Geoffrey Dean

Geoffrey Dean, who has died in Dublin aged 90, was best known as an epidemiologist who in several studies established the importance of an environmental influence on the pathogenesis of multiple sclerosis. This is regarded as his most important scientific contribution. His work is of particular relevance at present because of increasing evidence that the environmental factor in multiple sclerosis is sunlight exposure. Reduced sunlight exposure results in low vitamin D concentrations and increased susceptibility to autoimmune disease.

Dean’s interest in multiple sclerosis peaked after he arrived in South Africa in 1947 when he observed the marked variation in prevalence of the disease among the different ethnic groups. The prevalence of multiple sclerosis among English speaking white people born in South Africa was only one quarter and among the Afrikaans speaking white people born in South Africa only one 11th, as frequent as that of the immigrants from northern Europe. Subsequently, with John Kurtzke, he established that immigration before the age …