There have been repeated reports that Afro-Caribbean people living in the UK are more prone than white people to be diagnosed as having schizophrenia and mania, along with some evidence that they are less likely to receive a diagnosis of depression. We attempted to replicate these findings in a population of patients on lithium prophylaxis. We therefore assessed the clinical characteristics of people under the age of 55 from three ethnic groups attending a lithium clinic in south London, those of (1) white British (n = 88); (2) Afro-Caribbean (n = 31); and, (3) African (n = 15) origin.

Nineteen of the white patients met DSM-IV criteria for unipolar depression (UP) and eight met the criteria for bipolar II disorder (BP II); in contrast, only two black patients met the criteria for unipolar depression and none met the criteria for BP II. Among patients diagnosed as BP I, Africans were significantly more likely than whites to show exclusively or mainly manic presentations while Afro-Caribbeans were more likely to have had mood-incongruent delusions. On the other hand, white patients were significantly more likely than Afro-Caribbeans to have had suicidal ideas or actions, and showed a similar but not significant excess when compared with Africans.

Our findings could reflect either genuine ethnic differences in the presentation of severe affective disorder or be produced by the failure of British doctors to detect depression and deliver appropriate treatment to their black patients. The frequency with which Afro-Caribbean patients with mania present mood-incongruent delusions probably contributes to the high rates of diagnosed schizophrenia in this population.