Epidemiological study of multiple sclerosis in Israel: Part III Multiple sclerosis and socio-economic status

Abstract

The frequency of multiple sclerosis increases with latitude both in the northern and southern hemisphere (Dean, 1949; Kurland, Mulder, and West-lund, 1955; Acheson, Bachrach, and Wright, 1960; Sutherland, Tyrer, and Eadie, 1962). This peculiar distribution suggests that an environmental factor (or factors) whose distribution is also correlated with latitude plays a role in the aetiology of the disease. The nature of the environmental factor remains obscure, although a wide variety of factors, including climatic variables, e.g., sunlight, temperature, and cultural factors, e.g., diet, have been considered over the years. In view of the apparent difficulty in determining the nature of the aetiological agent in multiple sclerosis, attempts to narrow the range of possibilities have merit. In this regard, the observations of Miller, Ridley, and Schapira (1960) that multiple sclerosis is more common among individuals in the higher socioeconomic classes deserves attention. It is generally true that the socioeconomic level of populations in temperate zones where multiple sclerosis is common tends to be higher than in tropical regions where the disease is rare. Therefore , a relation between socioeconomic level and the distribution of multiple sclerosis seems feasible and the aetiological agent could conceivably be some condition related to socioeconomic status. Data collected in Israel afforded an opportunity to evaluate the suggestion of Miller et al. (1960) that there was a relation between socioeconomic status and risk of multiple sclerosis, and Israel offers a number of advantages for studies of socioeconomic factors in relation to chronic illnesses like multiple sclerosis. The country is small and its population is of a size permitting collection of data from the nation as a whole. Bias introduced by studying one region or another may thus be avoided in Israel. Moreover, "