Chakraborty & McKenzie (Reference Chakraborty and McKenzie2002) ask: ‘Does racial discrimination cause mental illness?’ In raising criticisms of their paper, one might risk allegations of political incorrectness, but hopefully readers will feel that science is a more important consideration.

The question that they pose is, to my mind, a simplistic one which is likely to give rise to a simplistic answer. To ask ‘does smoking cause physical illness?’ would give rise to the answer that it causes some physical illnesses and not others. The same relationship is likely between racial discrimination and mental illness.

That racial discrimination, like other aspects of social adversity, gives rise to an increased risk of depression is something that all psychiatrists almost certainly find entirely plausible. That it might cause schizophrenia, on the other hand, is surely much more contentious. Psychosocial stressors can undoubtedly precipitate relapse, but I know of no good evidence that such stressors can cause schizophrenia. Ethnic differences exist with regard to the epidemiology of multiple sclerosis (e.g. Reference Warren, Svenson and WoodheadWarren et al, 1996) but it would be regarded as absurd to invoke racial discrimination as a causative (or indeed a protective) factor. Is it politically incorrect to suggest that different ethnic groups may be biologically predisposed to different levels of risk with regard to developing illnesses which have predominantly biological aetiologies?

Finally, in quoting the work of Boydell et al (Reference Boydell, van Os and McKenzie2001), the authors may be confusing cause and effect. The fact that the incidence of schizophrenia is increased among ethnic minority groups living in London wards which have a lower percentage of ethnic minority inhabitants, may indicate that schizophrenia can give rise to people moving away from their families and their communities of origin.