MORBID RISK OF SCHIZOPHRENIA IN FIRST-DEGREE RELATIVES OF WHITE AND AFRICAN-CARIBBEAN PATIENTS WITH PSYCHOSIS

Background. The high rate of schizophrenia among the second-generation African-Caribbean population in Britain has prompted much concern and speculation. Sugarman and Craufurd have reported that the morbid risk in the siblings of second-generation African-Caribbean schizophrenic patients was unusually high compared with that of the siblings of Whit e patients. Method. We sought to replicate these findings by comparing the morbid risk fdr schizophrenia in the first-degree relatives of 11 1 White and 73 African-Caribbean psychotic probands. The latter compri sed 35 first-generation (born in the Caribbean) and 38 second-generati on (born in Britain) probands. Results. The morbid risk for schizophre nia was similar far the parents and siblings of White and first-genera tion African-Caribbean patients, and for the parents of the second-gen eration African-Caribbean probands. However, the siblings of second-ge neration African-Caribbean psychotic probands had a morbid risk for sc hizophrenia that was seven times that of their White counterparts (P=0 .007); similarly, the siblings of second-generation African-Caribbean schizophrenic probands had a morbid risk for schizophrenia that was fo ur times that of their White counterparts (P=0.05). Conclusions. These findings replicate those of the earlier report of Sugarman and Craufu rd, and suggest either that the second-generation African-Caribbean po pulation in Britain is particularly vulnerable to some environmental r isk factors far schizophrenia, or that some environmental factors act selectively on this population in Britain.