Purpose: Our understanding of psychotic disorders is largely based on studies conducted in North America, Europe and Australasia. Few methodologically robust and comparable studies have been carried out in other settings. INTREPID is a programme of research on psychoses in India, Nigeria, and Trinidad. As a platform for INTREPID, we sought to establish comprehensive systems for detecting representative samples of cases of psychosis by mapping and seeking to engage all professional and folk (traditional) providers and potential key informants in defined catchment areas. Method: We used a combination of official sources, local knowledge of principal investigators, and snowballing techniques. Results: The structure of the mental health systems in each catchment area was similar, but the content (i.e., type, extent, and nature) differed. Tunapuna–Piarco (Trinidad), for example, has the most comprehensive and accessible professional services. By contrast, Ibadan (Nigeria) has the most extensive folk (traditional) sector. We identified and engaged in our detection system—(a) all professional mental health services in each site (in- and outpatient services—Chengalpet, 6; Ibadan, 3; Trinidad, 5); (b) a wide range of folk providers (Chengalpet, 3 major healing sites; Ibadan, 19 healers; Trinidad: 12 healers); and c) a number of key informants, depending on need (Chengalpet, 361; Ibadan, 54; Trinidad, 1). Conclusions: Marked differences in mental health systems in each catchment area illustrate the necessity of developing tailored systems for the detection of representative samples of cases with untreated and first-episode psychosis as a basis for robust, comparative epidemiological studies.
