Is acute and transient psychotic disorder (ATPD) mini schizophrenia? The evidence from phenomenology and epidemiology.

Acute and transient psychotic disorders (ATPD) first appeared in ICD-10 but classification of acute psychosis has a long historical tradition. The prevalence rate of these disorders varies from 3.9 to 9.6 per 100,000 populations. Systematic clinical information that would provide definitive guidance on the classification of acute psychotic disorders is not yet available. Moreover there is no evidence available to guide the treatment of these disorders. In absence of the reliable epidemiological information the ATPD is treated as a form of 'mini schizophrenia' as if the disorder is an attenuated form of schizophrenia. A systematic review of the literature on acute and transient psychosis was conducted and all studies on epidemiology and treatment of acute and transient psychosis were identified. The existing evidence suggested that ATPD has little relationship with schizophrenia. ATPD is diagnostically unstable over time. Various estimates suggest that about 1/3 of patients with baseline ATPD retained their diagnosis over 3-12 years, the most frequent re-diagnosis being bipolar disorder and not schizophrenia. There are important differences in the epidemiology of this disorder from schizophrenia. These include gender distribution (ATPD has preponderance of females while equal gender distribution is one of the most established finding in epidemiology of schizophrenia) and much better premorbid level of functioning and social interactions. Other distinguishing features include the age at onset (onset throughout adult life, but usually between the 30- 50 years), development, and duration of symptoms (ATPD have an acute or even abrupt onset and the onset is only rarely precipitated by acute severe stress) and usually a favourable outcome, in spite of the fact that they are frequently recurrent. Literature on the subject is scanty and has serious methodological limitations. Treating ATPD has serious long term implications for the care of those suffering from ATPD. Long term treatments with antipsychotics which can induce metabolic disorders and reduce life expectancy, amongst many other side effects mean that we have to reconsider our approach to the diagnosis of ATPD seriously. Treating the acute and transient psychosis as a mini schizophrenia is seriously hindering research and clinical practice. I will review the epidemiology and phenomenology of acute and transient psychotic disorder, the current gaps in knowledge and its effects on our clinical practice in the light of systematic review of the evidence.