How common are psychotic and bipolar disorders? A 50-year follow-up of the Lundby population

Background: The purpose was to present the prevalence of all psychotic and bipolar (BP) disorders in a total general population (n=3563), which has been followed from 1947 to 1997. Materials and Methods: Best-estimate consensus DSM-IV diagnoses, supported by data from interviews, case notes, registers and key-informants, were assessed. The period prevalence from 1947 to 1997 and the lifetime prevalence (LTP) in 1997, respectively, was calculated. Results: The period prevalence per 100 was: 4.24 for any psychotic or BP disorder, 2.25 for non-affective psychotic (NAP) disorder, 0.76 for psychotic disorder related to a general medical condition (GMC), 0.62 for affective psychotic (AP) disorder and 0.59 for substance-induced psychotic (SIP) disorder. The LTP per 100 was: 2.82 for any psychotic or BP disorder, 1.38 for NAP disorder, 0.54 for psychotic disorder related to a GMC, 0.48 for SIP disorder and 0.42 for AP disorder. The specific diagnosis with the highest period prevalence 1.43 per 100 and LTP 0.84 per 100, respectively, was schizophrenia. The LTP of psychotic disorder related to a GMC, SIP disorder, schizophrenia and delusional disorder, respectively, was higher than in most recent community studies while the LTP of brief psychotic disorder, schizophreniform disorder and AP disorder, respectively, was lower. However, the findings were in approximate accord with the estimates in the Psychoses in Finland (PIF) Study 1. Conclusions: The findings suggest that psychotic disorders are common in the community, and should be considered a major public health concern.