Are multiple sclerosis patients risk-takers?

Several factors appear to be associated with multiple sclerosis (MS), and each has a postulated immune or environmental explanation, but a common theme is lacking. This article suggests that a unifying premise could be risk-associated behaviour. Evidence is reviewed for associations with smoking, alcohol, recreational drug use, oral contraception, cholesterol intake, risk attitude and behaviour, ultraviolet light and vitamin D exposure, frequency of MS in healthy societies, and viral infection. The evidence associated with smoking, not taking vitamin D supplements and Epstein-Barr viral infection appears good. There may be a pattern of risk-associated behaviour that characterizes patients with MS and brings them into contact with one or more causative agents. Of the possible agents, viral infection seems the most likely.