The Paradox of High Risk of Stroke in Populations with Low Risk of Coronary Heart Disease

The "paradoxical" occurrence of high rates of stroke and low rates of coronary heart disease observed in Asian and other populations has been examined using accumulated clinical and autopsy data obtained during the long-term follow-up from 1965 to 1985 of cohorts of Japanese men living in Hawaii and Japan. The search for explanatory variables revealed three with the characteristics of having both opposing patterns of associations with clinical stroke compared with coronary heart disease and of being more prevalent in Japan than in Hawaii. These variables were low serum cholesterol levels, high intake of alcohol, and some aspect of an Oriental diet characterized by low intake of fat and protein from animal sources. Analysis of associations of these variables with measures of atherosclerosis in coronary and cerebral arteries revealed no paradoxical differences, with the possible exception of some dietary variables. Associations with autopsy-measured myocardial infarctions, cerebral infarction, and hemorrhage, however, showed opposing patterns similar to those found for clinical disease. The main inference from this work is that the paradoxically high risk of stroke observed in populations with low risk of coronary heart disease is not due to atherosclerosis in the major cerebral arteries. Rather, it is more likely due to lesions in the small intracerebral arteries and appears to be related to low levels of serum cholesterol, high alcohol intake, and some aspect of a traditional Oriental diet.