Review: Vascular dementia: clinicopathologic and genetic considerations.

The incidence and severity of cerebrovascular disease (CVD) increase with advancing age, as does the risk of developing Alzheimer's disease (AD). Not surprisingly, heterogeneous forms of CVD may coexist with AD changes in the 'ageing brain'. These include angiopathies (affecting both large and small arteries) that result from 'classical' risk factors (hypertension, smoking and diabetes) and others (cerebral amyloid angiopathy) that are biochemically closely linked to AD. The morphologic consequences of these various vascular diseases are infarcts and/or haemorrhages of varying sizes within the brain, which lead to neurocognitive decline that may mimic AD - though the vascular abnormalities are usually detectable by neuroimaging. More subtle effects of CVD may include neuroinflammation and biochemical 'lesions' that have no reliable morphologic correlate and thus escape the attention of even an experienced Neuropathologist. The pathogenesis of hippocampal injury resembling ischaemic change - commonly seen in the brains of geriatric subjects - remains controversial. In recent years, genetically determined forms of microangiopathy (e.g. CADASIL, CARASIL, Trex1-related microangiopathies, CARASAL, familial forms of cerebral amyloid angiopathy or CAA) have provided interesting cellular and molecular clues to the pathogenesis of sporadic microvascular disease such as arteriolosclerosis and AD-related CAA.

Baseline Findings of PreventE4: A Double-Blind Placebo Controlled Clinical Trial Testing High Dose DHA in APOE4 Carriers before the Onset of Dementia.

INTRODUCTION: Lower blood levels of the omega-3 polyunsaturated fatty acid docosahexaenoic acid (DHA) are correlated with worse cognitive functions, particularly among APOE ε4 carriers. Whether DHA supplementation in APOE ε4 carriers with limited DHA consumption and dementia risk factors can delay or slow down disease progression when started before the onset of clinical dementia is not known. METHODS: PreventE4 is a double-blind, single site, randomized, placebo-controlled trial in cognitively unimpaired individuals with limited omega-3 consumption and dementia risk factors (n=368). Its objectives are to determine (1) whether carrying the APOE ε4 allele is associated with lower delivery of DHA to the brain; and (2) whether high dose DHA supplementation affects brain imaging biomarkers of AD and cognitive function. RESULTS: 365 cognitively unimpaired individuals between 55 and 80 (mean age 66) were randomized to 2 grams of DHA per day or identically appearing placebo for a period of 2 years. Half the participants were asked to complete lumbar punctures at baseline and 6-month visits to obtain cerebrospinal fluid (CSF). The primary trial outcome measure is the change in CSF DHA to arachidonic acid ratio after 6 months of the intervention (n=181). Secondary trial outcomes include the change in functional and structural connectivity using resting state functional MRI at 24 months (n=365). Exploratory outcomes include the change in Repeatable Battery of the Assessment of Neuropsychological Status at 24 months (n=365). CONCLUSIONS: Findings from PreventE4 will clarify the brain delivery of DHA in individuals carrying the APOE ε4 allele with implications for dementia prevention strategies. Trial was registered as NCT03613844.

Beyond-limit light focusing in the intermediate zone.

We experimentally verify that a new nanolens of a designed plasmonic aperture can focus visible light to a single line with its width smaller than the limit of half the wavelength in the intermediate zone. The experimental measurement indicates that while the near field plays a role to increase the spot size in the near zone, it is negligible at the beyond-limit focused region; i.e., the focused light is dominated by the radiative fields. The image taken by the optical microscope shows that the fields focused have propagated to the far zone. Besides being of academic interest, the nanolens capable in achieving a lower diffraction limit in the intermediate zone is important for application possibilities.

Plasticity of hippocampal circuitry in Alzheimer's disease.

Two markers of neuronal plasticity were used to compare the response of the human central nervous system to neuronal loss resulting from Alzheimer's disease with the response of rats to a similar neuronal loss induced by lesions. In rats that had received lesions of the entorhinal cortex, axon sprouting of commissural and associational fibers into the denervated molecular layer of the dentate gyrus was paralleled by a spread in the distribution of tritiated kainic acid-binding sites. A similar expansion of kainic acid receptor distribution was observed in hippocampal samples obtained postmortem from patients with Alzheimer's disease. An enhancement of acetylcholinesterase activity in the dentate gyrus molecular layer, indicative of septal afferent sprouting, was also observed in those patients with a minimal loss of cholinergic neurons. These results are evidence that the central nervous system is capable of a plastic response in Alzheimer's disease. Adaptive growth responses occur along with the degenerative events.

Particulate air pollutants, APOE alleles and their contributions to cognitive impairment in older women and to amyloidogenesis in experimental models.

Exposure to particulate matter (PM) in the ambient air and its interactions with APOE alleles may contribute to the acceleration of brain aging and the pathogenesis of Alzheimer's disease (AD). Neurodegenerative effects of particulate air pollutants were examined in a US-wide cohort of older women from the Women's Health Initiative Memory Study (WHIMS) and in experimental mouse models. Residing in places with fine PM exceeding EPA standards increased the risks for global cognitive decline and all-cause dementia respectively by 81 and 92%, with stronger adverse effects in APOE ɛ4/4 carriers. Female EFAD transgenic mice (5xFAD+/-/human APOE ɛ3 or ɛ4+/+) with 225 h exposure to urban nanosized PM (nPM) over 15 weeks showed increased cerebral ß-amyloid by thioflavin S for fibrillary amyloid and by immunocytochemistry for Aß deposits, both exacerbated by APOE ɛ4. Moreover, nPM exposure increased Aß oligomers, caused selective atrophy of hippocampal CA1 neurites, and decreased the glutamate GluR1 subunit. Wildtype C57BL/6 female mice also showed nPM-induced CA1 atrophy and GluR1 decrease. In vitro nPM exposure of neuroblastoma cells (N2a-APP/swe) increased the pro-amyloidogenic processing of the amyloid precursor protein (APP). We suggest that airborne PM exposure promotes pathological brain aging in older women, with potentially a greater impact in ɛ4 carriers. The underlying mechanisms may involve increased cerebral Aß production and selective changes in hippocampal CA1 neurons and glutamate receptor subunits.

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.

Visual evoked potentials in dementia: a meta-analysis and empirical study of Alzheimer's disease patients.

A meta-analytic review of flash and pattern reversal visual evoked potential research indicates that elderly demented patients have longer P100 latencies than age-matched control subjects. In the present empirical research, patients with research diagnoses of probable Alzheimer's disease were compared with sex- and age-matched control subjects using P100 latencies of visual evoked potentials (VEP) elicited by flash and pattern reversal. As compared to control subjects, Alzheimer's disease patients showed significantly longer P100 latencies of the VEP elicited by pattern reversal; the flash P100 only marginally distinguished them. These findings are discussed within the context of VEP recording practices, patient selection, sex and age matching of control subjects, and the visual system.

Stability of neuronal number in the human nucleus basalis of Meynert with age.

Numbers of neurons in the nucleus basalis of Meynert were estimated in seventeen non-demented patients who died of chronic hepatic or cardiopulmonary disease. Neurons were counted at the site of maximal neuronal density (SMND). This site was chosen by reviewing serial sections around the decussation of the anterior commissure and appeared to be comparable in different individuals. No correlation between numbers of neurons and age could be found. It appears that no uniform neuronal loss occurs in the nucleus basalis with age. Taken together with biochemical studies of cerebral cortical choline acetyltransferase activity, these findings suggest that there is no overall change in cholinergic input to cerebral cortex with age.

Comparison of methods for measuring longitudinal brain change in cognitive impairment and dementia.

PURPOSE: The goal of this project was to compare MRI measures of hippocampal, entorhinal cortex (ERC), and whole brain longitudinal change in cognitively normal elderly controls (C), non-demented subjects with cognitive impairment (CI), and demented (D) subjects. METHODS: 16 C, 6 CI, and 7 D subjects of comparable age were studied with MRI twice, at least 1 year apart. Longitudinal change in total brain size was measured by several methods, including computerized segmentation, non-linear warping, and change in the fluid/tissue boundaries between cerebrospinal fluid (CSF) and brain. Change in hippocampal volume was measured by semi-automated methods, and ERC volumes were manually measured. RESULTS: The annual rate of atrophy was greater in D versus C and D versus CI for cortical gray matter (cGM) (P=0.009 and 0.002), hippocampus (P=0.0001 and 0.002), and for the change in the fluid/tissue boundary (P=0.03 and 0.03). The annual rate of atrophy of ERC was greater in both CI and D versus C (P=0.01 and 0.0002). No significant differences between groups were found using non-linear warping. CONCLUSIONS: In CI, the greatest annual rates of atrophy were in ERC, while in D the greatest annual rates of atrophy were in hippocampus and cortex. Progressive ERC atrophy was observed with a greater degree of cognitive impairment, while hippocampal and cortical atrophy were only observed in demented subjects.

Olfactory tests as possible probes for detecting and monitoring Alzheimer's disease.

One of the characteristics of Alzheimer's disease is the early loss of neurons in pathways involved in processing olfactory information. Olfactory function was assessed in subjects with Alzheimer's disease using a conventional Smell Identification Test and a simple three odor match-to-sample problem. The patients exhibited a diminished capacity to identify common odors but were severely impaired in their ability to use novel odors in a match-to-sample task. Subjects with Parkinson's disease had a severe deficit for identifying common odors with the majority scoring as anosmic. Multiple sclerosis was not accompanied by detectable changes in olfactory functioning. The results of the Alzheimer's group are similar to recent animal studies that have shown lesions of the piriform-entorhinal cortex produce a variety of memory deficits that are particularly acute in tasks involving novel odors.

Multicenter clinicopathological correlation in dementia.

OBJECTIVE: The aim of the present study was to determine the accuracy of clinical diagnoses of dementia in a large group of patients evaluated in a multicenter, university-based, Alzheimer's disease diagnostic and treatment program. METHOD: Clinical diagnoses and neuropathological results from seven collaborating Alzheimer's disease research centers were compared for 196 cases of dementia. RESULTS: When diagnoses of probable Alzheimer's disease, possible Alzheimer's disease, and Alzheimer's disease plus another condition were combined, 163 (83%) of the patients were clinically regarded as likely to have had Alzheimer's disease. Of those patients, 134 (82%) were found to have neuropathological changes diagnostic of Alzheimer's disease or Alzheimer's disease plus another condition. A total of 116 patients were diagnosed as having probable Alzheimer's disease; 100 (86%) of those were found to have pathological diagnoses of Alzheimer's disease or Alzheimer's disease plus another condition. Cerebral infarcts were found in 17% of the patients clinically diagnosed with probable Alzheimer's disease. Lewy bodies with variable Alzheimer's disease-type pathological changes were found in 7% of the patients with clinical diagnoses of probable Alzheimer's disease. Conversely, significant Alzheimer's disease-type pathological changes were found in 55% of the patients clinically diagnosed as having vascular dementia. CONCLUSIONS: Clinicians accurately predict Alzheimer's disease-type neuropathological findings in a high proportion of cases of dementia but may not predict cerebrovascular pathology and Lewy bodies in some patients with apparent clinical Alzheimer's disease and may often fail to predict Alzheimer's disease-type pathological findings in patients with apparent vascular dementia. With the emergence of effective treatments for Alzheimer's disease, there is an increasing need to optimize methods for ante-mortem diagnosis of dementia.

Localization of amyloid P component in human brain: vascular staining patterns and association with Alzheimer's disease lesions.

Amyloid P component is a normal serum protein that is highly conserved across phylogeny. Although it resembles the classic acute-phase reactant C-reactive protein, and is considered to be a normal extracellular matrix component, its physiologic role in humans is unknown. Amyloid P component is also colocalized with accumulations of all recognized forms of amyloid. The present study uses light and electron microscopy to compare the cerebral localization of amyloid P component in cases with (n = 19) and without (n = 15) Alzheimer's disease (AD). In non-AD cases, amyloid P component was predominantly localized to the cerebrovasculature. Perivascular staining was observed in most cases, more so in the white than in the gray matter. In AD cases, amyloid P component was localized to all three characteristics histopathologic lesions, namely, neurofibrillary tangles, senile plaques, and amyloid angiopathy. Furthermore, in cases with prominent staining of gray matter parenchymal lesions, intravascular staining was decreased. Given the fixation and processing methods used, amyloid P component was never seen to be localized to the cerebrovascular basement membrane. These data argue against amyloid P component's postulated role as the anchor for vascular beta-amyloid deposition. Because there is no evidence for intrinsic amyloid P component production in brain, its perivascular and parenchymal distributions suggest either compromise of the blood-brain barrier or transport across vascular endothelium.

Dementia. A review emphasizing clinicopathologic correlation and brain-behavior relationships.

Numerous pathogenetic mechanisms may lead to the progressive loss of memory and intellectual function known as dementia. Currently, the dementias are classified according to clinicopathologic entities, although for clinical diagnosis, this introduces a degree of uncertainty. Characteristic patterns of behavior and anatomic pathology have been associated with specific clinicopathologic entities. Although somewhat simplistic, classification of the dementias as cortical vs subcortical embodies the precept that brain substrate is intimately tied to behavior. Lessons in brain-behavior relationships are reviewed for four clinicopathologic entities: Alzheimer's disease, Pick's disease, vascular dementia, and Parkinson's disease. Dementing illnesses have contributed significantly to our understanding of brain-behavior relationships. Major progress can be anticipated as diagnostic issues are resolved and biological and state-specific markers emerge.

Extrapyramidal signs and psychiatric symptoms predict faster cognitive decline in Alzheimer's disease.

OBJECTIVE: To identify clinical predictors of cognitive decline in Alzheimer's disease. DESIGN: A cohort of patients was followed up longitudinally and the likelihood of arriving at two cognitive end points was assessed using the Cox proportional hazards model and eight explanatory variables. SETTING: Subjects were chosen from patients examined for memory loss at two medical centers affiliated with the University of Southern California, Los Angeles. PATIENTS: The sample included 135 patients who met National Institute for Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria for probable or definite Alzheimer's disease, had initial Mini-Mental State Examination (MMSE) scores of 14 or greater, and had been seen on at least two occasions. MAIN OUTCOME MEASURES: The time to reach either of two end points, ie, MMSE score of 8 and a decline of six points on the MMSE, was assessed. RESULTS: After controlling for initial severity of dementia (eg, by dividing the sample into mild and moderate dementia subgroups or by using the individually defined end point of a six-point decline on the MMSE), the presence at baseline of extrapyramidal signs (risk-hazard ratio, 10.34; 95% confidence interval, 2.76 to 38.68; P = .0005), agitation (risk-hazard ratio, 2.98; 95% confidence interval, 1.35 to 6.61; P = .007), and hallucinations (risk-hazard ratio, 3.85; 95% confidence interval, 1.35 to 11; P = .01) predicted a shorter time to reach an end point. CONCLUSIONS: After controlling for initial severity of dementia, the presence of extrapyramidal signs and behavioral symptoms (agitation and hallucinations) significantly predict faster cognitive decline. These findings may reflect the effects of neuroleptic medication, the presence of underlying diffuse Lewy body disease, or alterations in biogenic amine systems.

Computerized tomographic scan findings in patients with autistic behavior.

An analysis of the computerized tomography scans of 17 patients with autistic behavior was carried out by investigators independent from those selecting the subjects. Mild abnormalities of the ventricular system were noted in several scans (increased size, altered left/right relation of lateral ventricles), and in three scans major hydrocephalus and circumscribed lesions of the parenchyma were seen. It was not possible to discern a singular abnormal pattern, the abnormalities appearing consequent to a variety of disease processes of the CNS.

Pathologic correlates of dementia in Parkinson's disease.

Histopathologic studies of the cerebral cortex, hippocampus, and three subcortical nuclei were performed in four patients with Parkinson's disease whose mental status had been evaluated by neuropsychologic testing. Clinicopathologic correlations suggest that dementia with marked visuospatial disturbance as well as severe aphasia may be associated with severe neuronal loss in subcortical nuclei, without significant numbers of plaques or tangles in the hippocampus and cerebral cortex. Furthermore, memory loss may not be consistently related to neuronal loss in the nucleus basalis of Meynert, particularly in non-Lewy body parkinsonism.

Physical aggression is associated with preservation of substantia nigra pars compacta in Alzheimer disease.

OBJECTIVE: To investigate specific neuropathologic correlates of agitation and physical aggression in Alzheimer disease (AD). DESIGN: Neuronal counts in the nucleus basalis, locus ceruleus, and substantia nigra were compared in the brains of patients with pathologically definite AD with or without histories of agitation or interpersonal violence. SETTING: Alzheimer disease center of a university department of neurology. MAIN OUTCOME MEASURES: Neuron densities in the nucleus basalis and absolute neuron counts in the locus ceruleus and substantia nigra pars compacta. RESULTS: The patients with AD who had histories of unequivocal interpersonal violence had significantly greater neuron counts in the substantia nigra pars compacta than did the nonviolent patients with AD. This finding remained significant after multiple clinical and neuropathologic variables were adjusted for. Neuropathologic findings in the nucleus basalis and locus ceruleus were not different between violent and nonviolent patients. CONCLUSION: Preservation of pigmented substantia nigra neurons may be a risk factor for physical aggression in AD.

Reliability and usefulness of a new immunochemical assay for Alzheimer's disease.

OBJECTIVE: To assess the reliability and usefulness of a new sandwich enzyme-linked immunoassay (ALZ-EIA) that detects Alzheimer's disease-associated proteins in the diagnosis of Alzheimer's disease. DESIGN: The reliability of the assay was assessed between two laboratories. Sensitivity and specificity of a diagnostic algorithm based on the results of the ALZ-EIA were determined using the Consortium to Establish a Registry for Alzheimer's Disease neuropathological diagnoses as the "gold standard." SETTING: Autopsy cases were obtained from a teaching hospital with a specialized Alzheimer Disease Diagnostic and Treatment Center. CASES: Brain tissue was selected from 24 cases with dementia and 10 normal controls. MAIN OUTCOME MEASURES: Optical density measurements from the ALZ-EIA in the hippocampus and three neocortical regions. RESULTS: A 95% concordance in ALZ-EIA activity was found between the two laboratories, and an 85% concordance was found between ALZ-EIA and the Consortium to Establish a Registry for Alzheimer's Disease diagnoses. Perfect agreement was obtained for "typical" Alzheimer's disease cases (those with plaques and tangles), while discrepancies occurred for "atypical" cases (those with predominantly plaques or tangles). CONCLUSIONS: The ALZ-EIA provides a highly reliable method of assessing neurofibrillary degeneration. Its clinical usefulness as a diagnostic test would be enhanced by the availability of a complementary assay for beta-amyloid.

Clinical criteria for the diagnosis of vascular dementia: a multicenter study of comparability and interrater reliability.

BACKGROUND: Several clinical criteria have been developed to standardize the diagnosis of vascular dementia (VaD). Significant differences in patient classification have been reported, depending on the criteria used. Few studies have examined interrater reliability. OBJECTIVE: To assess the concordance in classification and interrater reliability for the following 4 clinical definitions of VaD: the Hachinski Ischemic Score (HIS), the Alzheimer Disease Diagnostic and Treatment Centers (ADDTC), National Institute of Neurological Disorders and Stroke-Association Internationale pour la Recherche et l'Enseignement en Neurosciences (NINDS-AIREN), and Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). METHODS: Structured diagnostic checklists were developed for 4 criteria for VaD, 2 criteria for Alzheimer disease (AD), and 4 criteria for dementia. Twenty-five case vignettes, representing a spectrum of cognitive impairment and subtypes of dementia, were prepared in a standardized clinical format. Concordance in case classification using different criteria and interrater reliability among 7 ADDTCs given a specific set of criteria was assessed using the kappa statistic. RESULTS: The frequency of a diagnosis of VaD was highest using the modified HIS or DSM-IV criteria, intermediate using the original HIS and ADDTC criteria, and lowest using the NINDS-AIREN criteria. Scores for interrater reliability ranged from kappa = 0.30 (ADDTC) to kappa = 0.61 (original HIS). CONCLUSIONS: Clinical criteria for VaD are not interchangeable. Depending on the criteria selected, the reported prevalence of VaD will vary significantly. The traditional HIS has higher interrater reliability than the newer criteria for VaD. Prospective longitudinal studies with clinical-pathological correlation are needed to compare validity.

Recognition memory and verbal fluency differentiate probable Alzheimer disease from subcortical ischemic vascular dementia.

BACKGROUND: Alzheimer disease (AD) and vascular dementia are among the most frequently occurring causes of dementia in the world, and their accurate differentiation is important because different pharmaceutical strategies may modify the course of each disease. OBJECTIVE: To determine which of 10 neuropsychological test scores can accurately differentiate patients with probable AD from those with subcortical ischemic vascular dementia (SIVD) for use in evidence-based clinical practice. DESIGN: Patients with suspected dementia were referred to the study by family physicians, geriatricians, and neurologists. All participants received a thorough assessment according to standard diagnostic guidelines. Diagnoses of probable AD (n = 31) and probable SIVD (n = 31) were made according to consensus criteria. The diagnosticians were blind to the results of the 10 neuropsychological test scores. RESULTS: There were no significant differences between the groups in age or Mini-Mental State Examination scores. Logistic regression analyses identified 2 neuropsychological tests that best distinguished the groups (sensitivity = 81%; specificity = 84%; positive likelihood ratio = 5.1). These were the recognition memory subtest of the Rey Auditory Verbal Learning Test and the Controlled Oral Word Association Test. The AD group performed better on the oral association test, whereas the SIVD group did better on the recognition memory test. CONCLUSION: Patients with probable AD and probable SIVD can be distinguished with a high degree of accuracy using these 2 neuropsychological tests.