Low serum cholesterol as a risk factor for hemorrhagic stroke in men: a community-based mass screening in Okinawa, Japan

Up-regulation of endothelial nitric oxide activity as a central strategy for prevention of ischemic stroke - just say NO to stroke!

Nitric oxide (NO) produced by the endothelium of cerebral arterioles is an important mediator of endothelium-dependent vasodilation (EDV), and also helps to prevent thrombosis and vascular remodeling. A number of risk factors for ischemic stroke are associated with impaired EDV, and this defect is usually at least partially attributable to a decrease in the production and/or stability of NO. These risk factors include hypertension, high-sodium diets, homocysteine, diabetes, visceral obesity, and aging. Conversely, many measures which may provide protection from ischemic stroke - such as ample dietary intakes of potassium, arginine, fish oil, and selenium - can have a favorable impact on EDV. Protection afforded by exercise training, estrogen replacement, statin drugs, green tea polyphenols, and cruciferous vegetables may reflect increased expression of the endothelial NO synthase. IGF-I activity stimulates endothelial NO production, and conceivably is a mediator of the protection associated with higher-protein diets in Japanese epidemiology and in hypertensive rats. These considerations prompt the conclusion that modulation of NO availability is a crucial determinant of risk for ischemic stroke. Multifactorial strategies for promoting effective cerebrovascular NO activity, complemented by measures that stabilize platelets and moderate blood viscosity, should minimize risk for ischemic stroke and help maintain vigorous cerebral perfusion into ripe old age. The possibility that such measures will also diminish risk for Alzheimer's disease, and slow the normal age-related decline in mental acuity, merits consideration. A limited amount of ecologic epidemiology suggests that both stroke and senile dementia may be extremely rare in cultures still consuming traditional unsalted whole-food diets. Other lines of evidence suggest that promotion of endothelial NO activity may decrease risk for age-related macular degeneration.

Clinical demographics and long-term prognosis after stroke in patients on chronic haemodialysis. The Okinawa Dialysis Study (OKIDS) Group

BACKGROUND

Stroke is one of the leading causes of death in chronic dialysis patients. However, few epidemiological studies have reported on the demographics and long-term prognosis after stroke.

METHODS

We have observed the occurrence of stroke in the chronic dialysis population for the past 10 years in Okinawa, Japan. Definite cases of stroke were registered and categorized as cerebral haemorrhage (CB), cerebral infarction (CI), and subarachnoid hemorrhage (SAH).

RESULTS

Among 3741 chronic dialysis patients (2073 men, 1668 women), 271 patients (164 men, 107 women) had strokes (CB 162, CI 97, SAH 12) at least once during the study period from 1 April 1988 to 31 March 1998. The total duration of observation was 15 pound 748.8 patient-years (males 8990.5, females 6758.3). The incidence of stroke per 1000 patient-years was 17.2 overall, 10.3 for CB, 6.2 for CI, and 0.8 for SAH. Twenty-four per cent of stroke cases occurred within 1 year of starting dialysis therapy, and 57.7% occurred within 5 years after the beginning of therapy. The mean (SD) age at onset of stroke was 59.8 (13.0) years overall, 57.2 (12.6) for CB, 65.0 (12.1) for CI, and 53.6 (13.0) years for SAH. The survival rates after stroke were 53.4% at 1 month, 43.5% at 6 months, 35.7% at 12 months, and 23.2% at 60 months. Patients with diabetes mellitus (DM) had higher incidence of CI and a poorer prognosis than those without DM.

CONCLUSION

Incidence of stroke was high (17.2 per 1000 patient-years) in the dialysis population of our area and the long-term prognosis after stroke was poor.

Cholesterol, stroke risk, and stroke prevention

Serum cholesterol traditionally has been considered a poor predictor of total stroke risk; however, it is associated positively with ischemic stroke risk and associated negatively with hemorrhagic stroke risk. Although studies failed to demonstrate stroke reduction using older cholesterol-lowering medications, recent study of the statin class of medications shows both consistent stroke and other cardiovascular benefits. Ischemic stroke and coronary heart disease share similar underlying mechanisms, likely explaining much of the therapeutic benefit from statins. Current research is directed at further determining groups of patients most likely to benefit from lipid reduction in stroke prevention. In the interim, patients with established atherosclerosis should be treated with a statin to achieve a low-density lipoprotein cholesterol level less than 100 mg/dL.