INCREASED INCIDENCE OF PSYCHOTIC DISORDERS IN MIGRANTS FROM THE CARIBBEAN TO THE UNITED-KINGDOM

Background, Several studies have replicated the finding of increased i ncidence of schizophrenia and related psychoses in first and second ge neration migrants from the Caribbean. The finding has remained consist ent in studies employing different methods, but concern has been expre ssed about indirect methods of calculating the population at risk. Thi s study aims to overcome these shortcomings. Method. A further prospec tive study was undertaken in Nottingham assembling an inception cohort of psychotic patients (N = 168) presenting from a defined catchment a rea. The 1991 census, which includes codings for self-ascribed ethnic origin, was used to calculate the denominator, employing correction fa ctors for potential under-enumeration. Case-ascertainment was based up on all service contacts and subjects had in-depth assessments includin g the SCAN. Collateral history was obtained from informants. Results. Subjects born in the Caribbean, or who had one or both parents born in the Caribbean, had a greatly elevated risk (incidence ratios above 7) for all psychotic disorders and for ICD-10 (DCR)-defined F20 Schizoph renia. Conclusions. The size of the increase and the methodological sa feguards employed support the validity of this now highly replicated f inding. A personal or family history of migration from the Caribbean i s a major risk factor for psychosis; the consistency of this finding j ustifies a systematic evaluation of potential aetiological factors. An y hypothesis derived from the evidence so far must explain: increased incidence in first and second generation migrants; increased risk for all psychoses (including affective psychoses); and an effect specifica lly associated with a migration history from the Caribbean to Northern Europe.