 and F 23.2 ) had more family history of schizophrenia than the rest of the ATP subtypes. Conclusion: ATP as a group has a differential pattern of risk of illness compared to schizophrenia. Further, the subtypes subsumed under ICD-10 ATP may be genetically heterogeneous, those with schizophrenia-like symptomatology being possibly more akin to schizophrenia itself or forming an interface between ATP and schizophrenia.