An evaluation of the epidemiology of atherothrombotic brain infarction

Review of the epidemiology of atherothrombotic brain infarction (ABI) based largely on 18 years of prospective data from the Framingham cohort reveals that stroke is a potent force in morbidity and mortality, that hypertension is its dominant precursor, that it can be predicted and suggests that only a preventive approach can substantially reduce stroke morbidity. Data from Framingham on the relative frequency of the major types of stroke found in the community reveal that 57 percent are due to ABI and only 17 percent to intracranial hemorrhage--two-thirds of which is subarachnoid. Lacunar infarcts are common accounting for 13 percent of ABI's in men and 23 percent in women. Despite the sizeable geographic, seasonal and secular trends in stroke mortality, few environmental determinants of stroke have been uncovered. However, established hallmarks of the candidate for an atherothrombotic stroke include: hypertension (systolic or diastolic), glucose intolerance, high normal hemoglobin, the cigarette habit (men only), abnormal lipids (under age 60) and cardiac impairments. Many unresolved issues remain. Nevertheless, it is possible to identify a tenth of the general population from which half the strokes will emerge. This provides a rational basis for establishing a program of prevention.