Stroke is the third leading cause of death and a foremost cause of serious, long-term disability in the United States.1 Stroke is defined as a sudden episode of focal neurological dysfunction caused by a blockage or rupture of a blood vessel to the brain. Disruption of circulation results in tissue death, as evidenced by persistent clinical signs and abnormalities on neuroimaging that are characteristic of infarction.2 Depending on the extent and location of damage to brain tissue, stroke may profoundly affect individuals' physical, mental, and social functioning.3,4

With aging comes increased risk of stroke, and clinical and functional consequences may be compounded by other conditions associated with aging. As cardiovascular and metabolic disease incidence rises with age, older people are more likely to experience strokes. Age is the single most important risk factor for stroke. For each successive 10 years after age 55, the stroke rate more than doubles in both men and women.5 Nearly three quarters of all strokes occur in people older than 65 years. Stroke incidence rates are 1.25 times greater in men, but because women tend to live longer than men, more women than men die of stroke each year.6

However, stroke is not an inevitable consequence of aging. By identifying and modifying risk factors in older people, there are opportunities to reduce the incidence and mortality of this condition.7 Recent advances in emergency medical care have reduced mortality and stroke severity, resulting in greater numbers of older adults who survive strokes.8 Although stroke incidence in America seems stable and stroke mortality is slowly declining, the absolute magnitude of stroke is likely to grow over the next 30 years. With aging of the population, the number of older stroke survivors is likely to increase substantially.6 The very old are expected to become a growing part of the stroke survivor population.9

This article presents a discussion of stroke risk factors and primary and secondary prevention in the context of aging, with special considerations in the identification and management of acute stroke, recovery, and rehabilitation for older adults who survive stroke.

Stroke and Aging

Not only are older adults more likely to have strokes, but the physical, psychological, and social consequences may be more severe for those who survive. The burden of stroke is heterogeneous and is greatest among the elderly, men, and African Americans.6 Age is an independent predictor of outcome after ischemic stroke. Older patients, especially those older than 80 years, are more likely to die in the hospital after stroke and less likely to make a favorable long-term recovery.9 Other factors such as onset stroke severity, preexisting disability, and atrial fibrillation (AF) are also significant age-related independent predictors of prognosis after stroke.9

Risk Factors and Prevention of Stroke in Older Adults

Risk factors and the incidence of stroke peak in subjects aged 75 years or older. Patients with the highest risk benefit most from effective risk reduction therapy.10 For this reason, all strategies of demonstrated value in stroke prevention are pertinent in the care of older adults. Control of hypertension, resolution of dyslipidemia, management of diabetes mellitus, anticoagulation for AF, promotion of exercise and healthy diet, and cessation of cigarette smoking are obligatory at all ages but are of particular importance in older adults.10

Of the more than 700,000 strokes that occur each year, 200,000 are recurrent.6 Approximately 25% of people who recover from their first stroke will have another stroke within 5 years. Unless specific interventions are directed toward modifying stroke risk factors, the potential for recurrence persists.

Management of Hypertension

High blood pressure, once believed to represent a normal and progressive component of the aging process, is now recognized as a sign of structural and physiologic abnormalities of vascular function.11 Elevated blood pressure is a significant determinant of the long-term risk of stroke.12 Casual systolic hypertension is a prevalent finding in older adults (50% of women older than 80 years have casual systolic blood pressures >160 mm Hg).13 Isolated systolic hypertension, defined as a systolic blood pressure >=140 mm Hg with a diastolic blood pressure <90 mm Hg, affects most individuals aged 60 years and older.11

Antihypertensive treatment has established efficacy in primary prevention of fatal or nonfatal stroke in hypertensive and high-risk patients older than 60 years, particularly through treatment of systolic hypertension.14 In a summary of 17 treatment trials of hypertension throughout the world involving nearly 50,000 patients, investigators found a 38% reduction in all stroke and a 40% reduction in fatal stroke resulting from systematic treatment of hypertension. Treatment was also highly effective in preventing stroke in individuals older than 65 years with systolic hypertension.15 Importantly, there was no less impact on stroke prevention in patients older than 80 years, with incidence reduced by 40%.6 To prevent stroke, it is necessary to treat older adults with hypertension aggressively to the same target blood pressures identified for younger patients.11 Thiazide diuretics and angiotensin-converting enzyme inhibitors are the drug classes of choice from which therapy may be initiated in this population.16

There seems to be no age threshold beyond which treatment of hypertension would not be beneficial.17 Antihypertensive treatment in older adults up to the age of 80 who have blood pressures over 160 mm Hg systolic is associated with significant reductions in stroke and cardiovascular events.13 Optimal clinical management accounts for specific aspects of pathophysiology and metabolic characteristics of older adults. Treatment should be initiated with lower doses of antihypertensive agents, bringing pressure down slowly while monitoring for orthostatic hypotension, impaired cognition, and electrolyte abnormalities.11 Although the goal for blood pressure is to reach <140/90 mm Hg, a decrease of 20 to 30 mm Hg in systolic blood pressure, even if the overall treatment goal is not achieved, is still associated with reduced cardiovascular risk.17 For every 5-mm Hg reduction in systolic blood pressure, stroke mortality may decrease by as much as 14%.16

Management of Dyslipidemia

Elevated cholesterol levels are not uncommon in older adults; 61% of women aged between 65 and 74 years are reported to have total cholesterol levels over 240 mg/dL.18 Elevated total cholesterol and decreased high-density lipoprotein levels predispose older adults to ischemic stroke.18 The mechanism through which serum cholesterol increases stroke risk is based on its actions on the artery walls.

Possible benefits from lipid-lowering therapy are particularly relevant for the older population at high risk for stroke.18 Although associations are relatively weak, epidemiological evidence indicates that elevated total cholesterol and subfractions increase stroke risk.18 Lowering high serum cholesterol with HMG-CoA reductase inhibitors (statins) has been beneficial in the primary and secondary prevention of myocardial infarction, but further research is needed to determine the effect of lipid lowering on stroke occurrence.18 Few large-scale studies have investigated the specific effect of statins on stroke prevention in older individuals. To date, the largest trials suggest a beneficial effect for stroke prevention with statins in high-risk elderly subjects aged 82 years or younger.14

Indirect evidence suggests that the reduction in the stroke risk with statins is larger than would be expected with the reduction of serum cholesterol level alone. Antioxidant and endothelium-stabilizing properties of statins may contribute to reducing the risk of stroke by protecting vascular walls.18 Although the relative risk of stroke associated with elevated lipids is only moderate, its population-attributable risk is high, given the increase in the elderly population worldwide.18

Original Adult Treatment Panel III guidelines recommended that the low-density lipoprotein level be targeted for intervention, with the goal below 100 mg/dL in this population. However, an update released in 2005 suggests a more ambitious goal of less than 70 mg/dL for very high-risk patients, defined as those with a recent myocardial infarction, cardiovascular disease with diabetes, severe/poorly controlled risk factors, or metabolic syndrome.19 After lifestyle modifications of diet and exercise, statin agents are recommended as first-line choice of treatment, followed by the addition of bile acid sequestrants as needed.20

Management of Diabetes

There is an age-related increase in total body fat and visceral adiposity that often is accompanied by diabetes or impaired glucose tolerance. The prevalence of type 2 diabetes increases progressively with age, peaking at 16.5% in men and 12.8% in women at ages 75 to 84 years. Glucose intolerance or diabetes was present in 30% to 40% of Framingham Study subjects older than 65 years.21

Type 2 diabetes and obesity are both associated with a clustering of atherogenic risk factors. Diabetes, often associated with high blood pressure, contributes to increased frequency and severity of cerebral vascular events.22 The risk of macrovascular disease is actually increased before glucose levels reach the diagnostic threshold for diabetes, and 25% of newly diagnosed patients with diabetes already have overt cardiovascular disease.21 Diabetes and related complications including untreated or poorly treated hypertension may lead to premature arterial stiffening. The resulting stiffening and hypertrophy of the left ventricle yield a predisposition to coronary heart disease, heart failure, stroke, and other conditions.23 Other aspects of glucose metabolism may play a role in stroke risk, specifically hyperinsulinemia and increased insulin resistance. Both were shown to be risk factors for ischemic stroke even among subjects with normal glucose status by laboratory values.6

The risk of cardiovascular sequelae in patients with diabetes is variable. Most events occur in those with 2 or more additional risk factors. Comprehensive stroke risk reduction in older adults should include not only normalization of the blood sugar but also weight reduction, dietary fat restriction, strict blood pressure and lipid control, exercise, and avoidance of tobacco.21

AF Management

Atrial fibrillation (AF) is the most common clinically relevant dysrhythmia in persons younger than 75 years and is strongly associated with ischemic stroke and other adverse outcomes. It is also the most treatable cardiac precursor of stroke.24 It describes quivering of the upper chambers of the heart, leading to pooling of blood where clots may develop. The incidence and prevalence of AF increase with age. With each successive decade of life of a patient older than 55 years, incidence of AF doubles.6 Data from the Framingham Study and hospital discharges suggest that the prevalence of AF in the US population is increasing.12 More than 2.2 million Americans currently have AF, and this number is expected to increase by at least 2.5-fold over the next 50 years.24

Stroke is the most feared complication of AF. Multiple clinical trials have shown that warfarin sodium anticoagulation is effective in reducing the risk of stroke in older adults.25 However, the complex pharmacokinetics and narrow therapeutic window of warfarin make its use challenging. An adjusted dose of warfarin with a target International Normalized Ratio of between 2 and 3 prevents ischemic stroke in elderly patients with an acceptable hemorrhagic risk but is still largely underprescribed.14 Novel approaches to anticoagulation, including more potent antiplatelet agents and direct thrombin inhibitors, are currently undergoing clinical trials.25

Carotid Stenosis Treatment

Carotid stenosis refers to the buildup of atherosclerotic materials within the carotid arteries, leading to occlusion of vital circulation to the brain. Carotid endarterectomy is indicated in carotid artery stenosis >70%, and outcomes are even better in elderly than in younger patients. However, medical treatment is preferred in asymptomatic elderly patients with <70% stenosis.14 Elderly patients with severely symptomatic stenotic carotid artery disease should undergo endarterectomy. Evidence for benefit from endarterectomy in asymptomatic subjects at any age is weak and cannot be recommended as a preventive strategy.10,26 Carotid stenting, recently approved by the Food and Drug Administration for stroke risk reduction, has had mixed results in clinical trials and is currently being evaluated in more rigorous studies.26

Antiplatelet Therapy in Stroke Prevention

Finally, for most patients with noncardioembolic stroke, daily treatment with an antiplatelet agent is recommended by the American Association of Chest Physicians. Aspirin 50 to 325 mg daily is the least expensive option. Other antiplatelet agents, such as clopidogrel or extended-release dipyridamole with aspirin, may also be used in the absence of contraindications.26 Clinicians are advised to avoid combining clopidogrel and aspirin due to increased risks of bleeding, unless there is a specific cardiac indication.26

Recognition and Treatment of Acute Stroke in Older Adults

To minimize the impact from stroke, early recognition of signs and symptoms and immediate initiation of evaluation and treatment are imperative. Quantitative estimates of the rate of neural circuitry loss in ischemic stroke emphasize the urgency of timely and definitive care. The adage that "time lost is brain lost" takes on added significance when one realizes that the typical patient loses 1.9 million neurons each minute during which stroke goes untreated.27

Recognizing Stroke

Older adults often do not associate new onset symptoms with acute stroke, but rather attribute them to other illnesses (arthritis, weakness, headaches, or fatigue) and fail to take immediate action. The American Stroke Association has launched an educational campaign, "Operation Stroke," to educate the general public about the signs and symptoms of stroke. The campaign has been somewhat effective-70% of respondents in a recent random telephone survey of 2,173 correctly named one stroke warning sign, up from only 57% in 1995,28 but there is ongoing need for education and reinforcement.

Current practice guidelines recommend that persons with symptoms of stroke be transported immediately to a stroke-qualified facility where definitive diagnosis and care can be initiated. The first step in the evaluation of suspected acute stroke is a thorough history, physical, and neurological examination. Careful attention must be paid to the time of onset of symptoms because emergency treatment options are determined by the time window. Other important information includes review of medications and reports of recent medical or surgical events including trauma or a history of transient ischemic attacks.

Stroke must be differentiated from other conditions with similar symptoms, such as seizures, confusional states, syncope, metabolic disorders, brain tumor, or subdural hematoma. Brain imaging is mandatory to distinguish ischemic stroke from hemorrhage or other structural brain lesions and to determine vascular distribution of the ischemic lesion.29 Computerized tomography is the current minimal standard to exclude hemorrhagic events and identify patients who are candidates for recombinant tissue plasminogen activator (t-PA).29 Laboratory tests should include an electrocardiogram, complete blood count, and metabolic and coagulation panels.30

Timely evaluation and treatment initiation is crucial because the only currently approved treatment of ischemic stroke, recombinant t-PA, is effective only if administered with the first 3 hours after symptom onset.29,31 In the case of hemorrhagic stroke, with its higher mortality, immediate evaluation and neurosurgical treatment may be critical to survival.

Stroke Treatment in Older Adults

Thrombolysis

Recombinant t-PA binds to the fibrin in a thrombus and coverts the entrapped plasminogen to plasmin. This initiates local fibrinolysis and clears the blocked vessel to restore circulation. However, older adults may also be at increased risk for hemorrhagic complications from t-PA. Older patients have a higher risk of intracranial hemorrhage after thrombolysis for myocardial infarction, and patients older than 80 or 85 years were excluded from many clinical trials of thrombolysis for acute ischemic stroke.32 Older patients at the highest risk for poor stroke outcome are also at highest risk for complications of treatment. Because of limited experience with older adults, current evidence does not fully describe the risk of t-PA against the potential benefits.32

Overall, t-PA-treated patients were more likely to have a favorable outcome (score of <=1 on the National Institutes of Health Stroke Scale) at 90 days (P = .01).33 These data support current recommendations to administer intravenous t-PA to eligible ischemic stroke patients who can be treated within 3 hours of symptom onset.2 After intravenous t-PA treatment, patients older than 80 years have similar recanalization, short-term improvement, and symptomatic intracranial hemorrhage rates compared with younger patients. However, older patients tend to have higher in-hospital mortality.33

Recovery and Rehabilitation

Forty percent of patients with stroke are left with moderate functional impairments and 15% to 30% with severe disability.34 Effective rehabilitation interventions initiated early after stroke can enhance the recovery process and minimize functional disability.34 Stroke rehabilitation begins during the acute hospitalization as soon as the diagnosis of stroke is established and life-threatening problems are under control. The highest priorities during this early phase are to prevent recurrent stroke and complications, manage health issues, promote mobility and self-care activities, and provide emotional support to the patient and family.34 Poststroke guidelines recommend transfer to a stroke-specific rehabilitation unit as soon as possible to ensure early mobilization, availability of speech, physical and occupational therapy, rehabilitation psychology, and the social support derived from interaction with other stroke survivors.30 A growing body of evidence indicates that patients do better with a well-organized, multidisciplinary approach to postacute rehabilitation after a stroke.34

Even with identical stroke severity, increasing age was associated with greater disability in activities of daily living and mobility. Patients older than 85 years were nearly 10 times as likely to show a low response to rehabilitation in activities of daily living and nearly 6 times as likely to show low response in mobility as younger patients.35 Nevertheless, rehabilitation treatment is still valuable in patients older than 85 years because even small changes in function can improve independence and quality of life. Possibly less effective than for younger patients, inpatient rehabilitation is still substantially helpful for older patients.35

Role of Nursing in Assessment, Management, and Surveillance

Nurses can influence the course of events for older adults at risk for, or surviving, stroke. Older adults should be evaluated for stroke risk, educated, and actively engaged in self-management of individual risk factors. Many of the cardiovascular risk factors associated with stroke require changes in health behaviors, such as choosing a healthier diet, losing weight, beginning an exercise program, stopping smoking, or adhering to a medication regimen.30 Behavior change is closely associated with changing beliefs, essential to the adoption and maintenance of self care before and after stroke,36 and exercise after stroke.37 After stroke, regular exercise can facilitate motor recovery and can also help control the common comorbidities that influence recurrent stroke risk. Exercise can reduce hypertension, enhance glucose regulation, improve blood lipid profiles, and reduce body fat. Many older adults with stroke have never been advised by a healthcare professional to engage in a regular exercise or walking program,37 yet generalized recommendations have been formalized to promote physical activity after stroke.38 Although the field of poststroke exercise rehabilitation is still developing, stroke survivors can work with their healthcare providers to fight back against disability and limit risk profiles.

Conclusion

A discussion of stroke risk factors and prevention in the context of aging was presented. Specific age-related considerations were reviewed, including the identification and treatment of acute stroke, recovery, and rehabilitation in older stroke survivors. Although the chance of having a stroke increases with age, directed actions to manage risk and facilitate age-appropriate treatment can reduce its occurrence and impact.

Acknowledgment

This work was supported in part by the University of Maryland Claude D. Pepper Older Americans Independence Center, National Institute on Aging grant number 5-P60-AG12583, and the Department of Veterans Affairs and Baltimore Veterans Affairs Medical Center, Geriatric Research, Education and Clinical Center (GRECC).

REFERENCES