Vascular dementia: neuropathologic alterations and metabolic brain changes

Therapeutic potential of Thai herbal formula for cognitive impairment: A metabolomics approach for Comprehensive Insights

Chronic cerebral ischemia hypoperfusion plays a role in the initiation and progression of vascular dementia, which causes changes in metabolites. Currently, there is no standard treatment to treat, prevent and reduce the severity of this condition. Thai herbal Yahom no.20 (YHF20) is indicated for fatigue and dizziness. The components of YHF20 have been found to have pharmacological effects related to the pathology of chronic cerebral ischemia hypoperfusion. This study aimed to investigate metabolomic changes after YHF20 administration in a rat model of permanent bilateral common carotid artery occlusion (2-VO) induced chronic cerebral ischemia hypoperfusion, and to explore its impact on spatial learning and memory. Albino Wistar rats were randomly allocated to 5 groups; sham, 2-VO, 2-VO+ 100 mg/kg YHF20, 2-VO+300 mg/kg YHF20, and 2-VO+1000 mg/kg YHF20. The rats were administered YHF20 daily by oral gavage for 56 days after 2-VO induction. Plasma was collected weekly for metabolome change analysis using LC-MS/QTof and toxicity study. The rats were evaluated for spatial learning and memory using the Morris water maze. The results showed that 78 known metabolites and 10 tentative pathways altered after chronic cerebral hypoperfusion, although it was not able to determine the effect on memory and learning behaviors of rats. Glutathione and glutathione metabolism might be metabolite-pathway that were the affect after YHF20 administration in cerebral ischemic condition. The 4 known metabolites may be the metabolites from the constituents of YHF20 could be considered and confirmed for quality control purpose. In conclusion, YHF20 administration might contribute to metabolic changes related to cerebral ischemia condition without the effect on spatial learning and memory, including hepatotoxicity and nephrotoxicity after 56 days of treatment. Alterations in the potential metabolites may provide data support for elucidating dementia pathogenesis and selecting pathways for intervention.

Hepatopancreatic metabolic disorders and their implications in the development of Alzheimer's disease and vascular dementia

Dementia has been faced with significant public health challenges and economic burdens that urges the need to develop safe and effective interventions. In recent years, an increasing number of studies have focused on the relationship between dementia and liver and pancreatic metabolic disorders that result in diseases such as diabetes, obesity, hypertension and dyslipidemia. Previous reports have shown that there is a plausible correlation between pathologies caused by hepatopancreatic dysfunctions and dementia. Glucose, insulin and IGF-1 metabolized in the liver and pancreas probably have an important influence on the pathophysiology of the most common dementias: Alzheimer's and vascular dementia. This current review highlights recent studies aimed at identifying convergent mechanisms, such as insulin resistance and other diseases, linked to altered hepatic and pancreatic metabolism, which are capable of causing brain changes that ultimately lead to dementia.

Small vessel disease to subcortical dementia: a dynamic model, which interfaces aging, cholinergic dysregulation and the neurovascular unit

Background

Small vessels have the pivotal role for the brain’s autoregulation. The arteriosclerosis-dependent alteration of the brain perfusion is one of the major determinants in small vessel disease. Endothelium distress can potentiate the flow dysregulation and lead to subcortical vascular dementia (sVAD). sVAD increases morbidity and disability. Epidemiological studies have shown that sVAD shares with cerebrovascular disease most of the common risk factors. The molecular basis of this pathology remains controversial.

Purpose

To detect the possible mechanisms between small vessel disease and sVAD, giving a broad vision on the topic, including pathological aspects, clinical and laboratory findings, metabolic process and cholinergic dysfunction.

Methods

We searched MEDLINE using different search terms (“vascular dementia”, “subcortical vascular dementia”, “small vessel disease”, “cholinergic afferents”, etc). Publications were selected from the past 20 years. Searches were extended to Embase, Cochrane Library, and LILIACS databases. All searches were done from January 1, 1998 up to January 31, 2018.

Results

A total of 560 studies showed up, and appropriate studies were included. Associations between traditional vascular risk factors have been isolated. We remarked that SVD and white matter abnormalities are seen frequently with aging and also that vascular and endothelium changes are related with age; the changes can be accelerated by different vascular risk factors. Vascular function changes can be heavily influenced by genetic and epigenetic factors.

Conclusion

Small vessel disease and the related dementia are two pathologies that deserve attention for their relevance and impact in clinical practice. Hypertension might be a historical problem for SVD and SVAD, but low pressure might be even more dangerous; CBF regional selective decrease seems to be a critical factor for small vessel disease-related dementia. In those patients, endothelium damage is a super-imposed condition. Several issues are still debatable, and more research is needed.

Vascular cognitive impairment: A preventable component of dementia

For many decades during the 20th century, the common belief was that the slow strangulation of the brains' blood supply from hardening of the brain arteries led to chronic brain ischemia and neuronal death. Not surprisingly, to counter this, vasodilators rapidly became one of the most commonly used and profitable medications worldwide; however, no clinical benefits were ever proven. In the 1970s and early 1980s cerebral blood flow studies strongly disproved the idea of brain failure due to chronic ischemia. It was also shown that infarcts and not chronic ischemia caused dementia, leading to the concept of multiinfarct dementia. In addition to infarcts, it was then realized that other vascular lesions can also cause cognitive decline. Gradually, as "atherosclerotic dementia" lost ground, Alzheimer's disease (AD) that once had been considered a presenile dementia and rare, became almost synonymous with dementia. Subsequent memory-based definitions and evaluations of dementia led to a bias in favor of diagnosing AD, overshadowing vascular contributions. The widespread use of brain imaging in the 1980s and 1990s contributed to the resurgence of evidence of cerebrovascular diseases. Moreover, it was shown that most cognitive impairment of the elderly results from mixed pathologies, emphasizing the need for a change in the traditional categorical diagnosis of dementia, e.g., AD vs vascular dementia. The alternative diagnostic method was named the vascular cognitive impairment approach, meaning identifying any impairment caused by or associated with vascular factors. The importance of this approach is that vascular lesions are currently the most important treatable and preventable components of dementia, even before any symptoms manifest, i.e., at the brain at risk stage. This chapter provides a summary of the vascular cognitive impairment approach to diagnosis, treatment, and prevention of cognitive decline.

Platelets in the Alzheimer's disease brain: do they play a role in cerebral amyloid angiopathy?

Alzheimer’s disease (AD) is characterized by extracellular beta-amyloid plaques and intracellular tau tangles. AD-related pathology is often accompanied by vascular changes. The predominant vascular lesions in AD are cerebral amyloid angiopathy (CAA) and arteriosclerosis. Platelets circulate along the vessel wall responding immediately to vascular injury. The aim of the present study was to explore the presence and migration of platelets (thrombocytes) to sites of small vascular bleedings and/or to beta-amyloid plaques in the brain. We infused fluorescently labeled red PKH26 mouse platelets into transgenic Alzheimer mice overexpressing APP with Swedish/Dutch/Iowa mutations (APP_SDI) and explored if platelets migrate into the brain. Further we studied whether platelets accumulate in the vicinity of β-amyloid plaques. Our animal data shows that infused platelets are found in the liver and partly in the lung, while in the brain platelets were visible to a minor degree. In mice, we did not observe a significant association of platelets with beta-amyloid plaques or vessels. In the brain of Alzheimer postmortem patients platelets could be detected by immunohistochemistry for CD41 and CD62P, but the majority was found in vessels with or without beta-amyloid load, and only a few single platelets migrated deeper into the brain. Our findings suggest that platelets do not migrate into the brains of Alzheimer disease but are concentrated in brain vessels.

Pathogenesis and treatment of vascular cognitive impairment

SUMMARY 

Vascular cognitive impairment (VCI) defines a continuum of disorders ranging from mild cognitive impairment to full-blown dementia, attributable to cerebrovascular causes. Major morphological types – multi-infarct encephalopathy, strategic infarct type, subcortical arteriosclerotic leukoencephalopathy, multilacunar state, postischemic encephalopathy – result from systemic, cardiac and local large or small vessel disease. Cognitive decline is commonly caused by widespread small cerebrovascular lesions (CVLs) affecting regions/networks essential for cognition, memory and behavior. CVLs often coexist with Alzheimer-type and other pathologies, which interact in promoting dementia, but in many nondemented elderly individuals, mixed brain pathologies are also present. Due to the high variability of CVLs, no validated clinical and neuropathological criteria for VCI are available. Cholinesterase inhibitors and memantine produce small cognitive improvement but without essential effect. Antihypertensive treatment, cardiovascular control and lifestyle modifications reducing vascular risk factors are essential. Given its growing health, social and economic burden, prevention and treatment of VCI are a major challenge of neuroscience.

Pathology and pathogenesis of vascular cognitive impairment-a critical update

Vascular cognitive impairment (VCI) [vascular cognitive disorder (VCD), vascular dementia] describes a continuum of cognitive disorders ranging from mild cognitive impairment (MCI) to dementia, in which vascular brain injury involving regions important for memory, cognition and behavior plays an important role. Clinical diagnostic criteria show moderate sensitivity (ca 50%) and variable specificity (range 64-98%). In Western clinical series, VaD is suggested in 8-10% of cognitively impaired elderly subjects. Its prevalence in autopsy series varies from 0.03 to 58%, with means of 8 to 15% (in Japan 22-35%). Major types of sporadic VaD are multi-infarct encephalopathy, small vessel and strategic infarct type dementias, subcortical arteriosclerotic leukoencephalopathy (SAE) (Binswanger), multilacunar state, mixed cortico-subcortical type, granular cortical atrophy (rare), postischemic encephalopathy, and a mixture of cerebrovascular lesions (CVLs). They result from systemic, cardiac and local large or small vessel disease (SVD); their pathogenesis is multifactorial. Hereditary forms of VaD caused by gene mutations are rare. Cognitive decline is commonly associated with widespread small ischemic vascular lesions involving subcortical brain areas (basal ganglia and hemispheral white matter). The lesions affect neuronal networks involved in cognition, memory, and behavior (thalamo-cortical, striato-subfrontal, cortico-subcortical, limbic systems). CVLs often coexist with Alzheimer-type lesions and other pathologies; 25-80% of elderly demented show mixed pathologies. The lesion pattern of "pure" VaD differs from that in mixed dementia (AD + CVLs) suggesting different pathogenesis of both phenotypes. Minor CVLs, except for severe amyloid angiopathy, appear not essential for cognitive impairment in full-blown AD, while both mild AD-type pathology and SVD may interact synergistically in promoting dementia. However, in a large percentage of non-demented elderly individuals, both AD-related and vascular brain pathologies have been reported. Despite recent suggestions for staging and grading CVLs in specific brain areas, due to the high variability of CVLs associated with cognitive impairment, no validated neuropathological criteria are currently available for VaD and mixed dementia. Further clinico-pathological studies and harmonization of neuropathological procedures are needed to validate the diagnostic criteria for VaD and mixed dementia in order to clarify the impact of CVLs and other coexistent pathologies on cognitive impairment as a basis for further successful therapeutic options.

Is there pure vascular dementia in old age?

Vascular dementia (VaD) has been suggested to be the most common form of dementia in old age, but clinico-pathologic studies showed big differences in its epidemiology. A retrospective hospital-based study of the frequency and pathology of "pure" VaD (due to cerebrovascular disease without other pathologies) was performed in 1110 consecutive autopsy cases of demented elderly in Vienna, Austria. It assessed clinical, general autopsy data and neuropathology including immunohistochemistry. Neuropathologic diagnosis followed current consensus criteria. Four age groups (7th to 10th decades) were evaluated. "Pure" VaD was observed in 10.8% of the total cohort, decreasing from age 60 to 90+. 85-95% had histories of diabetes, morphologic signs of hypertension, 65% myocardial infarction/cardiac decompensation, and 75% a history of stroke(s). Neuritic AD-pathology was low (mean Braak stages 1.2-1.6). Morphologic subtypes (multi-infarct (MID), subcortical arteriosclerotic (SAE)-the most frequent, and strategic infarct dementia (SID)) showed no age-related differences. By contrast, AD (without vascular or Lewy pathologies), mixed dementia (AD+cerebrovascular encephalopathy), and AD with minor cerebrovascular lesions increased with age. AD+Lewy pathology and other dementias decreased significantly over age 90. This retrograde study using strict morphologic diagnostic criteria confirmed the existence of "pure" VaD in old age, with a tendency to decline at age 90+, while AD and AD+cerebrovascular pathologies showed considerable age-related increase. Another autopsy study distinguishing two age groups of demented showed a significant increase of both AD and cerebral amyloid angiopathy (CAA), but decrease of VaD over age 85, while in a small subgroup of old subjects CAA without considerable AD-pathology may be an independent risk factor for cognitive decline.

Prevalence of dementia disorders in the oldest-old: an autopsy study

The prevalence of Alzheimer disease (AD) and vascular dementia (VD) increases with advancing age, but less so after age 90 years. A retrospective hospital-based study of the relative prevalence of different disorders was performed in 1,110 consecutive autopsy cases of demented elderly in Vienna, Austria (66% females, MMSE <20; mean age 83.3 +/- 5.4 SD years). It assessed clinical, general autopsy data and neuropathology including immunohistochemistry. Neuropathologic diagnosis followed current consensus criteria. Four age groups (7-10th decade) were evaluated. In the total cohort AD pathology was seen in 82.9% ("pure" AD 42.9%; AD + other pathologies 39.9%), VD in 10.8% (mixed dementia, MIX, i.e. AD + vascular encephalopathy in 5.5%); other disorders in 5.7%, and negative pathology in 0.8%. The relative prevalence of AD increased from age 60 to 89 years and decreased slightly after age 90+, while "pure" VD diagnosed in the presence of vascular encephalopathy of different types with low neuritic AD pathology (Braak stages <3; mean 1.2-1.6) decreased progressively from age 60 to 90+; 85-95% of these patients had histories of diabetes, morphologic signs of hypertension, 65% myocardial infarction/cardiac decompensation, and 75% a history of stroke(s). Morphologic subtypes, subcortical arteriosclerotic (the most frequent), multi-infarct encephalopathy, and strategic infarct dementia showed no age-related differences. The relative prevalence of AD + Lewy pathology remained fairly constant with increasing age. Mixed dementia and AD with minor cerebrovascular lesions increased significantly with age, while other dementias decreased. This retrospective study using strict morphologic criteria confirmed increased prevalence of AD with age, but mild decline at age 90+, and progressive decline of VD, while AD + vascular pathologies including MIX showed considerable age-related increase, confirming that mixed pathologies account for most dementia cases in very old persons. A prospective clinicopathologic study in oldest-old subjects showed a significant increase in both AD and cerebral amyloid angiopathy (CAA), but decrease in VD over age 85, while in a small group of old subjects CAA without considerable AD pathology may be an independent risk factor for cognitive decline.

Contribution of vascular pathology to the clinical expression of dementia

Vascular lesions in the brain are common with advancing age; however, the independent and cumulative contributions of postmortem vascular lesions to antemortem cognitive status are not well established. We examined association of six vascular lesions (large infarcts, lacunar infarcts, leukoencephalopathy, microinfarcts, cribriform changes, and cerebral amyloid angiopathy) with antemortem diagnoses of dementia, Alzheimer's disease (AD), and vascular dementia (VaD) in 190 older adults from an autopsy series. We also developed a summary score based on three macroscopic vascular lesions: large infarcts (0, 1, and >or=2), lacunar infarcts (0, 1, and >or=2), and leukoencephalopathy (none, mild, and moderate-to-severe). Sixty-eight percent of cases had vascular lesions. Only leukoencephalopathy was associated with dementia (odds ratio (OR) 3.5, 95% CI 1.0-12.4), and only large infarcts were associated with VaD (OR 4.3, 95% CI 1.2-15.4). The vascular score was associated with dementia (OR 1.6, 95% CI 1.2-2.3), AD (OR 1.5, 95% CI 1.0-2.1) and VaD (OR 2.0, 95% CI 1.4-3.0). Leukoencephalopathy, large infarcts, and higher vascular burden is associated with the clinical expression of dementia and subtypes.

The enigma of vascular cognitive disorder and vascular dementia

The prevalence, morphology and pathogenesis of vascular dementia (VaD), recently termed vascular cognitive impairment, are a matter of discussion, and currently used clinical diagnostic criteria show moderate sensitivity (average 50%) and variable specificity (range 64-98%). In Western clinic-based series, VaD is suggested in 8-10% of cognitively impaired aged subjects. Its prevalence in autopsy series varies from 0.03 to 58%, with reasonable values of 8-15%, while in Japan it is seen in 22-35%. Neuropathologic changes associated with cognitive impairment include multifocal and/or diffuse disease and focal lesions: multi-infarct encephalopathy, white matter lesions or arteriosclerotic subcortical (leuko)encephalopathy, multilacunar state, mixed cortico-subcortical type, borderline/watershed lesions, rare granular cortical atrophy, post-ischemic encephalopathy and hippocampal sclerosis. They result from systemic, cardiac and local large or small vessel disease. Recent data indicate that cognitive decline is commonly associated with widespread small ischemic/vascular lesions (microinfarcts, lacunes) throughout the brain with predominant involvement of subcortical and functionally important brain areas. Their pathogenesis is multifactorial, and their pathophysiology affects neuronal networks involved in cognition, memory, behavior and executive functioning. Vascular lesions often coexist with Alzheimer disease (AD) and other pathologies. Minor cerebrovascular lesions, except for severe amyloid angiopathy, appear not essential for cognitive decline in full-blown AD, while both mild Alzheimer pathology and small vessel disease may interact synergistically. The lesion pattern of "pure" VaD, related to arteriosclerosis and microangiopathies, differs from that in mixed-type dementia (AD with vascular encephalopathy), more often showing large infarcts, which suggests different pathogenesis of both types of lesions. Due to the high variability of cerebrovascular pathology and its causative factors, no validated neuropathologic criteria for VaD are available, and a large variability across laboratories still exists in the procedures for morphologic examination and histology techniques.

The role of cerebrovascular disease in dementia

BACKGROUND

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

REVIEW SUMMARY

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

CONCLUSIONS

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

Vascular cognitive impairment

Cerebrovascular disease is the second most common cause of acquired cognitive impairment and dementia and contributes to cognitive decline in the neurodegenerative dementias. The current narrow definitions of vascular dementia should be broadened to recognise the important part cerebrovascular disease plays in several cognitive disorders, including the hereditary vascular dementias, multi-infarct dementia, post-stroke dementia, subcortical ischaemic vascular disease and dementia, mild cognitive impairment, and degenerative dementias (including Alzheimer's disease, frontotemporal dementia, and dementia with Lewy bodies). Here we review the current state of scientific knowledge on the subject of vascular brain burden. Important non-cognitive features include depression, apathy, and psychosis. We propose use of the term vascular cognitive impairment, which is characterised by a specific cognitive profile involving preserved memory with impairments in attentional and executive functioning. Diagnostic criteria have been proposed for some subtypes of vascular cognitive impairment, and there is a pressing need to validate and further refine these. Clinical trials in vascular cognitive impairment are in their infancy but support the value of therapeutic interventions for symptomatic treatment.

Vascular-ischemic dementia: an update

Both the clinical criteria and morphologic substrates of dementia resulting from cerebrovascular disease and its relation to Alzheimer disease and other age-related brain changes are controversial. In clinical and autopsy studies in the Western world the prevalence of vascular-ischemic dementia (VID) is around 7-10%, while vascular cognitive impairment without dementia is much more frequent and the risk of poststroke dementia is increased in patients with prestroke cognitive decline. In contrast to previous suggestions that VID was largely the result of large hemispheral infarcts, according to recent studies, it is most commonly associated with widespread small ischemic or vascular lesions (microinfarcts, lacunes) throughout the CNS with predominant subcortical lesions in the basal ganglia and white matter or in strategically important brain regions (thalamus, hippocampus). The lesion pattern of rare "pure" VID, which is related to arteriolosclerotic and hypertensive microangiopathy, differs from that in mixed type dementia (Alzheimer disease and cerebrovascular lesions) that more often shows larger hemispheral infarcts. Another form of VID that is not infrequent in very old subjects is hippocampal sclerosis, a selective damage to the hippocampus that is often accompanied by multiple other cerebrovascular lesions. Both, mild Alzheimer type pathology and small vessel disease-associated subcortical vascular pathology appear to be common and may interact in causing cognitive decline, but the impact of cerebrovascular lesions on cognitive impairment and dementia needs to be further elucidated.

Pathological lesions in vascular dementia

According to current diagnostic criteria, a definite diagnosis of vascular dementia (VaD) can be reached on pathological grounds by showing the presence of vascular lesions and the absence of degenerative changes exceeding those expected for age. However, while it is commonly accepted that VaD is a group of heterogeneous entities rather than a process with a unique pathological substrate, the spectrum of vessel and parenchyma changes etiologically associated with the clinical syndrome remains basically unidentified. The review of some recent clinical-pathological series shows that different studies have assessed the presence of dissimilar vascular lesions and that, in many cases, no pathological definition was given. This has hindered the clarification of clinical-pathological correlations in the field of VaD. In this scenario, the use of animal models of cerebrovascular diseases may help to elucidate the type of lesions possibly linked with cognitive impairment in humans and might provide insight into some of the pathophysiological mechanisms of vascular cognitive impairment. A consensus is today needed in order to harmonize the pathological examination of vascular lesions in cases of dementia. An ongoing survey aimed at collecting information about the procedures used in different pathological laboratories in the assessment of lesions possibly associated with dementia is finally presented.

Neuropathologic substrates of ischemic vascular dementia

Ischemic vascular dementia (IVD) is a relatively uncommon entity, in the course of which multiple ischemic brain lesions result in progressive cognitive and memory impairment. Ischemic brain lesions may also aggravate the neuropsychologic deficit of Alzheimer disease (AD). In this review we summarize our experience based upon autopsy examination of the central nervous system in 20 patients (age range 68-92 years) enrolled in a longitudinal investigation of structural, neurochemical, functional neuroimaging, and neuropsychologic components of IVD, especially dementia associated with cerebral microvascular disease. While cystic infarcts were present in the CNS of 5 patients, the most commonly observed neuropathologic abnormalities were lacunar infarcts and microinfarcts--both types of lesion were encountered in over half of patients' brains. Evidence of (remote) hippocampal injury was found in 11/20 patients. Severe atherosclerosis and arterio/ arteriolosclerosis were both associated with the occurrence of multiple lacunar infarcts. Pronounced cerebral amyloid angiopathy (CAA) was noted in a single patient, who also showed other microscopic changes of severe AD. While fairly unusual as a nosologic entity, IVD appears to correlate with widespread small ischemic lesions distributed throughout the CNS. We furthermore propose an approach to quantifying the burden of ischemic vascular and parenchymal disease that may be associated with a dementia syndrome. A brief review of neuropathologic features of vascular dementia (both familial and sporadic) is presented.

Efficacy and safety of nimodipine in subcortical vascular dementia: a subgroup analysis of the Scandinavian Multi-Infarct Dementia Trial

In Western countries, vascular dementia (VaD) is the most common form of cognitive deterioration after Alzheimer's disease. Therapeutic trials in VaD have so far failed to yield satisfactory results. One explanation of this failure may be the etiological and clinical heterogeneity of the included patients. Patients with subcortical VaD, defined on a clinical and radiological basis, may constitute a more homogeneous group. Thus, we conducted a post-hoc subgroup analysis of the Scandinavian Multi-Infarct Dementia Trial that evaluated the efficacy and safety of oral nimodipine administered for 6 months in 259 patients. The original patients sample was divided on the basis of head CT in those with subcortical VaD (n=92, 45 nimodipine, 47 placebo) and those with multi-infarct dementia (n=167, 83 nimodipine, 84 placebo). While in the total trial population a treatment effect could not be proved, in this subgroup analysis, the subcortical VaD patients treated with nimodipine performed better on the majority of neuropsychological tests and functional scales in comparison with patients on placebo. No trend could be evidenced in the multi-infarct dementia patients. Treatment efficacy was in particular suggested for the Zahlen-Verbindungs-Test, Fuld-Object-Memory Evaluation, Word Fluency, and for the Instrumental Activities of Daily Living scale. The results did not reach statistical significance in this small sample. Our study preliminarily indicates that nimodipine could be effective in patients with small vessel subcortical VaD and supports the rationale for a further controlled and adequately powered trial to test nimodipine in patients with subcortical VaD.

Dementia with leukoaraiosis: clinical differentiation by temporoparietal hypometabolism on (18)FDG-PET imaging

Patients with dementia and leukoaraiosis may have either Alzheimer's disease (AD) with cerebrovascular changes or a form of vascular dementia (VaD). The presence or absence of the characteristic AD pattern of bilateral temporoparietal hypometabolism on (18)FDG-PET was used to differentiate 30 patients with progressive dementia and severe leukoaraiosis. Compared to 18 patients with the typical AD pattern (group I), the remaining 12 (group II) had better recognition memory, and greater difficulty with sustained attention and serial reversals. Better recognition memory, confluent periventricular leukoaraiosis, and poorer sustained attention distinguished all group II patients from group I. Dementia patients with severe leukoaraiosis and bilateral temporoparietal hypometabolism may have predominant AD; those who lack this pattern and have confluent leukoaraiosis may have a greater contribution from VaD. Copyrightz1999S.KargerAG,Basel

Aging and cerebrovascular disease

Aging influences cerebrovascular disease expression by a variety of mechanisms. Age-related changes in cerebral autoregulation, cellular metabolism, the blood-brain barrier, and autonomic function may leave the cerebrovascular system vulnerable to injury. Certain cerebrovascular disease, such as atrial fibrillation, watershed infarctions, carotid artery atherosclerosis, cerebral hemorrhages, subdural hematomas, and transient global amnesia manifest in the elderly. Vascular dementia and white matter disease are better understood with newer neuroimaging studies, careful neuropsychological and histopathologic examinations. Atherosclerosis and cerebral amyloid angiopathy may have larger roles than previously understood in Alzheimer's disease.

Vascular pathology in three cases of progressive cognitive deterioration

The clinical condition known as vascular dementia remains poorly defined. Few studies have attempted a correlative link between the clinical syndrome and the structural abnormalities of the brain. Classically the clinical progression of the vascular dementing process is thought to be a multi-step process punctated by repeated episodes of ischemia, that are clinically expressed as strokes. In most instances it has been assumed that the substrate of vascular dementias consists of atherothrombotic infarcts. The objective of this report is to illustrate 3 cases of progressive (rather than stepwise) cognitive deterioration without clinical evidence of stroke, evolving over a period of several years, in which there were prominent vascular lesions. A complete autopsy and detailed neuropathologic examination demonstrated cerebral vascular lesions involving small arterial vessels (< 200 microns in diameter). The lesions consisted of moderate-to-severe arteriolosclerosis in two cases, and mild-to-moderate arteriolosclerosis in a case of Alzheimer's disease with severe cerebral amyloid angiopathy. Parenchymal lesions consisted of small cortical and subcortical infarcts, most of them smaller than 0.1 cm in average diameter, and subcortical leukoencephalopathy severe in two cases and mild-to-moderate in the third case. Severe atherosclerosis not accompanied by large infarcts was also present in one case. Arterial changes affecting small, distal branches causing sometimes small parenchymal lesions in association with diffuse cerebral white matter disease, appear to be the anatomical substrate that accompanies progressive cognitive impairment in some patients who are frequently diagnosed with Alzheimer's disease because in their clinical records there is neither history of strokes nor stepwise progression of symptoms.

Some methodological issues in neuroradiological research in psychiatry

An outline is given of some of the methodological issues discussed in neuroradiological research on psychiatric illness. Strengths and shortcomings of magnetic resonance imaging (MRI) in depicting and quantifying brain structures are described. Temporal lobe anatomy and pathology are easily accessible to MRI, whereas limits on anatomical delineation hamper approaches to frontal lobe study. White matter hyperintense lesions are sensitively depicted by MRI, but specificity is limited. Distinction of vascular and primary degenerative dementia is considerably improved by CT and MRI analysis. Computed tomography (CT) and MRI have enhanced the understanding of treatable organic psychiatric disorders, e.g., normal pressure hydrocephalus. Subcortical and white matter pathology has been replicated in CT and MRI studies of late-onset psychiatric disorders, clinical overlap with cerebrovascular disease or neurodegeneration may be of import. Transcranial sonography findings of brainstem structural change specific to unipolar depression may contribute to the understanding of affective psychoses. Magnetic resonance spectroscopy and functional MRI are likely to stimulate psychiatric research in the future.

Hippocampal sclerosis: a common pathological feature of dementia in very old (> or = 80 years of age) humans

In a neuropathological study of 81 brains of prospectively studied subjects of 80 years of age or older at the time of death, 13 cases (16%), including 4 men and 9 women, had hippocampal sclerosis (HpScl) affecting the vulnerable region of the hippocampus. In demented subjects of 80 years of age or older, the frequency of HpScl was even higher, 26%. Cases with HpScl had significantly fewer hippocampal senile plaques (SP) and neurofibrillary tangles (NFT) and parahippocampal NFT than cases without HpScl, but did not differ significantly in any of the other measured pathological parameters. Enzyme-linked analysis of synaptic protein immunoreactivity in a subset of 33 cases demonstrated significant decreases in the hippocampus, but not in frontal, temporal, parietal or parahippocampal cortices. All but 1 of the cases with HpScl had Blessed information, memory and concentration scores (BIMC) of 8 or more, and all were considered to be demented. In some patients memory disturbance was disproportionate to deficits in other cognitive areas. All but 4 of the cases with HpScl had many non-neuritic, amyloid plaques in the neocortex meeting NIA criteria for Alzheimer's disease (AD); however, given the advanced age of the subjects, amyloid plaques were considered to represent age-related cerebral amyloid deposition ("pathological aging") in most cases. Only 3 cases had both many SP and NFT in multiple cortical regions consistent with AD. Another case had brain stem and cortical Lewy bodies consistent with diffuse Lewy body disease (DLBD). A few ballooned neurons were present in the limbic cortices in 3 cases, including one case of dementia with argyrophilic grains (DAG) in limbic and orbital frontal and temporal cortices. The 8 cases without AD, DLBD or DAG included 4 cases in which no other obvious cause of dementia was detected and 4 cases in which HpScl was accompanied by either multiple cerebral infarcts or leukoencephalopathy, or both, that could have contributed to dementia. Patients with HpScl had risk factors, clinical signs and post-mortem pathological findings of cardiovascular disease, but due to the high prevalence of these conditions in very old humans, no significant correlation with HpScl was detected. This study demonstrates that HpScl is a common post-mortem finding in demented, but not normal, elderly subjects. It may contribute to. or be a marker for, the increased risk of dementia in subjects with documented cardiovascular disease or a history of myocardial infarction.

Pathological markers associated with normal aging and dementia in the elderly

We investigated the associations of pathological markers of Alzheimer's disease (AD) and diffuse Lewy body disease as well as possible markers of vascular dementia with cognitive function in a sample of 20 nondemented and 35 demented subjects (median age of both groups, 88 years) who had been studied prospectively for 4.0 +/- 2.1 years. Very old demented subjects almost always had nonneuritic senile plaques, but over half had no neuritic senile plaques and little other AD pathology. Five subjects had cortical Lewy bodies; all were demented. We propose that hippocampal sclerosis, leukoencephalopathy, and multiple lacunae are possible markers of vascular dementia. When grouped together, these markers were significantly associated with dementia and occurred in 40% of demented subjects. As the relative frequency of neuritic markers of AD (and possibly AD itself) declines in the tenth decade, vascular dementia may become an increasingly important type of dementia.