Stroke prevention in the elderly

What Should We Do with Asymptomatic Carotid Stenosis?

The benefit of prophylactic carotid endarterectomy (CEA) for patients with asymptomatic severe carotid stenosis in the major randomised surgical studies was small, expensive and may now be absorbed by improvements in best practice medical intervention. Strategies to identify patients with high stroke risk are needed. If surgical intervention is to be considered the complication rates of individual surgeons should be available. Clinicians will differ in their interpretation of the same published data. Maintaining professional relationships with clinicians from different disciplines often involves compromise. As such, the management of a patient will, in part, depend on what kind of specialist the patient is referred to. The clinician's discussion with patients about this complex issue must be flexible to accommodate differing patient expectations. Ideally, patients prepared to undergo surgical procedures should be monitored in a trial setting or as part of an audited review process to increase our understanding of current practice outcomes.

Transcriptomics of post-stroke angiogenesis in the aged brain

Despite the obvious clinical significance of post-stroke angiogenesis in aged subjects, a detailed transcriptomic analysis of post-stroke angiogenesis has not yet been undertaken in an aged experimental model. In this study, by combining stroke transcriptomics with immunohistochemistry in aged rats and post-stroke patients, we sought to identify an age-specific gene expression pattern that may characterize the angiogenic process after stroke. We found that both young and old infarcted rats initiated vigorous angiogenesis. However, the young rats had a higher vascular density by day 14 post-stroke. “New-for-stroke” genes that were linked to the increased vasculature density in young animals included Angpt2, Angptl2, Angptl4, Cib1, Ccr2, Col4a2, Cxcl1, Lef1, Hhex, Lamc1, Nid2, Pcam1, Plod2, Runx3, Scpep1, S100a4, Tgfbi, and Wnt4, which are required for sprouting angiogenesis, reconstruction of the basal lamina (BL), and the resolution phase. The vast majority of genes involved in sprouting angiogenesis (Angpt2, Angptl4, Cib1, Col8a1, Nrp1, Pcam1, Pttg1ip, Rac2, Runx1, Tnp4, Wnt4); reconstruction of a new BL (Col4a2, Lamc1, Plod2); or tube formation and maturation (Angpt1, Gpc3, Igfbp7, Sparc, Tie2, Tnfsf10), had however, a delayed upregulation in the aged rats. The angiogenic response in aged rats was further diminished by the persistent upregulation of “inflammatory” genes (Cxcl12, Mmp8, Mmp12, Mmp14, Mpeg1, Tnfrsf1a, Tnfrsf1b) and vigorous expression of genes required for the buildup of the fibrotic scar (Cthrc1, Il6ra, Il13ar1, Il18, Mmp2, Rassf4, Tgfb1, Tgfbr2, Timp1). Beyond this barrier, angiogenesis in the aged brains was similar to that in young brains. We also found that the aged human brain is capable of mounting a vigorous angiogenic response after stroke, which most likely reflects the remaining brain plasticity of the aged brain.

Carotid artery disease and interventional therapy

PURPOSE OF REVIEW

Major results of recent clinical trials for carotid artery disease are changing the understanding of management.

RECENT FINDINGS

A major trial comparing carotid endarterectomy with carotid angioplasty and stenting for symptomatic or asymptomatic patients suggests comparable results by overall outcomes analyses, and different results by subset analyses. These results modify the findings of prior trials.

SUMMARY

Based on age there appear to be differences in outcomes that may influence decision for management for such patients.

Perturbed cellular response to brain injury during aging

Old age is associated with an enhanced susceptibility to stroke and poor recovery from brain injury, but the cellular processes underlying these phenomena are only partly understood. Therefore, studying the basic mechanisms underlying structural and functional recovery after brain injury in aged subjects is of considerable clinical interest. Behavioral and cytological analyses of rodents that have undergone experimental injury show that: (a) behaviorally, aged rodents are more severely impaired by ischemia than are young animals, and older rodents also show diminished functional recovery; (b) compared to young animals, aged animals develop a larger infarct area, as well as a necrotic zone characterized by a higher rate of cellular degeneration and a larger number of apoptotic cells; (c) both astrocytes and macrophages are activated strongly and early following stroke in aged rodents; (d) in older animals, the premature, intense cytoproliferative activity following brain injury leads to the precipitous formation of growth-inhibiting scar tissue, a phenomenon amplified by the persistent expression of neurotoxic factors; (e) though the timing is altered, the regenerative capability of the brain is largely preserved in rats, at least into early old age. Whether endogenous neurogenesis contributes to spontaneous recovery after stroke has not yet been established. If neurogenesis from endogenous neuronal stem cells is to be used therapeutically, an individual approach will be required to assess the possible extent of neurogenic response as well as the possibilities to alter this response for functional improvement or prevention of further loss of brain function.

AMPA receptor downregulation induced by ischaemia/reperfusion is attenuated by age and blocked by meloxicam

AIM

Stroke prevalence increases with age, while alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor (AMPAR) and inflammation have been related to ischaemia-induced damage. This study shows how age and treatment with an anti-inflammatory agent (meloxicam) modify the levels of AMPAR subunits GluR1 and GluR2, as well as the mRNA levels of the GluR2-editing enzyme, ADAR2, in a global brain ischaemia/reperfusion (I/R) model.

METHODS

Two days after global ischaemia CA1, CA3, dentate gyrus and cerebral cortex were obtained from sham-operated and I/R-injured 3- and 18-month-old Sprague-Dawley rats. Real time polymerase chain reaction, Western blotting and immunohistochemical assays were performed. Meloxicam treatment was assayed on young animals.

RESULTS

Data showed that age attenuates the downregulation induced by I/R in the AMPAR subunits GluR1 and GluR2 and modifies the GluR1/GluR2 mRNA level ratio in a structure-dependent way. The study of the ADAR2 mRNA levels showed more downregulation in older animals than young ones. Meloxicam treatment prevented the transcriptional arrest induced by I/R.

CONCLUSION

Our data suggest that changes in the AMPAR isoforms could be associated with ageing in the different structures studied. Although GluR2 editing seems to be involved in age-dependent vulnerability to ischaemia supporting the 'GluR2 hypothesis', this alone does not explain the differential vulnerability in the different brain regions. Finally, inflammation could play a role in protection from I/R-induced injury.

The genomic response of the ipsilateral and contralateral cortex to stroke in aged rats

Aged rats recover poorly after unilateral stroke, whereas young rats recover readily possibly with the help from the contralateral, healthy hemisphere. In this study we asked whether anomalous, age-related changes in the transcriptional activity in the brains of aged rats could be one underlying factor contributing to reduced functional recovery. We analysed gene expression in the periinfarct and contralateral areas of 3-month- and 18-month-old Sprague Dawley rats. Our experimental end-points were cDNA arrays containing genes related to hypoxia signalling, DNA damage and apoptosis, cellular response to injury, axonal damage and re-growth, cell lineage differentiation, dendritogenesis and neurogenesis. The major transcriptional events observed were: (i) Early up-regulation of DNA damage and down-regulation of anti-apoptosis-related genes in the periinfarct region of aged rats after stroke; (ii) Impaired neurogenesis in the periinfarct area, especially in aged rats; (iii) Impaired neurogenesis in the contralateral (unlesioned) hemisphere of both young and aged rats at all times after stroke and (iv) Marked up-regulation, in aged rats, of genes associated with inflammation and scar formation. These results were confirmed with quantitative real-time PCR. We conclude that reduced transcriptional activity in the healthy, contralateral hemisphere of aged rats in conjunction with an early up-regulation of DNA damage-related genes and pro-apoptotic genes and down-regulation of axono- and neurogenesis in the periinfarct area are likely to account for poor neurorehabilitation after stroke in old rats.

Cellular and molecular events underlying the dysregulated response of the aged brain to stroke: a mini-review

BACKGROUND

Age-related brain injuries, including stroke, are a major cause of physical and mental disabilities.

OBJECTIVE

Therefore, studying the basic mechanism underlying functional recovery after brain stroke in aged subjects is of considerable clinical interest.

METHODS

This review summarizes the effects of age on recovery after stroke in an animal model, with emphasis on the underlying cellular mechanisms.

RESULTS

Data from our laboratory and elsewhere indicate that, behaviorally, aged rats were more severely impaired by stroke than young rats, and they also showed diminished functional recovery. Infarct volume did not differ significantly between young and aged animals, but critical differences were apparent in the cytological response to stroke, most notably an age-related acceleration in the development of the glial scar. Early infarct in older rats is associated with premature accumulation of BrdU-positive microglia and astrocytes, persistence of activated oligodendrocytes, a high incidence of neuronal degeneration and accelerated apoptosis. In aged rats, neuroepithelial-positive cells were rapidly incorporated into the glial scar, but these neuroepithelial-like cells did not make a significant contribution to neurogenesis in the infarcted cortex in young or aged animals. The response of plasticity-associated proteins like MAP1B, was delayed in aged rats. Tissue recovery was further delayed by an age-related increase in the amount of the neurotoxic C-terminal fragment of the beta-amyloid precursor protein (A-beta) at 2 weeks poststroke.

CONCLUSION

The available evidence indicates that the aged brain has the capability to mount a cytoproliferative response to injury, but the timing of the cellular and genetic response to cerebral insult is dysregulated in aged animals, thereby further compromising functional recovery. Elucidating the molecular basis for this phenomenon in the aging brain could yield novel approaches to neurorestoration in the elderly.

Accelerated infarct development, cytogenesis and apoptosis following transient cerebral ischemia in aged rats

Old age is associated with a deficient recovery from stroke, but the cellular mechanisms underlying such phenomena are poorly understood. To address this issue, focal cerebral ischemia was produced by reversible occlusion of the right middle cerebral artery in 3- and 20-month-old male Sprague-Dawley rats. Aged rats showed a delayed and suboptimal functional recovery in the post-stroke period. Using BrdU-labeling, quantitative immunohistochemistry and 3-D reconstruction of confocal images, we found that aged rats are predisposed to rapidly develop an infarct within the first few days after ischemia. The emergence of the necrotic zone is associated with a high rate of cellular degeneration, premature accumulation of proliferating BrdU-positive cells that appear to emanate from capillaries in the infarcted area, and a large number of apoptotic cells. With double labeling techniques, we were able to identify, for the first time, over 60% of BrdU-positive cells either as reactive microglia (45%), oligodendrocyte progenitors (17%), astrocytes (23%), CD8+ lymphocytes (4%), or apoptotic cells (<1%). Paradoxically, despite a robust reactive phenotype of microglia and astrocytes in aged rats, at 1-week post-stroke, the number of proliferating microglia and astrocytes was lower in aged rats than in young rats. Our data indicate that aging is associated with rapid infarct development and a poor prognosis for full recovery from stroke that is correlated with premature cellular proliferation and increased cellular degeneration and apoptosis in the infarcted area.

Oral anticoagulant treatment: risk factors involved in 500 intracranial hemorrhages

Intracranial bleeding is the most severe complication caused by anticoagulant or antiplatelet treatment. The increasing use of this therapy, especially in older people, makes the balance between clinical benefit and bleeding risk an important consideration. A retrospective study of all consecutive 500 intracranial hemorrhages in the West Valladolid area, approximately 220,000 people, during the period 1998 to 2004, was performed. In relation to mortality, predisposing conditions were included, such as age, antithrombotic treatment, arterial hypertension, cancer, blood diseases, vascular malformations, and traumatisms. The incidence of intracranial hemorrhage was 310 per 100,000 per year with a mortality of 30%. Higher mortality was found in antiplatelet-treated patients (44.9%) than in anticoagulated patients (31.1%). This may be related to a different mean age of 78 vs. 71 years. Arterial hypertension was the most frequent risk factor (45.1% in nontreated patients, 60% anticoagulated, and 75.5% antiplatelet). The relative risk of intracranial bleeding in anticoagulated patients was 11.2 (p < 0.001) with an incidence of 0.03% and a median of 14 months since treatment began. The median INR was 3.3. In 40% of the patients the previous five controls were in range. Strict consideration of indications criteria joined to a better control of risk factors may avoid intracranial bleeding episodes.

Stroke prevention and management in older adults

Stroke is the third leading cause of death and a foremost cause of serious, long-term disability in the United States. 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. However, stroke is not an inevitable consequence of aging. By identifying and modifying risk factors in older people, nurses can partner with other providers to reduce the incidence, morbidity, and mortality associated with stroke in older adults. Control of hypertension, resolution of dyslipidemia, management of diabetes mellitus, anticoagulation for atrial fibrillation, promotion of exercise and healthy diet, and cessation of cigarette smoking are of particular importance in older adults. Recognition of stroke symptoms, access to emergency evaluation and treatments, and participation in comprehensive rehabilitation may determine stroke outcomes in aging. This article presents 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.