Cognitive impairment of vascular origin: neuropathology of cognitive impairment of vascular origin

Neuroimaging determinants of cognitive impairment in the memory clinic: how important is the vascular burden?

While neurodegenerative and vascular neurocognitive disorder (NCD) often co-occur, the contribution of vascular lesions, especially stroke lesions identified on MRI, to global cognition in a real-life memory clinic population remains unclear. The main objective of this retrospective study was to determine NCD neuroimaging correlates: the GM atrophy pattern and vascular lesions (especially stroke lesion localization by voxel-based lesion-symptom mapping, VLSM) in a memory clinic. We included 336 patients with mild or major NCD who underwent cerebral MRI and a neuropsychological assessment. The GM atrophy pattern (obtained by voxel-based morphometry, VBM) and the stroke lesion localization (obtained by VLSM) associated with G5 z-score (a global cognitive score), were included as independent variables with other neuroimaging and clinical indices in a stepwise linear regression model. The mean age was 70.3 years and the mean MMSE score 21.3. On MRI, 75 patients had at least one stroke lesion. The G 5 z-score was associated with GM density in the pattern selected by the VBM analysis (R2 variation = 0.166, p < 0.001) and the presence of a stroke lesion in the region selected by the VSLM analysis (mainly in the right frontal region; R2 variation = 0.018, p = 0.008). The interaction between the two factors was insignificant (p = 0.374). In conclusion, in this first study combining VBM and VLSM analysis in a memory clinic, global cognition was associated with a specific GM atrophy pattern and the presence of a stroke lesion mainly in the right frontal region.

Association Between Acute Myocardial Infarction and Cognition

Importance

The magnitude of cognitive change after incident myocardial infarction (MI) is unclear.

Objective

To assess whether incident MI is associated with changes in cognitive function after adjusting for pre-MI cognitive trajectories.

Design, Setting, and Participants

This cohort study included adults without MI, dementia, or stroke and with complete covariates from the following US population-based cohort studies conducted from 1971 to 2019: Atherosclerosis Risk in Communities Study, Coronary Artery Risk Development in Young Adults Study, Cardiovascular Health Study, Framingham Offspring Study, Multi-Ethnic Study of Atherosclerosis, and Northern Manhattan Study. Data were analyzed from July 2021 to January 2022.

Exposures

Incident MI.

Main Outcomes and Measures

The main outcome was change in global cognition. Secondary outcomes were changes in memory and executive function. Outcomes were standardized as mean (SD) T scores of 50 (10); a 1-point difference represented a 0.1-SD difference in cognition. Linear mixed-effects models estimated changes in cognition at the time of MI (change in the intercept) and the rate of cognitive change over the years after MI (change in the slope), controlling for pre-MI cognitive trajectories and participant factors, with interaction terms for race and sex.

Results

The study included 30 465 adults (mean [SD] age, 64 [10] years; 56% female), of whom 1033 had 1 or more MI event, and 29 432 did not have an MI event. Median follow-up was 6.4 years (IQR, 4.9-19.7 years). Overall, incident MI was not associated with an acute decrease in global cognition (-0.18 points; 95% CI, -0.52 to 0.17 points), executive function (-0.17 points; 95% CI, -0.53 to 0.18 points), or memory (0.62 points; 95% CI, -0.07 to 1.31 points). However, individuals with incident MI vs those without MI demonstrated faster declines in global cognition (-0.15 points per year; 95% CI, -0.21 to -0.10 points per year), memory (-0.13 points per year; 95% CI, -0.22 to -0.04 points per year), and executive function (-0.14 points per year; 95% CI, -0.20 to -0.08 points per year) over the years after MI compared with pre-MI slopes. The interaction analysis suggested that race and sex modified the degree of change in the decline in global cognition after MI (race × post-MI slope interaction term, P = .02; sex × post-MI slope interaction term, P = .04), with a smaller change in the decline over the years after MI in Black individuals than in White individuals (difference in slope change, 0.22 points per year; 95% CI, 0.04-0.40 points per year) and in females than in males (difference in slope change, 0.12 points per year; 95% CI, 0.01-0.23 points per year).

Conclusions

This cohort study using pooled data from 6 cohort studies found that incident MI was not associated with a decrease in global cognition, memory, or executive function at the time of the event compared with no MI but was associated with faster declines in global cognition, memory, and executive function over time. These findings suggest that prevention of MI may be important for long-term brain health.

Lipocalin 2 regulates iron homeostasis, neuroinflammation, and insulin resistance in the brains of patients with dementia: Evidence from the current literature

Dementia accompanied by memory loss is considered one of the most common neurodegenerative diseases worldwide, and its prevalence is gradually increasing. Known risk factors for dementia include genetic background, certain lifestyle and dietary patterns, smoking, iron overload, insulin resistance, and impaired glucose metabolism in the brain. Here, we review recent evidence on the regulatory role of lipocalin 2 (LCN2) in dementia from various perspectives. LCN2 is a neutrophil gelatinase-associated protein that influences diverse cellular processes, including the immune system, iron homeostasis, lipid metabolism, and inflammatory responses. Although its functions within the peripheral system are most widely recognized, recent findings have revealed links between LCN2 and central nervous system diseases, as well as novel roles for LCN2 in neurons and glia. Furthermore, LCN2 may modulate diverse pathological mechanisms involved in dementia. Taken together, LCN2 is a promising therapeutic target with which to address the neuropathology of dementia.

Brain arteriolosclerosis

Brain arteriolosclerosis (B-ASC), characterized by pathologic arteriolar wall thickening, is a common finding at autopsy in aged persons and is associated with cognitive impairment. Hypertension and diabetes are widely recognized as risk factors for B-ASC. Recent research indicates other and more complex risk factors and pathogenetic mechanisms. Here, we describe aspects of the unique architecture of brain arterioles, histomorphologic features of B-ASC, relevant neuroimaging findings, epidemiology and association with aging, established genetic risk factors, and the co-occurrence of B-ASC with other neuropathologic conditions such as Alzheimer's disease and limbic-predominant age-related TDP-43 encephalopathy (LATE). There may also be complex physiologic interactions between metabolic syndrome (e.g., hypertension and inflammation) and brain arteriolar pathology. Although there is no universally applied diagnostic methodology, several classification schemes and neuroimaging techniques are used to diagnose and categorize cerebral small vessel disease pathologies that include B-ASC, microinfarcts, microbleeds, lacunar infarcts, and cerebral amyloid angiopathy (CAA). In clinical-pathologic studies that factored in comorbid diseases, B-ASC was independently associated with impairments of global cognition, episodic memory, working memory, and perceptual speed, and has been linked to autonomic dysfunction and motor symptoms including parkinsonism. We conclude by discussing critical knowledge gaps related to B-ASC and suggest that there are probably subcategories of B-ASC that differ in pathogenesis. Observed in over 80% of autopsied individuals beyond 80 years of age, B-ASC is a complex and under-studied contributor to neurologic disability.

Gastrodia elata Blume (Tianma): Hope for Brain Aging and Dementia

Since aging-related diseases, including dementia, represent major public health threats to our society, physician-scientists must develop innovative, interdisciplinary strategies to open new avenues for development of alternative therapies. One such novel approach may lie in traditional Chinese medicine (TCM). Gastrodia elata Blume (G. elata, tianma) is a TCM frequently used for treatment of cerebrocardiovascular diseases (CCVDs). Recent studies of G. elata-based treatment modalities, which have investigated its pharmacologically relevant activity, potential efficacy, and safety, have employed G. elata in well-characterized, aging-related disease models, with a focus on models of aging-related dementia, such as Alzheimer's disease (AD). Here, I examine results from previous studies of G. elata, as well as related herbal preparations and pure natural products, as prophylaxis and remedies for aging-related CCVDs and dementia. Concluding, data suggest that tianma treatment may be used as a promising complementary therapy for AD.

The Application of rs-fMRI in Vascular Cognitive Impairment

The incidence of vascular cognitive impairment (VCI) has been increasing for years and has become a major disabling factor in middle-aged and elderly populations. The pathogenesis of VCI is unclear, and there are no standard diagnostic criteria. Resting-state functional magnetic resonance imaging (rs-fMRI) can be used to detect spontaneous brain functional activity in a resting state, which facilitates in-depth investigation of the pathogenesis of VCI and provides an objective reference for early diagnosis, differential diagnosis, and prognostic evaluation. This article mainly reviews the principle and analysis of rs-fMRI data, as well as the progress of its application for VCI diagnosis.

Yuzu and Hesperidin Ameliorate Blood-Brain Barrier Disruption during Hypoxia via Antioxidant Activity

Yuzu and its main component, hesperidin (HSP), have several health benefits owing to their anti-inflammatory and antioxidant properties. We examined the effects of yuzu and HSP on blood-brain barrier (BBB) dysfunction during ischemia/hypoxia in an in vivo animal model and an in vitro BBB endothelial cell model, and also investigated the underlying mechanisms. In an in vitro BBB endothelial cell model, BBB permeability was determined by measurement of Evans blue extravasation in vivo and in vitro. The expression of tight junction proteins, such as claudin-5 and zonula occludens-1 (ZO-1), was detected by immunochemistry and western blotting, and the reactive oxygen species (ROS) level was measured by 2'7'-dichlorofluorescein diacetate intensity. Yuzu and HSP significantly ameliorated the increase in BBB permeability and the disruption of claudin-5 and ZO-1 in both in vivo and in vitro models. In bEnd.3 cells, yuzu and HSP were shown to inhibit the disruption of claudin-5 and ZO-1 during hypoxia, and the protective effects of yuzu and HSP on claudin-5 degradation seemed to be mediated by Forkhead box O 3a (FoxO3a) and matrix metalloproteinase (MMP)-3/9. In addition, well-known antioxidants, trolox and N-acetyl cysteine, significantly attenuated the BBB permeability increase, disruption of claudin-5 and ZO-1, and FoxO3a activation during hypoxia, suggesting that ROS are important mediators of BBB dysfunction during hypoxia. Collectively, these results indicate that yuzu and HSP protect the BBB against dysfunction via maintaining integrity of claudin-5 and ZO-1, and these effects of yuzu and HSP appear to be a facet of their antioxidant properties. Our findings may contribute to therapeutic strategies for BBB-associated neurodegenerative diseases.

The Neuropathological Diagnosis of Alzheimer's Disease-The Challenges of Pathological Mimics and Concomitant Pathology

The definitive diagnosis of Alzheimer's disease (AD) rests with post-mortem neuropathology despite the advent of more sensitive scanning and the search for reliable biomarkers. Even though the classic neuropathological features of AD have been known for many years, it was only relatively recently that more sensitive immunohistochemistry for amyloid beta (Aβ) and hyperphosphorylated tau (HP-tau) replaced silver-staining techniques. However, immunohistochemistry against these and other proteins has not only allowed a more scientific evaluation of the pathology of AD but also revealed some mimics of HP-tau pathological patterns of AD, including age-related changes, argyrophilic grain disease and chronic traumatic encephalopathy. It also highlighted a number of cases of AD with significant additional pathology including Lewy bodies, phosphorylated TDP-43 (p-TDP-43) positive neuronal cytoplasmic inclusions and vascular pathology. This concomitant pathology can cause a number of challenges including the evaluation of the significance of each pathological entity in the make-up of the clinical symptoms, and the threshold of each individual pathology to cause dementia. It also raises the possibility of underlying common aetiologies. Furthermore, the concomitant pathologies could provide explanations as to the relative failure of clinical trials of anti-Aβ therapy in AD patients.

White matter alterations in Alzheimer's disease without concomitant pathologies

Aims

Most individuals with AD neuropathological changes have co‐morbidities which have an impact on the integrity of the WM. This study analyses oligodendrocyte and myelin markers in the frontal WM in a series of AD cases without clinical or pathological co‐morbidities.

Methods

From a consecutive autopsy series, 206 cases had neuropathological changes of AD; among them, only 33 were AD without co‐morbidities. WM alterations were first evaluated in coronal sections of the frontal lobe in every case. Then, RT‐qPCR and immunohistochemistry were carried out in the frontal WM of AD cases without co‐morbidities to analyse the expression of selected oligodendrocyte and myelin markers.

Results

WM demyelination was more marked in AD with co‐morbidities when compared with AD cases without co‐morbidities. Regarding the later, mRNA expression levels of MBP, PLP1, CNP, MAG, MAL, MOG and MOBP were preserved at stages I–II/0–A when compared with middle‐aged (MA) individuals, but significantly decreased at stages III–IV/0–C. This was accompanied by reduced expression of NG2 and PDGFRA mRNA, reduced numbers of NG2‐, Olig2‐ and HDAC2‐immunoreactive cells and reduced glucose transporter immunoreactivity. Partial recovery of some of these markers occurred at stages V–VI/B–C.

Conclusions

The present observations demonstrate that co‐morbidities have an impact on WM integrity in the elderly and in AD, and that early alterations in oligodendrocytes and transcription of genes linked to myelin proteins in WM occur in AD cases without co‐morbidities. These are followed by partial recovery attempts at advanced stages. These observations suggest that oligodendrocytopathy is part of AD.

Cerebrospinal fluid lipocalin 2 as a novel biomarker for the differential diagnosis of vascular dementia

The clinical diagnosis of vascular dementia (VaD) is based on imaging criteria, and specific biochemical markers are not available. Here, we investigated the potential of cerebrospinal fluid (CSF) lipocalin 2 (LCN2), a secreted glycoprotein that has been suggested as mediating neuronal damage in vascular brain injuries. The study included four independent cohorts with a total n = 472 samples. LCN2 was significantly elevated in VaD compared to controls, Alzheimer’s disease (AD), other neurodegenerative dementias, and cognitively unimpaired patients with cerebrovascular disease. LCN2 discriminated VaD from AD without coexisting VaD with high accuracy. The main findings were consistent over all cohorts. Neuropathology disclosed a high percentage of macrophages linked to subacute infarcts, reactive astrocytes, and damaged blood vessels in multi-infarct dementia when compared to AD. We conclude that CSF LCN2 is a promising candidate biochemical marker in the differential diagnosis of VaD and neurodegenerative dementias.

Diagnosis of vascular dementia is hampered by the lack of biochemical markers for this disease. Here, the authors show that vascular dementia is associated with increased lipocalin-2 in cerebrospinal fluid, compared to controls and patients with other forms of dementia.

The standardization of cerebrospinal fluid markers and neuropathological diagnoses brings to light the frequent complexity of concomitant pathology in Alzheimer's disease: The next challenge for biochemical markers?

During the last two decades, neuropathological examination of the brain has evolved both technically and scientifically. The increasing use of immunohistochemistry to detect protein aggregates paralleled a better understanding of neuroanatomical progression of protein deposition. As a consequence, an international effort was achieved to standardize hyperphosphorylated-Tau (phospho-TAU), ßAmyloid (Aß), alpha syncuclein (alpha-syn), phosphorylated transactive response DNA-binding protein 43 (phospho-TDP43) and vascular pathology detection. Meanwhile harmonized staging systems emerged in order to increase inter rater reproducibility. Therefore, a refined definition of Alzheimer's disease was recommended., a clearer picture of the neuropathological lesions diversity emerged secondarily to the systematic assessment of concomitant pathology highlighting finally a low rate of pure AD pathology. This brings new challenges to laboratory medicine in the field of cerebrospinal fluid (CSF) markers of Alzheimer's disease: how to further validate total Tau, phospho-TAU, Aß40 and Aß42 and new marker level cut-offs while autopsy rates are declining?

Width of sulcus and thickness of gyrus in patients with cerebral atherosclerosis: a new tool for the prevention of vascular cognitive impairment

BACKGROUND AND PURPOSE

Cerebral atherosclerosis is the main cause of lesions that contribute to vascular cognitive impairment and vascular dementia, followed by arteriosclerosis of small vessels and cerebral amyloid angiopathy. The purpose of this study was to compare the post-mortem radiological alterations of autopsied adults with the macroscopic alterations in the posterior region of these brains in order to establish a relationship between the two forms of analysis and to discuss the relevance of the prevention of vascular cognitive impairment in patients with encephalic atherosclerosis.

MATERIALS AND METHODS

Thirteen brains were analysed macroscopically to assess the degree of atherosclerosis of the basilar and the posterior cerebral arteries. The patients were autopsied in the Subject of General Pathology at General Hospital of Triângulo Mineiro Federal University in Uberaba, state of Minas Gerais, Brazil. The qualitative analysis of atherosclerosis was performed with classification into mild, moderate or severe. In the posterior region of the brains, width of sulcus and thickness of gyrus were measured by macroscopic analysis and by tomographic analysis.

RESULTS AND CONCLUSIONS

There was a decrease in calcarine sulcus width and an increase in medial temporal occipital gyrus thickness in patients with a higher degree of atherosclerosis, macroscopically and in tomography, respectively. Low oxygenation caused by atherosclerosis probably leads to an encephalic parenchyma inflammation that causes microglial cells hypertrophy provoking increase in the gyrus thickness and decrease in the sulcus width, as observed in the present study.

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.

Identifying preclinical vascular dementia in symptomatic small vessel disease using MRI

Sporadic cerebral small vessel disease is an important cause of vascular dementia, a syndrome of cognitive impairment together with vascular brain damage. At post-mortem pure vascular dementia is rare, with evidence of co-existing Alzheimer's disease pathology in 95% of cases. This work used MRI to characterize structural abnormalities during the preclinical phase of vascular dementia in symptomatic small vessel disease. 121 subjects were recruited into the St George's Cognition and Neuroimaging in Stroke study and followed up longitudinally for five years. Over this period 22 individuals converted to dementia. Using voxel-based morphometry, we found structural abnormalities present at baseline in those with preclinical dementia, with reduced grey matter density in the left striatum and hippocampus, and more white matter hyperintensities in the frontal white-matter. The lacunar data revealed that some of these abnormalities may be due to lesions within the striatum and centrum semiovale. Using support vector machines, future dementia could be best predicted using hippocampal and striatal Jacobian determinant data, achieving a balanced classification accuracy of 73%. Using cluster ward linkage we identified four anatomical subtypes. Successful predictions were restricted to groups with lower levels of vascular damage. The subgroup that could not be predicted were younger, further from conversion, had the highest levels of vascular damage, with milder cognitive impairment at baseline but more rapid deterioration in processing speed and executive function, consistent with a primary vascular dementia. In contrast, the remaining groups had decreasing levels of vascular damage and increasing memory impairment consistent with progressively more Alzheimer's-like pathology. Voxel-wise rates of hippocampal atrophy supported these distinctions, with the vascular group closely resembling the non-dementing cohort, whereas the Alzheimer's like group demonstrated global hippocampal atrophy. This work reveals distinct anatomical endophenotypes in preclinical vascular dementia, forming a spectrum between vascular and Alzheimer's like pathology. The latter group can be identified using baseline MRI, with 73% converting within 5 years. It was not possible to predict the vascular dominant dementia subgroup, however 19% of negative predictions with high levels of vascular disease would ultimately develop dementia. It may be that techniques more sensitive to white matter damage, such as diffusion weighted imaging, may prove more useful for this vascular dominant subgroup in the future. This work provides a way to accurately stratify patients using a baseline MRI scan, and has utility in future clinical trials designed to slow or prevent the onset of dementia in these high-risk cohorts.

The role of biopsies and autopsies in the diagnosis of cognitive impairment, with emphasis on small vessel diseases: A critical appraisal enriched by personal experience

Acquired and hereditary microangiopathies cause cerebral small vessel diseases (CSVD) that impair cognition. The most frequent is primary angiitis of the CNS (PACNS), whose diagnosis remains challenging, requiring a multidisciplinary approach. Secondary vasculitis, CADASIL, miscellaneous microangiopathies and lymphomas, also cause cognitive impairment. Despite the fact that the need for biopsy has decreased in the era of new neuroimaging methods, biopsies that include small leptomeningeal and parenchymal arterial vessels still remain the gold standard to diagnose PACNS and other CSVD, and to exclude mimics such as infections and malignancies. New approaches for pathological consequences relevant to vascular cognitive impairment such as silent brain lesions, microinfarcts, microbleeds and subtle loss of microstructural integrity, may be detected in autopsies. This article addresses the role of biopsies and autopsies for the diagnosis of cognitive impairment related to small vessel diseases or other inflammatory/ischemic processes, and presents a critical appraisal based on personal experience.

Sisyphus in Neverland

The study of life and living organisms and the way in which these interact and organize to form social communities have been central to my career. I have been fascinated by biology, neurology, and neuropathology, but also by history, sociology, and art. Certain current historical, political, and social events, some occurring proximally but others affecting people in apparently distant places, have had an impact on me. Epicurus, Seneca, and Camus shared their philosophical positions which I learned from. Many scientists from various disciplines have been exciting sources of knowledge as well. I have created a world of hypothesis and experiments but I have also got carried away by serendipity following unexpected observations. It has not been an easy path; errors and wanderings are not uncommon, and opponents close to home much more abundant than one might imagine. Ambition, imagination, resilience, and endurance have been useful in moving ahead in response to setbacks. In the end, I have enjoyed my dedication to science and I am grateful to have glimpsed beauty in it. These are brief memories of a Spanish neuropathologist born and raised in Barcelona, EU.

Hypertension, diabetes and obesity are associated with lower cognitive performance in community-dwelling elderly: Data from the FIBRA study

Background

Systemic hypertension (SH), diabetes mellitus (DM) and abdominal obesity may negatively impact cognitive performance.

Objective

To evaluate the association between SH, DM and abdominal obesity and cognitive performance among cognitively unimpaired elderly.

Methods

A cross-sectional study of individuals aged 65+ from seven Brazilian cities was conducted. SH and DM diagnoses were self-reported and abdominal circumference was objectively measured. Individuals who scored below the education-adjusted cutoff scores on the Mini-Mental State Examination (MMSE) were excluded.

Results

Among 2,593 elderly, 321 (12.38%) had SH, DM and abdominal obesity concomitantly (Group I) and 421 (16.23%) had none of the three diseases (Group II). Group I had a higher proportion of individuals that were women, aged 70-74 years, illiterate and with lower income. Group I had a higher number of participants with low cognitive performance (28.04% vs. 17.58% in Group II). Variables associated with poor cognitive performance were: female gender (OR: 2.43, p < 0.001); and lower education (OR: 0.410, p < 0.001). The presence of the three diseases and age were not significant in the education-adjusted model.

Conclusion

There was an association between cognition and the presence of SH, DM and obesity. However, education seems to be decisive in determining cognitive performance in the presence of these three conditions.

Neuropathology of cerebrovascular diseases

The chapter describes the epidemiology of cerebrovascular diseases, anatomy of the cerebral blood vessels, pathophysiology of ischemia, hypoxia, hypoxemia, anemic hypoxia, histotoxic hypoxia, carbon monoxide damage, hyperoxid brain damage and decompression sickness, and selective cell and regional vulnerability; diseases of the blood vessels including atherosclerosis, hypertensive angiopathy, small vessel disease, inflammatory vascular diseases, cerebral amyloid angiopathies, CADASIL, CARASIL and other diseases that can lead to cerebrovascular occlusion; intracranial and intraspinal aneurysms and vascular malformations; hematologic disorders that can cause cerebral infarct or hemorrhage; brain ischemic damage; and spontaneous intracranial bleeding. Within ischemic brain damage, focal cerebral ischemia, hemorrhagic infarct, brain edema, penumbra, global cerebral ischemia, venous thrombosis, lacunas and lacunar state, status cribosus, granular atrophy of the cerebral cortex, hippocampal sclerosis, vascular leukoencephalopathy Binswanger type and multi-infarct encephalopathy are discussed in detail. Cognitive impairment of vascular origin deserves an individual section.

Update on Vascular Dementia

Vascular dementia (VaD) is a major contributor to the dementia syndrome and is described as having problems with reasoning, planning, judgment, and memory caused by impaired blood flow to the brain and damage to the blood vessels resulting from events such as stroke. There are a variety of etiologies that contribute to the development of vascular cognitive impairment and VaD, and these are often associated with other dementia-related pathologies such as Alzheimer disease. The diagnosis of VaD is difficult due to the number and types of lesions and their locations in the brain. Factors that increase the risk of vascular diseases such as stroke, high blood pressure, high cholesterol, and smoking also raise the risk of VaD. Therefore, controlling these risk factors can help lower the chances of developing VaD. This update describes the subtypes of VaD, with details of their complex presentation, associated pathological lesions, and issues with diagnosis, prevention, and treatment.

Post-mortem assessment in vascular dementia: advances and aspirations

BACKGROUND

Cerebrovascular lesions are a frequent finding in the elderly population. However, the impact of these lesions on cognitive performance, the prevalence of vascular dementia, and the pathophysiology behind characteristic in vivo imaging findings are subject to controversy. Moreover, there are no standardised criteria for the neuropathological assessment of cerebrovascular disease or its related lesions in human post-mortem brains, and conventional histological techniques may indeed be insufficient to fully reflect the consequences of cerebrovascular disease.

DISCUSSION

Here, we review and discuss both the neuropathological and in vivo imaging characteristics of cerebrovascular disease, prevalence rates of vascular dementia, and clinico-pathological correlations. We also discuss the frequent comorbidity of cerebrovascular pathology and Alzheimer's disease pathology, as well as the difficult and controversial issue of clinically differentiating between Alzheimer's disease, vascular dementia and mixed Alzheimer's disease/vascular dementia. Finally, we consider additional novel approaches to complement and enhance current post-mortem assessment of cerebral human tissue.

CONCLUSION

Elucidation of the pathophysiology of cerebrovascular disease, clarification of characteristic findings of in vivo imaging and knowledge about the impact of combined pathologies are needed to improve the diagnostic accuracy of clinical diagnoses.

Chronic cerebral hypoperfusion induces memory deficits and facilitates Aβ generation in C57BL/6J mice

Alzheimer's disease (AD) is the most common type of dementia frequently responsible for cognitive decline in the elderly. The etiology and molecular mechanism of AD pathogenesis remain inconclusive. Aging and vascular factors are important independent causes and contributors to sporadic AD. Clinical imaging studies showed that cerebral blood flow decreases before cognitive impairment in patients with AD. To investigate the effect of chronic cerebral hypoperfusion (CCH) on cognitive impairment and morphological features, we developed a new manner of CCH mouse model by narrowing bilateral common carotid arteries. Mice started to manifest spatial memory deficits 1month after the surgery and exhibited behavioral changes in a time-dependent manner. Mice also presented memory deficits accompanied with morphological changes at the neuronal and synaptic levels. CCH damaged the normal neuronal morphology and significantly reduced the expression level of PSD95. CCH activated astrocytes, increased the co-expression of GFAP and AQP4, and destroyed the blood-brain barrier (BBB). Furthermore, CCH facilitated intracellular and extracellular Aβ deposition by up-regulating γ-secretase and β-secretase levels. Our results showed good reproducibility of post-CCH pathological processes, which are characterized by neuronal apoptosis, axonal abnormalities, glial activation, BBB damage, amyloid deposition, and cognitive dysfunction; these processes may be used to decipher the complex interplay and pathological process between CCH and AD. This study provides laboratory evidence for the prevention and treatment of cognitive malfunction and AD.

Impaired Cerebral Hemodynamics and Cognitive Performance in Patients with Atherothrombotic Disease

BACKGROUND AND OBJECTIVE

Patients with pre-existing atherothrombotic disease are prone to cognitive impairment. We tested whether impaired cerebrovascular reactivity (CVR), a marker of cerebral microvascular hemodynamic dysfunction, is associated with poorer cognitive scores among patients with and without carotid large-vessel disease.

METHODS

A subgroup of non-demented patients with chronic coronary heart disease followed-up for 15 ± 3 years was assessed for cognitive function (Neurotrax Computerized Cognitive Battery; scaled to an IQ style scale with a mean of 100 and SD of 15) and for CVR using the breath-holding index (BHI) with transcranial Doppler and for carotid plaques using ultrasound. We assessed cognitive scores in specific domains in patients with and without impaired CVR (BHI <0.47; bottom quartile).

RESULTS

Among 415 patients (mean age 71.7 ± 6.2 y) median BHI was 0.73 (25% 0.47, 75% 1.04). Impaired CVR was associated with diabetes and peripheral artery disease. Adjusting for potential confounders, impaired CVR was associated with lower executive function (p = 0.02) and global cognitive scores (p = 0.04). There was an interaction with carotid large-vessel disease for executive function (p <  0.001), memory (p = 0.03), and global cognitive scores (p = 0.02). In the carotid large-vessel disease group there were pronounced differences by CVR status in executive function (p <  0.001), memory (p = 0.02), attention (p <  0.001), and global cognitive scores (p = 0.001).

CONCLUSION

Impaired CVR, a marker of cerebral microvascular dysfunction, is associated with poorer cognitive functions and in particular executive dysfunction among non-demented patients with concomitant carotid large-vessel disease. These findings emphasize the importance of cerebral hemodynamics in cognitive performance.

Transcranial Parenchymal Sonographic Findings in Patients With Cerebral Small Vessel Disease: A Preliminary Study

OBJECTIVES

Patients with cerebral small vessel disease often present with various motor, cognitive, and emotional changes, including gait disturbances, parkinsonism, and depression. Substantia nigra hyperechogenicity, brain stem raphe hypoechogenicity, ventricle diameters, and sonographic characteristics of other brain structures on transcranial sonography have been increasingly used as biomarkers in a range of neurologic diseases. We aimed to explore the frequency and clinical correlates of transcranial sonographic findings in symptomatic patients with small vessel disease.

METHODS

In a cross-sectional study, neurologic, cognitive, and emotional statuses and transcranial sonographic and magnetic resonance imaging findings were compared between 102 patients with small vessel disease and 45 healthy age- and sex-matched control participants.

RESULTS

Compared to healthy controls, small vessel disease cases had more frequent brain stem raphe hypoechogenicity (55.9% versus 11.1%; P < .0001), substantia nigra hyperechogenicity (30.4% versus 11.1%; P = .022), and enlarged third ventricles (P < .0001). Substantia nigra hyperechogenicity correlated with gait disturbances, extrapyramidal features, and cognitive impairment. Brain stem raphe hypoechogenicity was associated with the diagnosis of depression. Enlargement of the third and lateral ventricles was more frequent in patients with cognitive impairment. Pathologic substantia nigra hyperechogenicity and enlarged ventricles were associated with the severity of cerebral ischemic lesions.

CONCLUSIONS

Transcranial sonography shows pathologic findings in a substantial number of patients with small vessel disease, probably reflecting disruption of frontostriatal pathways.

The Glymphatic System: A Beginner's Guide

The glymphatic system is a recently discovered macroscopic waste clearance system that utilizes a unique system of perivascular tunnels, formed by astroglial cells, to promote efficient elimination of soluble proteins and metabolites from the central nervous system. Besides waste elimination, the glymphatic system also facilitates  brain-wide distribution of several compounds, including glucose, lipids, amino acids, growth factors, and neuromodulators. Intriguingly, the glymphatic system function mainly during sleep and is largely disengaged during wakefulness. The biological need for sleep across all species may therefore reflect that the brain must enter a state of activity that enables elimination of potentially neurotoxic waste products, including β-amyloid. Since the concept of the glymphatic system is relatively new, we will here review its basic structural elements, organization, regulation, and functions. We will also discuss recent studies indicating that glymphatic function is suppressed in various diseases and that failure of glymphatic function in turn might contribute to pathology in neurodegenerative disorders, traumatic brain injury and stroke.

The potential role of perlecan domain V as novel therapy in vascular dementia

Vascular dementia (VaD) is the second most common cause of dementia and leads to a decline in cognitive thinking via conditions that lead to blockage or reduced blood flow to the brain. It is a poorly understood disease, and the changes that occur are often linked to other types of dementia such as Alzheimer's disease. To date, there are no approved therapies or drugs to treat the symptoms of VaD, even though there is some evidence of drugs approved for Alzheimer's that might have some benefit in patients diagnosed with VaD. The altered blood flow that precedes VaD may result in compensatory mechanisms, such as angiogenesis, to increase blood flow in the brain. Angiogenesis, the process of new blood vessel formations from pre-existing ones, involves several pro-angiogenic factors such as vascular endothelial growth factor (VEGF) and is regulated by a variety of growth factors from neurons, astrocytes, and pericytes in the brain as well the extracellular matrix (ECM). The ECM highly regulates angiogenesis and other processes in the brain. One such ECM component is the heparan sulfate proteoglycan perlecan and its bioactive region, Domain V (DV). Here we discuss the potential role of DV as a novel therapy to treat VaD.

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.

PET imaging in ischemic cerebrovascular disease: current status and future directions

Cerebrovascular diseases are caused by interruption or significant impairment of the blood supply to the brain, which leads to a cascade of metabolic and molecular alterations resulting in functional disturbance and morphological damage. These pathophysiological changes can be assessed by positron emission tomography (PET), which permits the regional measurement of physiological parameters and imaging of the distribution of molecular markers. PET has broadened our understanding of the flow and metabolic thresholds critical for the maintenance of brain function and morphology: in this application, PET has been essential in the transfer of the concept of the penumbra (tissue with perfusion below the functional threshold but above the threshold for the preservation of morphology) to clinical stroke and thereby has had great impact on developing treatment strategies. Radioligands for receptors can be used as early markers of irreversible neuronal damage and thereby can predict the size of the final infarcts; this is also important for decisions concerning invasive therapy in large ("malignant") infarctions. With PET investigations, the reserve capacity of blood supply to the brain can be tested in obstructive arteriosclerosis of the supplying arteries, and this again is essential for planning interventions. The effect of a stroke on the surrounding and contralateral primarily unaffected tissue can be investigated, and these results help to understand the symptoms caused by disturbances in functional networks. Chronic cerebrovascular disease causes vascular cognitive disorders, including vascular dementia. PET permits the detection of the metabolic disturbances responsible for cognitive impairment and dementia, and can differentiate vascular dementia from degenerative diseases. It may also help to understand the importance of neuroinflammation after stroke and its interaction with amyloid deposition in the development of dementia. Although the clinical application of PET investigations is limited, this technology had and still has a great impact on research into cerebrovascular diseases.

Impact of aphasia on consciousness assessment: a cross-sectional study

BACKGROUND

Previous findings suggest that language disorders may occur in severely brain-injured patients and could interfere with behavioral assessments of consciousness. However, no study investigated to what extent language impairment could affect patients' behavioral responses. Objective. To estimate the impact of receptive and/or productive language impairments on consciousness assessment.

METHODS

Twenty-four acute and subacute stroke patients with different types of aphasia (global, n = 11; Broca, n = 4; Wernicke, n = 3; anomic, n = 4; mixed, n = 2) were recruited in neurology and neurosurgery units as well as in rehabilitation centers. The Coma Recovery Scale-Revised (CRS-R) was administered.

RESULTS

We observed that 25% (6 out of 24) of stroke patients with a diagnosis of aphasia and 54% (6 out of 11) of patients with a diagnosis of global aphasia did not reach the maximal CRS-R total score of 23. An underestimation of the consciousness level was observed in 3 patients with global aphasia who could have been misdiagnosed as being in a minimally conscious state, even in the absence of any documented period of coma. More precisely, lower subscores were observed on the communication, motor, oromotor, and arousal subscales.

CONCLUSION

Consciousness assessment may be complicated by the co-occurrence of severe language deficits. This stresses the importance of developing new tools or identifying items in existing scales, which may allow the detection of language impairment in severely brain-injured patients.

Acute watershed infarcts with global cerebral hypoperfusion in symptomatic CADASIL

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common form of hereditary cerebral angiopathy. We present a case in which a pattern of diffusion signal change compatible with bihemispheric acute watershed infarcts occurred in a symptomatic patient demonstrating global hypoperfusion. To our knowledge, watershed infarcts in the clinical presentation of CADASIL have not been previously described.

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.

Vascular disease and dementias: paradigm shifts to drive research in new directions

Vascular disease was once considered the principal cause of aging-related dementia. More recently, however, research emphasis has shifted to studies of progressive neurodegenerative disease processes, such as those giving rise to neuritic plaques, neurofibrillary tangles, and Lewy bodies. Although these studies have led to critical insights and potential therapeutic strategies, interest in the role of systemic and cerebrovascular disease mechanisms waned and has received relatively less attention and research support. Recent studies suggest that vascular disease mechanisms play an important role in the risk for aging-related cognitive decline and disorders. Vascular disease frequently coexists with cognitive decline in aging individuals, shares many risk factors with dementias considered to be of the "Alzheimer type," and is observed more frequently than expected in postmortem material from individuals manifesting "specific" disease stigmata, such as abundant plaques and tangles. Considerable difficulties have emerged in attempting to classify dementias as being related to vascular versus neurodegenerative causes, and several systems of criteria have been used. Despite multiple attempts, a lack of consensus remains regarding the optimal means of incorporating vascular disease into clinical diagnostic, neurocognitive, or neuropathologic classification schemes for dementias. We propose here an integrative, rather than a strictly taxonomic, approach to the study and elucidation of how vascular disease mechanisms contribute to the development of dementias. We argue that, instead of discriminating between, for example, "Alzheimer's disease," "vascular dementia," and other diseases, there is a greater need to focus clinical and research efforts on elucidating specific pathophysiologic mechanisms that contribute to dementia phenotypes and neuropathologic outcomes. We outline a multitiered strategy, beginning with clinical and public health interventions that can be implemented immediately, enhancements to ongoing longitudinal studies to increase their informative value, and new initiatives to capitalize on recent advances in systems biology and network medicine. This strategy will require funding from multiple public and private sources to support collaborative and interdisciplinary research efforts to take full advantage of these opportunities and realize their societal benefits.

Effect of Western medicine therapy assisted by Ginkgo biloba tablet on vascular cognitive impairment of none dementia

OBJECTIVE

To discuss the clinical effects of Western medicine therapy assisted by Ginkgo biloba tablet (GBT) on patients with vascular cognitive impairment of none dementia (VCIND).

METHODS

A total of 80 patients with VCIND were divided into two groups randomly: Conventional treatment group (control group) and combined treatment group. Conventional treatment group was given conventional treatment with anti-platelet aggregation. In this group, 75 mg aspirin was given three times a day for 3 months. While in combined treatment group, 19.2 mg GBT was given three times a day for 3 months together with conventional treatment (anti-platelet aggregation drugs). Montreal cognitive assessment (MoCA) and transcranial Doppler (TCD) were used to observe changes of cognitive ability and cerebral blood flow in VCIND patients before and after treatment in both groups. Then the clinical data were analyzed so as to compare the efficacy in two groups.

RESULTS

After 3 month-treatment in combined treatment group, the scores of executive ability, attention, abstract, delayed memory, orientation in the MoCA were significantly increased compared with those before treatment and those in control group after treatment. Besides, blood flow velocity of anterior cerebral artery increased significantly than that before treatment and that in control group after treatment.

CONCLUSIONS

GBT tablet can improve the therapeutic efficacy as well improve cognitive ability and cerebral blood flow supply of patients with VCIND.

Vascular dementia: different forms of vessel disorders contribute to the development of dementia in the elderly brain

The diagnosis of vascular dementia (VaD) describes a group of various vessel disorders with different types of vascular lesions that finally contribute to the development of dementia. Most common forms of VaD in the elderly brain are subcortical vascular encephalopathy, strategic infarct dementia, and the multi infarct encephalopathy. Hereditary forms of VaD are rare. Most common is the cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Sporadic forms of VaD are caused by degenerative vessel disorders such as atherosclerosis, small vessel disease (SVD) including small vessel arteriosclerosis, arteriolosclerosis, and lipohyalinosis, and cerebral amyloid angiopathy (CAA). Less frequently inflammatory vessel disorders and tumor-associated vessel lesions (e.g. angiocentric T-cell or angiotropic large cell lymphoma) can cause symptoms of dementia. Here, we review and discuss the impact of vessel disorders to distinct vascular brain tissue lesions and to the development of dementia in elderly individuals. The impact of coexisting neurodegenerative pathology in the elderly brain to VaD as well as the correlation between SVD and CAA expansion in the brain parenchyma with that of Alzheimer's disease (AD)-related pathology is highlighted. We conclude that "pure" VaD is rare and most frequently caused by infarctions. However, there is a significant contribution of vascular lesions and vessel pathology to the development of dementia that may go beyond tissue damage due to vascular lesions. Insufficient blood blow and alterations of the perivascular drainage mechanisms of the brain may also lead to a reduced protein clearance from extracellular space and subsequent increase of proteins in the brain parenchyma, such as the amyloid β-protein, and foster, thereby, the development of AD-related neurodegeneration. As such, it seems to be important for clinical practice to consider treatment of potentially coexisting AD pathology in cognitively impaired patients with vascular lesions.

Brain perfusion SPECT imaging and acetazolamide challenge in vascular cognitive impairment

Cerebrovascular disease is recognized as a common cause of cognitive impairment and dementia, alone or coexisting with other neurodegenerative diseases, mostly Alzheimer's disease. Vascular cognitive impairment (VCI) is a part of the heterogenous disorders group related to cerebral vessel disease. Although age is one of the most important risk factors for VCI, other common cardiovascular risk factors are also involved. By investigating these risk factors, a high proportion of these cognitive disorders can be prevented and/or delayed. Until now, only treatment of midlife arterial hypertension has been recognized as a preventing factor of vascular dementia. Brain MRI is becoming the method of choice to investigate cerebral vascular pathologies. However, this form of morphological imaging remains inadequate and does not provide useful functional information during VCI exploration, despite which functional imaging such as brain perfusion single-photon computed tomography, performed in baseline conditions and/or after an acetazolamide challenge, is underutilized in VCI exploration. The common strategies for VCI screening have not been standardized until now, and therefore further long-term imaging studies are needed to establish early diagnostic protocols. The present review summarizes the potential benefits of brain perfusion single-photon computed tomography imaging and possible scintigraphic quantification of cerebral hemodynamic reserves in investigation of VCI.

Vascular dementia: Current concepts and nomenclature harmonization

Several types of cerebrovascular lesions are associated with cognitive decline, but the role of each type in dementia manifestation has yet to be determined. One of the greatest barriers of conducting clinicopathological studies in vascular dementia concerns the overlapping of nomenclature for these lesions. The aim of the present review was to discuss current nomenclature for cerebrovascular lesions and suggest modifications to allow better diagnostic reproducibility in this field.

The need to unify neuropathological assessments of vascular alterations in the ageing brain: multicentre survey by the BrainNet Europe consortium

Here, we summarise the results after carrying out a large survey regarding the assessment of vascular alterations, both vessel changes and vascular lesions in an inter-laboratory setting. In total, 32 neuropathologists from 22 centres, most being members of BrainNet Europe (BNE), participated by filling out a questionnaire with emphasis on assessment of common vascular alterations seen in the brains of aged subjects. A certain level of harmonisation has been reached among BNE members regarding sectioning of the brain, harvesting of brain tissue for histology and staining used when compared to the survey carried out in 2006 by Pantoni and colleagues. The most significant variability was seen regarding the assessment of severity and of clinical significance of vascular alterations. Two strategies have recently been recommended regarding the assessment of vascular alterations in aged and demented subjects. The National Institute on Aging - Alzheimer's Association (NIA-AA) recommends the assessment of hippocampal sclerosis, vascular brain injury and microvascular lesions in 12 regions. Although this strategy will be easy to follow, the recommendations do not inform how the load of observed alterations should be assessed and when the observed lesions are of significance. Deramecourt and his colleagues recommend an assessment and semiquantitative grading of various pathologies in 4 brain regions. This strategy yielded a total score of 0 to 20 as an estimate of pathology load. It is, however, not clear which score is considered to be of clinical significance. Furthermore, in several BNE trials the semiquantitative assessment has yielded poor agreement rates; an observation that might negatively influence the strategy proposed by Deramecourt and his colleagues. In line with NIA-AA, a dichotomised approach of easily recognisable lesions in a standardised set of brain regions harvested for neuropathological assessment and applying reproducible sampling and staining strategies is recommended by BNE. However, a simple strategy regarding assessment of load of alteration is urgently needed to yield reproducible, and at the same time, comparable results between centres.

White matter myelin loss in the brains of aged dogs

The significance of cerebral white matter (WM) demyelination in the cognitive decline of elderly humans is disputed. Cognitive decline also occurs in aged dogs, although the age-related changes that occur in the canine cerebral WM are yet to be studied, particularly with regard to their relevance to the WM alterations of elderly humans. The present study revealed age-dependent myelin loss in the frontal lobe WM of canine brains. The accumulation of ceroid-lipofuscin-laden phagocytes was observed in the perivascular spaces of the WM and was correlated with the decrease in myelination. Also, myelin basic protein was detected in some of the vacuoles of these phagocytes. In the WM, beta-amyloid (Aβ) was deposited focally in capillary walls, and colocalized with apolipoprotein E (Apo E). Note that the dog is homozygous for Apo E4, which genotype is related to capillary CAA in humans. These findings indicate that WM demyelination occurs in aged dogs as well as in aged humans, hence WM alterations may account for age-related behavioral changes of the dog. In conclusion, dogs are useful for chronological studies of age-related WM changes.