Chronic ischemia and neurocognition

Effects of carotid artery stenting on cognitive impairment in patients with severe symptomatic carotid artery stenosis

The effect of carotid artery stenting and medication on improvement of cognitive function in patients with severe symptomatic carotid artery stenosis is unknown. To investigate the effect of stenting compared with medication alone for severe carotid atherosclerotic stenosis on cognitive impairment. Patients with carotid stenosis and cognitive impairment were prospectively randomly divided into 2 groups of stenting or medication alone. Cognitive function was evaluated with the Montreal cognitive assessment (MoCA), Mini-Mental State Examination, and Barthel Index of Activities of Daily Living (BI). Continuous data in normal distribution were tested with the t-test but with the Mann-Whitney U test if not in normal distribution. Categorical data were presented as frequency and percentages and tested with the Fisher exact test. A P value < .05 was regarded as statistical significant. Carotid artery stenting was successfully performed in all patients (100%) in the stenting group. Compared with before treatment, the Mini-Mental State Examination, MoCA and BI scores at 6 months in the medication alone group and at 1, 3, and 6 months in the stenting group were significantly (P < .005) improved. The stenting group had significantly (P < .05) better scores than the medication alone group at the same time. At 6-month follow-up, the visuospatial/executive functions (3.69 ± 1.42 vs 2.42 ± 1.23), attention (5.24 ± 1.52 vs 3.63 ± 1.47), and language (2.64 ± 0.71 vs 1.96 ± 0.69) were significantly (P < .05) improved in the stenting group compared with the medication alone group. Carotid artery stenting may significantly improve cognitive impairment and neurological function compared with medication alone in patients with severe carotid atherosclerotic stenosis concurrent with cognitive impairment.

High-Resolution MRI for Evaluation of the Possibility of Successful Recanalization in Symptomatic Chronic ICA Occlusion: A Retrospective Study

BACKGROUND AND PURPOSE

Accurate radiologic evaluation of the possibility of successful recanalization in symptomatic chronic ICA occlusion remains challenging. This study aimed to investigate the high-resolution MR imaging characteristics of symptomatic chronic ICA occlusion and their association with successful recanalization.

MATERIALS AND METHODS

Consecutive patients with symptomatic chronic ICA occlusion who underwent balloon dilation plus stent implantation were identified retrospectively and divided into 2 groups: a successful recanalization group and an unsuccessful recanalization group. Clinical and high-resolution MR imaging characteristics were compared between the groups. Univariate and multivariate analyses were used to identify the characteristics associated with successful recanalization.

RESULTS

A total of 114 patients were included in the study. High-resolution MR imaging characteristics independently associated with unsuccessful recanalization were longer lesion length (OR, 0.41; 95% CI, 0.36-0.55; P = .009) and larger calcification volume (OR, 0.56; 95% CI, 0.37-0.68; P = .002) for proximal occlusion and reversed distal ICA flow at the level of ophthalmic segment or above (OR, 0.14; 95% CI, 0.08-0.48; P = .001). Reversed distal ICA flow at the level of the petrous segment or below (OR, 4.07; 95% CI, 1.65-8.38; P = .001) and lumen area (OR, 1.13; 95% CI, 1.04-1.61; P = .002) for distal occlusion were risk factors of successful recanalization.

CONCLUSIONS

In symptomatic chronic ICA occlusion, lesion length and calcification volume (for proximal occlusion), the level of reversed distal ICA flow, and the lumen area (for distal occlusion) appear to be predictors of successful recanalization. High-resolution MR imaging can evaluate chronic ICA occlusion and help in clinical decision-making.

An Overview on the Differential Interplay Among Neurons-Astrocytes-Microglia in CA1 and CA3 Hippocampus in Hypoxia/Ischemia

Neurons have been long regarded as the basic functional cells of the brain, whereas astrocytes and microglia have been regarded only as elements of support. However, proper intercommunication among neurons-astrocytes-microglia is of fundamental importance for the functional organization of the brain. Perturbation in the regulation of brain energy metabolism not only in neurons but also in astrocytes and microglia may be one of the pathophysiological mechanisms of neurodegeneration, especially in hypoxia/ischemia. Glial activation has long been considered detrimental for survival of neurons, but recently it appears that glial responses to an insult are not equal but vary in different brain areas. In this review, we first take into consideration the modifications of the vascular unit of the glymphatic system and glial metabolism in hypoxic conditions. Using the method of triple-labeling fluorescent immunohistochemistry coupled with confocal microscopy (TIC), we recently studied the interplay among neurons, astrocytes, and microglia in chronic brain hypoperfusion. We evaluated the quantitative and morpho-functional alterations of the neuron-astrocyte-microglia triads comparing the hippocampal CA1 area, more vulnerable to ischemia, to the CA3 area, less vulnerable. In these contiguous and interconnected areas, in the same experimental hypoxic conditions, astrocytes and microglia show differential, finely regulated, region-specific reactivities. In both areas, astrocytes and microglia form triad clusters with apoptotic, degenerating neurons. In the neuron-astrocyte-microglia triads, the cell body of a damaged neuron is infiltrated and bisected by branches of astrocyte that create a microscar around it while a microglial cell phagocytoses the damaged neuron. These coordinated actions are consistent with the scavenging and protective activities of microglia. In hypoxia, the neuron-astrocyte-microglia triads are more numerous in CA3 than in CA1, further indicating their protective effects. These data, taken from contiguous and interconnected hippocampal areas, demonstrate that glial response to the same hypoxic insult is not equal but varies significantly. Understanding the differences of glial reactivity is of great interest to explain the differential susceptibility of hippocampal areas to hypoxia/ischemia. Further studies may evidence the differential reactivity of glia in different brain areas, explaining the higher or lower sensitivity of these areas to different insults and whether glia may represent a target for future therapeutic interventions.

Comprehensive Evaluation of White Matter Damage and Neuron Death and Whole-Transcriptome Analysis of Rats With Chronic Cerebral Hypoperfusion

Background/Aims

Chronic cerebral hypoperfusion (CCH) is induced by chronic deficit of brain perfusion, contributes to a persistent or progressive cognitive dysfunction, which is characterized by diverse neuropathological manifestations. There are currently no effective medications available. White matter damage (WMD) and cortical neuron death may be caused by CCH, which are related to cognitive impairment, while the underlying molecular mechanisms remain unclear. In the study, a database of the transcriptome level was built to determine potential biomarkers in cortex of CCH.

Methods

CCH was induced in male Sprague-Dawley rats by permanent occlusion of the bilateral common carotid arteries. Rats were randomly divided into three groups: Sham-operated group (n = 24), the 4th and 8th week of CCH groups (total = 56, n = 28 for each group). Cognitive function was evaluated using the Morris water maze task. WMD and neuron damage were detected using diffusion tensor imaging and histological analysis, respectively. Western blotting analysis of various markers was used to examine neuronal death. Whole-transcriptome microarray was performed to assess mRNA, circRNA, and lncRNA expression profiles at 4th and 8th weeks after CCH. Diversified bioinformatic tools were performed to analyze and predict the key biological processes and signaling pathways of differentially expressed RNAs and co-expressed potential target genes. Co-expression networks of mRNA–circRNA–miRNA and lncRNA–mRNA were constructed.

Results

Compared to the sham group, cognitive impairment, disintegration of white matter, blood-brain barrier damage and neuron death were induced by CCH. Neuron death including apoptosis and necroptosis might occur in the cortex of CCH. We constructed the regulatory networks of whole-transcriptomic including differentially expressed mRNAs, circRNAs, and lncRNAs, and related biological functions and pathways involved in neurological disease, cell death and survival, energy and metabolism, et al. Our results also indicated that Cyr61 mRNA may play a role in the CCH-related cortical neuronal death.

Conclusion

WMD and cortical neuronal death are worthy of attention in the pathogenesis of CCH. Additionally, the present results provide potential evidence at the whole-transcription level for CCH, offering candidate biomarkers and therapeutic targets.

Is Hemispheric Hypoperfusion a Treatable Cause of Cognitive Impairment?

PURPOSE OF REVIEW

To review the current literature that supports the notion that cerebral hemodynamic compromise from internal carotid artery stenosis may be a cause of vascular cognitive impairment that is amenable to treatment by revascularization.

RECENT FINDINGS

Converging evidence suggests that successful carotid endarterectomy and carotid artery stenting are associated with reversal of cognitive decline in many patients with severe but asymptomatic carotid artery stenosis. Most of these findings have been derived from cohort studies and comparisons with either normal or surgical controls. Failure to find treatment benefit in a number of studies appears to have been the result of patient heterogeneity or confounding from concomitant conditions independently associated with cognitive decline, such as heart failure and other cardiovascular risk factors, or failure to establish pre-procedure hemodynamic failure. Patients with severe carotid artery stenosis causing cerebral hemodynamic impairment may have a reversible cause of cognitive decline. None of the prior studies, however, were done in the context of a randomized clinical trial with large numbers of participants. The ongoing CREST-2 trial comparing revascularization with medical therapy versus medical therapy alone, and its associated CREST-H study determining whether cognitive decline is reversible among those with hemodynamic compromise may address this question.

Hemodynamics and oxygen extraction in chronic large artery steno-occlusive disease: Clinical applications for predicting stroke risk

Depending on the adequacy of collateral sources of blood flow, arterial stenosis or occlusion may lead to reduced perfusion pressure and ultimately reduced blood flow in the distal territory supplied by that vessel. There are two well-defined compensatory mechanisms to reduced pressure or flow - autoregulatory vasodilation and increased oxygen extraction fraction. Other changes, such as metabolic downregulation, are likely. The positive identification of autoregulatory vasodilation and increased oxygen extraction fraction in humans is an established risk factor for future ischemic stroke in some disease states such as atherosclerotic carotid stenosis and occlusion. The mechanisms by which ischemic stroke may occur are not clear, and may include an increased vulnerability to embolic events. The use of hemodynamic assessment to identify patients with occlusive vasculopathy at an increased risk for stroke is very appealing for several different patient populations, such as those with symptomatic intracranial atherosclerotic disease, moyamoya phenomenon, complete internal carotid artery occlusion, and asymptomatic cervical carotid artery stenosis. While there is very good data for stroke risk prediction in some of these groups, no intervention based on these tools has been proven effective yet. In this manuscript, we will review these topics above and identify areas for future research.

Magnetic resonance imaging for assessment of cerebrovascular reactivity and its relationship to cognition: a systematic review

BACKGROUND

Cerebrovascular reactivity (CVR) refers to the responsiveness of cerebral vasculature to vasoactive stimuli. CVR is an indicator of brain health and can be assessed using vasodilatory techniques and magnetic resonance imaging (MRI). Using such approaches, some researchers have explored the relationship between CVR and cognition; here we systematically review this work.

RESULTS

We extracted information pertaining to: (1) study location and design, participant characteristics, sample sizes, (2) design of vascular challenge, end-tidal CO 2 (etCO 2 ) concentrations (if applicable), (3) MRI protocol, (4) cognitive assessment, (5) CVR values, and outcomes of statistical analyses with cognitive tests. Five studies assessed participants with cognitive impairment compared to controls, one studied patients with multiple sclerosis with or without cognitive impairment compared to controls, one examined patients with moyamoya disease with or without cognitive impairment, two investigated patients with Type 2 diabetes mellitus (T2DM), and one was a cross-sectional study with younger and older healthy adults. Cognition was typically probed using the MMSE and tests of executive function, while a number of vasodilatory techniques were employed.

CONCLUSION

CVR was associated with cognition in six of ten studies, but heterogeneity of study samples, designs and vasodilatory methods may have a role in the inconsistent findings. We make recommendations for future research that includes use of a multi-domain cognitive assessment and standardised hypercapnic challenge with MRI.

The neuron-astrocyte-microglia triad in CA3 after chronic cerebral hypoperfusion in the rat: Protective effect of dipyridamole

We investigated the quantitative and morphofunctional alterations of neuron-astrocyte-microglia triads in CA3 hippocampus, in comparison to CA1, after 2 Vessel Occlusion (2VO) and the protective effect of dipyridamole. We evaluated 3 experimental groups: sham-operated rats (sham, n=15), 2VO-operated rats treated with vehicle (2VO-vehicle, n=15), and 2VO-operated rats treated with dipyridamole from day 0 to day 7 (2VO-dipyridamole, n=15), 90days after 2VO. We analyzed Stratum Pyramidalis (SP), Stratum Lucidum (SL) and Stratum Radiatum (SR) of CA3. 1) ectopic neurons increased in SL and SR of 2VO-vehicle, and 2VO-dipyridamole rats; 2) apoptotic neurons increased in SP of 2VO-vehicle rats and dipyridamole reverted this effect; 3) astrocytes increased in SP, SL and SR of 2VO-vehicle and 2VO-dipyridamole rats; 4) TNF-α expression increased in astrocytes, blocked by dipyridamole, and in dendrites in SR of 2VO-vehicle rats; 5) total microglia increased in SL and SR of 2VO-vehicle and 2VO-dipyridamole rats; 6) triads increased in SR of 2VO-vehicle rats and dipyridamole reverted this effect. Microglia cooperated with astrocytes to phagocytosis of apoptotic neurons and debris, and engulfed ectopic non-fragmented neurons in SL of 2VO-vehicle and 2VO-dipyridamole rats, through a new mechanism called phagoptosis. CA3 showed a better adaptive capacity than CA1 to the ischemic insult, possibly due to the different behaviour of astrocytes and microglial cells. Dipyridamole had neuroprotective effects.

Effect of Carotid Artery Stenting on Cognitive Function in Patients with Internal Carotid Artery Stenosis and Cerebral Lacunar Infarction: A 3-Year Follow-Up Study in China

BACKGROUND AND OBJECTIVES

Carotid artery stenting (CAS) is an important therapeutic strategy for patients with carotid artery stenosis. However, the potential influence of CAS on cognitive function in patients with carotid artery stenosis and cerebral lacunar infarction has not been determined. This study investigated changes in cognitive function associated with CAS and the factors related to these changes.

METHODS

This prospective cohort study comprised 579 Chinese patients with cerebral lacunar infarction and carotid artery stenosis for whom CAS was indicated, and a matched control group of 552 healthy individuals. Cognitive function before CAS and at scheduled intervals from 6 months to 3 years was assessed with instruments that included the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) scale. Potential factors that might affect cognitive function were analyzed via logistic regression.

RESULTS

The MMSE and MoCA scores of the patients before CAS were significantly lower than that of the control subjects. These scores were significantly higher 6 months after CAS and sustained or increased throughout the 3-year follow-up. Also significantly improved after CAS from baseline were scores for an alternating trail test, cube copying, clock-drawing, attention, and delayed recall in an auditory-verbal learning test. Logistic regression analyses showed that age greater than 65 y, little education, diabetes, and hypertension were independent risk factors for deteriorated MoCA scores 3 years after CAS.

CONCLUSION

CAS was associated with significantly improved cognitive function in cerebral lacunar infarction patients with severe stenosis.

The neuron-astrocyte-microglia triad in a rat model of chronic cerebral hypoperfusion: protective effect of dipyridamole

Chronic cerebral hypoperfusion during aging may cause progressive neurodegeneration as ischemic conditions persist. Proper functioning of the interplay between neurons and glia is fundamental for the functional organization of the brain. The aim of our research was to study the pathophysiological mechanisms, and particularly the derangement of the interplay between neurons and astrocytes-microglia with the formation of "triads," in a model of chronic cerebral hypoperfusion induced by the two-vessel occlusion (2VO) in adult Wistar rats (n = 15). The protective effect of dipyridamole given during the early phases after 2VO (4 mg/kg/day i.v., the first 7 days after 2VO) was verified (n = 15). Sham-operated rats (n = 15) were used as controls. Immunofluorescent triple staining of neurons (NeuN), astrocytes (GFAP), and microglia (IBA1) was performed 90 days after 2VO. We found significantly higher amount of "ectopic" neurons, neuronal debris and apoptotic neurons in CA1 Str. Radiatum and Str. Pyramidale of 2VO rats. In CA1 Str. Radiatum of 2VO rats the amount of astrocytes (cells/mm(2)) did not increase. In some instances several astrocytes surrounded ectopic neurons and formed a "micro scar" around them. Astrocyte branches could infiltrate the cell body of ectopic neurons, and, together with activated microglia cells formed the "triads." In the triad, significantly more numerous in CA1 Str. Radiatum of 2VO than in sham rats, astrocytes and microglia cooperated in the phagocytosis of ectopic neurons. These events might be common mechanisms underlying many neurodegenerative processes. The frequency to which they appear might depend upon, or might be the cause of, the burden and severity of neurodegeneration. Dypiridamole significantly reverted all the above described events. The protective effect of chronic administration of dipyridamole might be a consequence of its vasodilatory, antioxidant and anti-inflammatory role during the early phases after 2VO.

Influence of carotid artery stenting on cognition of elderly patients with severe stenosis of the internal carotid artery

Background

The aim of this study was to investigate the influence of carotid artery stenting (CAS) on the cognition and quality of life of elderly patients with severe stenosis of the internal carotid artery.

Material/Methods

65 elderly patients with symptomatic severe stenosis of internal carotid artery were recruited into 2 groups: the pharmacotherapy group (n=29) and the CAS group (n=36). Before surgery and 1, 3, 6, and 12 months after surgery, Montreal cognitive assessment (MoCA) was used for the evaluation of cognition and WHOQOL-BREF was used for the assessment of quality of life.

Results

At 12 months after surgery, total MoCA score and WHOQOL-BREF score in the pharmacotherapy group was significantly reduced when compared with those before surgery (P<0.05). In the CAS group, the total MoCA score, scores of attention and delayed recall, and WHOQOL-BREF score increased significantly at different time points after surgery when compared with those before surgery (P<0.05). Moreover, in CAS group, the MoCA score and WHOQOL-BREF markedly increased gradually over time (P<0.05). Compared with the pharmacotherapy group, cognition and quality of life in the CAS group were improved dramatically during the follow-up period (P<0.05).

Conclusions

Severe stenosis of the internal carotid artery is a cause of cognition impairment, and CAS may improve cognition and quality of life.

Comparison of cognitive performance between two rat models of vascular dementia

BACKGROUND AND PURPOSE

An ideal animal model to explore that pathogenesis and prevention of dementia is essential. The present study was designed to compare the difference of behavior and cerebral blood flow of the two vascular dementia rat models at different time intervals.

METHODS

The rats were randomly allocated to three groups: bilateral common carotid artery occlusion (BCCAO) group, thromboembolism (TE) group and sham-operated (SHAM) group. The performance in the Morris water maze (MWM) was analyzed at 7, 14 and 28 d after operation and cerebral blood flow (CBF) was analyzed at 28 days after operation.

RESULT

The results showed that the two models exhibited longer latency, less times to crossing platform in MWM and lower CBF than the SHAM rats. Compared with the TE rats, the BCCAO rats have a significant prolongation of escape latency at 7 days and 28 days. In the probe trial, the BCCAO rats showed less number of times across the platform.

CONCLUSION

The BCCAO rats maybe provide a more useful model to study the physiopathological mechanisms of cognitive impairment related to chronic cerebral ischemia.

ADC mapping of chronic cerebral hypoperfusion induced by carotid artery stenosis

BACKGROUND

Carotid artery stenosis is associated with the occurrence of acute and chronic ischemic lesions that increase with age in the elderly population. Diffusion Imaging and ADC mapping may be an appropriate method to investigate patients with chronic hypoperfusion consecutive to carotid stenosis. This non-invasive technique allows to investigate brain integrity and structure, in particular hypoperfusion induced by carotid stenosis diseases. The aim of this study was to evaluate the impact of a carotid stenosis on the parenchyma using ADC mapping.

METHODS

Fifty-nine patients with symptomatic (33) and asymptomatic (26) carotid stenosis were recruited from our multidisciplinary consultation. Both groups demonstrated a similar degree of stenosis. All patients underwent MRI of the brain including diffusion-weighted MR imaging with ADC mapping. Regions of interest were defined in the anterior and posterior paraventricular regions both ipsilateral and contralateral to the stenosis (anterior circulation). The same analysis was performed for the thalamic and occipital regions (posterior circulation).

RESULTS

ADC values of the affected vascular territory were significantly higher on the side of the stenosis in the periventricular anterior (P<0.001) and posterior (P<0.01) area. There was no difference between ipsilateral and contralateral ADC values in the thalamic and occipital regions.

CONCLUSIONS

We have shown that carotid stenosis is associated with significantly higher ADC values in the anterior circulation, probably reflecting an impact of chronic hypoperfusion on the brain parenchyma in symptomatic and asymptomatic patients. This is consistent with previous data in the literature.

Does extracranial arterial pathology play a role in late-onset psychiatric disorders?

INTRODUCTION

Carotid interventions are commonly performed to reduce the risk of disabling stroke and stroke-related death. Carotid interventions may also have an effect on cognitive functions. Mental disorders in the elderly have been related to structural brain pathology. This review of literature was performed to test the hypothesis that atherosclerotic lesions in the carotid and vertebral arteries may have an impact on the development and treatment of late-onset psychiatric disorders.

METHODS

A literature search identified articles focusing on the key issues using the Pubmed and Cochrane databases.

RESULTS

Cardiovascular risk factors seem to be increased in patients with late-onset mania, depression, and schizophrenia. Cerebral infarctions, especially right-sided, have repeatedly been associated with various psychiatric disorders. Several case reports suggest that chronic cerebral hypoperfusion may also induce psychiatric disease and that these disorders might disappear after reconstruction.

CONCLUSIONS

There seems to be an association between occlusive carotid and vertebral disease and the late-onset of various psychiatric disorders. Both thromboembolic and chronic cerebral hypoperfusion might contribute to its pathophysiology. This group of patients might benefit from an intervention.

Carotid artery ultrasound and echocardiography testing to lower the prevalence of Alzheimer's disease

The use of two clinic office techniques, carotid artery ultrasound and echocardiography (CAUSE), to detect deficient brain blood flow delivery in the healthy, cognitively normal, older individual is proposed. Evidence indicates that persistent heart-to-brain blood flow deficit involving low cardiac output or low ejection fraction and carotid artery narrowing can promote cognitive impairment and that such impairment may lead to Alzheimer's disease (AD) or vascular dementia (VaD). A number of independent epidemiologic studies reported cardiovascular and cerebrovascular disease to be risk factors to AD and VaD. The clinical rationale for CAUSE is to detect and prevent progression of cognitive dysfunction in elderly persons and is based on the general understanding that mild cognitive impairment is a preclinical threshold to AD or VaD with high conversion rates to either dementia. The use of CAUSE is anticipated to prevent or attenuate, by appropriate clinical management, mild cognitive impairment arising from persistent brain hypoperfusion, a condition implicated in the promotion of cognitive impairment in the elderly and a common preclinical feature seen in AD and VaD. As detection of lowered cerebral perfusion from cardiac and carotid artery pathology is achieved using these cost-effective, noninvasive, and relatively accurate ultrasound procedures, a significant reduction in the number of new AD and VaD cases would be anticipated after appropriate patient treatment. In this context, a brief summary is presented outlining recent medical and surgical treatments that may improve cerebral blood flow insufficiency. The merit of CAUSE in screening and treating mentally healthy elderly persons who are identified as being at risk of cognitive decline is that it could blunt the soaring socioeconomic impact that will hammer the health care system of many nations by the mounting dementia prevalence rate expected in the next 25 years. A 5- year delay in the onset of AD could reduce the prevalence of AD by 50%. We are making preparations to test the merit of CAUSE in a clinical study of a cognitively healthy elderly population.

Current Concepts in Vascular Cognitive Impairment and Pharmacotherapeutic Implications

Objective:

To review evolution of the vascular cognitive impairment (VCI) construct, including diagnosis, pharmacotherapeutic implications, and address challenges that will shape future developments.

Data Sources:

Literature retrieval was accessed through PubMed, from 1966 to December 2008, using the terms vascular cognitive impairment, vascular dementia, post-stroke dementia, vascular cognitive disorder, mild cognitive impairment, criteria, disease progression, outcomes, treatment, prevention, biomarkers, and neuroimaging.

Study Selection and Data Extraction:

All articles in published English identified from the data sources were evaluated for inclusion. Regarding pharmacotherapy, prospective double-blind, placebo-controlled studies were included as well as extensions or relevant post hoc analyses.

Data Synthesis:

In the 1970s, “senile dementia due to hardening of the arteries” was used to describe dementia due to vascular causes. This was a narrow view of what is now known to be a common form of cognitive impairment in older people. Multiple infarct dementia (MID) was first proposed to describe dementia attributable to multiple cerebral infarcts, followed by the vascular dementia (VaD) construct, itself meant to be an improvement over MID. The VaD construct had limitations, not the least of which was that, by the time a patient was diagnosed with VaD, the opportunity for prevention was lost. Thus arose the concept of VCI, representing a group of heterogeneous disorders that share presumed vascular causes. The importance of VCI is centered on the fact that vascular risk factors are treatable, and thus should lead to a reduction in the incidence of cognitive impairment due to vascular causes. There is evidence that treatment of hypertension can lead to a reduction in the incidence of cognitive impairment and dementia, and that treatment of VaD with acetylcholinesterase inhibitors may be beneficial.

Conclusions:

Careful attention needs to be given to controlling vascular risk factors in at-risk patients. Pharmacists should play an active role in this important area of geriatric pharmacotherapy.

The evolution of cerebral revascularization surgery

Among the relatively few surgeons to be awarded the Nobel Prize was Alexis Carrel, a French surgeon and pioneer in revascularization surgery at the turn of the 20th century. The authors trace the humble beginnings of cerebral revascularization surgery through to the major developments that helped shape the modern practice of cerebral bypass surgery. They discuss the cornerstone studies in the development of this technique, including the Extracranial/Intracranial Bypass Study initiated in 1977. Recent innovations, including modern techniques to monitor cerebral blood flow, microanastomosis techniques, and ongoing trials that play an important role in the evolution of this field are also evaluated.

Upregulation of BACE1 and beta-amyloid protein mediated by chronic cerebral hypoperfusion contributes to cognitive impairment and pathogenesis of Alzheimer's disease

Chronic cerebral hypoperfusion (CCH) increases the risk of Alzheimer disease (AD) through several biologically plausible pathways, but the relationship between CCH and the development of AD remains uncertain. To investigate expression of APP, BACE1 and A beta in the hippocampus of BCCAO rats and study pathophysiological mechanism of AD from CCH. CCH rat model was established by chronic bilateral common carotid artery occlusion (BCCAO). Behavior was evaluated after BCCAO with Morris water maze and open-field task. Expression of A beta was measured by enzyme linked immunosorbent assay (ELISA). beta-Amyloid precursor protein cleavage enzyme 1 (BACE1) and beta-amyloid precursor protein (APP) were tested by ELISA, Western blotting and RT-PCR. Cognitive impairment occurred with CCH by Morris water maze test and open-field task. The BACE1 and A beta level in BCCAO rats was more increased than sham-operation control rats (P < 0.01) but APP had no difference(P > 0.05). The expression of BACE1 and A beta has no inter-group difference in BCCAO rats (P > 0.05). The level of BACE1 and A beta had positive correlation with cognitive impairment (P < 0.01) while no correlation was observed between APP and cognitive impairment. Chronic cerebral ischemia contributes to cognitive impairment and vascular pathogenesis of Alzheimer's disease that chronic cerebral hypoperfusion increases BACE1 and A beta level in brain.