Is vascular dementia really Alzheimer's disease or mixed dementia?

Delayed-onset dementia after stroke or transient ischemic attack

INTRODUCTION

Patients surviving stroke without immediate dementia are at high risk of delayed-onset dementia. Mechanisms underlying delayed-onset dementia are complex and may involve vascular and/or neurodegenerative diseases.

METHODS

Dementia-free patients with stroke and/or transient ischemic attack (TIA; n = 919) were studied for 3 years prospectively, excluding those who developed dementia 3 to 6 months after stroke and/or TIA.

RESULTS

Forty subjects (4.4%) developed dementia during the study period. Imaging markers of severe small vessel disease (SVD), namely presence of ≥3 lacunes and confluent white matter changes; history of hypertension and diabetes mellitus independently predicted delayed-onset dementia after adjustment for age, gender, and education. Only 6 of 31 (19.4%) subjects with delayed cognitive decline harbored Alzheimer's disease-like Pittsburg compound B (PiB) retention. Most PiB cases (16/25, 64%) had evidence of severe SVD.

DISCUSSION

Severe SVD contributes importantly to delayed-onset dementia after stroke and/or TIA. Future clinical trials aiming to prevent delayed-onset dementia after stroke and/or TIA should target this high-risk group.

Frequency of dementia syndromes with a potentially treatable cause in geriatric in-patients: analysis of a 1-year interval

In addition to neurodegenerative and vascular causes of dementia, in the differential diagnosis potentially reversible conditions of dementia also must be assessed. Routine laboratory parameters and neuroimaging, which are recommended for the differential diagnosis of suspected dementia by the German S3 Guideline "Dementia", were retrospectively studied in 166 geriatric patients with suspected dementia. Delirium was diagnosed in six patients (3.6%). These six patients were excluded from the study. Of the 160 remaining patients, there were 99 (59.6%) with an already known dementia. In this subgroup of patients, we found a potentially treatable cause of dementia in 18.2%. In the remaining 61 patients (36.8%), the newly diagnosed dementia syndrome was established according to ICD-10 criteria. Potentially reversible causes of the dementia syndrome were found in 19 of these patients (31.1%). The most common cause was depressive pseudodementia in eight patients followed by vitamin B12 deficiency in six patients. A significant amount of our patients showed laboratory or imaging changes suggestive of potentially reversible causes of the dementia syndrome upon admission. The results of our study indicate the importance of careful differential diagnosis of dementia based on the recommendations of guidelines. Although therapy of these potential causes is not always accompanied by a full recovery, the identification and therapy of treatable causes of cognitive deficits are possible even for general practitioners, who often are the primary contact persons of affected individuals.

Small vessel versus large vessel vascular dementia: risk factors and MRI findings

OBJECTIVE

The aim of this study was a cross-sectional comparison of clinical and MRI characteristics and risk factor profiles between patients with small vessel disease (lacunae and white matter hyperintensities) and large vessel disease (large territorial or strategical infarcts) in a large cohort of VaD patients.

METHODS

Patients with VaD (NINDS-AIREN) were included in a large multicenter treatment trial (the VantagE study). All patients were examined by a neurologist and interviewed about their medical history. Based on MRI, patients were classified as having large vessel VaD, small vessel VaD, or a combination. Other MRI characteristics included white matter hyperintensities (WMH), medial temporal lobe atrophy (MTA) and general cortical atrophy.

RESULTS

Of the 706 patients, 522 (74 %) had small vessel disease, 126 (18 %) had large vessel disease and 58 (8 %) had both. Patients with small vessel disease were older and less educated, and showed more cortical and medial temporal lobe atrophy than patients with large vessel disease. The most prevalent vascular risk factors (hypertension, diabetes and smoking) were equally distributed between the different types of VaD. However, patients with large vessel disease had more hypercholesterolemia and cardiac risk factors compared to patients with small vessel disease.

CONCLUSION

Cerebrovascular disease underlying VaD consists in the majority of small vessel disease and in about one fifth of large vessel disease. This study demonstrates heterogeneity between these two groups with regard to risk factor profile and atrophy scores on MRI.

Neuroimaging and correlates of cognitive function among patients with heart failure

BACKGROUND/AIMS

We purposed to investigate the relationship between cerebral abnormalities detected by magnetic resonance imaging (MRI) and cognitive performance in nondemented outpatients with heart failure (HF).

METHODS

In 58 patients with HF neuropsychological assessment was performed including tests of mental speed, executive functions, memory, language and visuospatial functions. Deep, periventricular and total white matter hyperintensities (WMH), lacunar and cortical infarcts, global and medial temporal lobe atrophy (MTA) were investigated on MRI of the brain. Correlations between MRI findings and the cognitive measures were calculated.

RESULTS

MTA correlated with memory (r = -0.353, p < 0.01), with executive functions (r = -0.383, p < 0.01) and the Mini Mental State Examination (r = -0.343, p < 0.05). Total WMH and deep WMH were found to correlate with depression and anxiety scores, but not with cognitive measures. Age, estimated premorbid intelligence and MTA were independent predictors of diminished cognitive performance.

CONCLUSIONS

In HF patients, MTA was related to cognitive dysfunction, involving memory impairment and executive dysfunction, whereas WMH was related to depression and anxiety.

Cognitive impact of subcortical vascular and Alzheimer's disease pathology

OBJECTIVE

To assess the interactions among three types of pathology (ie, cerebrovascular disease, hippocampal sclerosis [HS], and Alzheimer's disease [AD]), cognitive status, and apolipoprotein E genotype.

METHODS

We report clinicopathological correlations from 79 autopsy cases derived from a prospective longitudinal study of subcortical ischemic vascular disease and AD.

RESULTS

Thirty percent of the cases had significant cerebrovascular parenchymal pathology scores (CVDPS), 54% had significant AD pathology, and 18% had HS. In an ordinal logistic regression analysis that included interaction terms to assess the effects of each pathological variable when the other variables are interpolated to zero, each of the three pathology variables contributed independently to cognitive status: Braak and Braak stage odds ratio (OR) = 2.84 (95% confidence interval, 1.81-4.45), HS score OR = 2.43 (95% confidence interval, 1.01-5.85), and CVDPS OR = 1.02 (95% confidence interval, 1.00-1.04). Only Braak and Braak stage contributed to a global neuropsychological measure of cognitive impairment. Apolipoprotein E4 genotype was associated with Braak and Braak stage (OR, 1.31 [95% confidence interval, 1.03-1.68]), but not CVDPS or HS scores.

INTERPRETATION

In this convenience sample enriched for subcortical ischemic vascular disease, HS was a common unsuspected neuropathological finding. Apolipoprotein E4 genotype was associated with cerebral amyloid angiopathy, but not HS or arteriosclerosis. When Braak and Braak stage was interpolated to zero, both CVDPS and HS contributed to cognitive impairment. However, advancing stages of AD pathology overwhelmed the effects of CVDPS and HS, to become the major determinant of dementia.

A pilot study evaluating the efficacy and safety of rivastigmine in patients with mixed dementia

BACKGROUND AND OBJECTIVE

The two most common causes of dementia in the elderly are Alzheimer's disease (AD) and vascular dementia (VaD), which can coexist as mixed dementia. The object of this study was to assess the efficacy and safety of rivastigmine in patients with mixed dementia (AD with VaD).

STUDY DESIGN

This 26-week open-label pilot study was conducted at 19 centres in the US. To reduce bias, the Alzheimer's Disease Assessment Scale-Cognitive (ADAS-Cog) raters were blinded to all efficacy measures and to patient dosage information. Patients were treated with rivastigmine and titrated to their highest tolerated dose, up to 12 mg/day (6 mg twice daily). The primary efficacy measure was cognitive function assessed by the ADAS-Cog subscale (without the concentration/distractibility item, to be consistent with cognitive outcome measures used in previous rivastigmine trials).

RESULTS

Forty-seven percent of patients treated with rivastigmine 6-12 mg/day demonstrated improvement on the ADAS-Cog at 26 weeks, with >25% of patients having a clinically significant improvement of > or =4 points. Treatment with rivastigmine (6-12 mg/day) was well tolerated by the majority of patients. The most common adverse effects occurring in >10% of patients were nausea, vomiting, dizziness and diarrhoea.

CONCLUSION

This pilot study suggests that rivastigmine treatment may have beneficial effects in the treatment of patients with mixed dementia.

Determinants of prestroke cognitive impairment in stroke associated with small vessel disease

Understanding the determinants of prestroke cognitive impairment (PCI) in stroke associated with small vessel disease (SVD) may shed light on how to prevent further cognitive deterioration after stroke. We administered the Informant Questionnaire on Cognitive Decline (IQCODE) to close informants of 78 consecutive stroke patients who had SVD. PCI, as defined by an average score of IQCODE > or =3.4 was found in 19 (24%) patients. Regression analyses were performed on the following risk factors for PCI: age, years of education, gender, previous stroke, volume of white matter changes, measures of silent lacunes, cerebral atrophy index, medial temporal lobe atrophy and frontal lobe atrophy. Multivariate regression analyses revealed that only cerebral atrophy index (OR 1.5, CI 1.2-1.9, p < 0.001) predicted PCI among patients with SVD.

William M. Feinberg Lecture: Cognitive Vitality and the Role of Stroke and Cardiovascular Disease Risk Factors

BACKGROUND AND PURPOSE

Vascular risk factors are common in the elderly, and some such as hypertension may be important predictors of cognitive impairment.

SUMMARY OF REVIEW

In this article, the role that vascular risk factors may play in the prevention of vascular and nonvascular forms of cognitive impairment is reviewed.

CONCLUSIONS

Because vascular risk factors may have negative effects on brain structure and cognitive function, and because vascular risk factors may be present in midlife or possibly earlier, we may need to develop long-term intervention strategies to control or prevent vascular risk factors in an effort to preserve cognitive vitality as we age.

Risk factors for vascular dementia and Alzheimer disease

Alzheimer disease and vascular cognitive impairment are important causes of cognitive decline in the elderly. It has now been shown that vascular risk factors have measurable negative effects on the brain and are associated with cognitive impairment. We review vascular factors that might be responsible to cognitive decline in Alzheimer disease and vascular cognitive impairment and the corresponding interventions that might prevent cognitive impairment as we age.

Relevant clinical outcomes in probable vascular dementia and Alzheimer's disease with cerebrovascular disease

Two important prerequisites for assessing therapeutic benefits in patients with vascular dementia (VaD), or Alzheimer's disease (AD) with cerebrovascular disease (CVD), are the inclusion of appropriate patients and the use of relevant outcome measures. There is substantial overlap in the clinical symptomatology, risk factors, imaging changes, pathophysiology and neurochemical mechanisms between VaD, AD and AD with CVD. While validated and acceptable clinical criteria suitable for clinical trials have been developed for VaD, there is still debate as to how mixed cases (i.e. AD with CVD) are best conceptualized. As with AD, there is consensus that outcome measures in studies of patients with VaD, or AD with CVD, should include assessments of cognitive and global function, of ability to perform activities of daily living (ADL) and of behavioral symptoms. Other measures, e.g., caregiver burden, would be desirable. Care must be taken in extrapolating AD-specific evaluations to VaD, however, because different specific domains are affected and the disease course is different. In clinical trials, cognitive performance and global function decline steadily in patients with untreated AD compared with smaller changes in patients with untreated VaD, while behavior and ADL deteriorate over 6 months in patients with either untreated AD or untreated VaD. Such differences in untreated outcome need to be considered when interpreting trial results using outcome measures that were largely designed for studies of patients with AD.

Vascular dementia revisited: diagnosis, pathogenesis, treatment, and prevention

VaD is the second most common cause of dementia in the elderly after AD. VaD is defined as the loss of cognitive function resulting from ischemic, ischemic-hypoxic, or hemorrhagic brain lesions as a result of CVD and cardiovascular pathologic changes. Diagnosis requires (1) cognitive loss (often predominantly subcortical), (2) vascular brain lesions demonstrated by imaging, and (3) exclusion of other causes of dementia, such as AD. VaD is excluded by brain imaging showing no evidence of vascular lesions. VaD may be caused by multiple strokes (MID or poststroke dementia) but also by single strategic strokes, multiple lacunes, and hypoperfusive lesions such as border zone infarcts and ischemic periventricular leukoencephalopathy (Binswanger's disease). Primary and secondary prevention of stroke and cardiovascular disease decreases the burden of VaD. Genetic advice is needed in patients with familial forms, such as CADASIL. Treatment involves control of risk factors (i.e., hypertension, diabetes, smoking, hyperfibrinogenemia, hyperhomocystinemia, orthostatic hypotension, cardiac arrhythmias). Anticholinergic medications used for AD are also useful in VaD, and atypical antipsychotic agents and antidepressants (e.g., selective serotonin reuptake inhibitors) may be required in some patients.

Prevalence of dementia in the older Japanese-Brazilian population

The prevalence of dementing disorders in Campo Grande of a community of Japanese-Brazilians who immigrated from Okinawa was studied. Previous reports showed that the dietary pattern in Japanese immigrants in Brazil, which characterized by a low fish and large meat intake, is possibly responsible for increased risk of cardiovascular diseases compared with Japanese in Okinawa. A total of 157 persons over 70-year-old were examined, and 19 cases were diagnosed as having dementia. The prevalence (cases/100 aged 70-year-older) was 12.1 for all types of dementia, 5.7 for Alzheimer's disease (AD), 0.6 for vascular dementia (VD), 4.5 for mixed dementia (AD/VD) and 1.3 for other types of dementia. There was no case of dementia with Lewy bodies or frontotemporal lobar degeneration. These results are similar to many previous studies in Western countries and some recent surveys in Japan, and clearly show that more AD than VD appears even in the Japanese-Brazilian population. The higher prevalence rate of dementia in Japanese-Brazilians compared with several studies in Japan may indicate the importance of dietary factors rather than genetic factors.

MRI predictors of cognition in subcortical ischemic vascular disease and Alzheimer's disease

BACKGROUND

Causes of cognitive impairment in subcortical ischemic vascular disease (SIVD) are less well understood than in AD, but have been thought to result from direct effects of subcortical lacunes and white matter lesions, perhaps related to disruption of important cortical-subcortical pathways.

OBJECTIVE

To examine the relation between cognitive abilities and quantitative MRI measures of subcortical cerebrovascular disease and cortical and hippocampal atrophy.

METHODS

Subjects were 157 participants in a multicenter study of SIVD and AD who included cognitively normal, cognitively impaired, and demented individuals with and without subcortical lacunar infarcts. Dependent variables were neuropsychological tests of global cognitive function, memory, language, and executive function. Independent variables were quantitative MRI measures of volume of lacunar infarcts in specific subcortical structures, volume of white matter lesion (WML), volume of cortical gray matter (cGM), and total hippocampal volume (HV). Multiple regression analyses were used to identify MRI predictors of cognition.

RESULTS

Subcortical lacunes were not related to cognitive measures independent of effects of other MRI variables. WML was independently related to selected, timed measures. HV and cGM were strong and independent predictors of cognitive variables, with effects that did not differ in subjects with and without subcortical lacunes.

CONCLUSIONS

Results suggest that cognitive impairment associated with subcortical ischemic vascular disease is primarily a result of associated hippocampal and cortical changes.

Hippocampal and cortical atrophy predict dementia in subcortical ischemic vascular disease

BACKGROUND

The cause of dementia in subcortical ischemic vascular disease (SIVD) is controversial.

OBJECTIVES

To determine whether cognitive impairment in SIVD 1) correlates with measures of ischemic brain injury or brain atrophy, and/or 2) is due to concomitant AD.

METHODS

Volumetric MRI of the brain was performed in 1) elderly subjects with lacunes (L) and a spectrum of cognitive impairment-normal cognition (NC+L, n = 32), mild cognitive impairment (CI+L, n = 26), and dementia (D+L, n = 29); 2) a comparison group with probable AD (n = 28); and 3) a control group with normal cognition and no lacunes (NC). The authors examined the relationship between the severity of cognitive impairment and 1) volume, number, and location of lacunes; 2) volume of white matter signal hyperintensities (WMSH); and 3) measures of brain atrophy (i. e., hippocampal, cortical gray matter, and CSF volumes).

RESULTS

Among the three lacune groups, severity of cognitive impairment correlated with atrophy of the hippocampus and cortical gray matter, but not with any lacune measure. Although hippocampal atrophy was the best predictor of severity of cognitive impairment, there was evidence for a second, partially independent, atrophic process associated with ventricular dilation, cortical gray matter atrophy, and increase in WMSH. Eight autopsied SIVD cases showed variable severity of ischemic and neurofibrillary degeneration in the hippocampus, but no significant AD pathology in neocortex. The probable AD group gave evidence of only one atrophic process, reflected in the severity of hippocampal atrophy. Comparison of regional neocortical gray matter volumes showed sparing of the primary motor and visual cortices in the probable AD group, but relatively uniform atrophy in the D+L group.

CONCLUSIONS

Dementia in SIVD, as in AD, correlates best with hippocampal and cortical atrophy, rather than any measure of lacunes. In SIVD, unlike AD, there is evidence for partial independence between these two atrophic processes. Hippocampal atrophy may result from a mixture of ischemic and degenerative pathologies. The cause of diffuse cortical atrophy is not known, but may be partially indexed by the severity of WMSH.

Epidemiology of dementia: concepts and overview

This article reviews current knowledge about the prevalence and incidence of dementia and the risk and protective factors for dementia. Relevant epidemiologic concepts and methodological issues are reviewed, focusing on the implications of designing and interpreting epidemiologic studies of dementia and illustrating the integrative role of epidemiology.

Stroke in African Americans

There is an excess burden of cerebrovascular disease in African Americans. This article will define possible reasons for excess stroke risk, review racial differences in stroke subtype and stroke prevention programs in the African American Community, and delineate sequelae of stroke. The authors provide insights about stroke prevention in African Americans and highlight challenges to reduce the burden of cerebrovascular disease in this high-risk group.

Alzheimer's disease and vascular dementia. Some points of confluence

The lack of biologic markers for Alzheimer's disease and vascular dementia, the controversy regarding the definition of vascular dementia, and the new evidence of vascular risk factors for Alzheimer's disease suggest that the traditional differentiation between Alzheimer's disease and vascular dementia is no longer very clear. We believe that both vascular and degenerative mechanisms contribute to the development of dementia, especially in very old age. The question of whether they are two independent parallel processes or interacting pathologies needs to be clarified.

Vascular dementia: a contemporary review of epidemiology, diagnosis, prevention, and treatment

The past decade has seen a renewed interest in vascular dementia. Key epidemiologic studies have examined the prevalence, incidence, course and risk factors of vascular dementia. New classification systems have been developed to improve the reliability of the diagnosis, and there have been advances in diagnostic methodology, such as neuroimaging and neuropsychological assessment. New treatments for vascular dementia are being developed to protect the brain from cerebral ischemia and to limit progression of cognitive impairment. Diagnostic criteria for vascular dementia remain to be validated by carefully designed, systematic, clinicopathologic study. Once such criteria are validated, meaningful study of subgroups of vascular dementia can be explored. Until the relationship between vascular dementia and Alzheimer's disease is better defined, the nosology for vascular dementia may be defined best as dementia associated with stroke.

Status of risk factors for dementia associated with stroke

BACKGROUND

Cognitive impairment associated with vascular disease may be the only preventable form of dementia of late life. Identification of risk factors for dementia associated with stroke may be a prelude to improved intervention.

SUMMARY OF REVIEW

I reviewed putative risk factors for dementia associated with stroke. These included demographic, atherogenic, stroke-related, and genetic factors. Key studies from the English literature were reviewed and graded according to quality of evidence ratings (classes I, II, and III). Although many of the cardiovascular disease risk factors are logical antecedents of dementia associated with stroke, age was the only factor that could be considered a well-documented risk factor.

CONCLUSIONS

We should continue to support efforts directed at primary stroke prevention and the brain-at-risk and predementia stages. Additional rigorous epidemiological study is needed to clarify risk factors for dementia associated with stroke.