Relationships of cerebral MRI findings to ultrasonographic carotid atherosclerosis in older adults : the Cardiovascular Health Study. CHS Collaborative Research Group

Silent brain infarcts: a systematic review

As the availability and quality of imaging techniques improve, doctors are identifying more patients with no history of transient ischaemic attack or stroke in whom imaging shows brain infarcts. Until recently, little was known about the relevance of these lesions. In this systematic review, we give an overview of the frequency, causes, and consequences of MRI-defined silent brain infarcts, which are detected in 20% of healthy elderly people and up to 50% of patients in selected series. Most infarcts are lacunes, of which hypertensive small-vessel disease is thought to be the main cause. Although silent infarcts, by definition, lack clinically overt stroke-like symptoms, they are associated with subtle deficits in physical and cognitive function that commonly go unnoticed. Moreover, the presence of silent infarcts more than doubles the risk of subsequent stroke and dementia. Future studies will have to show whether screening and treating high-risk patients can effectively reduce the risk of further infarcts, stroke, and dementia.

Cognition and dementia in Type 2 diabetes: brain imaging correlates and metabolic and vascular risk factors

This review addresses the impact of Type 2 diabetes mellitus on the brain. We show that there is convincing evidence that Type 2 diabetes mellitus is associated with accelerated cognitive decline and dementia. The structural basis for these cognitive deficits includes both vascular lesions and global cerebral atrophy. Cerebral changes may already develop in prediabetes mellitus stages. Several areas of uncertainty need to be resolved in order to develop effective preventive strategies. Information on the risk factors for accelerated cognitive decline in patients with Type 2 diabetes mellitus is still scarce. Identification of these factors might help to identify individuals who are at risk for clinically relevant impairments and to develop specific interventions. Further studies on the course of development of cognitive decline in Type 2 diabetes mellitus may help to decide at what stage these interventions should be initiated.

Dementia epidemiology research: it is time to modify the focus of research

The incidence and prevalence of dementia are increasing. There is an urgent need to develop a preventive strategy. The identification of modifiable risk factors must therefore be a high priority. Newer imaging techniques provide an opportunity to identify subclinical manifestations of "dementias" that can be limited to the risk factors and subsequent clinical disease. The contribution of vascular disease to dementia and Alzheimer's disease (AD) should be a high priority as it offers a potential preventive strategy. Study designs need to be modified, including a greater emphasis on geographic variations in AD and dementia based on imaging studies, longitudinal studies of successful aging without cardiovascular disease (CVD) or AD, gene-environment interactions, and studies of unique populations that may be at lower risk because of specific lifestyles. Primary prevention trials for vascular disease should include a dementia component. Most, if not all, studies should include newer imaging studies.

Increased Intima Media Thickness and Atherosclerotic Plaques in the Carotid Artery as Risk Factors for Silent Brain Infarcts

The presence of silent cerebral infarcts (SCIs), defined as lesions > or = 3 mm in diameter on magnetic resonance imaging (MRI), is considered a predictor of symptomatic cerebrovascular disorders (CVDs). Similarly, SCI-like lesions < 3 mm in diameter, lesions which often occur in the deep white matter and basal ganglia, also may be a risk factor for CVD. This study evaluated the relationships between SCI and SCI-like brain lesions, as defined by MRI, and 2 findings on extracranial carotid ultrasonography: intima-media thickness (IMT) and atherosclerotic plaque. We studied data obtained by carotid ultrasonography and cerebral MRI in 448 consecutive subjects without a history of stroke who had undergone comprehensive brain screening (mean age, 51.1 years). The subjects were classified into 4 groups according to the presence of increased (> or = 1 mm) IMT (I) and plaque (P). A total of 110 subjects demonstrated increased IMT (24.6%), and 54 subjects had increased plaque (12.1%). SCI-like lesions were found in 38 subjects (8.5%); single SCI, in 24 (5.4%); and multiple SCIs, in 51 (11.4%). Frequencies of SCI-like lesion(s), single SCI, and multiple SCIs were 6.1%, 12.2%, and 8.7%, respectively, in the I(-)P(-) group; 14.6%, 22.0%, and 13.4% in the I(+)P(-) group; 7.7%, 30.8%, and 26.9% in the I(-)P(+) group; and 17.9%, 39.3%, and 21.4% in the I(+)P(+) group. Multivariate analysis found that the presence of carotid plaques was significantly associated with (1) SCI-like lesion(s) and SCI (odds ratio [OR] = 2.20; 95% confidence interval [CI] = 1.17-4.34), (2) single and multiple SCI (OR = 2.33; 95% CI = 1.16-4.67), and (3) multiple SCIs (OR = 2.31; 95% CI = 1.06-5.03). However, the presence of increased carotid IMT was not significantly associated with any of these 3 categories. Coexistence of increased IMT and plaque was more strongly correlated with SCI than with either lesion alone.

Carotid atherosclerosis is associated with brain atrophy in Japanese elders

BACKGROUND

The relation between atherosclerosis and brain atrophy remains unclear in patients with risk factors for cardiovascular diseases.

OBJECTIVE

This study was performed to clarify the relation between brain atrophy and carotid atherosclerosis.

METHODS

A total of 142 patients (78 women and 64 men, mean age 74 years) with no neurologic disturbances were studied. Brain atrophy was evaluated on the basis of the brain atrophy index (BAI, BAI = brain parenchyma/intracranial space A 100%), calculated by means of digitized computed tomographic scans obtained at the level of the basal ganglia. Carotid atherosclerosis was evaluated on the basis of the plaque score (PS), defined as the sum of all plaque heights in both carotid arteries, intima-media thickness (IMT), and vessel diameter (VD) of the common carotid artery as assessed by ultrasonography.

RESULTS

Age negatively correlated with BAI in both men (r = -0.587, p < 0.001) and women (r = -0.724, p < 0.001). PS of the carotid artery also negatively correlated with BAI in men (r = -0.502, p < 0.001) as well as women (r = -0.480, p < 0.001). VD and IMT of the right carotid artery negatively correlated with BAI in women (VD; -0.256, p < 0.05, IMT; -0.216, p < 0.05) but not in men. Other characteristics were unrelated to BAI. Multiple regression analysis showed that age and PS were independent predictors of brain atrophy in both sexes. The percentage of variance of BAI values explained by this model in women (51.9%) was much greater than that in men (35.5%).

CONCLUSION

Carotid atherosclerosis may be a useful morphological index of brain atrophy.

Apolipoprotein E polymorphisms predict low density lipoprotein cholesterol levels and carotid artery wall thickness but not incident coronary heart disease in 12,491 ARIC study participants

Elevated levels of low density lipoprotein (LDL) cholesterol is a well-established risk factor for cardiovascular disease, and recent advancements have provided evidence that carotid artery intima-media thickness (IMT) is associated with increased occurrence of cardiovascular events. Apolipoprotein E (ApoE) has been widely studied in regard to its role in lipid transport and metabolism, but the role that ApoE genetic variation plays in relation to carotid artery IMT and risk of incident coronary heart disease remains a subject of debate. In 1987-2001, the authors examined the effect of each ApoE allele (epsilon2, epsilon3, epsilon4) on LDL cholesterol and carotid IMT, as well as the association with coronary heart disease risk, in 12,491 participants of the US Atherosclerosis Risk in Communities Study. ApoE epsilon2, epsilon3, and epsilon4 allele frequencies were determined, respectively, in Whites (0.08, 0.77, 0.15) and African Americans (0.11, 0.67, 0.22). These alleles did not predict incident coronary heart disease in either racial group. The ApoE epsilon2 allele was associated with lower LDL cholesterol and the epsilon4 allele with higher LDL cholesterol in both Whites and African Americans. The ApoE epsilon2 and epsilon4 alleles were associated with carotid IMT measures in both racial groups, but, after adjusting for lipid parameters, only the epsilon4 allele was associated with carotid IMT measures in African Americans.

Progression of white matter lesions and hemorrhages in cerebral amyloid angiopathy

OBJECTIVE

To determine the rate of progression of white matter lesions and hemorrhages in a cohort with cerebral amyloid angiopathy (CAA).

METHODS

The authors analyzed data from 26 patients with possible (3) or probable (23) CAA, diagnosed by the Boston Criteria. Brain maps of white matter hyperintensities, normalized to head size (nWMH), were created by blinded computer-assisted segmentation of MRI images obtained at baseline and after a median follow-up interval of 1.1 year.

RESULTS

There was a substantial nWMH volume increase over the interscan interval (median 0.5 mL/year, interquartile range 0.1 to 2.8, p < 0.001). The median yearly increase, expressed as a percentage of the baseline WMH volume, was 18%. The characteristic most strongly associated with nWMH volume increase was the baseline nWMH volume (r = 0.57, p = 0.002). The volume of nWMH progression was also associated with history of cognitive impairment (median 5.0 mL/year in cognitively impaired subjects vs 0.3 mL/year in cognitively unimpaired, p = 0.02) but not age or hypertension. This association remained present in an analysis stratified by baseline WMH volume. New hemorrhages, including asymptomatic microbleeds, were seen in 46% of subjects. The number of new MRI hemorrhages correlated strongly with baseline nWMH (r = 0.53, p = 0.005) but not with nWMH progression (r = 0.22, p = 0.28).

CONCLUSIONS

There is a progressive increase in white matter lesions in subjects with cerebral amyloid angiopathy. The association of white matter lesions with incident lobar hemorrhages suggests that white matter damage may reflect a progressive microangiopathy due to cerebral amyloid angiopathy.

White matter grade and ventricular volume on brain MRI as markers of longevity in the cardiovascular health study

High white matter grade (WMG) on magnetic resonance imaging (MRI) is a risk factor for dementia, stroke and disability. Higher ventricular size is a marker of brain "atrophy." In the Cardiovascular Health Study (CHS) (n=3245) mean age 75 years, 50% black and 40% men, we evaluated WM and ventricular grade (VG), total, cardiovascular and noncardiovascular mortality and longevity before and after adjusting for numerous determinants of longevity over an approximate 10-12 years of follow-up. A low WMG and VG was a marker for low total, cardiovascular and noncardiovascular mortality and for increased longevity over 10+ years of follow-up. We estimated that a 75-year-old with WMG below median would have about a 5-6 years greater longevity and for VG about 3 years, than above the median even after adjustment for numerous risk factors. Low WMG and VG on MRI is a powerful determinant of long-term survival among older individuals.

Cerebral White Matter Hyperintensities on MRI: Current Concepts and Therapeutic Implications

BACKGROUND

White matter hyperintensities (WMH) are commonly observed MRI abnormalities in the elderly, which generally reflect covert vascular brain injury. WMH cumulatively produce substantial neurologic, psychiatric, and medical morbidity. This review provides an overview of current knowledge on vascular WMH, and describes some pharmacological agents that may have a role in mitigating this condition.

SUMMARY OF REVIEW

This review has two main focus areas. The first is a discussion of currently available knowledge regarding the public health burden, pathogenesis, and various risk factors associated with the presence of vascular white matter lesions noted on brain MRI. The second section of the article details the mechanistic and clinical basis for promising pharmacological treatment modalities that could potentially prevent progression of ischemic cerebral white matter brain injury. Many of these therapies are already of proven efficacy in preventing recurrent stroke.

CONCLUSIONS

Individuals with vascular white matter lesions on MRI may represent a potential target population likely to benefit from secondary stroke prevention therapies.

Multifractal analysis of deep white matter microstructural changes on MRI in relation to early-stage atherosclerosis

Multifractal analysis based on generalized concepts of fractals has been applied to evaluate biological tissues composed of complex structures. This type of analysis can provide a precise quantitative description of a broad range of heterogeneous phenomena. Previously, we applied multifractal analysis to describe heterogeneity in white matter signal fluctuation on T2-weighted MR images as a new method of texture analysis and established Deltaalpha as the most suitable index for evaluating white matter structural complexity (Takahashi et al. J. Neurol. Sci., 2004; 225: 33-37). Considerable evidence suggests that pathophysiological processes occurring in deep white matter regions may be partly responsible for cognitive deterioration and dementia in elderly subjects. We carried out a multifractal analysis in a group of 36 healthy elderly subjects who showed no evidence of atherosclerotic risk factors to examine the microstructural changes of the deep white matter on T2-weighted MR images. We also performed conventional texture analysis, i.e., determined the standard deviation of signal intensity divided by mean signal intensity (SD/MSI) for comparison with multifractal analysis. Next, we examined the association between the findings of these two types of texture analysis and the ultrasonographically measured intima-media thickness (IMT) of the carotid arteries, a reliable indicator of early carotid atherosclerosis. The severity of carotid IMT was positively associated with Deltaalpha in the deep white matter region. In addition, this association remained significant after excluding 12 subjects with visually detectable deep white matter hyperintensities on MR images. However, there was no significant association between the severity of carotid IMT and SD/MSI. These results indicate the potential usefulness of applying multifractal analysis to conventional MR images as a new approach to detect the microstructural changes of apparently normal white matter during the early stages of atherosclerosis.

Blood pressure variability and white matter hyperintensities in older adults with cardiovascular disease

The present study examined the relationship between multiple blood pressure (BP) indices and white matter hyperintensities (WMH) in a sample of 39 older adults with cardiovascular disease (CVD). Resting BP was measured using an automated monitor every 10 min for 2 h. WMH were quantified on FLAIR images and separate indices were generated for neocortical, periventricular and subcortical brain regions. Correlation analyses revealed systolic BP variability was related to neocortical and total WMH. A function of systolic BP variability and average diastolic pressure showed the strongest relationships, including significant correlation to neocortical, subcortical and total WMH. No BP index was related to WMH in periventricular regions. Exploratory analyses showed only the function of systolic BP variability and average diastolic pressure predicted total WMH, whereas as age, CVD conditions and psychosocial factors did not. These findings demonstrate BP variability is an important contributor to WMH in older adults with CVD and suggests it may have differential relationships to WMH in different brain regions. Additional studies are needed to examine the role of autoregulatory systems in the development of WMH, particularly those using beat-to-beat measures of BP.

Association between carotid hemodynamics and asymptomatic white and gray matter lesions in patients with essential hypertension

The aim of this study was to clarify the magnitude of common carotid artery (CCA) structural and hemodynamic parameters on brain white and gray matter lesions in patients with essential hypertension (EHT). The study subjects were 49 EHT patients without a history of previous myocardial infarction, atrial fibrillation, diabetes mellitus, impaired glucose tolerance, chronic renal failure, symptomatic cerebrovascular events, or asymptomatic carotid artery stenosis. All patients underwent brain MRI and ultrasound imaging of the CCA. MRI findings were evaluated by periventricular hyperintensity (PVH), deep and subcortical white matter hyperintensity (DSWMH), and état criblé according to the Japanese Brain dock Guidelines of 2003. Intima media thickness (IMT), and mean diastolic (Vd) and systolic (Vs) velocities were evaluated by carotid ultrasound. The Vd/Vs ratio was further calculated as a relative diastolic flow velocity. The mean IMT and max IMT were positively associated with PVH, DSWMH, and état criblé (mean IMT: rho=0.473, 0.465, 0.494, p=0.0007, 0.0014, 0.0008, respectively; max IMT: rho=0.558, 0.443, 0.514, p=0.0001, 0.0024, 0.0004, respectively). Vd/Vs was negatively associated with état criblé (rho=-0.418, p=0.0038). Carotid structure and hemodynamics are potentially related to asymptomatic lesions in the cerebrum, and might be predictors of future cerebral vascular events in patients with EHT.

Age-related microvascular degeneration in the human cerebral periventricular white matter

Clinical studies have identified white matter (WM) lesions as hyperintensive regions in the MRI images of elderly patients. Since a cerebrovascular origin was attributed to such lesions, the present analysis set out to define the microvascular histopathologic changes in the periventricular WM in the aged. Post-mortem samples of the frontal, parietal, and occipital periventricular WM of 40-90-year-old subjects were prepared for quantitative light and electron microscopy. Light microscopic examination revealed microvascular fibrohyalinosis as the most common type of microvascular damage in the elderly. Ultrastructural analysis identified the microvascular thickening as collagen deposits affecting the basement membrane. The vascular density did not correlate with the age. The basement membrane pathology significantly increased, while the number of intact microvessels gradually decreased, with advancing age in the frontal and occipital WM. Finally, peripheral atherosclerosis coincided with massive microvascular fibrosis, particularly in the frontal WM. Our results demonstrate an age-related microvascular degeneration in the periventricular WM, which may contribute to the development of WM lesions by hindering a sufficient supply of nutrients to the affected WM sites. Furthermore, the data accord with previous observations identifying the frontal lobe as the site at which WM vulnerability is most pronounced. Finally, atherosclerosis in large, peripheral vessels is considered to be a predictive marker of microvascular pathology in the WM.

Cerebral MRI findings and cognitive functioning: the Atherosclerosis Risk in Communities study

OBJECTIVE

To examine the association between prevalent cerebral abnormalities identified on MRI and cognitive functioning in a predominantly middle-aged, population-based study cohort.

METHODS

Cerebral MRI was performed on 1,538 individuals (aged 55 to 72) from the Atherosclerosis Risk in Communities (ARIC) cohort, with no history of stroke or TIA, at study sites in Forsyth County, NC, and Jackson, MS. White matter hyperintensities (WMHs), ventricular size, and sulcal size were graded by trained neuroradiologists on a semiquantitative, 10-point scale. Cognitive functioning was assessed using the Delayed Word Recall Test (DWRT), Digit Symbol Substitution Test (DSST), and Word Fluency Test (WFT).

RESULTS

High ventricular grade was independently associated with significantly lower scores on the DWRT and DSST and greater risk (odds ratio [OR] 2.32, 95% confidence interval [CI] 1.51 to 3.56) of impaired scores (i.e., < or =10th percentile) on the DWRT. High sulcal grade was associated with a modest decrement in scores on the DWRT. The presence of coexisting high grade WMHs and silent infarcts was independently associated with lower scores on all cognitive tests and greater risk of impaired functioning on the DSST (OR 2.91, 95% CI: 1.23 to 6.89) and WFT (OR 2.28, 95% CI 1.03 to 5.08). The presence of two or more high-grade abnormalities was associated with increased risk of impaired functioning on all cognitive tests (DWRT: OR 2.23, 95% CI 1.40 to 3.55; DSST: OR 2.06, 95% CI 1.13 to 3.76; WFT: OR 2.07, 95% CI 1.23 to 3.49) independent of multiple covariates and silent infarcts.

CONCLUSION

Common changes in brain morphology are associated with diminished cognitive functioning in middle-aged and young-elderly individuals.

Determinants of vascular dementia in the Cardiovascular Health Cognition Study

OBJECTIVE

The authors evaluated 3,375 participants without dementia at the time of MRI in 1991 to 1994 over 5.7 years for incident dementia and type of dementia.

METHODS

Incidence of and risk factors for vascular dementia (VaD) were measured using both pre-MRI and modified State of California Alzheimer's Disease Diagnostic and Treatment Centers (ADDTC) post-MRI review and further classified Alzheimer disease (AD) by the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) criteria.

RESULTS

Approximately 44% (213) of 480 incident dementia cases were classified as possible or probable VaD by ADDTC. The incidence of VaD increased with age and was greater in blacks than whites. Risk factors for VaD included age, Modified Mini-Mental State Examination, high white matter grade, number of MRI infarcts, ventricular size, and history of stroke.

CONCLUSIONS

Vascular disease in the brain is prevalent among incident dementia cases. There is a substantial overlap between cases classified as Alzheimer disease by Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association and vascular dementia (VaD) by modified State of California Alzheimer's Disease Diagnostic and Treatment Centers criteria. The substantial contribution of vascular disease would be missed without inclusion of MRI. Treatment of risk factors for VaD could have an important impact on incidence of dementia.

Screening for cancer: are resources being used wisely?

Cancer screening is commonly offered in order to detect tumors at an early, treatable stage. These efforts are highly advocated and widely accepted by the general public. However, there is conflicting evidence about the benefits of screening for breast cancer in pre-menopausal women, prostate cancer in older men, and colorectal cancer for both sexes. This paper examines cancer screening in relation to a disease reservoir hypothesis. There is a reservoir of undetected disease that can be found with more aggressive screening. However, much of the disease that is detected may be classified as pseudodisease because it will have no effect of life expectancy or health-related quality of life. Pseudodisease is defined as detectable disease that will never be clinically significant. A second concern about screening is that randomized clinical trials often show benefits of cancer screening for disease-specific endpoints but no benefit for total mortality. Further, screening for some cancers may significantly increase healthcare costs without enhancing population health status. Improvements in biomarkers and in screening methodologies will significantly increase the number of cancers detected. Future research is necessary in order to determine which population-based screening programs are the best use of public health resources.

Carotid intima-media thickness in late-onset major depressive disorder

BACKGROUND

This study explored whether patients with late-onset major depressive disorder showed higher carotid artery intima-medium thickness (IMT) and investigated the relationship between the IMT and white matter hyperintensities on magnetic resonance imaging (MRI) among patients.

METHODS

Fourteen elderly patients with late-onset major depressive disorder from a psychiatric outpatient clinic and 11 non-depressed controls received a comprehensive psychiatric assessment, ultrasound IMT measurements of the carotid arteries, and cerebral MRI.

RESULTS

The carotid IMT was higher in the patient group vs the control group (1.26 +/- 0.30 vs 1.00 +/- 0.20 mm; t = 2.40, p < 0.03). The difference was more apparent in the common carotid artery (1.20 +/- 0.32 vs 0.97 +/- 0.13 mm; t = 2.31, p < 0.04). There was a high correlation (r = 0.55, p < 0.05) between the carotid IMT and white matter hyperintensities among patients with late-onset major depressive disorder.

CONCLUSION

Results of this study suggest that atherosclerosis represented by the carotid IMT contributes to the development of late-onset major depressive disorder. The findings support the vascular depression hypothesis.

Cerebral white matter hyperintense lesions are associated with unstable carotid plaques

OBJECTIVES

The aim of this study was to determine whether unstable carotid plaques, a known risk factor for cerebral emboli, are associated with cerebral white matter lesions.

METHODS

Seventy-one symptomatic patients undergoing magnetic resonance imaging prior to carotid endarterectomy for high grade carotid stenosis were included in this study. The number and volume of white matter hyperintense lesions (WMHL) on fluid attenuated inversion recovery brain scans were compared according to the morphology of carotid plaque based upon the American Heart Association (AHA) histological classification.

RESULTS

Of the 57 patients who had good quality brain scans and non-fragmented carotid plaques, 15 plaques were defined as stable (type V) and 42 as unstable (type VI). After adjustment for the major risk factors affecting WMHL, unstable carotid plaques were found to be associated with more WMHL in the ipsilateral cerebral hemisphere than stable plaques (transformed means 2.50+/-1.2 vs. 1.53+/-1.1, p=0.016), however, there was only a trend towards larger WMHL volumes (p=0.079).

CONCLUSIONS

The observed association between unstable carotid plaques and the number of white matter lesions suggest that thromboembolic plaque activity may contribute to the development of leukoaraiosis, in particular smaller individual lesions. Larger studies are warranted to confirm this finding and explore the potential clinical impact for selecting candidates for carotid endarterectomy.

Clinical Research in Primary Stroke Prevention: Needs, Opportunities, and Challenges

Most ( approximately 70%) of strokes are first-ever strokes, and hence to substantially reduce the neurological burden, primary prevention is crucial. Here, highlights of the National Institute of Neurological Disorders and Stroke workshop "Stroke Risk Assessment and Future Stroke Primary Prevention Trials" held January 12-13, 2004 are summarized. The Workshop discussions focused on stroke risk assessment; the high-risk vs. population-based approaches to primary prevention; desirable characteristics of candidate treatments and potential novel treatments, such as the 'polypill'; subclinical disease as risk assessment tool and as surrogate outcome, and methodological issues in stroke primary prevention trials. The importance of assessing cognitive decline as an important consequence of covert and overt vascular injury of the brain was emphasized. The scientific or logistic barriers to stroke primary prevention trials are challenging, but are not insurmountable.

Common carotid artery intima-media thickness for the risk assessment of lacunar infarction versus intracerebral haemorrhage

BACKGROUND AND PURPOSE

Arterial hypertension is the major risk factor for intracerebral haemorrhage (ICH) and lacunar infarction (LI) and both types of cerebral lesions originate from pathology of the same deep perforating small arteries. We aimed to evaluate the relationship between vascular risk factors including common carotid artery intima-media thickness (CCA-IMT) with LI versus ICH.

METHODS

We prospectively collected data from 159 first ever stroke patients (67 cases with ICH and 92 cases with LI) with documented history of hypertension. All subjects underwent B-mode ultrasonographic measurements of the CCA-IMT. Logistic regression modelling was used to determine the factors (established vascular risk factors, severity and duration of hypertension, concomitant medications and CCA-IMT) that may significantly differentiate LI from ICH.

RESULTS

Patients with LI had significantly (p=0.002) larger CCA-IMT values (0.926 mm, 95% CI: 0.881-0.971) than subjects with ICH (0.815 mm, 95% CI: 0.762-0.868) even after adjusting for baseline characteristics and cardiovascular medications. The multivariate logistic regression procedure selected CCA-IMT, diabetes mellitus and hypercholesterolaemia as the only independent factors able to discriminate between LI and ICH. The risk for LI versus ICH increased continuously with increasing CCA-IMT. For each increment of 0.1 mm in CCA-IMT the probability of suffering from LI versus ICH increased by 36.6% (95 % CI: 13%-65.2%, p=0.001) even after adjustment for cardiovascular risk factors.

CONCLUSIONS

Increased CCA-IMT values are a factor favouring LI over ICH in hypertensive patients. The measurement of CCA-IMT may be a useful non-invasive diagnostic tool for the risk assessment of LI with respect to ICH in such patients.

White matter lesions in watershed territories studied with MRI and parenchymography: a comparative study

Brain aging affects an increasing segment of the population and the role of chronic cerebrovascular disease is considered to be one of the main parameters involved. For this purpose we compared retrospectively MRI data with digitized subtraction angiography (DSA) data in a group of 50 patients focusing onto the watershed area of the carotid artery vascular territories. In order to evaluate the presence of white matter lesions (WML) in the hemispheric watershed areas, coronal fluid-attenuated inversion-recovery or axial T2 weighted MRI images of patients with symptomatic cerebrovascular insufficiency areas were compared with the capillary phase of DSA studies in anterior-posterior projection. Presence of cerebrovascular occlusive disease was evaluated on DSA using North American symptomatic carotid endarterectomy trial criteria and including evaluation of collateral vascular supply. Pathological MRI findings in the region of the watershed territories correlated overall in 66% of cases with a defect or delayed filling on DSA. In the case of asymmetrical MRI findings, there was a pathological finding of the capillary phase in the watershed area in 92% of DSA studies. Hypoperfusion in the capillary phase of the watershed area as seen on DSA correlated with the stenosis degree of the concerned carotid artery. Our findings suggest that asymmetrical findings of WML in the watershed areas as seen on MRI are caused by hemodynamic effect and a differentiation between small vessel disease and a consequence of distant stenosis may be possible under such conditions.

Hypertensive retinopathy: there's more than meets the eye

Hypertension is associated with increased cardiovascular risk, leading to systemic end-organ damage, including retinopathy. However, the recent European Society of Hypertension-European Society of Cardiology and World Health Organization-International Society of Hypertension 2003 guidelines propose new prognostic indications for the classification of hypertensive retinopathy. In particular, grades I and II are no longer included among signs of end-organ damage, and only grades III and IV are retained as associated clinical conditions for the stratification of global cardiovascular risk. This review article will focus on the wider implications of clinical markers of microvascular damage in the retina, with specific reference to hypertension and end-organ damage. Early recognition of retinal changes remains an important step in the risk stratification of hypertensive patients.

Epidemiology of white matter lesions

This is an overview of the prevalence of, and risk factors for white matter lesions in older persons. The prevalence of white matter lesions is high and increases with age. Most risk factors that have been examined in association with white matter lesions are similar to those for cardiovascular disease, including elevated blood pressure, diabetes atherosclerosis, homocysteine levels, and markers of oxidative stress. The genetic contributions to white matter lesions are also reviewed.

Increased frequency of white matter lesions in patients with osteonecrosis (WMLeOn) of the femoral head

White matter lesions (WML) are commonly seen in cerebral MR imaging in normal and demented elderly people or young people suffering from migraine. We present data showing that WML are detected in an unexpectedly high frequency (56.9%) in patients with non-traumatic osteonecrosis of the femoral head compared to age and sex-matched controls. We designated the coexistence of WML and osteonecrosis as white matter lesions in osteonecrosis (WMLeON). We examined the possible association of WMLeON with hyperlipidaemia and other risk factors for WML or osteonecrosis of the femoral head. The frequency of history of corticosteroid treatment was statistically lower in patients with WMLeON (58.6%) compared to those without it (90.1%) (P = 0.03). We found no association of WMLeON with diabetes, stroke, hyperlipidaemia, migraine, smoking, alcohol consumption, hypertension, atrial fibrillation, or systemic lupus erythematosus. Although, the clinical significance of WMLeON is still unknown, this finding supports, at least, the hypothesis that non-traumatic osteonecrosis is indeed a multisystem disorder rather than a disease of human skeleton.

Common carotid artery intima media thickness and post-stroke cognitive impairment

BACKGROUND AND PURPOSE

Acute stroke and other forms of cerebrovascular disease are well-recognized causes of cognitive impairment. Common carotid artery intima media thickness (CCA-IMT) has been associated with certain forms of cerebrovascular disease, but its association with cognitive impairment of vascular origin has not been elucidated. The purpose of this study was to investigate whether CCA-IMT is associated with cognitive impairment 1 year after an acute ischemic stroke.

METHODS

A total of 171 consecutive patients with the first ever stroke (mean age 66+/-11.5, 41% female) underwent carotid ultrasonography during hospitalization. Demographic data, vascular risk factors and presenting stroke features were also recorded. One year later, patients' cognitive performance and depression were assessed using the Mini-Mental State Examination (MMSE), and the Montgomery Asberg Depression Rating Scale (MADRS).

RESULTS

Cognitive impairment (MMSE score<24) was found in 67 (39%) of the 171 patients. CCA-IMT was significantly associated with cognitive impairment, and this association remained unchanged (OR 1.94; 95% CI 1.19-3.18) after adjustment for demographic data, vascular risk factors, stroke features, other carotid ultrasonography measurements and depression. Older age, low education level, large hemispheric lesions, hyperdense carotid plaques and depression were also independently associated with post-stroke cognitive impairment.

CONCLUSIONS

In this study, CCA-IMT was independently associated with cognitive impairment 1 year after an acute ischemic stroke, and thus, it might help with the screening of stroke patients at risk of cognitive impairment.

Vascular factors in dementia: an overview

Alzheimer's disease and cerebrovascular disease are two illnesses common to the elderly. Conventional wisdom has sought to separately describe and treat these two diseases. Accumulating evidence, however, shows that cerebrovascular risk factors may cause asymptomatic brain injury, share genetic risk with Alzheimer's disease and possibly accelerate the Alzheimer's process. Such evidence suggests that these two diseases may act additively or synergistically to cause clinical dementia. This review focuses on evolving data that support this hypothesis.

The role of cerebrovascular disease in dementia

BACKGROUND

Improvements in health care over the last 50 years have lengthened average life expectancy significantly, resulting in considerable growth of the population over 65 years of age. With increased age, however, comes an increased risk for Alzheimer's disease (AD), and the prevalence of AD is predicted to reach epidemic proportions by the later half of the 21st century. The prevalence of cerebrovascular disease also increases with age, and recent evidence suggests that cerebrovascular risk factors such as hypertension and hypercholesterolemia also increase an individual's risk for AD, suggesting a potential interaction between these two very common disorders. The potential impact of cerebrovascular disease on general cognitive health is not yet well understood, but is now being actively explored and clarified.

REVIEW SUMMARY

Cerebrovascular disease may manifest itself in many ways, and this review begins by discussing the possible spectrum of brain injury associated with common cerebrovascular risk factors. The prominent role of brain imaging to detect clinically silent cerebrovascular disease is recognized and reviewed. The neuropsychological consequences of cerebrovascular disease across the cognitive spectrum is also reviewed, including potential mechanisms by which cerebrovascular disease may interact with AD to increase the expression or hasten the progression of dementia.

CONCLUSIONS

Cerebrovascular risk factors, common to the elderly, lead to pernicious brain injury and subtle cognitive impairment that most probably places the individual at greater lifetime risk for dementia. The cause of dementia among individuals with cerebrovascular disease, however, remains AD. Recognition of the potential role of cerebrovascular disease as an independent risk factor for AD offers the possibility of primary prevention through treatment of well-recognized risk factors and deserves further study. In the meantime, clinicians presented with an individual suffering from a slowly progressive dementia and findings of clinically silent cerebrovascular brain injury should recognize the potential role of cerebrovascular disease in the dementia process but not ignore the likely overwhelming effects of AD and treat appropriately.

Homocysteine and brain atrophy on MRI of non-demented elderly

Patients with Alzheimer's disease have higher plasma homocysteine levels than controls, but it is uncertain whether higher plasma homocysteine levels are involved in the early pathogenesis of the disease. Hippocampal, amygdalar and global brain atrophy on brain MRI have been proposed as early markers of Alzheimer's disease. In the Rotterdam Scan Study, a population-based study of age-related brain changes in 1077 non-demented people aged 60-90 years, we investigated the association between plasma homocysteine levels and severity of hippocampal, amygdalar and global brain atrophy on MRI. We used axial T(1)-weighted MRIs to visualize global cortical brain atrophy (measured semi-quantitatively; range 0-15) and a 3D HASTE (half-Fourier acquisition single-shot turbo spin echo) sequence in 511 participants to measure hippocampal and amygdalar volumes. We had non-fasting plasma homocysteine levels in 1031 of the participants and in 505 of the participants with hippocampal and amygdalar volumes. Individuals with higher plasma homocysteine levels had, on average, more cortical atrophy [0.23 units (95% CI 0.07-0.38 units) per standard deviation increase in plasma homocysteine levels] and more hippocampal atrophy [difference in left hippocampal volume -0.05 ml (95% CI -0.09 to -0.01) and in right hippocampal volume -0.03 ml (95% CI -0.07 to 0.01) per standard deviation increase in plasma homocysteine levels]. No association was observed between plasma homocysteine levels and amygdalar atrophy. These results support the hypothesis that higher plasma homocysteine levels are associated with more atrophy of the hippocampus and cortical regions in elderly at risk of Alzheimer's disease.

Quality of life: an outcomes perspective

This article compares a traditional biomedical model with an outcomes model for evaluating medical and rehabilitation care. The traditional model emphasizes diagnosis and disease-specific outcomes. In contrast, the outcomes model emphasizes life expectancy and health-related quality of life (QOL). Although the models are similar, they lead to different conclusions with regard to some interventions. For some conditions, diagnosis and treatment may reduce the impact of a particular disease without extending life expectancy or improving QOL. Older individuals with multiple comorbidities may not benefit from treatments for a particular disease if competing health problems threaten life or reduce QOL. Overall outcomes and benefits of treatment can be summarized by using measures of life expectancy that adjust for QOL. The quality-adjusted life year (QALY) has been proposed as a comprehensive summary index. QALYs have gained widespread usage in many areas of medicine. The outcomes model has been applied widely in rehabilitation research, but few studies estimate the benefits of treatments using QALYs. These methodologies can also serve as a basis for approaches to sharing medical decisions between patients and providers. Opportunities to apply these new methods are discussed.

Current practice and future promise for clinical noninvasive measurements of subclinical atherosclerotic disease in the elderly

The detection, treatment, and follow-up of subclinical vascular disease are becoming clinically essential components of cardiovascular disease prevention in the elderly. Noninvasive measurements are available for different vascular beds, including carotid, coronary, aortic, and peripheral arterial circulation. Current interest in these measures is aimed at improving the accuracy of risk prediction for coronary heart disease and cardiovascular disease. Indirect physical examination and imaging evaluations detect significant obstruction of flow in the peripheral arteries. Doppler measures of ankle-arm blood pressure index represent a simple, indirect test that has been shown to be predictive of incident cardiovascular disease independent of risk factors. Newer, high-resolution tests allow direct detection and quantitation of the burden of atherosclerosis and vascular disease within the arterial wall, independent of flow obstruction. Carotid intimal-medial thickness predicts incident coronary heart disease and stroke in the elderly, even after adjustment for traditional risk factors. Coronary calcium can be accurately detected by computed tomography and is a strong predictor of the incidence of coronary heart disease events. Evidence is accruing that coronary calcium screening will play a role in prevention in the elderly. Magnetic resonance imaging is currently under study as a promising modality for detection and quantification of aortic and carotid plaque. Ongoing studies will provide important information regarding the appropriate role of the many newer, high-resolution tests of subclinical atherosclerosis in disease prediction, treatment, and tracking of disease progression in the elderly.

Cerebral white matter lesions in essential hypertension

The pathogenesis and clinical significance of cerebral white matter lesions (WML) remain controversial. Most studies have shown that age, hypertension, diabetes mellitus, and a history of stroke or heart disease are the most important factors related to the presence of cerebral WML. Moreover, some studies suggest that the presence of WML are closely related to cerebrovascular disease and cognitive impairment in elderly patients with vascular risk factors, particularly hypertension. In this review, different points of view about cerebral WML are discussed, with special focus on the presence of WML in essential hypertension. Some authors suggest that the presence of WML in hypertensive patients could be considered an early marker of brain damage.

Carotid plaque characterization by magnetic resonance imaging: review of the literature

Magnetic resonance imaging (MRI) of carotid plaque has undergone significant improvements in the last decade. Early studies utilizing ex vivo specimens and spin-echo or fast spin-echo imaging led to the conclusion that T2 weighting is the best single contrast to characterize carotid plaque morphology. On these images, the fibrous plaque appears bright and the lipid core is dark; thrombus can have variable intensity. There can be an overlap in T2-weighted signal intensities among the various plaque components, which can be partially offset by the use of multispectral analysis of multiple contrast images. With improvements in coil design, sequence design, and main field and gradient capabilities, accurate in vivo differentiation and measurement of these various carotid plaque components should be possible in 3 to 5 years. Ex vivo and in vivo studies have yielded high-resolution measurements of the complex three-dimensional lumen geometry, which are being used to predict hemodynamic forces acting on the lumenal surface. Carotid plaque burden can be accurately measured in vivo today; ongoing longitudinal studies should lead to a better understanding of the relationship between plaque burden and the risk of thromboembolic complications, as well as the effect of diet and drug therapy in hyperlipidemic patients. With these developments in place or soon to be available, MRI of the diseased carotid artery wall may prove to be even more important than magnetic resonance angiography.