RESUMEN
INTRODUCTION: The prevalence of schizophrenia and other psychoses can vary between close geographic locations and can be biased by the use of epidemiological designs. With data derived from a public mental health centre with close relations to primary care teams we have compared the distribution of psychotic disorders in two neighborhoods in Barcelona with marked psycho-social differences. METHODS: Using a computerized database from Barcelona's National Health Service covering 5 basic health-care areas with a total population of 103,615 inhabitants, we have accessed case records showing any psycho-pathology between the years of 1982 and 2000. RESULTS: From the case records of 21,536 registered patients showing any psycho-pathology, and using strict diagnostic, clinical and assistance criteria, we found that there were 476 patients diagnosed as "schizophrenic" and 362 that were "affected by other psychoses." Despite being evaluated by the same mental health personal, the same research team using identical criteria and over the same period of time (thus precluding operator and selection bias) the prevalence of these disorders was twice as high in La Mina (a district with a marked accumulation of psycho-social risk-factors) as compared to the neighboring district of La Verneda. CONCLUSIONS: When assessing prevalence of psychoses, it is necessary to consider the impact of social and psycho-social factors, even in neighboring communities.