Primary prevention of stroke

Physiologic monitoring and anesthesia considerations in acute ischemic stroke

Acute ischemic stroke is considered a neurologic emergency. The perioperative anesthesia management of acute ischemic stroke is challenging owing to the dynamic pathophysiology of the disease itself and the patients' comorbid factors and conditions. Herein, the authors review preoperative assessment, intraoperative and postoperative physiologic monitoring, and anesthesia management, with a focus on the control of the cerebrovascular and cardiovascular circulations. Issues specific to anesthesia monitoring and management in the radiology suite are emphasized.

Secondary prevention strategies in ischemic stroke: identification and optimal management of modifiable risk factors

The identification and treatment of modifiable Ischemic stroke risk factors, in addition to appropriate antithrombotic therapy, can reduce the likelihood of first or recurrent stroke, prevent long-term morbidity and mortality after first stroke or transient Ischemic attack, and lower health care costs. Long-term morbidity and mortality in patients with ischemic stroke includes patients with coronary artery disease. Therefore, in patients with ischemic stroke (especially those with carotid artery disease and lacunar disease), the goal is to prevent not only recurrent stroke but also coronary artery disease. Neurologists and general practitioners must be aware of the specific risk factors and recommendations for patients with ischemic stroke and apply the information systematically. We review known risk factors for ischemic stroke and current recommendations for treatment, focusing primarily on atherosclerotic risk factors as they apply to patients with stroke. In particular, recent data on hypertension and hyperlipidemia are described. In addition, we discuss the challenges in managing these risk factors and the potential strategies for overcoming them.

Homogeneity of large and small vessel disease over time: Arguments from a study on recurrent stroke in 998 patients with first cerebral infarct

BACKGROUND

Data on subtype and location of recurrent stroke after a first cerebral infarct may be relevant for prognosis and for understanding progression of the vascular disease underlying stroke subtypes over time. Therefore, we studied 30-day case fatality, stroke subtype, and stroke location in first and recurrent stroke, accounting for stroke subtype.

METHODS

We conducted a cross-sectional follow-up of 998 patients with first cerebral infarct registered in a hospital-based stroke registry.

RESULTS

After a follow-up of 691 +/- 521 (SD) days, there were 138 (13.8%) first recurrent strokes, 84 (61%) of which had computed tomography. Recurrent stroke was of the same subtype as the first stroke in 27 (57%) of 339 lacunar, 38 (83%) of 435 atherothrombotic, and 33 (94%) of 224 cardioembolic cerebral infarcts. The annual stroke recurrence rate was about 7% for the whole group. Logistic regression analysis showed lacunar first stroke and hypertension as independent predictors for recurrent lacunar stroke, and atherothrombotic first stroke type for recurrent atherothrombotic stroke. Stroke recurrences that were of the same type as the first stroke occurred in the same brain area as the first stroke in 70% of lacunar and 79% of atherothrombotic cases. This was more frequent when compared with nonsimilar recurrence types: odds ratio (OR) 4.38, 95% confidence interval (CI) 1.09-15.79; and OR 5.63, 95% CI 1.38-22.92, respectively. Only 33% of cardioembolic recurrent strokes occurred in the same area. The 30-day case fatality in index and recurrent stroke was, respectively, 2% and 14% (OR 7.90, 95% CI 2.78-22.48) for lacunar, 10% and 26% (OR 3.27, 95% CI 1.62-6.60) for atherothrombotic, and 23% and 31% (OR 1.47, 95% CI 0.55-3.93) for cardioembolic index infarcts.

CONCLUSIONS

The annual stroke recurrence rate after a first brain infarcts is about 7%. Early case fatality after recurrent stroke is higher than after first stroke, with marked differences between stroke subtypes. Progression of small and large vessel disease, and the brain area of their location, are rather homogeneous over time.

Prevention and treatment of stroke in patients with hypertension

BACKGROUND

Each year, stroke occurs in 30.9 million individuals worldwide and is responsible for approximately 4 million deaths. In the United States, it is the third leading cause of death, occurring with greater frequency than myocardial infarction in patients with hypertension. The greatest burden of stroke, apart from death, is serious long-term physical and mental disability. Stroke survivors often experience physical handicap, depression, and cognitive dysfunction, which together affect their daily functioning, quality of life, and survival. The treatment of stroke is associated with extremely high costs, with stroke-related illnesses responsible for >$49 billion in the United States in 2002. Despite intensive research efforts, few effective treatments are available once stroke has occurred; thus, stroke prevention should be a primary focus for all health care providers.

OBJECTIVE

The purpose of this article was to review the epidemiology and burden of stroke in terms of disability, quality of life, and cost of care, and to summarize the evidence for treatments having therapeutic benefit, with an emphasis on antihypertensive agents.

METHODS

Relevant studies were identified through a MEDLINE search of English-language articles published between 1990 and 2004. The search terms were stroke, epidemiology, economic impact, disability, quality of life, hypertension, drug therapy, and angiotensin II-receptor antagonists. Articles describing major clinical studies, new data, or new mechanisms pertinent to the therapy of stroke were selected for review.

CONCLUSIONS

Identifying and modifying key risk factors is crucial to reducing the morbidity and mortality of stroke. Hypertension is one of the most important risk factors for stroke, and treatment with a variety of antihypertensive agents reduces the risk. Recent evidence suggests that the angiotensin II (ATII)-receptor antagonist losartan may offer advantages beyond blood pressure lowering, including attenuation of the central aortic reflected pressure wave, molecule-specific properties, and neural protective influences on brain ATII type 2 receptors.

Impaired endothelial function of the retinal vasculature in hypertensive patients

BACKGROUND AND PURPOSE

Arterial hypertension constitutes a central factor in the pathogenesis of stroke. We examined endothelial function of the retinal vasculature as a model of the cerebral circulation.

METHODS

Thirty-eight young subjects (19 hypertensive and 19 normotensive) were treated with the AT1-receptor blocker candesartan cilexetil and placebo, each over 7 days. Retinal capillary flow and blood flow velocity in the central retinal artery were assessed with scanning laser Doppler flowmetry and pulsed Doppler ultrasound, respectively. N(G)-monomethyl-L-arginine (L-NMMA) was infused to inhibit nitric oxide (NO) synthesis. Diffuse luminance flicker was applied to stimulate NO release.

RESULTS

In normotensive subjects, L-NMMA decreased retinal capillary flow by 8.2%+/-13% (P<0.05) and flickering light increased mean blood flow velocity in the central retinal artery by 19%+/-29% (P<0.01). In contrast, no significant change to these provocative tests was seen in hypertensive subjects. Treatment with candesartan cilexetil restored a normal pattern of reactivity in retinal capillaries (l-NMMA: decrease in perfusion by 10%+/-17%, P<0.05) and the central retinal artery (flicker: increase in mean blood flow velocity by 42%+/-31%, P<0.001) in hypertensive patients.

CONCLUSIONS

Endothelial function of the retinal vasculature is impaired in early essential hypertension but can be improved by AT1-receptor blockade.

Nutrition and prevention of ischemic stroke: present knowledge, limitations and future perspectives

Stroke, particularly ischemic stroke, has a major impact on public health due to its high incidence, prevalence and rate of subsequent disability in Italy as in most industrialised countries. Apart from age, many modifiable factors, such as hypertension, smoking, diabetes, dyslipidemia, obesity, physical inactivity, alcohol abuse and hyperhomocysteinemia, have been recognised as playing a role in the pathogenesis of this disease. While appropriate pharmacological therapy has proven effective in the prevention of stroke in particular categories of patients, most of the above mentioned predisposing conditions are amenable to be affected by nutrition. Unequivocal demonstration of a protective or adverse role of single foods and nutrients against the risk of stroke has been however difficult to achieve due to confounding by biological variability, methodological inadequacies in the assessment of individual nutritional habits and difficulty to carry out long-term randomised controlled trials in the nutritional area. Notwithstanding, in several cases, causal relationships could be inferred from case-control and cohort studies in the presence of plausible and reproducible associations, evidence of dose-dependent effects and consistency in the results of different studies. The aim of this paper was to review present knowledge and highlight limitations and future perspectives about the role of nutrition in the prevention of ischemic stroke.

Dietary restriction differentially protects from neurodegeneration in animal models of excitotoxicity

Reduced caloric intake obtained through long-term dietary restriction has been found beneficial in some animal models of neurodegeneration. We report here that rats maintained under dietary restriction from the second to the eighth month of age are fully protected towards degeneration of GABAergic neurons in the hippocampus and the olfactory-entorhinal cortex caused by systemic administration of the convulsant toxin, kainic acid. However, in a different model of excitotoxic neurodegeneration, injection of ibotenic acid in the forebrain magnocellular basal nucleus, the decrease of a cholinergic marker in the target areas of the cortex was only partially protected by dietary restriction. Thus, in different experimental models neurodegeneration can be differentially rescued by dietary restriction. Analysis of alterations in the expression of relevant genes in different experimental conditions, could help in better understanding these differences.

New Perspectives on the Pharmacotherapy of Ischemic Stroke

OBJECTIVE

To provide an overview of the impact of ischemic stroke and the steps that can be taken to reduce its burden through greater awareness of the disease, improved diagnosis and better treatment, with emphasis on the use of antiplatelet agents.

DATA SOURCES

Recent (1995-2003) published scientific literature, as identified by the authors through Medline searches, using the terms stroke, transient ischemic attack, cerebrovascular disease, atherothrombosis, risk factors, pharmacotherapy, prevention, and reviews on treatment.

STUDY SELECTION

Recent systematic English-language review articles and reports of controlled randomized clinical trials were screened for inclusion.

DATA SYNTHESIS

Ischemic stroke is generally the result of an atherothrombotic process leading to vessel obstruction or narrowing. Of the two types of ischemic stroke, thrombotic stroke is caused by a thrombus that develops within the cerebral vasculature, while embolic stroke arises from a distant embolus that lodges in a cerebral artery. The neurologic manifestations of stroke depend on the location of injury in the brain and the degree of ischemia or infarction. Symptoms may be reversible or irreversible and range from sensory deficits to hemiplegia. Risk factors for development of ischemic stroke include hypertension, diabetes, dyslipidemia, smoking, atrial fibrillation, prior stroke, and transient ischemic attack. Tissue plasminogen activator is currently the only available drug treatment for acute ischemic stroke. Stroke recurrence rates are high (about 40% over 5 years), and all ischemic stroke patients should receive antithrombotic therapy (unless contraindicated) for secondary prevention. Of the oral antiplatelet therapies, aspirin, clopidogrel (Plavix--Bristol-Myers Squibb/Sanofi Pharmaceuticals Partnership), and the extended-release dipyridamole plus aspirin combination are acceptable first-line agents, while anticoagulants (warfarin) are preferred in patients with atrial fibrillation.

CONCLUSION

Lifestyle changes and drug therapy are important components of primary and secondary prevention strategies in ischemic stroke. Risk factors such as elevated blood pressure and high cholesterol should be aggressively treated. Antiplatelet agents, antihypertensive agents, and cholesterol-lowering agents are therapeutic cornerstones for secondary prevention.

Quality of care in stroke prevention: results of an audit study among general practitioners

BACKGROUND

In identifying opportunities to improve the quality of stroke prevention in general practice, insight in areas of suboptimal care is essential. This study investigated the quality of care in stroke prevention in general practice and its relation to the occurrence of stroke.

METHODS

Retrospective case-based audit with guideline-based review criteria and final judgment of suboptimal care by an expert panel.

RESULTS

A total of 292 stroke patients were identified through stroke registers of two main referral hospitals for stroke in Rotterdam. The general practitioners (GPs) (n = 95) of these patients were approached. The overall response rate from GPs was 81%, and a total of 193 patients from 77 GPs were included in the study. Data on the process of care at patient level were collected by chart review and by structured interviews with GPs during site visits. All cases were presented to a six-member panel of GPs and neurologists. In 44% of the cases, suboptimal care was identified (31% judged as possibly or likely failing to prevent stroke). Of the total number of identified shortcomings, 52% was related to inadequate hypertension control, particularly lack of follow-up after established hypertension. Another 17% of identified shortcomings concerned inadequate cardiovascular risk assessment.

CONCLUSIONS

A substantial number of shortcomings in care, particularly in the domain of hypertension control and the assessment of patient's risk profiles for cardiovascular disease (CVD), were identified. This study suggests that improving preventive care delivery in general practice could reduce the occurrence of stroke.

Risk factors, subtypes and outcome of ischaemic stroke in Kuwait--a hospital-based study

OBJECTIVE

To report on stroke subtypes, associated risk factors and outcome in Kuwait.

METHODS

The records of 62 patients (30 male, 32 female) admitted with diagnosis of stroke to Kuwait Oil Company Hospital, Kuwait, a tertiary care hospital, during a 5-year period (1995-1999), were retrospectively reviewed.

RESULTS

Small artery infarction was the most common subtype and occurred in 37 subjects (59.7%); less common were atherosclerotic large artery strokes (19 patients, 30.6%) and strokes of cardio-embolic origin (6 patients, 9.7%). Identifiable risk factors or associated morbidities were hypertension (72.5%), diabetes mellitus (69.4%), ischaemic heart disease (14.5%), history of migraine (8.1%), lone atrial fibrillation (5.0%), and valvular heart disease (1.6%). The most important determinants of a deleterious 30-day outcome, as indicated by severe disability or death, were female gender, lack of use of anti-platelet drugs, presence of a large artery infarction stroke subtype, and cardio-embolic stroke.

CONCLUSION

Prevalence of hypertension and diabetes is high among patients with stroke in Kuwait, with rates higher than those found in any previous reports from the Gulf region. Two unusual observations were that women had a rather high frequency of stroke, and infarction of the small artery was more common than that of the large artery. Outcome, as indicated by severe disability or death, was worse among women, elderly patients, and those with large artery atherosclerotic and cardio-embolic strokes. There is some evidence that such a deleterious outcome might be ameliorated with use of anti-platelet drugs.

Mechanisms of stroke protection by physical activity

Regular physical activity is associated with a decrease of cerebrovascular and cardiovascular events, which may relate to enhanced endothelium-dependent vasodilation. Here, we provide evidence that physical activity protects against ischemic stroke via mechanisms related to the upregulation of endothelial nitric oxide synthase (eNOS) in the vasculature. Voluntary training on running wheels or exercise on a treadmill apparatus for 3 weeks, respectively, reduced cerebral infarct size and functional deficits, improved endothelium-dependent vasorelaxation, and augmented cerebral blood flow in wild-type mice. The neuroprotective effects of physical training were completely absent in eNOS-deficient mice, indicating that the enhanced eNOS activity by physical training was the predominant mechanism by which this modality protects against cerebral injury. Our results suggest that physical activity not only decreases stroke risk, but also provides a prophylactic treatment strategy for increasing blood flow and reducing brain injury during cerebral ischemia.

Relation among stroke knowledge, lifestyle, and stroke-related screening results

Stroke is a leading cause of individual and public health burden in the United States. A better understanding of the relation among stroke knowledge, lifestyle, and stroke-related screening results may be useful for improving prevention efforts. This paper assesses the relation among demographics, lifestyle, stroke awareness, and the presence of stroke risk factors determined by screening tests for a select elderly population. A population of 322 participants in the 1999 World Senior Games received 1 or more free screening tests and completed a stroke awareness questionnaire. Results indicate that stroke education efforts should be targeted at the very elderly, those who have less than a college education, and those who do not have a history of chronic disease. It also may be effectively directed toward those with higher cholesterol.

Papel da curva de agregação plaquetária no controle da antiagregação na prevenção secundária do acidente vascular cerebral isquêmico

INTRODUÇÃO: O acidente vascular cerebral (AVC) é atualmente a primeira causa de morte no Brasil. O risco de recorrência de AVC é de aproximadamente 30% em cinco anos. Agentes antiagregantes plaquetários são frequentemente prescritos para a prevenção de recorrência do AVC, porém sem um parâmetro laboratorial de ajuste terapêutico. OBJETIVO: Determinar a aplicabilidade da curva de agregação plaquetária, no controle do antiagregante, na prevenção secundária do acidente vascular cerebral isquêmico (AVCi). MÉTODO: Estudo retrospectivo de janeiro de 1990 a janeiro de 2001; foram analisados 189 pacientes com diagnóstico de AVCi acompanhados durante este período com curva de agregação plaquetária. Foram excluídos os portadores de doenças cardioembólicas. Consideraram-se hipoagregados os doentes com agregação plaquetária ativada pelo ADP e/ou pela adrenalina menor ou igual a 50%. Os doentes tiveram acompanhamento por 1 a 6 anos e a taxa de recorrência de AVCi foi comparada entre os normoagregados e os hipoagregados. RESULTADOS: Nove doentes apresentaram novo AVCi no período do seguimento. Entre os hipoagregados ocorreu 2,6% de recidiva e entre os normoagregados, 15,1% (0,03<OR<0,69, p<0,05). A maioria dos doentes tiveram o novo episódio no segundo ano após o primeiro evento. CONCLUSÃO: A curva de agregação plaquetária mostrou ser um exame laboratorial eficiente como auxiliar para o controle da antiagregação na prevenção secundária do AVCi.

Blood pressure and lipid lowering in the prevention of stroke: a note to neurologists

Stroke is the leading cause of adult disability and dependency in western society. Despite the determined efforts of basic science and clinical investigators, neuroprotective therapies for acute stroke have yet to be realised. Stroke prevention, therefore, remains the key route for reducing morbidity and mortality. Hypertension and hypercholesterolaemia are the most important modifiable risk factors for stroke. Several recent landmark studies have shown that lipid lowering with statins can reduce the risk of ischaemic stroke, as well as coronary heart disease. In addition, clinical trials evaluating the effects of blood pressure lowering have shown that antihypertensive agents such as angiotensin-converting enzyme (ACE) inhibitors, calcium channel blockers (CCBs) and angiotensin II receptor antagonists can reduce stroke risk. Accumulating evidence suggests certain antihypertensive agents such as CCBs might also prevent the formation and progression of carotid atheroma, independently of their blood-pressure-lowering effects. It follows that rigorous identification and targeting of high- risk or stroke-prone individuals for blood pressure and lipid-lowering interventions should be of practical importance to all physicians involved in the management of stroke.

Cerebral vasospasm after subarachnoid hemorrhage: putative role of inflammation

Cerebral vasospasm is a common, formidable, and potentially devastating complication in patients who have sustained subarachnoid hemorrhage (SAH). Despite intensive research efforts, cerebral vasospasm remains incompletely understood from both the pathogenic and therapeutic perspectives. At present, no consistently efficacious and ubiquitously applied preventive and therapeutic measures are available in clinical practice. Recently, convincing data have implicated a role of inflammation in the development and maintenance of cerebral vasospasm. A burgeoning (although incomplete) body of evidence suggests that various constituents of the inflammatory response, including adhesion molecules, cytokines, leukocytes, immunoglobulins, and complement, may be critical in the pathogenesis of cerebral vasospasm. Recent studies attempting to dissect the cellular and molecular basis of the inflammatory response accompanying SAH and cerebral vasospasm have provided a promising groundwork for future studies. It is plausible that the inflammatory response may indeed represent a critical common pathway in the pathogenesis of cerebral vasospasm pursuant to SAH. Investigations into the nature of the inflammatory response accompanying SAH are needed to elucidate the precise role(s) of inflammatory events in SAH-induced pathologies.

Cardiovascular prevention and blood pressure reduction: a quantitative overview updated until 1 March 2003

BACKGROUND

In a meta-analysis published in October 2001, we reported that new and old classes of antihypertensive drugs had similar long-term efficacy and safety. Furthermore, we observed that in clinical trials in hypertensive or high-risk patients gradients in systolic pressure accounted for most differences in outcome.

OBJECTIVE

To test whether our previous conclusions would hold, we updated our quantitative overview with new information from 14 clinical trials presented before 1 March 2003.

METHODS

To compare new and old antihypertensive drugs, we computed pooled odds ratios from stratified 2 x 2 contingency tables. If Zelen's test of heterogeneity was significant, we used a random effects model. In a meta-regression analysis, we correlated odds ratios with corresponding between-group differences in systolic pressure. We then contrasted observed odds ratios with those predicted from gradients in systolic pressure.

MAIN OUTCOMES

Differences in achieved systolic blood pressure and incidence of total and cardiovascular mortality, cardiovascular events, stroke, myocardial infarction and heart failure. NEW VERSUS OLD DRUGS: In 15 trials, 120 574 hypertensive patients were randomized to old drugs (diuretics or beta-blockers) or new agents [calcium-channel blockers, alpha-blockers, angiotensin-converting enzyme (ACE) inhibitors or angiotensin type-1 receptor (AR1) blockers]. Old and new drugs provided similar protection against total and cardiovascular mortality and fatal plus non-fatal myocardial infarction. Calcium-channel blockers, including (-8%, P = 0.07) or excluding verapamil (-10%, P = 0.02), as well as AR1 blockers (-24%, P = 0.0002) resulted in better stroke prevention than did the old drugs, whereas the opposite trend was observed for ACE inhibitors (+10%, P = 0.03). The risk of heart failure was higher (P < 0.0001) on calcium-channel blockers (+33%) and alpha-blockers (+102%) than on conventional therapy involving diuretics. META-REGRESSION: Between-group differences in achieved systolic pressure ranged from 0.1 to 3.2 mmHg in seven actively controlled trials (73 237 patients), and from 2.1 to 22.1 mmHg in seven studies comparing varying intensities of blood pressure lowering (11 128 patients). For these 14 new trials, we predicted outcome from achieved systolic blood pressure using our previously published meta-regression models based on 30 trials with 149 407 patients. In general, predicted and observed odds ratios were similar. Larger reductions in systolic pressure (weighted mean 1.8 mmHg) in two trials accounted for the advantage of AR1 blockers over conventional therapy in the prevention of stroke. Only for cardiovascular mortality in very old patients (P = 0.02) and for cardiovascular events and myocardial infarction in old Australians (P < 0.05), the observed odds ratios deviated from our predictions based on the gradients in systolic blood pressure.

INTERPRETATION

The hypothesis that new antihypertensive drugs, such as calcium-channel blockers, alpha-blockers, ACE inhibitors or AR1 blockers might influence cardiovascular prognosis over and beyond their antihypertensive effects remains unproven. The finding that blood pressure differences largely accounted for cardiovascular outcome emphasizes the desirability of tight blood pressure control. However, the level to which blood pressure must be lowered to achieve maximal benefit remains currently unknown.

Self-rated ill-health strengthens the effect of biomedical risk factors in predicting stroke, especially for men -- an incident case referent study

OBJECTIVES

To examine how self-rated ill-health interacts with biomedical stroke risk factors in predicting stroke and to explore differences between men and women and educational groups.

DESIGN

An incident case-referent study where the study subjects had participated in a prior health survey.

SETTING

Nested within the Västerbotten Intervention Program (VIP) and the Northern Sweden MONICA cohorts.

SUBJECTS

The 473 stroke cases had two referents per case, matched for age, sex and residence, from the same study cohorts.

RESULTS

Self-rated ill-health independently increased the risk of stroke, specifically for men. The interaction effect between self-rated health and biomedical risk factor load was greater for men than for women. The attributable proportion due to interaction between having a risk factor load of 2+ and self-rated ill-health was 42% for men and 15% for women. Better-educated individuals with self-rated ill-health and two or more of the biomedical risk factors had a higher risk of stroke than the less educated. Calculations of the respective contribution to the stroke cases of self-rated health, hypertension and smoking showed that self-rated ill-health had a role in 20% of the cases and could alone explain more than one-third of the cases among those who rated their health as bad, more so for men than for women.

CONCLUSIONS

The results underscore the importance of including both a gender and a social perspective in discussing the role of self-rated health as a predictor of disease outcome. Physicians must be more gender sensitive when discussing their patient's own evaluation of health in relation to biomedical risk factors.

Plasma lipid profile and incident ischemic stroke: the Atherosclerosis Risk in Communities (ARIC) study

BACKGROUND AND PURPOSE

The role of circulating lipids and lipoproteins in the pathogenesis of ischemic stroke remains uncertain despite 3 decades of research. We examined this issue in a large population-based cohort.

METHODS

Between 1987 and 1989, 14 175 middle-aged men and women, free of clinical cardiovascular disease, took part in the first examination of the Atherosclerosis Risk in Communities (ARIC) study cohort. Baseline measurements included plasma levels of LDL cholesterol, HDL cholesterol, apolipoprotein B, apolipoprotein A-1, and triglycerides and myriad risk factors for cardiovascular disease. The cohort was followed for cardiovascular disease end points.

RESULTS

Over an average follow-up of 10 years (142 704 person-years at risk), we documented clinical ischemic stroke in 305 participants (161 men and 144 women). After multivariable adjustment for stroke risk factors, categorical and spline regression analyses of the entire sample, as well as the sample of men alone, revealed weak and inconsistent associations between ischemic stroke and each of the 5 lipid factors. Among women, the most consistent findings were decreasing risk of ischemic stroke within the top half of the distribution of HDL cholesterol and increasing risk within the lower range of the triglyceride distribution.

CONCLUSIONS

The relation of circulating cholesterol to ischemic stroke does not resemble its well-known relation to coronary heart disease. Either the pathogenesis of a substantial proportion of ischemic strokes does not involve classic atherosclerotic mechanisms, or the effect of plasma lipids on atherogenesis is substantially different in the intracranial vascular bed.

Meal size and frequency affect neuronal plasticity and vulnerability to disease: cellular and molecular mechanisms

Although all cells in the body require energy to survive and function properly, excessive calorie intake over long time periods can compromise cell function and promote disorders such as cardiovascular disease, type-2 diabetes and cancers. Accordingly, dietary restriction (DR; either caloric restriction or intermittent fasting, with maintained vitamin and mineral intake) can extend lifespan and can increase disease resistance. Recent studies have shown that DR can have profound effects on brain function and vulnerability to injury and disease. DR can protect neurons against degeneration in animal models of Alzheimer's, Parkinson's and Huntington's diseases and stroke. Moreover, DR can stimulate the production of new neurons from stem cells (neurogenesis) and can enhance synaptic plasticity, which may increase the ability of the brain to resist aging and restore function following injury. Interestingly, increasing the time interval between meals can have beneficial effects on the brain and overall health of mice that are independent of cumulative calorie intake. The beneficial effects of DR, particularly those of intermittent fasting, appear to be the result of a cellular stress response that stimulates the production of proteins that enhance neuronal plasticity and resistance to oxidative and metabolic insults; they include neurotrophic factors such as brain-derived neurotrophic factor (BDNF), protein chaperones such as heat-shock proteins, and mitochondrial uncoupling proteins. Some beneficial effects of DR can be achieved by administering hormones that suppress appetite (leptin and ciliary neurotrophic factor) or by supplementing the diet with 2-deoxy-d-glucose, which may act as a calorie restriction mimetic. The profound influences of the quantity and timing of food intake on neuronal function and vulnerability to disease have revealed novel molecular and cellular mechanisms whereby diet affects the nervous system, and are leading to novel preventative and therapeutic approaches for neurodegenerative disorders.

Periodontal disease, tooth loss, and incidence of ischemic stroke

BACKGROUND AND PURPOSE

Periodontal and other infections have been suggested as potential risk factors for stroke. This study evaluates periodontal disease and tooth loss as risk factors for ischemic stroke.

METHODS

The study population consisted of 41 380 men who were free of cardiovascular disease and diabetes at baseline. Periodontal disease history was assessed by mailed validated questionnaires. During 12 years of follow-up, stroke incidence was assessed and subclassified by use of medical history, medical records, and imaging reports. Hazard ratios (HRs) were adjusted for age, amount smoked, obesity, alcohol, exercise, family history of cardiovascular disease, multivitamin use, vitamin E use, profession, baseline reported hypertension, and hypercholesterolemia. Sex and socioeconomic status were inherently controlled for by restriction. Confounding variables were updated in the analyses for each 2-year follow-up interval.

RESULTS

We documented 349 ischemic stroke cases during the follow-up period. Men who had < or =24 teeth at baseline were at a higher risk of stroke compared to men with > or =25 teeth (HR=1.57; 95% CI, 1.24 to 1.98). There was little evidence of an increased risk with recent tooth loss during follow-up. A modest association was seen between baseline periodontal disease history and ischemic stroke (HR=1.33; 95% CI, 1.03 to 1.70). Addition of dietary factors to the model changed the HR only slightly.

CONCLUSIONS

Our results suggest that periodontal disease and fewer teeth may be associated with increased risk of ischemic stroke.

Research agenda for understanding Alzheimer disease in diverse populations: work group on cultural diversity, Alzheimer's association

The emerging evidence of ethnic variations in apolipoprotein polymorphism and Alzheimer disease risk shows that one cannot generalize findings based on a single cultural group too broadly ( Tang et al., 2001). Presence of one apolipoprotein E epsilon 4 allele is a stronger risk factor for Alzheimer disease in whites and Asians than in blacks ( Farrer et al., 1997). Environmental or genetic cofactors may modulate the effects of epsilon 4 on beta-amyloid metabolism differently in different subpopulations ( Shadlen, 1998). Recognizing this, the Alzheimer's Association has extended its goals to strengthen the scientific information base on the interactions of population diversity and Alzheimer disease heterogeneity ( NIA, 1998). This new focus is timely since minority elderly are the most rapidly increasing segment of the elderly population ( Lilienfeld and Perl, 1994, Brookmeyer et al., 1998). In this article, the authors highlight recent progress in research on Alzheimer disease among culturally diverse populations with a special emphasis on gaps in the knowledge base. The authors recommend four priorities for future Alzheimer disease research: (1) determine whether genetic causative factors interact differently in different populations; (2) reexamine the nature and role of cerebral ischemia and infarction and variations in symptom severity of Alzheimer disease; (3) explore the interaction of genes and environmental influences that are protective against Alzheimer disease; and (4) recruit and enroll ethnically diverse subjects in Alzheimer disease clinical trials.

cDNA microarray analysis of changes in gene expression induced by neuronal hypoxia in vitro

We used cDNA microarray gene expression profiling to characterize the transcriptional response to exposure of cultured mouse cerebral cortical neurons to hypoxia for 24 hr. Of 11,200 genes examined, 1,405 (12.5%) were induced or repressed at least 1.5-fold, whereas 26 known genes were induced and 20 known genes were repressed at least 2.5-fold. The most strongly induced genes included genes coding for endoplasmic reticulum proteins (Ero1L/Giig11, Sac1p, Ddit3/Gadd153), proteins involved in ubiquitination (Arih2, P4hb), proteins induced by hypoxia in non-neuronal systems (Gpi1, Aldo1, Anxa2, Hig1), and proteins that might promote cell death (Gas5, Egr1, Ndr1, Vdac2). These findings reinforce the importance of endoplasmic reticulum-based mechanisms and of protein-ubiquitination pathways in the neuronal response to hypoxia.

Why do treated hypertensives suffer strokes? An internist's perspective

Despite widespread treatment of hypertension, stroke continues to be the third leading cause of death in the United States. Antihypertensive therapy is more effective in preventing hemorrhagic strokes than ischemic strokes. In order to understand the reasons why antihypertensive therapy is only partially successful in the eradication of ischemic strokes, differences in the pathogenesis and treatment of subtypes of stroke must be considered. There are three main stroke subtypes of ischemic strokes: small-vessel arteriopathic (lacunar), large-artery atherothrombotic, and cardioembolic. Hypertension is the major cause of lacunar strokes but plays a lesser role in the pathogenesis of atherothrombotic strokes. Antihypertensive therapy prevents the majority of lacunar strokes but may not have a major impact on the occurrence of atherothrombotic strokes. Due to impaired cerebral autoregulation, overtreatment of hypertension, especially in the elderly and in patients with previous strokes, may paradoxically lead to stroke (J-curve). Assuming that the majority of lacunar strokes are prevented by judicious antihypertensive therapy, future therapeutic efforts should concentrate on the prevention of atherothrombotic and cardioembolic strokes. In this regard, refinement of surgical techniques, pharmacologic approaches aimed at plaque stabilization, and the application of transesophageal echocardiography for the diagnosis of embolic strokes (and anticoagulation for a probable source) are promising. Besides the obvious reasons of noncompliance and inadequate therapy, overly aggressive treatment of hypertension in the elderly and stroke mechanisms unrelated to blood pressure may explain the occurrence of strokes despite our efforts to treat hypertension.

Modification of brain aging and neurodegenerative disorders by genes, diet, and behavior

Multiple molecular, cellular, structural, and functional changes occur in the brain during aging. Neural cells may respond to these changes adaptively, or they may succumb to neurodegenerative cascades that result in disorders such as Alzheimer's and Parkinson's diseases. Multiple mechanisms are employed to maintain the integrity of nerve cell circuits and to facilitate responses to environmental demands and promote recovery of function after injury. The mechanisms include production of neurotrophic factors and cytokines, expression of various cell survival-promoting proteins (e.g., protein chaperones, antioxidant enzymes, Bcl-2 and inhibitor of apoptosis proteins), preservation of genomic integrity by telomerase and DNA repair proteins, and mobilization of neural stem cells to replace damaged neurons and glia. The aging process challenges such neuroprotective and neurorestorative mechanisms. Genetic and environmental factors superimposed upon the aging process can determine whether brain aging is successful or unsuccessful. Mutations in genes that cause inherited forms of Alzheimer's disease (amyloid precursor protein and presenilins), Parkinson's disease (alpha-synuclein and Parkin), and trinucleotide repeat disorders (huntingtin, androgen receptor, ataxin, and others) overwhelm endogenous neuroprotective mechanisms; other genes, such as those encoding apolipoprotein E(4), have more subtle effects on brain aging. On the other hand, neuroprotective mechanisms can be bolstered by dietary (caloric restriction and folate and antioxidant supplementation) and behavioral (intellectual and physical activities) modifications. At the cellular and molecular levels, successful brain aging can be facilitated by activating a hormesis response in which neurons increase production of neurotrophic factors and stress proteins. Neural stem cells that reside in the adult brain are also responsive to environmental demands and appear capable of replacing lost or dysfunctional neurons and glial cells, perhaps even in the aging brain. The recent application of modern methods of molecular and cellular biology to the problem of brain aging is revealing a remarkable capacity within brain cells for adaptation to aging and resistance to disease.

Cholesterol predicts stroke mortality in the Women's Pooling Project

BACKGROUND AND PURPOSE

Cholesterol is emerging as a risk factor for stroke; however, few data are available regarding the relation of cholesterol and stroke mortality in women and ethnic minorities.

METHODS

We evaluated the risk of death caused by total stroke, nonhemorrhagic stroke, and hemorrhagic stroke by race, age, and cholesterol quintile in 24 343 women with no previous cardiovascular disease who were participating in 8 US longitudinal, prospective, cohort studies included in the Women's Pooling Project.

RESULTS

We observed 568 stroke deaths (461 nonhemorrhagic, 83 hemorrhagic) for women > or =30 years of age without previous cardiovascular disease during 339 215 person-years of follow-up. In multivariate models, black women <55 years of age had a 76% increased risk of death caused by stroke compared with white women [relative risk (RR), 1.76; 95% confidence interval (CI), 1.10 to 2.81]. For black women <55 years of age, the top compared with the lowest cholesterol quintile (Q5 versus Q1) remained an independent predictor of stroke mortality (RR, 2.58; 95% CI, 1.05 to 6.32) in multivariate models. For white women <55 years of age, Q5 versus Q1 cholesterol did not predict stroke mortality with significance (RR, 1.47; 95% CI, 0.57 to 3.76). In analogous multivariate models, we found a positive relation between continuous cholesterol and nonhemorrhagic stroke death in women <55 years of age (RR, 1.23; 95% CI, 1.02 to 1.49).

CONCLUSIONS

Our results show that cholesterol is a risk factor for nonhemorrhagic stroke death in women <55 years of age and is more strongly associated with mortality in black women <55 years of age than in white women. These data document the importance of cholesterol in addition to established risk factors for predicting stroke mortality in young women and may guide prevention strategies.

Elucidation of the thromboregulatory role of CD39/ectoapyrase in the ischemic brain

Endothelial CD39 metabolizes ADP released from activated platelets. Recombinant soluble human CD39 (solCD39) potently inhibited ex vivo platelet aggregation in response to ADP and reduced cerebral infarct volumes in mice following transient middle cerebral artery occlusion, even when given 3 hours after stroke. Postischemic platelet and fibrin deposition were decreased and perfusion increased without increasing intracerebral hemorrhage. In contrast, aspirin did not increase postischemic blood flow or reduce infarction volume, but did increase intracerebral hemorrhage. Mice lacking the enzymatically active extracellular portion of the CD39 molecule were generated by replacement of exons 4-6 (apyrase-conserved regions 2-4) with a PGKneo cassette. Although CD39 mRNA 3' of the neomycin cassette insertion site was detected, brains from these mice lacked both apyrase activity and CD39 immunoreactivity. Although their baseline phenotype, hematological profiles, and bleeding times were normal, cd39(-/-) mice exhibited increased cerebral infarct volumes and reduced postischemic perfusion. solCD39 reconstituted these mice, restoring postischemic cerebral perfusion and rescuing them from cerebral injury. These data demonstrate that CD39 exerts a protective thromboregulatory function in stroke.

Cardiorespiratory fitness and stroke mortality in men

PURPOSE

We examined the association between cardiorespiratory fitness and stroke mortality in men.

METHODS

This is a prospective cohort study. We followed 16,878 men, ages 40-87 yr, who had a complete medical evaluation including a maximal treadmill exercise test and self-reported health habits. There were 32 stroke deaths during an average of 10 yr of follow-up (167,961 man-yr).

RESULTS

After adjustment for age and examination year, there was an inverse association between cardiorespiratory fitness and stroke mortality (P = 0.005 for trend). This association remained after further adjustment for cigarette smoking, alcohol intake, body mass index, hypertension, diabetes mellitus, and parental history of coronary heart disease (P = 0.02 for trend). High-fit men (most fit 40%) had 68% (95% CI: 0.12, 0.82) and moderate-fit men had 63% (95% CI: 0.17, 0.83) lower risk of stroke mortality when compared with low-fit men (least fit 20%), respectively.

CONCLUSIONS

Moderate and high levels of cardiorespiratory fitness were associated with lower risk of stroke mortality in men in the Aerobics Center Longitudinal study population.

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Dehydroascorbic acid, a blood-brain barrier transportable form of vitamin C, mediates potent cerebroprotection in experimental stroke

Neuronal injury in ischemic stroke is partly mediated by cytotoxic reactive oxygen species. Although the antioxidant ascorbic acid (AA) or vitamin C does not penetrate the blood-brain barrier (BBB), its oxidized form, dehydroascorbic acid (DHA), enters the brain by means of facilitative transport. We hypothesized that i.v. DHA would improve outcome after stroke because of its ability to cross the BBB and augment brain antioxidant levels. Reversible or permanent focal cerebral ischemia was created by intraluminal middle cerebral artery occlusion in mice treated with vehicle, AA, or DHA (40, 250, or 500 mg/kg), either before or after ischemia. Given before ischemia, DHA caused dose-dependent increases in postreperfusion cerebral blood flow, with reductions in neurological deficit and mortality. In reperfused cerebral ischemia, mean infarct volume was reduced from 53% and 59% in vehicle- and AA-treated animals, respectively, to 15% in 250 mg/kg DHA-treated animals (P < 0.05). Similar significant reductions occurred in nonreperfused cerebral ischemia. Delayed postischemic DHA administration after 15 min or 3 h also mediated improved outcomes. DHA (250 mg/kg or 500 mg/kg) administered at 3 h postischemia reduced infarct volume by 6- to 9-fold, to only 5% with the highest DHA dose (P < 0.05). In contrast, AA had no effect on infarct volumes, mortality, or neurological deficits. No differences in the incidence of intracerebral hemorrhage occurred. Unlike exogenous AA, DHA confers in vivo, dose-dependent neuroprotection in reperfused and nonreperfused cerebral ischemia at clinically relevant times. As a naturally occurring interconvertible form of AA with BBB permeability, DHA represents a promising pharmacological therapy for stroke based on its effects in this model of cerebral ischemia.

Nutritional disorders among workers in North China during national turmoil

Previously undescribed disorders of nutrition of thiamin, niacin and pyridoxin were observed among the poor people of North China during periods of prolonged deprivation. These disorders were often elicited or exacerbated by physical exertion. Thiamin deficiency syndromes included great toe pain, heel pain, temporomandibular joint click, and painful click of the knee. Syndromes of niacin deficiency included pellagral scrotal dermatitis, hypersecretion of ear wax, and night terrors. Episodic nocturnal motor hyperfunction was caused by pyridoxin deficiency. Several cases with cardiovascular diseases were observed in which nutritional debt appeared to occur simultaneously with oxygen debt following severe physical labor. Intramuscular thiamin HCl ameliorated symptoms of impending stroke. Persons with the same symptoms who did not receive thiamin progressed to fatal stroke.

A controlled study of MRI signal hyperintensities in older depressed patients with and without hypertension

OBJECTIVES

To compare the frequency/severity of signal hyperintensities--likely markers of cerebrovascular disease--in the subcortical gray and deep white matter on magnetic resonance imaging (MRI) scans of brains of hypertensive and normotensive older depressed and nondepressed comparison subjects.

DESIGN

Between-groups comparison of cross-sectional MRI data employing analyses of covariance controlling for the effects of age, gender, and height.

SETTING

A comprehensive inpatient-outpatient geriatric psychiatry service in a university hospital.

PARTICIPANTS

Nondemented older depressed (n = 81) and nondepressed comparison (n = 70) subjects divided into four groups (hypertensive depressed (n = 40), hypertensive normals (n = 21), normotensive depressed (n = 41), normotensive normals (n = 49)).

MEASUREMENTS

Signal hyperintensities were rated on T-2 weighted MRI scans blind to patient diagnoses employing two standardized hyperintensity rating systems (Fazekas, Boyko).

RESULTS

Hypertensive depressives had significantly more- severe hyperintensity ratings in both subcortical gray and deep white matter than did normotensive depressives and controls (P < .05) and significantly more-severe hyperintensity ratings only in subcortical gray matter (P < .05) than did hypertensive controls. Hypertensive controls had significantly more-severe ratings in deep white matter than either normotensive group (P < .05).

CONCLUSIONS

Findings suggest a relationship between deep white matter hyperintensities and hypertension (regardless of depressive state), and a particular role of subcortical gray matter hyperintensities (possibly interacting with more-severe deep white matter lesions) in older depressed hypertensives, as compared with older depressed normotensives of similar ages and severity of depression. These data support possible heterogeneous pathogenic contributions in late-life depression subgroups, one of which appears to be influenced by cerebrovascular disease.

Assessment of dementia in nursing home residents by nurses and assistants: criteria validity and determinants

OBJECTIVES

To describe the criterion validity of nursing home staff's assessment of organic disorder compared with ICD-10 criteria, and to identify determinants of staff assessment of organic disorder.

METHOD

Two hundred and eighty-eight residents were diagnosed using the GMS-AGECAT. Nursing staff members were interviewed about the residents' activities of Daily Living, behavioural problems, orientation in surroundings and communication skills, and asked if the resident had an organic disorder. Multiple logistic regression was used to select the items that most strongly determined staff assessment of organic disorder.

RESULTS

Sixty-two per cent of the residents were diagnosed by GMS-AGECAT as having organic disorder, 78% of these were correctly identified by the staff. Whether analysed among residents with or without organic disorder, or in the total group of residents, the staff assessment of the presence of organic disorder depended on a limited set of behavioural characteristics of the resident, namely 'going to the toilet in inappropriate places', 'saying things that do not make sense' and impairment in orientation.

CONCLUSIONS

Staff comprehension of organic disorder resulted in over- as well as under-labelling of residents, a tendency that will affect communication with medical personnel and may lead to inadequate or wrong medical treatment and to negative performance as well as negative role expectations in everyday life in nursing homes.

Association of Hemostatic Variables with MRI-Detected Cerebral Abnormalities: The Atherosclerosis Risk in Communities Study

OBJECTIVES

Population-based and clinical prospective studies have shown independent associations of several hemostatic factors with ischemic heart disease and stroke. MRI-detected cerebral infarcts and white matter lesions are often detected in elderly individuals without clinical disease. It has been hypothesized that these types of lesions are often the consequence of cerebral ischemic damage and may be the precursors of clinical stroke.

METHODS

This study examined the relation between a range of hemostatic factors measured at baseline in middle-aged participants who were free of diagnosed cardiovascular disease in the Atherosclerosis Risk in Communities Study and MRI-detected cerebral abnormalities at a 6-year follow-up examination.

RESULTS

Plasma fibrinogen and perhaps von Willebrand factor were associated positively, and protein C was associated negatively, with cerebral infarctions. Adjusted for other risk factors, the odds ratio for cerebral infarction was 1.21 (95% confidence interval, CI = 1.02-1.44) per standard deviation increment for fibrinogen, 1.15 (95% CI = 0.97-1.37) per standard deviation increment for von Willebrand factor, and 0.77 (95% CI = 0.62-0.95) per standard deviation increment for protein C. No hemostatic factor, however, was associated with white matter disease.

CONCLUSIONS

This study has only a follow-up MRI, and it is likely that some MRI lesions were present at baseline. Nevertheless, increased levels of fibrinogen and von Willebrand factor and reduced levels of protein C appear to be associated with cerebral infarction identified by MRI.

Hormone replacement therapy and stroke: risk, protection or no effect?

Despite declining death rates due to stroke over the last several decades, stroke remains the third leading killer (after heart disease and cancer) of women in most developed countries. Because stroke not only kills but also leaves many survivors mentally and physically impaired, control of the disease must be through primary prevention. Several observations lead to the speculation that estrogen may reduce stroke risk. This paper reviews the epidemiologic studies that have evaluated the association of hormone replacement therapy (HRT) and stroke. In the past 25 years, 29 studies have produced no conclusive evidence of a beneficial effect. The lack of consistency in stroke endpoints, definition of HRT user, estrogen preparation, and influence of combined regimen might account in part for the unclear relationship. Nonetheless, the preponderance of evidence suggests that HRT does not increase stroke risk. Some data indicate that estrogen users have a moderately reduced risk of fatal stroke, but details about the optimal dose, duration and type of estrogen are insufficient. The apparent difference in the findings of studies of fatal and non-fatal stroke suggests that estrogen may prevent the most lethal form of stroke or may improve survival. Additional data from ongoing randomized clinical trials in the coming years may help resolve the question of the effect of HRT on stroke morbidity and mortality.

Whole grain intake and risk of ischemic stroke in women

In a recent prospective study, whole grain intake was associated with a reduced risk of ischemic stroke. Refined grain, however, did not elicit such protection. Given the potential health benefits associated with whole grain diets, further exploration on the effects of whole grains on health and risk of chronic disease is warranted.

Antithrombotic and thrombolytic therapy for ischemic stroke

Antithrombotic and thrombolytic agents form the cornerstone of stroke prevention and treatment. Large, randomized trials have also highlighted the effectiveness and safety of early and continuous antiplatelet therapy in reducing atherothrombotic stroke recurrence. Aspirin is the antiplatelet treatment standard against which several other antiplatelet agents (ticlopidine, clopidogrel, aspirin-dipyridamole) have been shown to be more effective. The prevention of cardioembolic stroke is best accomplished with oral anticoagulation, barring any contraindications. The thrombolytic agent, rt-PA, improves outcome in ischemic stroke patients treated within 3 hours of onset. The risk-benefit ratio is narrow because of an increased risk for bleeding but studies do not support a higher risk in the geriatric population.

The effect of disease prevention and health promotion on workplace productivity: a literature review

This report was prepared by the Center for Disease Prevention and Health Promotion in the Institute for Health and Productivity Management as part of an effort to improve understanding of the connection between employee health and performance and to begin to identify new strategies through which treating health as an investment in human capital can lead to greater business success. Computer database searches of peer-reviewed literature published between 1993 and 1998 and manual reviews of 20 journals were used to identify research on the link between employee health and performance. Data was extracted to summarize the overall findings on the magnitude of health problems addressed by health promotion and disease prevention programs, and the impact of interventions on improving health risk, reducing medical care cost, and improving worker performance. From this summary, major conclusions on early detection of disease, the impact of behavior change programs, and appropriate care-seeking were drawn. This systematic review is supplemented with summaries of 15 seminal articles and descriptions of five leading-practices programs. The influence of developments in work/family issues, complementary and alternative medicine, and quality of care and health outcomes research are briefly discussed. Finally, a conceptual framework for studying the impact of health and productivity is described.

Primary stroke prevention

Stroke is one of the leading causes of death and disability worldwide. Although important advances in therapeutic approaches have been made, treatment is still far from satisfactory. Thus, major efforts should be made on stroke prevention. We present evidence-based recommendations for primary stroke prevention. Changes to modifiable risk factors, the role of drugs and surgery are discussed. New markers may help identification of subjects at high risk.

Neuroprotective signaling and the aging brain: take away my food and let me run

It is remarkable that neurons are able to survive and function for a century or more in many persons that age successfully. A better understanding of the molecular signaling mechanisms that permit such cell survival and synaptic plasticity may therefore lead to the development of new preventative and therapeutic strategies for age-related neurodegenerative disorders. We all know that overeating and lack of exercise are risk factors for many different age-related diseases including cardiovascular disease, diabetes and cancers. Our recent studies have shown that dietary restriction (reduced calorie intake) can increase the resistance of neurons in the brain to dysfunction and death in experimental models of Alzheimer's disease, Parkinson's disease, Huntington's disease and stroke. The mechanism underlying the beneficial effects of dietary restriction involves stimulation of the expression of 'stress proteins' and neurotrophic factors. The neurotrophic factors induced by dietary restriction may protect neurons by inducing the production of proteins that suppress oxyradical production, stabilize cellular calcium homeostasis and inhibit apoptotic biochemical cascades. Interestingly, dietary restriction also increases numbers of newly-generated neural cells in the adult brain suggesting that this dietary manipulation can increase the brain's capacity for plasticity and self-repair. Work in other laboratories suggests that physical and intellectual activity can similarly increase neurotrophic factor production and neurogenesis. Collectively, the available data suggest the that dietary restriction, and physical and mental activity, may reduce both the incidence and severity of neurodegenerative disorders in humans. A better understanding of the cellular and molecular mechanisms underlying these effects of diet and behavior on the brain is also leading to novel therapeutic agents that mimick the beneficial effects of dietary restriction and exercise.

What else adds to hypertension in predicting stroke? An incident case-referent study

OBJECTIVES

To examine to what extent traditional biomedical risk factors and social factors can predict, separately or jointly, first-ever stroke event, and to explore to what extent other risk factors might add to hypertension/elevated blood pressure as a stroke risk factor.

DESIGN

An incident case-referent study.

SETTING

The study was nested within the Västerbotten Intervention Program (VIP) and the Northern Sweden MONICA cohorts.

SUBJECTS

The study involves 129 stroke cases with two randomly selected referents per case from the same study cohorts.

RESULTS

History of diabetes, daily smoking, obesity (body mass index greater than or = 30 kg m(-2)), hypertension and living as an unmarried person were associated with an increased risk in univariate analysis. However, in the multivariate logistic regression analysis, only hypertension, diabetes and single marital status remained significant. There was a statistically significant interaction between hypertension and smoking and stroke. Interaction of possible clinical relevance was also observed between hypertension, history of diabetes and stroke.

CONCLUSIONS

The study both emphasizes the multifactorial nature of stroke and illustrates that knowledge of interactions offers different strategic approaches when preventing stroke in clinical work. It is important, but not enough, to focus on blood pressure control. Diabetes prevention as well as prevention of smoking must also be considered as factors of major importance.

Estrogen decreases infarct size after temporary focal ischemia in a genetic model of type 1 diabetes mellitus

BACKGROUND AND PURPOSE

It is unclear how genetic type 1 diabetes mellitus (DM) influences infarct size when blood glucose is tightly controlled. The aim of this study was to determine the effect of genetic type 1 DM, as occurs in BB rats, on infarct size after transient unilateral middle cerebral artery occlusion (MCAO) in male and female rats. In addition, studies suggest that male type 1 DM rats have a higher incidence of end-organ complications than do females. A second aim of this study was to determine the effect of chronic 17beta-estradiol (E(2)) administration on infarct size in male BB rats.

METHODS

Diabetic male (MDiab, n=14) and female (FDiab, n=8) BB rats were studied and compared with background strain Wistar rats (MWist, n=16; FWist, n=14). Two additional male cohorts (MWist+E(2), n=15; MDiab+E(2), n=14) received subcutaneous 25 microg E(2) implants 7 to 10 days before MCAO. Rats underwent 1 hour of MCAO followed by 22 hours of reperfusion. Physiological variables were controlled among groups, and the intraischemic laser Doppler flow signal was reduced similarly in all animals. Infarction volume was evaluated by 2,3,5-triphenyltetrazolium chloride staining and image analysis.

RESULTS

Preischemic blood glucose was 94+/-5, 127+/-13, 90+/-15, 63+/-18, 122+/-8, and 81+/-14 mg/dL in MWist, FWist, MDiab, FDiab, MWist+E(2), and MDiab+E(2) rats, respectively (mean+/-SE). Intraischemic laser Doppler flow was reduced to 20% to 25% of baseline in all groups. Striatal infarct size (percentage of ipsilateral caudate putamen) was increased in male diabetic rats relative to nondiabetic MWist rats (41+/-3% versus 28+/-3%). Striatal injury was not increased in FDiab rats, and infarction volume was smaller than that in FWist rats (23+/-4% in FWist versus 13+/-3% in FDiab). Chronic estrogen treatment reduced cortical and striatal infarction in MDiab+E(2) rats compared with untreated MDiab rats.

CONCLUSIONS

Type 1 DM is associated with increased infarct size after temporary MCAO, despite tight control of blood glucose. The deleterious effect of DM is evident only in males rats; female diabetic BB rats sustain small infarcts. Chronic E(2) treatment reduced injury in the male BB rat, providing neuroprotection even in the presence of DM. These data suggest that genetic diabetes even with mild glucose elevation plays a role in determining neuropathology in experimental stroke. However, factors such as reproductive steroids also determine outcome in DM stroke.

The usefulness of ratios for allocation decisions: the case of stroke

Economic evaluation is becoming increasingly important in the field of stroke as well. The results of economic evaluation can be expressed in cost per quality-adjusted life years (QALY) gained, which enables policy makers to compare the relative efficiency of different interventions regarding different diseases. Although using the concept of QALY is preferable from a theoretical point of view, in medical practice more often cost-effectiveness analysis (CEA), and not cost-utility analysis, is applied for practical reasons. One of the main limitations of CEA is that the results may be compared only with results of other CEAs, using the same effect parameter. The calculation of cost-effectiveness ratios (CERs) in many cases is misleading for resource allocation. Effects should be expressed in interval or ratio scales in order to calculate CERs, which is rarely the case. The calculation of a CER in a CEA should only be performed if, and only if, the investigator is convinced that there is a constant relation between the specific effect parameter and the ultimate gain in health.

Population attributable fraction of stroke incidence in middle-aged and elderly people: contributions of hypertension, smoking and atrial fibrillation

We determined the population attributable fraction (PAF) of stroke due to hypertension (HT), atrial fibrillation (Af) and smoking in a Japanese community. Residents of Shibata (n = 2,302) who were surveyed initially in 1977 were followed until 1997. Two hundred and thirteen first strokes occurred. Among those 40-64 years of age, the risk ratio (RR) of Af was 11.24, followed by untreated HT (3.61), uncontrolled HT (3.69) and smoking (1.84). The PAFs, however, were 14.9% for smoking, 13.5% for untreated HT, 8.6% for uncontrolled HT and 3.6% for Af. Among those over 65 years, only Af was significant (RR 3.89) and the PAF was 6.0%. Determination of PAFs is also essential for designing effective stroke prevention programs in communities.

Nifedipine or prazosin as a second agent to control early severe hypertension in pregnancy: a randomised controlled trial

OBJECTIVE

To determine whether nifedipine or prazosin is the more appropriate second-line antihypertensive agent in pregnancy.

DESIGN

Randomised controlled trial.

SETTING

Tygerberg Hospital, a tertiary referral centre.

POPULATION

Women with early, severe pre-eclampsia or hypertension in pregnancy, whose blood pressure could not be adequately controlled by methyldopa 2 g/day, but were otherwise stable.

METHODS

Nifedipine or prazosin were given and increased as necessary in a stepwise fashion. Once the maximum dose was reached, the other drug was added in a crossover pattern. Failure to control blood pressure, or the onset of maternal/fetal complications were indications for delivery. Patients reaching a minimum gestation of 34 weeks without complications were delivered electively.

MAIN OUTCOME MEASURES

Antenatal days gained; major maternal complications and perinatal survival.

RESULTS

Days gained on the second antihypertensive agent did not differ significantly (P = 0.9), while more days were gained using nifedipine as the crossover 'third agent' (P = 0.01). In the nifedipine group better renal function was recorded, but more cases with isolated low platelet counts occurred. More cases of pulmonary oedema as well as more nonviable mid-trimester and third trimester intrauterine deaths occurred in the prazosin group.

CONCLUSION

Nifedipine and prazosin as second agents allowed comparable amounts of time to be gained, although this changed when used as crossover third-line agents. The efficacy and safety of nifedipine in this study are consistent with the results of other studies. A greater number of intrauterine deaths occurred in the prazosin group.

Long-term prevention of ischaemic stroke and stroke recurrence

Stroke is the third most important cause of mortality, but the leading cause of severe handicap, dependency, and loss of social competence. Because of the high recurrence rate, active secondary prevention is mandatory once a stroke has occurred. Secondary prevention of stroke implies the primary prevention of cardiovascular disorders as well. Among the modifiable risk factors hypertension is worst and should be normalized according to recent WHO criteria, also in the elderly. Smoking is another major risk factor and hard to delete. Diabetes mellitus and hyperlipidaemia are also important risk factors and should be treated consequently by diet and medication. Moderate alcohol intake, normalization of body weight and regular physical activity also contribute considerably to prevention of stroke. Whether hyperhomocysteinaemia should be normalized has not yet been clarified. Cardiovascular disorders are an important source of ischemic strokes, particularly atrial fibrillation. Low dose anticoagulation can dramatically reduce stroke risk. Carotid endarterectomy in symptomatic stenoses is the most expensive means of stroke prevention. In less severe stenoses, or ICA occlusions, antiplatelet agents are the treatment of choice. Composite drugs with ASS and other antiplatelet agents seem to be superior to either compound alone. Dissections of the cervical arteries should not be operated on but may be treated by anticoagulation or antiplatelet agents in the acute and subacute phase. The potency of a consequent and comprehensive stroke prevention in preventing disability and death is much greater than any sophisticated acute stroke treatment.