Subcortical ischaemic vascular dementia

Comparison of regional cerebral blood flow in two subsets of subcortical ischemic vascular dementia: statistical parametric mapping analysis of SPECT

BACKGROUND

The brain imaging criteria for subcortical ischemic vascular dementia (SIVD), as proposed by Erkinjuntti, incorporated two clinical entities, the lacunar state and Binswanger's disease. However it has not been proven whether these two subtypes of SIVD have common pathophysiological features. This study investigated the changes of regional cerebral blood flow (CBF) in the two subsets of SIVD to establish whether these two subtypes could be incorporated into the same group for the purpose of conducting clinical trials.

METHODS

Twelve SIVD patients with predominant white matter lesions, 13 patients with predominant lacunar infarctions and 17 controls were evaluated. Single photon emission computed tomography (SPECT) was performed to measure the regional CBF, and statistical parametric mapping (SPM) was applied to the analysis of the SPECT data.

RESULTS

The normalized CBF (nCBF) in the bilateral thalami, the anterior cingulate gyri, the superior temporal gyri, the caudate heads and the left parahippocampal gyrus was significantly decreased in the SIVD patients compared to the controls. This pattern of nCBF reduction was same in both the two subtypes of SIVD patients.

CONCLUSION

Our study suggests that the two subsets of SIVD may have a common nCBF abnormality, and Erkinjuntti's criteria offer a solution for researchers to identify the more homogeneous group of vascular dementia patients.

Spatial memory formation and memory-enhancing effect of glucose involves activation of the tuberous sclerosis complex-Mammalian target of rapamycin pathway

The tuberous sclerosis complex-mammalian target of rapamycin (TSC-mTOR) cascade integrates growth factor and nutritional signals to regulate the synthesis of specific proteins. Because both growth factor signaling and glucose have been implicated in memory formation, we questioned whether mTOR activity is required for long-term spatial memory formation and whether this cascade is involved in the memory-augmenting effect of centrally applied glucose. To test our hypothesis, we directly administered rapamycin (an inhibitor of mTOR), glucose, 5-aminoimidazole-4-carboxamide-1beta-4-ribonucleoside (AICAR; an activator of AMP kinase), or glucose plus rapamycin into the dorsal hippocampus after we trained rats in the Morris water maze task. The results from these studies indicate that glucose enhances, whereas AICAR and rapamycin both impair, long-term spatial memory. Furthermore, the memory-impairing effect of targeted rapamycin administration could not be overcome by coadministration of glucose. Consistent with these behavioral results, biochemical analysis revealed that glucose and AICAR had opposing influences on the activation of the TSC-mTOR cascade, as indicated by the phosphorylation of ribosomal S6 kinase (S6K) and 4E binding protein 1 (4EBP1), targets of mTOR. Together, these findings suggest that memory formation requires the mTOR cascade and that the memory-enhancing effect of glucose involves its ability to activate this pathway.

Metacognition in stroke: bedside assessment and relation to location, size, and stroke severity

BACKGROUND

Frontal syndromes are poorly represented on stroke scales, yet may constitute an important component of the neurologic deficit impacting treatment and rehabilitation efforts.

AIMS

To validate an assessment of a frontal network syndrome score (FNSS) in stroke and to ascertain the relationship of the FNSS to lesion location, volume, and severity in young people with stroke.

METHODS

Accrual through a cognitive stroke registry of young, alert, nonaphasic, nonencephalopathic, nonsubstance abuse prone people who were tested with the 16 domain FNSS within 4 weeks of their stroke. Lesion location was determined by the Cerefy 3-dimensional, digital, coxial brain atlas identifying 6 regions of cerebral interest. Lesion severity was assessed by the National Institute of Health Stroke Score and infarct volume was measured in cubic centimeters.

RESULTS

From a sample of 456 cases in the registry after exclusions of encephalopathy, depression, and aphasia, cases with frontal network syndrome encompassed 132 of 341 persons (39%). Of these patients (n=80) with mean age 45.7 years [confidence interval (CI): 43.4, 48.1], educational level 13.1 years (CI:12.5, 13.6), mean National Institute of Health Stroke Score of 3.3 (CI: 2.6, 4.0), and mean lesion volume 30.3 mL (CI: 13.7, 46.9), had full testing with the FNSS battery yielding sensitivity (93%), specificity (74%), positive predictive value (79%), negative predictive value (90%), and a good interrater reliability (kappa=0.89, P=0.001). Construct validity testing with 15 frontal neuropsychologic tests revealed good to excellent significant Pearson r values in 14 of 15 of the tests. There was no correlation (Pearson's) for lesion volume (r=0.07, P=0.52) but significant correlation with stroke severity (r=0.23, P=0.03). Analysis of variance testing of the FNSS revealed significant differences for all 6 domains without intergroup significant differences for frontal network syndrome domains in the stroke group.

CONCLUSIONS

The FNSS is a valid, practical measure of frontal syndromes in stroke. Frontal syndromes are common in young people with stroke and may be present no matter where the lesion, are not dependent on size of stroke and have a low correlation with stroke severity.

18FDG PET in vascular dementia: differentiation from Alzheimer's disease using voxel-based multivariate analysis

The brain metabolic pattern of vascular dementia (VaD) remains poorly characterized. Univariate voxel-based analysis ignores the functional correlations among structures and may lack sensitivity and specificity. Here, we applied a novel voxel-based multivariate technique to a large ((18)F)2-fluoro-2-deoxy-D-glucose positron emission tomography data set. The sample consisted of 153 subjects, one-third each being probable subcortical VaD, probable Alzheimer disease (AD) (matched for Mini-Mental-State examination (MMSE) and age), and normal controls (NCs). We first applied principal component (PC) analysis and removed PCs significantly correlated to age. The remainders were used as feature vectors in a canonical variate analysis to generate canonical variates (CVs), that is, linear combinations of PC-scores. The first two CVs efficiently separated the groups. CV(1) separated VaD from AD with 100% accuracy, whereas CV(2) separated NC from demented subjects with 72% sensitivity and 96% specificity. Images depicting CV(1) and CV(2) showed that lower metabolism differentiating VaD from AD mainly concerned the deep gray nuclei, cerebellum, primary cortices, middle temporal gyrus, and anterior cingulate gyrus, whereas lower metabolism in AD versus VaD concerned mainly the hippocampal region and orbitofrontal, posterior cingulate, and posterior parietal cortices. The hypometabolic pattern common to VaD and AD mainly concerned the posterior parietal, precuneus, posterior cingulate, prefrontal, and anterior hippocampal regions, and linearly correlated with the MMSE. This study shows the potential of voxel-based multivariate methods to highlight independent functional networks in dementing diseases. By maximizing the separation between groups, this method extracted a metabolic pattern that efficiently differentiated VaD and AD.

Vascular cognitive impairment

Cerebrovascular disease is increasingly recognized as a common cause of cognitive impairment and dementia in later life either alone or in conjunction with other pathologies, most often Alzheimer disease (AD). Progress in the field has been limited by difficulties in terminology; for example, use of the term dementia necessitates the presence of memory impairment, which is the norm in AD, but not in cognitive disorders associated with cerebrovascular disease. The term vascular cognitive impairment (VCI) has been proposed as an umbrella term to recognize the broad spectrum of cognitive, and indeed behavioral, changes associated with vascular pathology. It is characterized by a specific cognitive profile with predominantly attentional and executive impairments together with particular noncognitive features (especially depression) and a relatively stable course, at least in clinical trial populations. Subtypes of VCI have been proposed based on clinical and pathologic differences, including cortical, subcortical, strategic infarct, hypoperfusion, hemorrhagic, and mixed (with AD) type. Diagnostic criteria are emerging but require refinement and validation, especially for mixed dementias. There remain fundamental gaps in our understanding of pathophysiology, predicting prognosis and outcome, and in therapeutics. Clinical trials to date, mainly in populations selected using currently accepted criteria for vascular dementia, have generally been disappointing. A relatively modest cognitive benefit of agents such as nimodipine, memantine, and cholinesterase inhibitors has been reported, although the clinical significance of these improvements remains to be established. Further studies, focusing on particular subtypes of VCI and involving subjects at earlier stages of the disease, are required. The aim of this article is to review the concept of VCI in terms of the evidence base surrounding diagnosis, clinical features, pathophysiology, and management and to make some recommendations regarding further research in the area. It begins with a discussion on the historical background, which is important to understand the different and somewhat confusing terminology that currently exists in the field.

Can the detection of misery perfusion in chronic cerebrovascular disease be based on reductions in baseline CBF and vasoreactivity?

PURPOSE

The aim of this study was to clarify whether decreases in baseline regional cerebral blood flow (rCBF) and in residual cerebral vasoreactivity (CVR), assessed by the acetazolamide (ACZ) challenge, can detect misery perfusion in patients with chronic cerebrovascular disease (CVD).

METHODS

Oxygen extraction fraction (OEF) and other haemodynamic parameters were measured in 115 patients (64+/-9 years old) with unilateral cerebrovascular steno-occlusive disease (>70% stenosis) using (15)O-gas and water PET. A significant elevation of OEF, by greater than the mean+2SD compared with healthy controls, was defined as misery perfusion. CBF, CVR determined by percent change in CBF after ACZ administration, OEF and other haemodynamic parameters in the territories of the bilateral middle cerebral arteries were analysed. Diagnostic accuracy for the detection of misery perfusion using the criteria determined by baseline CBF and CVR was evaluated in all patients and in only those patients with occlusive lesions.

RESULTS

Ten of 24 patients with misery perfusion showed a significant reduction in CVR. Using criteria determined by significant decreases in CVR and baseline CBF, misery perfusion was detected with a sensitivity of 42% and a specificity of 95% in all patients. In patients with occlusive lesions (n=50), sensitivity was higher but specificity was slightly lower. The diagnostic accuracy of the threshold determined by baseline CBF alone was similar in all patients and in only those patients with occlusive lesions, and was higher than that achieved using the asymmetry index of OEF.

CONCLUSION

Reductions in CVR and baseline CBF in the ACZ challenge for CVD would detect misery perfusion with high specificity. Reduction in baseline rCBF is more accurate than reduction in CVR alone for the detection of misery perfusion.

Correlations between MRS and DTI in cerebral small vessel disease

Cerebral small vessel disease results in lacunar infarcts and cognitive impairment. Diffusion tensor imaging (DTI) demonstrates a reduction in fractional anisotropy and increase in mean diffusivity, which correlates more strongly with cognition than conventional MRI. The underlying pathological basis for these DTI changes is not known. In this study magnetic resonance spectroscopy was used to determine the biochemical basis of these DTI alterations. Twenty-five patients with lacunar stroke and radiological leukoaraiosis were recruited. Chemical shift imaging (CSI) and DTI were performed on a 1.5 T MRI scanner. A region of interest was positioned in the white matter of the centrum semiovale. Multivoxel CSI data were processed and the metabolite ratios estimated. DTI parameters corresponding to the exact region of tissue excited by CSI were obtained. Mean spectroscopy data and DTI values for each subject were correlated. Univariate analysis revealed a positive correlation between N-acetyl aspartate-creatine (NAA/Cr) and fractional anisotropy (r = 0.52, p = 0.008), and a negative correlation with mean diffusivity (r = -0.51, p = 0.009). Results remained little changed after controlling for mean percentage lesion and mean percentage white matter per voxel (with fractional anisotropy r = 0.54, p = 0.008, and with mean diffusivity r = -0.52, p = 0.01). These findings are consistent with axonal loss or dysfunction, or both, accounting for at least part of the DTI abnormalities found in patients with small vessel disease. It provides evidence that DTI identifies axonal disruption in white matter tracts.

Magnetic resonance imaging of Alzheimer's disease

A modern challenge for neuroimaging techniques is to contribute to the early diagnosis of neurodegenerative diseases, such as Alzheimer's disease (AD). Early diagnosis includes recognition of pre-demented conditions, such as mild cognitive impairment (MCI) or having a high risk of developing AD. The role of neuroimaging therefore extends beyond its traditional role of excluding other conditions such as neurosurgical lesions. In addition, early diagnosis would allow early treatment using currently available therapies or new therapies in the future. Structural imaging can detect and follow the time course of subtle brain atrophy as a surrogate marker for pathological processes. New MR techniques and image analysis software can detect subtle brain microstructural, perfusion or metabolic changes that provide new tools to study the pathological processes and detect pre-demented conditions. This review focuses on markers of macro- and microstructural, perfusion, diffusion and metabolic MR imaging and spectroscopy in AD.

Clinical manifestations in neuropathologically defined subgroups of vascular dementia

AIMS

To study cardio-cerebrovascular disease and clinical features, such as falls, dizziness/unsteadiness, urinary incontinence, hallucinations/delusions and delirium in neuropathologically defined subgroups of vascular Dementia (VaD): pure Small Vessel Dementia (SVD), combined SVD and Alzheimer's disease (SVD-AD), pure Large Vessel Dementia (LVD) and pure Hypoxic Hypoperfusive Dementia (HHD), and to analyse the clinical differences between these groups.

MATERIALS AND METHODS

From 175 consecutive cases with neuropathologically verified VaD cases with pure SVD (n = 36) and SVD-AD (n = 38) with varying severity of AD pathology were selected and studied with respect to cardio-cerebrovascular and other clinical features. Furthermore, a comparison between pure SVD, pure LVD (n = 7) and pure HHD (n = 6) was made.

RESULTS

Neither cardiovascular symptoms, hypertension, Transitoric Ischemic Attacks (TIA) nor complete cerebrovascular lesions (CVL) differed significantly between the pure SVD and SVD-AD groups. However, a wide variation of clinical features were reported. The prevalence of cardiovascular features varied markedly in the pure groups, with the highest prevalence consistently found in the LVD group. Hypertension was common in the pure LVD and SVD-groups, while it was a rare finding in the HHD-group. TIA and/or CVL were, as expected, most common in the LVD-group.

CONCLUSION

In conclusion, this longitudinal and retrospective study of VaD shows important clinical similarities as well as differences between pathologically defined subgroups. Hopefully these findings will contribute to a better understanding of etiopathogenetic and diagnostic issues and form a solid basis for possible treatment strategies in VaD.

Frequency and clinical determinants of poststroke cognitive impairment in nondemented stroke patients

The objective of this study was to examine the prevalence and clinical correlates of poststroke cognitive impairment in Chinese stroke patients in Hong Kong. One hundred seventy-nine stroke patients were interviewed by a psychiatrist 3 months after their stroke. Cognitive impairment was determined according to the Mini-Mental State Examination score. Thirty-nine participants (21.8%) had cognitive impairment. Univariate analysis found that cognitive impairment was associated with age, female sex, level of education, previous stroke, prestroke Rankin score, National Institutes of Health Stroke Scale dysarthria and total scores, urinary incontinence, and cerebral atrophy index. Multivariate logistic regression suggested that female sex, education, National Institutes of Health Stroke Scale dysarthria score, urinary incontinence, and atrial fibrillation were independent risk factors of poststroke cognitive impairment. After removal of 54 patients with previous stroke from the sample, the frequency of cognitive impairment decreased to 18.4%. It was concluded that cognitive impairment is common among nondemented Chinese stroke patients in Hong Kong.

The effects of APOE and tau gene variability on risk of frontotemporal dementia

Frontotemporal dementia (FTD) is a complex dementing syndrome whose genetic/non genetic risk factors are mostly unknown. Aim of the present work was to investigate whether APOE and/or tau gene variability does affect the risk of FTD. A sample of FTD cases (sporadic: n = 54; familial: n = 46, one subject per family) was collected in a genetically homogeneous population (Calabria, southern Italy) and analyzed in comparison with an age- and sex-matched control group (n = 180) extracted from the same population. Logistic regression analysis showed that APOE gene variability affects the probability of disease, with allele epsilon4 increasing (exp(beta1) = 2.68 with [1.51-4.76] 95% confidence interval; p = 0.001) and allele epsilon2 decreasing (exp(beta1) = 0.28 with [0.12-0.66] 95% confidence interval; p = 0.003) the risk of FTD. On the contrary, tau gene variability was ineffectual (exp(beta1) non significantly different from 1 for either H1 or H2 haplotypes), although a small effect was observed by the H1 haplotype in increasing the protective effect of the epsilon2 allele (p = 0.007).

Neuroprotection in Vascular Dementia

Vascular dementia (VaD) is the second most common form of dementia after Alzheimer's disease (AD), and one of the major causes of mental and physical disability in developed countries. As such, the identification and implementation of strategies which prevent the development of the condition or enable improvements in patients with VaD are healthcare objectives of the first order. VaD is now regarded as a combined group of clinical-pathological entities rather than one disease, that is, multiple pathogenic mechanisms and lesion types underlie a cognitive impairment of vascular origin. The clinical diagnosis of VaD is complex and difficult because of the heterogeneous nature of its clinical presentation and progression and the low sensitivity of existing clinical criteria. Moreover, there is growing evidence of the epidemiological significance of mixed forms of dementia, and that ischemic processes may precipitate and exacerbate cognitive impairment in AD. Numerous compounds have been proposed as potentially useful in the treatment of patients with VaD, comprising vasodilatative, antithrombotic, hemorrheological, nootropic, antiserotoninergic and, most recently, antiglutamatergic and cholinergic approaches. In spite of some initially favorable reports based on the use of memantine, donepezil and galantamine, there is as yet no conclusive evidence of a definitive treatment for VaD. Unsatisfactory results from VaD drug trials may be attributed in part to the diversity of the patients included (underlying pathogenic mechanisms, number, type, and location of vascular lesions), and to methodological limitations in the design of the trials (outcome measures, end-points, size, follow-up period). The treatment of modifiable vascular risk factors - hypertension, diabetes mellitus, hypercholesterolemia and heart disease - is an important strategy for the reduction of the risk of dementia, and is likely to slow the progress of cognitive decline.

Vascular cognitive impairment

Vascular cognitive impairment encompasses a spectrum of clinically defined syndromes ranging from vascular cognitive impairment-no dementia, to vascular dementia. The underlying cerebrovascular pathology includes both overt infarction as well as rarefaction of gray and white matter. Alzheimer's pathology may coexist with vascular pathology. Diagnosis rests on identifying acquired cognitive impairment in the setting of documented cerebrovascular disease, based on clinical presentation and neuroimaging; MRI is more sensitive than CT. The course can be stepwise or gradually progressive. The clinical picture is typically dominated by deficits in executive function rather than the short-term memory deficit typical of Alzheimer's disease. No specific therapies exist, but treatment with anticholinesterase agents and N-methyl-d-aspartate antagonists may result in clinical improvement. Prevention remains paramount, with early recognition of populations at risk and early and aggressive management of risk factors, including hypertension, dyslipidemia, diabetes, and tobacco use as well as antithrombotic therapy, in appropriate populations.

The Role of Conventional MR and CT in the Work-Up of Dementia Patients

Dementia is a clinical syndrome with many causes. There often is overlap in the clinical manifestations of various forms of dementia, making them difficult to categorize. Neuroimaging can play an important role in distinguishing one form of dementia from another. Advanced imaging techniques continue to provide greater insight into the underlying pathologic processes in patients who have dementia. Conventional MRI and CT, however, still can contribute useful information when interpreting radiologists are familiar with the patterns of volume loss and signal or density changes that are characteristic of various forms of dementia.

Changes in Mini Mental State Examination score after stroke: lacunar infarction predicts cognitive decline

Stroke and cognitive impairment are inter-related. The purpose of this study was to show the natural evolution of cognitive performance during the first year after a stroke, and to show which factors that predict cognitive decline. Subjects were patients with a first-ever stroke who were treated in a stroke unit. A total of 160 patients were included. At baseline patients were evaluated with regard to stroke type, stroke severity, pre-stroke dementia and other risk factors. Mini Mental State Examinations (MMSE) were performed after 1 week and after 1 year. Patients had a median increase of 1 point (range -8 to +9) on the MMSE. Thirty-two pre cent of the patients deteriorated, 13% were unchanged, and 55% improved. Lacunar infarction (LI) and left-sided stroke were associated with a failure to exhibit improvement. Patients with LI had an average decline of 1.7 points, whilst patients with other stroke types had an average increase of 1.8 points. Most stroke survivors improve cognitively during the first year after the event. The outcome for LI patients is worse, which suggests that LI may serve as a marker for concomitant processes that cause cognitive decline.

[Alzheimer's disease: cardiovascular risk factors must be assessed]

BACKGROUND

Dementia is nowadays of major importance in public health. Alzheimer's disease and vascular cognitive impairments are its main aetiology in the elderly. The cause of Alzheimer's disease remains unknown. The factor initiating the physiopathology of this neurodegenerative disease is source of controversy.

CURRENT KNOWLEDGE AND KEY POINTS

The theory of a neurotoxicity initiated by amyloid deposition is questioned. A growing number of data suggest a central role of cardiovascular risk factors and alteration of arterial walls, inducing chronic brain hypoperfusion, as the primary trigger in the physiopathology of the disease. These data are based on epidemiological, physiopathological, neuroimaging, neuropathological and pharmacological studies. However, the exact link between arteriosclerosis, vascular cognitive impairment and Alzheimer's disease remains controversial.

FUTURE PROSPECTS AND PROJECTS

These debates point out the crucial importance of the assessment of cardiovascular risk factors, as a preventable cause, either of cognitive decline, morbidity and mortality. In this aim, major targets could be different when primary or secondary prevention are at stake. These controversies also suggest new research directions towards Alzheimer's disease physiopathology, and for pharmacological interventions aimed on the prevention of cognitive decline or the curative treatment for this disease.

Small vessel disease and subcortical vascular dementia

Atherothromboembolism and intracranial small vessel disease are considered to be the main causes of cerebrovascular injury, which may lead to cognitive impairment and vascular dementia (VaD). VaD appears to be the second most common type of dementia with prevalence estimates of 10-15%. Cortical or multi-infarct dementia and subcortical vascular dementia (SVD) are suggested to be the two main forms of VaD. The main clinical features of SVD comprise decreased motor performance, early impairment of attention and executive function with slowing of information processing. SVD results from lacunar infarcts or multiple microinfarcts in the basal ganglia, thalamus, brainstem and white matter and are associated with more than 50% of the VaD cases. White matter changes including regions of incomplete infarction are usually widespread in VaD but their contribution to impairment of subcortical regions is unclear. While most of VaD occurs sporadically only a small proportion of cases bear clear familial traits. CADASIL is likely the most common form of hereditary VaD, which arises from subcortical arteriopathy. SVD needs unambiguous definition to impact on preventative and treatment strategies, and critical for selective recruitment to clinical trials.

Sex hormones and neuropathology in elderly men: the HAAS

Experimental studies suggest 17-beta estradiol (E2) and testosterone (T) may have neuroprotective properties that are associated with Alzheimer's and vascular pathology. However, there are limited studies correlating steroid hormones with autopsy findings in humans. In this community-based autopsy study of elderly men (n=232) participating in the Honolulu Asia Aging Study, we found a significant decrease of neurofibrillary tangles in the highest tertile of free serum estradiol [IRR=0.43 (0.3-0.7)] after controlling for age at blood draw, interval from blood draw until death, ApoE allele, and socio-demographic health factors. Higher Free-T levels were associated with a two-fold increased risk for micro infarcts [IRR=2.2; 95% CI (1.2-4.1)]. There was no association between sex hormones and amyloid plaques or cerebral amyloid angiopathy. This community-based autopsy study suggests that peripheral levels of sex hormones are associated with neurofibrillary tangles and micro-infarcts, but not with other neuropathologic markers of brain disease in elderly men.

Cognitive profile in CADASIL

BACKGROUND

The spectrum of cognitive alterations associated with CADASIL, a model of pure vascular dementia, has not been thoroughly evaluated.

OBJECTIVES

The aims of this study were: (i) to describe the cognitive profile in CADASIL patients according to age; (ii) to compare the profile of patients with dementia with that of patients without dementia; and (iii) to determine the association between alterations in performance in different cognitive domains.

METHODS

Forty two consecutive individuals with CADASIL (35-73 years old) were investigated. Cognitive skills were analysed in five domains (executive functions, reasoning, attention, memory, visuospatial abilities) according to age and compared between patients with and without dementia. Associations between cognitive performance and stroke were tested.

RESULTS

The youngest patients presented with attention (69%), memory (70%), and executive disturbances (100%). Visuospatial abilities and reasoning deteriorated with age, mainly after the age of 60. About one quarter of patients had dementia, and 75% of these were >60 years of age. Age >60 years was associated with a Rankin score >3 and a significant deficit in all cognitive domains. No association was found between dementia and the number of ischaemic attacks. Episodic memory disorder was characterised by difficulties in retrieval rather than impairment of the encoding process.

CONCLUSION

Cognitive decline in CADASIL is dominated by early impairment of executive functions. Skills in other cognitive domains deteriorate with age and are found to be diffusely impaired in patients with dementia. The relative preservation of the encoding process in episodic memory impairment, even in individuals with dementia, is noteworthy.

Depressive symptoms and white matter changes in patients with dementia

OBJECTIVE

The aim of the present study was to investigate if depressive symptoms in demented patients are associated with white matter changes (WMCs) in the brain.

BACKGROUND

WMCs are frequently found in patients with dementia, as well as among elderly nondemented patients with depressive symptoms. However, it is less established whether or not WMCs are related to depressive symptoms in demented patients.

METHODS

67 (26 men, 41 women) patients with primary degenerative dementia (Alzheimer's disease, frontotemporal dementia), vascular dementia (VaD), or mixed Alzheimer/VaD dementia were included in the study. The patients were young-old (mean 68.1, SD 7.3). All patients underwent a standardized examination procedure and MRI of the brain. The degree of WMCs was visually rated, blindly. Depressive symptoms were rated according to the Gottfries-Bråne-Steen scale (anxiety, fear-panic, depressed mood).

RESULTS

No significant relationship was found between WMCs and depressive symptoms in the demented patients.

CONCLUSION

The possible involvement of WMCs in the pathogenesis of depressive symptoms in dementia is unclear. A link between disruptions of frontal-subcortical pathways, due to WMCs, and depressive symptomatology in dementia has been hypothesised from earlier findings, which would imply common elements of pathogenesis for depressive symptomatology and cognitive impairment in dementia. However, the results of the present study do not add further support to this hypothesis.

The role of conventional MR and CT in the work-up of dementia patients

Neuroimaging can play an important role in distinguishing one form of dementia from another. Advanced imaging techniques continue to provide greater insight into the underlying pathologic processes in patients who have dementia. Conventional MRI and CT, however, can contribute useful information when interpreting radiologists are familiar with the patterns of volume loss and signal or density changes that are characteristic of various forms of dementia.

Diagnostic tools for the study of vascular cognitive dysfunction in hypertension and antihypertensive drug research

Arterial hypertension is one of the main risk factors for cerebrovascular diseases, and antihypertensive treatment has significantly reduced their associated mortality. However, morbidity has not been reduced to a similar extent and a still increasing number of patients suffers from recurring strokes and from the disabling consequences of cerebrovascular diseases and develops progressive cognitive impairment. It is still debated to what extent antihypertensive treatment may prevent the development of cognitive dysfunction, due to the lack of a focused approach to vascular cognitive impairment, to the lack of a systematic study of the early phases of dementia, and to the use of diagnostic tests that are not sensitive and specific for a slow onset clinical condition, such as dementia. The aim of the present expert consensus report is to enlist the diagnostic tools that are currently available to assess mild cognitive impairment (MCI) and early dementia and that are sensitive and specific enough to be used in observational, longitudinal, and interventional clinical research studies, aiming to investigate the impact of antihypertensive drugs on vascular dementia (VD).

Cognitive profile of subcortical ischaemic vascular disease

OBJECTIVES

Subcortical ischaemic vascular disease (SIVD) is a subtype of vascular cognitive impairment characterised by extensive white matter lesions and multiple lacunar infarcts. Radiologically defined diagnostic criteria for SIVD have been introduced, but only a few studies have presented empirical data on its clinical and cognitive features. The aim of this study is to describe in detail the neuropsychological characteristics of patients with SIVD from a large well defined stroke cohort.

METHODS

A sample of 323 consecutive patients with ischaemic stroke, aged 55-85 years, was investigated using neuropsychological examination and magnetic resonance imaging (MRI). Patients fulfilling the MRI criteria of SIVD (n = 85) were compared to the other stroke patients (n = 238) and to normal control subjects (n = 38).

RESULTS

Cognitive performance of the SIVD group was inferior to that of the normal control group throughout all domains. As compared to the other stroke patients, the SIVD group performed significantly worse in tests measuring executive functions and delayed memory recall. Adjusting for depression had no effect on these results. Instead, after controlling for medial temporal lobe atrophy, the differences disappeared for delayed memory but remained significant for executive functions.

CONCLUSION

Executive deficits are the most prominent cognitive characteristic associated with SIVD. Patients with SIVD also exhibit subtle deficits in delayed memory, which is explained in part by medial temporal lobe atrophy. Cognitive and mood changes seem to be parallel but independent processes related to SIVD. The results support the concept of SIVD as a separate clinical entity.

Subcortical vascular dementia: integrating neuropsychological and neuroradiologic data

BACKGROUND

Research criteria for subcortical vascular dementia are based on radiologic evidence of vascular pathology and greater impairment on tests of executive control than memory. The relationship(s) between neuroradiological evidence of subcortical vascular disease and neuropsychological impairments has not been specified.

OBJECTIVE

To define these research criteria, the authors rated the severity of MRI white matter abnormalities (WMAs) and neuropsychological data from patients with dementia.

METHODS

Sixty-nine outpatients who met the criteria for dementia were studied with neuropsychological tests that assessed executive (mental) control, declarative memory, visuoconstruction (clock drawing), and language (semantic category fluency). MRI-WMAs were rated using a leukoaraiosis (LA) scale (range 0 to 40).

RESULTS

First, regression analyses demonstrated that neuropsychological measures accounted for 60.7% of the variance in WMA severity (47.3% of this variance attributable to executive/visuoconstructive test performance, 13.4% attributable to memory/language test performance). Second, patients were grouped according to the severity of WMAs (i.e., low, moderate, and severe white matter groups). Only patients with mild WMA (mean LA = 3.61 +/- 2.63, approximately 2.4 to 15.6% of the subcortical white matter) presented with greater impairment on memory/language tests vs executive control/visuoconstructive tests, a neuropsychological profile typically associated with Alzheimer disease. Patients with moderate WMA (mean LA = 12.76 +/- 2.49, approximately 25.6 to 38.1% of the subcortical white matter) presented with equal impairment on executive/visuoconstructional vs memory/language tests. Patients with severe WMA (mean LA = 21.76 +/- 2.97, approximately 46.9 to 62.4% of the subcortical white matter) displayed a profile of greater executive/visuoconstructional impairment relative to memory/language disabilities.

CONCLUSION

A profile of equal impairment on tests of executive control and memory along with radiologic evidence involving about one-fourth of the cerebral white matter as measured by the Leukoaraiosis Scale may be sufficient for a diagnosis of subcortical vascular 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.

Systemic Blood Pressure Profile in Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy

Background and Purpose— Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a genetic form of subcortical ischemic vascular dementia (SIVD). The most common vascular risk factors are unremarkable in CADASIL; however, studies on systemic blood pressure (BP) changes over time are substantially lacking. Because BP instability is a relevant risk factor for developing or worsening white matter changes in sporadic SIVD, we aimed to study the BP profile of CADASIL to investigate its relationship with cognitive decline and white matter injury.

Methods— Twenty-four–hour ambulatory BP monitoring was performed in a group of 14 CADASIL patients (12 males and 2 females) and in a group of 15 healthy age-matched control subjects. The following BP variables were compared between the 2 groups: mean daytime and nighttime systolic, diastolic, and mean arterial BP (SABP day , DABP day , and MABP day , and SABP night , DABP night , and MABP night ) and nocturnal percentage decline in arterial BP (%MABP reduction). Cognitive performances were tested by mini mental status examination (MMSE), and brain MRI was performed to extrapolate the T2-weighted lesion volume (LV) in each CADASIL patient. The 24-hour arterial BP variables were compared between CADASIL and controls. In addition, for CADASIL patients only, MMSE, LV, and age were compared with each pressure variable.

Results— Patients with CADASIL showed a significant reduction ( P <0.05) of SABP day , DABP day , MABP day and %MABP decline with respect to controls. In addition, MMSE of CADASIL subjects correlated significantly ( P <0.0001) with daytime MABP.

Conclusions— The low systemic BP profile observed in CADASIL patients was specifically attributable to reduced diurnal BP values. This may further affect cerebral hemodynamics and increase the risk of cognitive impairment in these patients. The pathogenesis of abnormal BP profile in CADASIL remains to be clarified. It is likely that central and peripheral mechanisms controlling BP variations are involved.

Spontaneous slow hemodynamic oscillations are impaired in cerebral microangiopathy

Small-vessel disease or cerebral microangiopathy (CMA) is a common finding in elderly people. It is related to a variety of vascular risk factors and may finally lead to subcortical ischemic vascular dementia. Because vessel stiffness is increased, we hypothesized that slow spontaneous oscillations are reduced in cerebral hemodynamics. Accordingly, we examined spontaneous oscillations in the visual cortex of 13 patients suffering from CMA, and compared them with 14 age-matched controls. As an imaging method we applied functional near-infrared spectroscopy, because it is particularly sensitive to the microvasculature. Spontaneous low-frequency oscillations (LFOs) (0.07 to 0.12 Hz) were specifically impaired in CMA in contrast to spontaneous very-low-frequency oscillations (0.01 to 0.05 Hz), which remained unaltered. Vascular reagibility was reduced during visual stimulation. Interestingly, changes were tightly related to neuropsychological deficits, namely executive dysfunction. Vascular alterations had to be attributed mainly to the vascular risk factor arterial hypertension. Further, results suggest that the impairments might be, at least partly, reversed by medical treatment such as angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers. Results indicate that functional near-infrared spectroscopy may detect changes in the microvasculature due to CMA, namely an impairment of spontaneous LFOs, and of vascular reagibility. Hence, CMA accelerates microvascular changes due to aging, leading to impairments of autoregulation.

Diffusion Magnetic Resonance Histograms as a Surrogate Marker and Predictor of Disease Progression in CADASIL

Background and Purpose— Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a cerebral small vessel disease caused by mutations in the NOTCH3 gene. MRI is sensitive in detecting preclinical involvement and changes over time. However, little is known about correlations between MRI metrics and clinical measures on a longitudinal scale. In this study, we assessed the role of quantitative MRI (T2-lesion volume and diffusion tensor imaging [DTI]–derived metrics) in monitoring and predicting disease progression.

Methods— Sixty-two CADASIL subjects were followed prospectively over a period of 26.3±1.2 months. Dual-echo scans, DTI scans, and clinical scales were obtained at baseline and at follow-up. T2-lesion volumes were determined quantitatively, and histograms of mean diffusivity (MD) were produced.

Results— At follow-up, T2-lesion volumes and MD histogram metrics had changed significantly (all P <0.01). Lesion volumes and average MD correlated with clinical scores at baseline. Changes of average MD correlated with changes of the Rankin score, the National Institutes of Health Stroke Scale score, and the structured interview for the diagnosis of Alzheimer dementia and multiinfarct dementia score (all P <0.01). On multivariate analysis, average MD and systolic blood pressure at baseline were predictors of changes of average MD during follow-up. Moreover, average MD was the main predictor of clinical progression. Sample size estimates showed that the number of individuals required to detect a treatment effect in an interventional trial may be reduced when using MD histograms as an end point.

Conclusions— This study establishes correlations between changes of DTI histogram metrics and clinical measures over time. DTI histograms may be used as an adjunct outcome measure in future therapeutic trials. Moreover, DTI histogram metrics predict disease progression in CADASIL.

Pathological aging of the brain: an overview

The number of elderly people is increasing rapidly and, therefore, an increase in neurodegenerative and cerebrovascular disorders causing dementia is expected. Alzheimer disease (AD) is the most common cause of dementia. Vascular dementia, dementia with Lewy bodies, and frontotemporal dementia are the most frequent causes after AD, but a large proportion of patients have a combination of degenerative and vascular brain pathology. Characteristic magnetic resonance (MR) imaging findings can contribute to the identification of different diseases causing dementia. The MR imaging protocol should include axial T2-weighted images (T2-WI), axial fluid-attenuated inversion recovery (FLAIR) or proton density-weighted images, and axial gradient-echo T2*-weighted images, for the detection of cerebrovascular pathology. Structural neuroimaging in dementia is focused on detection of brain atrophy, especially in the medial temporal lobe, for which coronal high resolution T1-weighted images perpendicular to the long axis of the temporal lobe are extremely important. Single photon emission computed tomography and positron emission tomography may have added value in the diagnosis of dementia and may become more important in the future, due to the development of radioligands for in vivo detection of AD pathology. New functional MR techniques and serial volumetric imaging studies to identify subtle brain abnormalities may also provide surrogate markers for pathologic processes that occur in diseases causing dementia and, in conjunction with clinical evaluation, may enable a more rigorous and early diagnosis, approaching the accuracy of neuropathology.

Do vascular lesions and related risk factors influence responsiveness to donepezil chloride in patients with Alzheimer's disease?

The purpose was to identify vascular influences on the responsiveness to donepezil chloride. The study included 50 untreated probable Alzheimer's disease patients with the Modified Hachinski Ischemic Score <4. We assessed baseline cognitive status using the Revised Hasegawa Dementia Scale (HDS-R), Clinical Dementia Rating (CDR) and the clock drawing test (CDT). The response to 5 mg of donepezil was monitored by the CDT for 12 months. Patients were classified as true responders (TR), unchanged (UC) and non-responders according to changes on the CDT in response to treatment. High HDS-R scores, low CDT scores, low CDR and presence of hypertension (HBP) and periventricular hyperintensities (PVH) predicted a TR- or UC-type outcome. Aggravation of executive function by HBP and/or PVH and its improvement by donepezil may have been detected by the CDT.

[Arterial hypertension and dementia]

Arterial hypertension (AH) is considered to be an important risk factor for vascular cognitive impairment and probably for Alzheimer's disease, too. In the current review we provide an overview of the major prospective clinical trials on this issue. With respect to the inconsistent findings of these studies one must state that the interrelations between AH and dementia are still incompletely understood. Regarding therapy there thus is a simple rule: AH should be treated until normal blood pressure values are reached. As long as the hypothesis of a J-curve between blood pressure and cognitive dysfunction has not been disproved, overaggressive blood pressure lowering cannot be recommended. Regarding the aim of preventing dementia, there is no evidence for the superiority of a specific antihypertensive treatment regimen.

Characteristics of Mini-Mental State Examination 1 year after stroke

OBJECTIVES

The Mini-Mental State Examination (MMSE) is commonly used to evaluate cognition after stroke. The purpose of this study was to describe the properties of MMSE in relation to different stroke characteristics.

MATERIALS AND METHODS

Subjects were survivors (n = 253) of a population-based cohort who had had a first-ever stroke 1 year earlier. At baseline, patients were evaluated with regard to stroke type, stroke severity, unilateral neglect, and prestroke dementia. The 1-year follow-up included an MMSE, a functional evaluation according to the modified Rankin Scale (MRS) and a question regarding subjective memory problems.

RESULTS

The mean MMSE was 24.9. Patients with lacunar infarction scored 26.6. Impact of hemisphere localization was insignificant. Twenty-nine percent of the patients had cognitive impairment (cut-off <24). After adjustment for age and education, 16% had cognitive impairment; 41% of the patients had subjective memory problems. The kappa-value between subjective memory problems and dichotomized MMSE was 0.21. Patients with cognitive impairment scored at average 1.8 higher on the MRS.

CONCLUSIONS

If cut-off is used, the MMSE should be adjusted for age and education; otherwise the prevalence of cognitive impairment may be overestimated. Cognitive impairment heavily influences functional outcome. Subjective memory problems correlate poorly with MMSE. The impact of hemisphere location may previously have been overestimated.

Lack of Effect of Pravastatin on Cerebral Blood Flow or Parenchymal Volume Loss in Elderly at Risk for Vascular Disease

Background and Purpose— Ageing is associated with a decline in cerebral blood flow. Animal studies have shown that cholesterol-lowering therapy with statins might preserve cerebral blood flow (CBF). We examined the effect of 40 mg pravastatin on the decline in CBF and brain volume in a subset of elderly subjects participating in the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) trial.

Methods— Randomization was not stratified according to whether or not subjects participated in the MRI substudy. In 391 men (n=226) and women (n=165) aged 70 to 82 years (mean±SD, 75±3.2), we measured total CBF (in mL/min) at baseline and after a mean±SD follow-up of 33±1.4 months with a gradient-echo phase-contrast MRI technique. Total CBF was defined as the summed flows in both internal carotid and vertebral arteries. Parenchymal volume (whole brain) was segmented with the use of in-house–developed semiautomatic software.

Results— Total CBF significantly declined in the placebo-allocated group, from 521±83 to 504±92 mL/min ( P =0.0036) and in the pravastatin-allocated group from 520±94 to 506±92 mL/min ( P =0.018). This decline was not significantly different between treatment groups ( P =0.56). There was also a significant reduction in brain volume over time ( P <0.001), which was not different between the treatment groups ( P =0.47). When expressed per unit of parenchymal volume, the decline in CBF over time was no longer statistically significant.

Conclusions— Elderly people at risk for cerebral vascular disease had a significant decline in CBF with increasing age that was explained by a concomitant reduction in brain volume. Treatment with 40 mg pravastatin daily had no beneficial effect on total CBF.

Treatment of vascular dementia: evidence from epidemiologic studies

This article discusses the most relevant recent evidence on the prevention and treatment of vascular dementia from epidemiologic studies. Vascular dementia is the most common form of dementia after Alzheimer's disease and remains the only one that is preventable, although most of our knowledge about primary and secondary prevention of vascular dementia comes from direct extrapolation from works in stroke. Furthermore, at present there are no approved therapeutic agents for the treatment of vascular dementia. Recently, however, a number of reasonable studies on vascular dementia have been available. It is clear that rigorous control of vascular risk factors is important in primary and secondary prevention of vascular dementia, and perhaps in ameliorating its mild form. A rational therapeutic approach to the treatment of vascular dementia should be based on an understanding of its broad clinical spectrum and the diverse causes that may be responsive to currently available treatments.

Retinal vascular image analysis as a potential screening tool for cerebrovascular disease: a rationale based on homology between cerebral and retinal microvasculatures

The retinal and cerebral microvasculatures share many morphological and physiological properties. Assessment of the cerebral microvasculature requires highly specialized and expensive techniques. The potential for using non-invasive clinical assessment of the retinal microvasculature as a marker of the state of the cerebrovasculature offers clear advantages, owing to the ease with which the retinal vasculature can be directly visualized in vivo and photographed due to its essential two-dimensional nature. The use of retinal digital image analysis is becoming increasingly common, and offers new techniques to analyse different aspects of retinal vascular topography, including retinal vascular widths, geometrical attributes at vessel bifurcations and vessel tracking. Being predominantly automated and objective, these techniques offer an exciting opportunity to study the potential to identify retinal microvascular abnormalities as markers of cerebrovascular pathology. In this review, we describe the anatomical and physiological homology between the retinal and cerebral microvasculatures. We review the evidence that retinal microvascular changes occur in cerebrovascular disease and review current retinal image analysis tools that may allow us to use different aspects of the retinal microvasculature as potential markers for the state of the cerebral microvasculature.

Cerebral small-vessel disease and decline in information processing speed, executive function and memory

Cerebral small-vessel disease is common in older people and may contribute to the development of dementia. The objective of the present study was to evaluate the relationship between measures of cerebral small-vessel disease on MRI and the rate of decline in specific cognitive domains in participants from the prospective, population-based Rotterdam Scan Study. Participants were 60-90 years of age and free from dementia at baseline in 1995-1996. White matter lesions (WML), cerebral infarcts and generalized brain atrophy were assessed on the baseline MRI. We performed neuropsychological testing at baseline and repeatedly in 1999-2000 and in 2001-2003. We used random-effects models for repeated measures to examine the association between quantitative MRI measures and rate of decline in measures of global cognitive function, information processing speed, executive function and memory. There were a total of 2266 assessments for the 832 participants in the study, with an average time from the initial to last assessment of 5.2 years. Increasing severity of periventricular WML and generalized brain atrophy and the presence of brain infarcts on MRI were associated with a steeper decline in cognitive function. These structural brain changes were specifically associated with decline in information processing speed and executive function. The associations between MRI measures of cerebral small-vessel disease and cognitive decline did not change after additional adjustment for vascular risk factors or depressed mood. After exclusion of participants with an incident stroke, some of the associations of periventricular WML, brain infarcts and generalized brain atrophy with measures of information processing speed and executive function were no longer significant. This may indicate that stroke plays an intermediate role in the relationship between cerebral small-vessel disease and cognitive decline. Our results suggest that in older people cerebral small-vessel disease may contribute to cognitive decline by affecting information processing speed and executive function.

Cognitive Consequences of Thalamic, Basal Ganglia, and Deep White Matter Lacunes in Brain Aging and Dementia

Background and Purpose— Most previous studies addressed the cognitive impact of lacunar infarcts using radiologic correlations that are known to correlate poorly with neuropathological data. Moreover, absence of systematic bilateral assessment of vascular lesions and masking effects of Alzheimer disease pathology and macrovascular lesions may explain discrepancies among previous reports. To define the relative contribution of silent lacunes to cognitive decline, we performed a detailed analysis of lacunar and microvascular pathology in both cortical and subcortical areas of 72 elderly individuals without significant neurofibrillary tangle pathology or macrovascular lesions.

Methods— Cognitive status was assessed prospectively using the Clinical Dementia Rating (CDR) scale; neuropathological evaluation included Aβ-protein deposition staging and bilateral assessment of microvascular ischemic pathology and lacunes; statistical analysis included multivariate models controlling for age, amyloid deposits, and microvascular pathology.

Results— Thalamic and basal ganglia lacunes were negatively associated with CDR scores; cortical microinfarcts, periventricular and diffuse white matter demyelination also significantly affected cognition. In a multivariate model, cortical microinfarcts and thalamic and basal ganglia lacunes explained 22% of CDR variability; amyloid deposits and microvascular pathology explained 12%, and the assessment of thalamic and basal ganglia lacunes added an extra 17%. Deep white matter lacunes were not related to cognitive status in univariate and multivariate models.

Conclusions— In agreement with the recently proposed concept of subcortical ischemic vascular dementia, our autopsy series provides important evidence that gray matter lacunes are independent predictors of cognitive decline in elderly individuals without concomitant dementing processes such as Alzheimer disease.

Unifying concept for Alzheimer's disease, vascular dementia and normal pressure hydrocephalus - a hypothesis

The three common forms of dementias in the elderly include Alzheimer's disease (AD), vascular dementia (VD) and normal pressure hydrocephalus (NPH). These disorders are distinguished by their specific pathological features. However, overlapping clinical and imaging features in a given case are not too uncommon. Based on alterations in CSF dynamics study, a unifying concept in the pathogenesis of AD and NPH has been proposed recently which may have therapeutic implications. Altered CSF dynamics by affecting the absorptive process may lead to hydrocephalic change. This may also affect clearance of amyloid protein leading to increased amyloid deposition in brain parenchyma resulting in AD pathology. Hence it is likely that a subgroup of patients may have an AD-NPH syndrome who may be benefitted by CSF drainage procedure. The present author attempts to extend this concept to hypothesise a unifying concept to explain the pathophysiology of all the three disorders which may explain overlapping features observed clinically and in neuroimaging studies. It is surmised that altered CSF dynamics and hypoperfusion from vascular disease may be interlinked. The defective clearance of amyloid may also lead to amyloid angiopathy perpetuating hypoperfusion. Hypoperfusion may also affect formation as well as absorption of CSF altering clearance of amyloid and promoting vascular and parenchymal deposition. Thus the pathologies of AD, VaD and NPH get interrelated.

Donepezil: a clinical review of current and emerging indications

This article reviews the piperidine derivative, donepezil hydrochloride (E2020, Aricept), a reversible central acetylcholinesterase inhibitor currently approved for treatment of mild-to-moderate Alzheimer's disease. Donepezil is well absorbed orally, unaffected by food or by time of administration; it reaches therapeutic levels in doses of 5-10 mg/day and peak plasma concentrations are obtained 3-4 h after oral administration. A single bedtime dose is recommended due to the long elimination half-life of the drug (70 h). Donepezil does not cause liver toxicity or significant drug interactions and is relatively well-tolerated. Initial side effects include nausea, vomiting, diarrhoea, insomnia, muscle cramps, fatigue, anorexia and syncope. Caution is advised in patients with bradycardia. Long-term use of donepezil in AD has been found to delay nursing-home placement and to result in caregiver respite. Donepezil also slows deterioration of cognition and global function in patients with moderate-to-severe AD, with improvement of abnormal behaviours. In addition to AD, donepezil demonstrates significant improvement in cognition, global function and activities of daily living in comparison with placebo-treated patients with vascular dementia and has potential therapeutic benefit for other neurological conditions.

Efficacy and Safety of Nimodipine in Subcortical Vascular Dementia

Background and Purpose— Evidence of drug efficacy in vascular dementia (VaD) is scanty. Therapeutic trials should address VaD subtypes. We studied the efficacy and safety of the calcium antagonist nimodipine in subcortical VaD.

Methods— 242 patients defined as affected by subcortical VaD based on clinical (ICD-10) and computed tomography criteria were randomized to oral nimodipine 90 mg/d or placebo.

Results— 230 patients (121 nimodipine, mean age 75.2±6.1; 109 placebo, 75.4±6.0) were valid for the intention-to-treat analysis. At 52 weeks, the Sandoz Clinical Assessment Geriatric scale 5-point variation (primary outcome measure) did not differ significantly between the 2 groups. However, patients on nimodipine performed better than placebo patients in lexical production ( P <0.01) and less frequently showed deterioration (3 or more point-drop versus baseline) on a Mini-Mental State Examination (28.1% versus 50.5%; χ 2 P <0.01) and Global Deterioration Scale ( P <0.05). Dropouts and adverse events were all significantly more common among placebo than nimodipine patients, particularly cardiovascular (30 versus 13; RR, 2.26; 95% CI, 1.11 to 4.60) and cerebrovascular events (28 versus 10; RR, 2.48; 95% CI, 1.23 to 4.98), and behavioral disturbances requiring intervention (22 versus 5; RR, 3.88; 95% CI, 1.49 to 10.12). A worst-rank analysis, performed to correct for the effect of the high dropout rate in the placebo group, showed additional significant differences in favor of nimodipine in Set Test and MMSE total scores.

Conclusions— Nimodipine may be of some benefit in subcortical VaD. Confirming previous results, the safety analysis of this study shows that in this high-risk population, nimodipine might protect against cardiovascular comorbidities.

Cholinergic dysfunction in vascular dementia

Vascular dementia (VaD) is the second most common type of dementia in the elderly after Alzheimer's disease (AD). Evidence is presented indicating the occurrence of cholinergic dysfunction in VaD, independent from AD. Controlled clinical trials of cholinesterase inhibitors (ChEIs) in VaD and in patients with AD plus cerebrovascular disease are reviewed. Compared with placebo, ChEI treatment improves cognition, behavior, and activities of daily living. Cholinergic deficits in patients with VaD may result from ischemia of basal forebrain cholinergic nuclei that are irrigated by penetrating arteries that are highly susceptible to arterial hypertension, or from ischemic lesions in basal ganglia or white matter that sever the extensive cholinergic cortical projections. Cholinergic stimulation produces increases in cortical cerebral blood flow that may be relevant to the therapeutic effect of ChEIs.

Rivastigmine in vascular dementia

Patients with vascular dementia (VaD) show cholinergic deficits that may result in characteristic clinical syndromes for different subtypes of the condition. Subcortical VaD is characterised by executive dysfunction and behavioural problems, reflecting deterioration of the frontal lobe. Based on limited open-labelled controlled studies of rivastigmine in VaD, this article aims to determine whether rivastigmine, a dual inhibitor of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), has any effects on the typical symptoms of subcortical VaD. Long-term rivastigmine treatment is safe and effective. Improvements in domains that characterise subcortical VaD were observed, indicating that rivastigmine may have provided targeted treatment in areas of the brain that are particularly affected in this patient population. A large, double-blind study of rivastigmine in patients with VaD is clearly warranted.

Facts, myths, and controversies in vascular dementia

Significant progress in the field of VaD resulted from publication of the NINIDS-AIREN Diagnostic Criteria for VaD (G.C. Roman, T.K. Tatemichi, T. Erkinjuntti, et al., Vascular dementia (VaD): diagnostic criteria for research studies. Report of the NINDS-AIREN International Workshop. Neurology 43 (1993) 250-260). Epidemiological studies confirmed the importance of VaD as the second most common cause of dementia in the elderly, representing 15-20% of all cases of dementia. In Europe and North America, Alzheimer's disease (AD) predominates over VaD in a 2:1 ratio; in contrast, in Japan and China VaD accounts for almost 50% of all dementias. Case-control studies have identified risk factors for VaD including ageing, hypertension, diabetes mellitus, hyperlipidemia, recurrent stroke, cardiac disease, smoking, sleep apnea, and more recently, hyperhomocysteinemia, among others. Hypertension treatment may prevent VaD and AD. This finding has enormous importance from the Public Health viewpoint to decrease the future number of patients with dementia in the elderly. Along with advances in the field of VaD came a number of controversies and damaging misconceptions and myths. Myth no. 1--Vascular dementia is a non-entity: The false idea that VaD does not exist is particularly destructive because it creates the perspective that VaD is unworthy of study or research. A condition that either does not exist or represents only a minute proportion of all cases of dementia in the elderly, lacks public health relevance and becomes a low priority for research by funding agencies and industry. In fact, vascular brain lesions are the commonest and most important component of dementia in the elderly. Myth no. 2--Vascular dementia is so difficult to diagnose that only experts can recognize and identify it accurately: VaD does exist and the diagnosis of post-stroke VaD, in particular is straightforward. Most cases fulfill NINDS-AIREN criteria for probable VaD; i.e., (1) there is acute onset of dementia demonstrated by impairment of memory and two other cognitive domains, such as orientation, praxis or executive dysfunction; (2) relevant cerebrovascular lesions are demonstrated by neuroimaging; and (3) a temporal relation between stroke and cognitive loss is evident. In the donepezil trials on VaD, post-stroke dementia represented about 75% of the >1,200 patients enrolled. Myth no. 3--Improvement in clinical trials of cholinergics in VaD is due to underlying AD, not to the vascular lesions. Experimental, clinical and pathological evidence has demonstrated cholinesterase deficits in VaD (independently of any concomitant AD pathology), including low acetylcholine in cerebrospinal fluid, and reduced choline acetyltransferase (ChAT) in the brain.

Treatment of vascular dementia: evidence from trials with non-cholinergic drugs

A considerable number of therapeutic trials have been performed in vascular dementia (VaD). The results of these trials have generally been considered as disappointing and no drug treatment has been so far approved for the treatment of VaD by regulatory agencies. The aim of the present paper is to critically review the results of randomized clinical trials performed with non-cholinergic drugs in VaD. The conclusions of the present review are that: (1) some drugs such as nicergoline, memantine, posatirelin, propentofylline, and pentoxifylline have shown some, although partly limited, benefits in VaD patients; (2) besides a lack of efficacy of the tested drugs, possible causes of the negative results of many randomized clinical trials in VaD are the enrollment of patients with heterogeneous subtypes of VaD, the small sample size, and the use of end-points and cognitive tests inadequate for the VaD setting because derived from previous experience in the field of Alzheimer disease. Preliminary analyses show that focusing therapeutic trials on specific forms of VaD such as the subcortical type may lead to results different from those obtained in a heterogeneous VaD group. This selective focus seems to be better suited for disclosing specific treatments in the field of VaD.

White matter lesions impair frontal lobe function regardless of their location

OBJECTIVE

To analyze the effect of white matter lesions in different brain regions on regional cortical glucose metabolism, regional cortical atrophy, and cognitive function in a sample with a broad range of cerebrovascular disease and cognitive function.

METHODS

Subjects (n = 78) were recruited for a study of subcortical ischemic vascular disease (SIVD) and Alzheimer disease (AD) contributions to dementia. A new method was developed to define volumes of interest from high-resolution three-dimensional T1-weighted MR images. Volumetric measures of MRI segmented white matter signal hyperintensities (WMH) in five different brain regions were related to regional PET glucose metabolism (rCMRglc) in cerebral cortex, MRI measures of regional cortical atrophy, and neuropsychological assessment of executive and memory function.

RESULTS

WMH was significantly higher in the prefrontal region compared to the other brain regions. In all subjects, higher frontal and parietal WMH were associated with reduced frontal rCMRglc, whereas occipitotemporal WMH was only marginally associated with frontal rCMRglc. These associations were stronger and more widely distributed in nondemented subjects where reduced frontal rCMRglc was correlated with WMH for all regions measured. In contrast, there was no relationship between WMH in any brain region and rCMRglc in either parietal or occipitotemporal regions. WMHs in all brain regions were associated with low executive scores in nondemented subjects.

CONCLUSIONS

The frontal lobes are most severely affected by SIVD. WMHs are more abundant in the frontal region. Regardless of where in the brain these WMHs are located, they are associated with frontal hypometabolism and executive dysfunction.

Differential pattern of hand-tapping compromise in vascular versus idiopathic parkinsonism: A study based on computerized movement analysis

We tested the characteristics and the differential pattern of upper extremity motor compromise, comparing hand tapping in patients with subcortical vascular encephalopathy (SVE; n = 18), idiopathic Parkinson's disease (PD; n = 18), and in healthy controls (n = 18). Both patient groups showed significant compromise in hand tapping compared with that in controls, with higher coefficients of variability (CV) regarding tapping amplitude and angular velocity, determined using a computerized movement analysis system. A differential tapping pattern in both patient groups could be demonstrated in that patients with PD showed lower tapping amplitudes than patients with SVE. Both patient groups displayed abnormalities in tapping rhythmicity compared with that in the control group.

A life course approach to cognitive reserve: A model for cognitive aging and development?

The concept of reserve in neuroscience maintains that there are aspects of brain structure and function that can buffer the effects of neuropathology such that the greater the reserve, the more severe the pathology must be to cause functional impairment. This article provides a concise overview of structural and functional approaches to reserve and shows how reserve may be conceived as the sum of its lifetime input. In this context, reserve therefore provides an empirical yet general model of cognitive aging and development.