Clinico-neuropathological correlation of Alzheimer's disease in a community-based case series

Biomarkers in Alzheimer's disease

Alzheimer's disease (AD) is the most common form of dementia in the elderly, and it is characterized by progressive impairment in multiple cognitive domains of sufficient severity to interfere with individuals' daily living activities. Historically, the diagnosis of AD has been based on the identification of a clinical syndrome, and accuracy studies of the current clinical criteria conducted in referral clinics have shown high sensitivity for AD. However, the identification of the disease is still not perfect, and there is growing evidence that the use of biomarkers will increase our ability to better indentify the underlying biology of AD, especially in its early stages. These biomarkers will improve the detection of the patients suitable for research studies and drug trials, and they will contribute to a better management of the disease in the clinical practice. In this review, we discuss the most studied biomarkers in AD: cerebrospinal fluid proteins, structural magnetic resonance imaging, functional neuroimaging techniques, and amyloid imaging.

Synergistic memory impairment through the interaction of chronic cerebral hypoperfusion and amlyloid toxicity in a rat model

BACKGROUND AND PURPOSE

Vascular pathology and Alzheimer disease (AD) pathology have been shown to coexist in the brains of dementia patients. We investigated how cognitive impairment could be exacerbated in a rat model of combined injury through the interaction of chronic cerebral hypoperfusion and amyloid beta (Aβ) toxicity.

METHODS

In Wistar rats, chronic cerebral hypoperfusion was modeled by permanent occlusion of bilateral common carotid arteries (BCCAo). Further, AD pathology was modeled by bilateral intracerebroventricular Aβ (Aβ toxicity) using a nonphysiological Aβ peptide (Aβ 25 to 35). The experimental animals were divided into 4 groups, including sham, single injury (Aβ toxicity or BCCAo), and combined injury (BCCAo-Aβ toxicity) groups (n=7 per group) . Cerebral blood flow and metabolism were measured using small animal positron emission tomography. A Morris water maze task, novel object location and recognition tests, and histological investigation, including neuronal cell death, apoptosis, neuroinflammation, and AD-related pathology, were performed.

RESULTS

Spatial memory impairment was synergistically exacerbated in the BCCAo-Aβ toxicity group as compared to the BCCAo or Aβ toxicity groups (P<0.05). Compared to the sham group, neuroinflammation with microglial or astroglial activation was increased both in multiple white matter lesions and the hippocampus in other experimental groups. AD-related pathology was enhanced in the BCCAo-Aβ toxicity group compared to the Aβ toxicity group.

CONCLUSIONS

Our experimental results support a clinical hypothesis of the deleterious interaction between chronic cerebral hypoperfusion and Aβ toxicity. Chronic cerebral hypoperfusion-induced perturbation in the equilibrium of AD-related pathology may exacerbate cognitive impairment in a rat model of combined injury.

Operationalizing diagnostic criteria for Alzheimer's disease and other age-related cognitive impairment-Part 2

This article focuses on the effects of operational differences in case ascertainment on estimates of prevalence and incidence of cognitive impairment and/or dementia of the Alzheimer type. Experience and insights are discussed by investigators from the Framingham Heart Study, the East Boston Senior Health Project, the Chicago Health and Aging Project, the Mayo Clinic Study of Aging, the Baltimore Longitudinal Study of Aging, and the Aging, Demographics, and Memory Study. There is a general consensus that the single most important factor determining prevalence estimates of Alzheimer's disease (AD) is the severity of cognitive impairment used as a threshold to define cases. Studies that require a level of cognitive impairment in which persons are unable to provide self-care will have much lower estimates than the studies aimed at identifying persons in the earliest stages of AD. There are limited autopsy data from the aforementioned epidemiological studies to address accuracy in the diagnosis of etiological subtype, namely the specification of AD alone or in combination with other types of pathology. However, other community-based cohort studies show that many persons with mild cognitive impairment and also some persons without dementia or mild cognitive impairment meet pathological criteria for AD, thereby suggesting that the number of persons who would benefit from an effective secondary prevention intervention is probably higher than the published prevalence estimates. Improved accuracy in the clinical diagnosis of AD is anticipated with the addition of molecular and structural biomarkers in the next generation of epidemiological studies.

PET amyloid imaging as a tool for early diagnosis and identifying patients at risk for progression to Alzheimer's disease

Current theory suggests that β-amyloid accumulation may be an early step in the cascade that leads to cognitive impairment in Alzheimer's disease. β-Amyloid targeted positron emission tomography (PET) imaging potentially provides a direct, relatively noninvasive estimate of brain β-amyloid burden. This has recently been supported by demonstration that amyloid plaque binding on PET was strongly correlated with brain β-amyloid burden at autopsy. Additionally, there is growing consensus that PET imaging can identify subjects with elevated β-amyloid burden, even at early stages of disease. Finally, preliminary evidence suggests that abnormal β-amyloid accumulation, as evidenced by PET imaging, has implications for both present nd future cognitive performance. Although large longitudinal studies like the ongoing ADNI trial will be required for definitive evaluation, present data suggest that PET amyloid imaging has the potential to promote earlier and more specific diagnosis of dementia.

Almitrine-Raubasine combination for dementia

BACKGROUND

Almitrine-raubasine combination (brand name Duxil), has been considered as an alternative treatment for dementia.

OBJECTIVES

To determine the clinical efficacy and safety of Duxil in the treatment of patients with dementia.

SEARCH STRATEGY

We searched the Cochrane Dementia and Cognitive Improvement Group Specialised Register (now known as ALOIS) (September 2009), the China Biological Medicine Database (CBM-disc 1979 to December 2009), the Chinese National Knowledge Infrastructure (www.cnki.net 1979 to December 2009), the Stroke Trials Registry at www.strokecentre.org/trials/index.aspx. We searched identified citations for additional trials, contacted the first author of identified trials for additional references and unpublished data. We also contacted the pharmaceutical company manufacturing Duxil (Servier Pharmaceutical Co Ltd) for additional unpublished data.

SELECTION CRITERIA

Randomised controlled trials studying the efficacy and safety of Duxil for dementia were included, irrespective of blinding, publication status, or language. If the trial was cross-over in nature, only data from the first period were included.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, assessed trial quality and extracted the data.

MAIN RESULTS

Three trials involving a total of 206 participants were included, all patients with vascular dementia. All three included studies were assessed as being at high risk of bias. When analysing these trials together, there was significant beneficial effect of Duxil on the improvement of cognitive function measured by MMSE (WMD 2.04, 95% CI 1.43 to 2.66). No data on behaviour and death at the end of treatment and follow-up were available from the included trials. Two trials failed to show an improvement of functional performance measured by ADL (WMD -1.68; 95% CI -3.70 to 0.35). Of the three included trials, all described the adverse events in detail, there were no statistically significant differences across the trials (OR 4.84, 95%CI 0.55 to 42.67). Behaviour disturbance, quality of life, caregiver burden were not undertaken in the included trials.

AUTHORS' CONCLUSIONS

Due to the low methodological quality of included trials, small number of trials and probable publication bias, this review did not provide sufficient evidence to support the routine use of Duxil for the treatment of patients with dementia. High-quality and large-scale randomised controlled trials are needed to confirm or refute these results.

Multimodal EEG, MRI and PET data fusion for Alzheimer's disease diagnosis

Alarmingly increasing prevalence of Alzheimer's disease (AD) due to the aging population in developing countries, combined with lack of standardized and conclusive diagnostic procedures, make early diagnosis of Alzheimer's disease a major public health concern. While no current medical treatment exists to stop or reverse this disease, recent dementia specific pharmacological advances can slow its progression, making early diagnosis all the more important. Several noninvasive biomarkers have been proposed, including P300 based EEG analysis, MRI volumetric analysis, PET based metabolic activity analysis, as alternatives to neuropsychological evaluation, the current gold standard of diagnosis. Each of these approaches, have shown some promising outcomes, however, a comprehensive data fusion analysis has not yet been conducted to investigate whether these different modalities carry complementary information, and if so, whether they can be combined to provide a more accurate analysis. In this effort, we provide a first look at such an analysis in combining EEG, MRI and PET data using an ensemble of classifiers based decision fusion approach, to determine whether a strategic combination of these different modalities can improve the diagnostic accuracy over any of the individual data sources when used with an automated classifier. Results show an improvement of up to 10%-20% using this approach compared to the classification performance obtained when using each individual data source.

Familial aggregation of dementia with Lewy bodies

BACKGROUND

Familial aggregation of dementia with Lewy bodies (DLB) remains unclear.

OBJECTIVES

To determine the degree of family aggregation of DLB by comparing DLB risk between siblings of probands with clinically diagnosed DLB and siblings of probands with clinically diagnosed Alzheimer disease in a cohort of Caribbean Hispanic families and to explore the degree of aggregation of specific clinical manifestations (ie, cognitive fluctuations, visual hallucinations, and parkinsonism) in DLB.

DESIGN

Familial cohort study.

SETTING

Academic research.

PATIENTS

We separately compared risks of possible DLB, probable DLB, and clinical core features of DLB (cognitive fluctuations, visual hallucinations, and parkinsonism) between siblings of probands with clinically diagnosed DLB (n = 344) and siblings of probands with clinically diagnosed Alzheimer disease (n = 280) in 214 Caribbean Hispanic families with extended neurologic and neuropsychological assessment.

MAIN OUTCOME MEASURES

We applied general estimating equations to adjust for clustering within families. In these models, age and proband disease status were independent variables, and disease status of siblings was the measure of disease risk and the dependent variable.

RESULTS

Compared with siblings of probands having clinically diagnosed Alzheimer disease, siblings of probands having clinically diagnosed DLB had higher risks of probable DLB (odds ratio [OR], 2.29; 95% confidence interval [CI], 1.04-5.04) and visual hallucinations (2.32; 1.16-4.64). They also had increased risks of possible DLB (OR, 1.51; 95% CI, 0.97-2.34) and cognitive fluctuations (1.55; 0.95-2.53).

CONCLUSIONS

Dementia with Lewy bodies and core features of DLB aggregate in families. Compared with siblings of probands having clinically diagnosed AD, siblings of probands having clinically diagnosed DLB are at increased risks of DLB and visual hallucinations. These findings are an important step in elucidating the genetic risk factors underlying DLB and in delineating DLB from other neurodegenerative diseases, such as Alzheimer disease.

World Federation of Societies of Biological Psychiatry (WFSBP) guidelines for the biological treatment of Alzheimer's disease and other dementias

OBJECTIVES

To define a practice guideline for biological treatment of dementia and to make transparent the development of the guideline connecting the original data with the resulting recommendations.

METHODS

This guideline includes pharmacologic treatment considerations for patients with Alzheimer's disease, vascular dementia, DLB, and fronto-temporal dementia. Studies were selected that represent double-blind placebo-controlled trials of at least 3 months duration in patients with a diagnosis of dementia according to accepted international diagnostic criteria (for example the NINCDS/ADRDA or NINDS/AIREN criteria). Moreover, to be included studies had to fulfill a restrictive set of methodological criteria. Original studies and not meta-analyses determined the evaluation and the development of recommendations.

RESULTS

Antidementia pharmaceuticals neither cure nor arrest the disease. A modest effect of improvement of symptoms compared with placebo can be observed. Antidementia pharmaceuticals show different efficacy and side effect profiles. The type of dementia, the individual symptom constellation and the tolerability should determine what medication should be used. There are hints that combination therapy of drugs with different therapeutic mechanisms might improve the efficacy. In treating neuropsychiatric symptoms (NPS), psychosocial intervention should be the treatment of first choice. Pharmaceuticals can only be recommended when psychosocial interventions is not adequate. However, even then the side effects of pharmaceuticals limit their use.

CONCLUSIONS

Depending on the diagnostic entity and the pathology treated different anti-dementia drugs can be recommended to improve symptoms. In the management of NPS, side effects limit the use of medications even when psychosocial interventions have failed. Thus, there is an urgent need to develop more efficacious medications for the treatment of dementia.

Prospects for delaying the rising tide of worldwide, late-life dementias

Worldwide, lifespan is lengthening. Concomitantly, late-life dementias are increasingly common, challenging both personal and public health internationally. After age 65, rates of dementia tend to double every five years in developed countries and every seven in developing ones. The late-life dementias, particularly Alzheimer's disease, have profound effects on aging individuals and their caregivers. Multidisciplinary research has explored the potential for various approaches to prevent or delay the onset of late-life dementias. Outlining that research, including our team's Adult Changes in Thought and Kame studies, this review concludes that delaying the onset of these dementias appears feasible, although absolute prevention may not be. Today, the most promising methods appear to include controlling vascular risk factors like hypertension and engaging in physical exercise - and possibly mental exercise. If people can delay the onset of dementias, they can lead more fulfilling lives for longer, spending less time suffering from dementia and letting their families spend less time coping with the disease. It is possible that trends toward more knowledge-based societies, where cognitive health is so vital, may increasingly exert evolutionary pressure favoring larger and healthier brains - and a "compression of cognitive morbidity" - well into old age. Public health's great triumph, increased lifespan, should give more of the world's people the reward of many years of dementia-free life. Rather than the personal difficulties and public health burdens of many years of functional impairment, dependency, and suffering with dementia, some interventions may delay the onset of Alzheimer's disease and other dementias.

The neuropathology of older persons with and without dementia from community versus clinic cohorts

Community-based cohorts of older persons may differ neuropathologically from clinic-based cohorts. This study investigated age-related pathologies in persons with and without dementia and included autopsied participants from two community-based cohorts, the Rush Religious Orders Study (n=386) and the Memory and Aging Project (n=195), and one clinic-based cohort, the Clinical Core of the Rush Alzheimer's Disease Center (n=392). Final clinical diagnoses included no cognitive impairment (n=202), mild cognitive impairment (MCI) (n=150), probable Alzheimer's disease (AD) (n=474), possible AD (n=88), and other dementias (n=59). Postmortem diagnoses included pathologic AD, cerebral infarcts, and Lewy body disease. Community-based persons with clinical AD had less severe AD pathology (p<0.001) and had more cerebral infarcts (p<0.001) compared to clinic-based persons. Additionally, community-based persons with MCI had more infarcts compared to clinic-based persons. Overall, there was a higher proportion of Lewy bodies and atypical pathologies in the clinic-based compared to the community-based cohorts (p<0.001). Community-based persons with probable AD show less severe AD pathology and more often have infarcts and mixed pathologies; those with MCI more often have infarcts and mixed pathologies. Overall, clinic-based persons have more Lewy bodies and atypical pathologies. The spectrum of pathologies underlying cognitive impairment in clinic-based cohorts differs from community-based cohorts.

Measuring cognitive reserve based on the decomposition of episodic memory variance

In later adulthood brain pathology becomes common and trajectories of cognitive change are heterogeneous. Among the multiple determinants of late-life cognitive course, cognitive reserve has been proposed as an important factor that modifies or buffers the impact of brain pathology on cognitive function. This article presents and investigates a novel method for measuring and investigating such factors. The core concept is that in a population where pathology is common and variably present, 'reserve' may be defined as the difference between the cognitive performance predicted by an individual's level of pathology and that individual's actual performance. By this definition, people whose measured cognitive performance is better than predicted by pathology have high reserve, whereas those who perform worse than predicted have low reserve. To test this hypothesis, we applied a latent variable model to data from a diverse ageing cohort and decomposed the variance in a measure of episodic memory into three components, one predicted by demographics, one predicted by pathology as measured by structural MRI and a 'residual' or 'reserve' term that included all remaining variance. To investigate the plausibility of this approach, we then tested the residual component as an operational measure of reserve. Specific predictions about the effects of this putative reserve measure were generated from a general conceptual model of reserve. Each was borne from the results. The results show that the current level of reserve, as measured by this decomposition approach, modifies rates of conversion from mild cognitive impairment to dementia, modifies rates of longitudinal decline in executive function and, most importantly, attenuates the effect of brain atrophy on cognitive decline such that atrophy is more strongly associated with cognitive decline in subjects with low reserve than in those with high reserve. Decomposing the variance in cognitive function scores offers a promising new approach to the measure and study of cognitive reserve.

In vivo imaging of amyloid deposition in Alzheimer disease using the radioligand 18F-AV-45 (florbetapir [corrected] F 18)

An (18)F-labeled PET amyloid-beta (Abeta) imaging agent could facilitate the clinical evaluation of late-life cognitive impairment by providing an objective measure for Alzheimer disease (AD) pathology. Here we present the results of a clinical trial with (E)-4-(2-(6-(2-(2-(2-(18)F-fluoroethoxy)ethoxy)ethoxy)pyridin-3-yl)vinyl)-N-methyl benzenamine ((18)F-AV-45 or florbetapir [corrected] F 18).

METHODS

An open-label, multicenter brain imaging, metabolism, and safety study of (18)F-AV-45 was performed on 16 patients with AD (Mini-Mental State Examination score, 19.3 +/- 3.1; mean age +/- SD, 75.8 +/- 9.2 y) and 16 cognitively healthy controls (HCs) (Mini-Mental State Examination score, 29.8 +/- 0.45; mean age +/- SD, 72.5 +/- 11.6 y). Dynamic PET was performed over a period of approximately 90 min after injection of the tracer (370 MBq [10 mCi]). Standardized uptake values and cortical-to-cerebellum standardized uptake value ratios (SUVRs) were calculated. A simplified reference tissue method was used to generate distribution volume ratio (DVR) parametric maps for a subset of subjects.

RESULTS

Valid PET data were available for 11 AD patients and 15 HCs. (18)F-AV-45 accumulated in cortical regions expected to be high in Abeta deposition (e.g., precuneus and frontal and temporal cortices) in AD patients; minimal accumulation of the tracer was seen in cortical regions of HCs. The cortical-to-cerebellar SUVRs in AD patients showed continual substantial increases through 30 min after administration, reaching a plateau within 50 min. The 10-min period from 50 to 60 min after administration was taken as a representative sample for further analysis. The cortical average SUVR for this period was 1.67 +/- 0.175 for patients with AD versus 1.25 +/- 0.177 for HCs. Spatially normalized DVRs generated from PET dynamic scans were highly correlated with SUVR (r = 0.58-0.88, P < 0.005) and were significantly greater for AD patients than for HCs in cortical regions but not in subcortical white matter or cerebellar regions. No clinically significant changes in vital signs, electrocardiogram, or laboratory values were observed.

CONCLUSION

(18)F-AV-45 was well tolerated, and PET showed significant discrimination between AD patients and HCs, using either a parametric reference region method (DVR) or a simplified SUVR calculated from 10 min of scanning 50-60 min after (18)F-AV-45 administration.

Amyloid imaging results from the Australian Imaging, Biomarkers and Lifestyle (AIBL) study of aging

The Australian Imaging, Biomarkers and Lifestyle (AIBL) study of aging, a participant of the worldwide Alzheimer's Disease Neuroimaging Initiative (ADNI), performed (11)C-Pittsburgh Compound B (PiB) scans in 177 healthy controls (HC), 57 mild cognitive impairment (MCI) subjects, and 53 mild Alzheimer's disease (AD) patients. High PiB binding was present in 33% of HC (49% in ApoE-epsilon4 carriers vs 21% in noncarriers) and increased with age, most strongly in epsilon4 carriers. 18% of HC aged 60-69 had high PiB binding rising to 65% in those over 80 years. Subjective memory complaint was only associated with elevated PiB binding in epsilon4 carriers. There was no correlation with cognition in HC or MCI. PiB binding in AD was unrelated to age, hippocampal volume or memory. Beta-amyloid (Abeta) deposition seems almost inevitable with advanced age, amyloid burden is similar at all ages in AD, and secondary factors or downstream events appear to play a more direct role than total beta amyloid burden in hippocampal atrophy and cognitive decline.

Comorbid depression is associated with an increased risk of dementia diagnosis in patients with diabetes: a prospective cohort study

BACKGROUND

Both depression and diabetes have been found to be risk factors for dementia. This study examined whether comorbid depression in patients with diabetes increases the risk for dementia compared to those with diabetes alone.

METHODS

We conducted a prospective cohort study of 3,837 primary care patients with diabetes (mean age 63.2 +/- 13.2 years) enrolled in an HMO in Washington State. The Patient Health Questionnaire (PHQ-9) was used to assess depression at baseline, and ICD-9 diagnoses for dementia were used to identify cases of dementia. Cohort members with no previous ICD-9 diagnosis of dementia prior to baseline were followed for a 5-year period. The risk of dementia for patients with both major depression and diabetes at baseline relative to patients with diabetes alone was estimated using cause-specific Cox proportional hazard regression models that adjusted for age, gender, education, race/ethnicity, diabetes duration, treatment with insulin, diabetes complications, nondiabetes-related medical comorbidity, hypertension, BMI, physical inactivity, smoking, HbA(1c), and number of primary care visits per month.

RESULTS

Over the 5-year period, 36 of 455 (7.9%) patients with major depression and diabetes (incidence rate of 21.5 per 1,000 person-years) versus 163 of 3,382 (4.8%) patients with diabetes alone (incidence rate of 11.8 per 1,000 person-years) had one or more ICD-9 diagnoses of dementia. Patients with comorbid major depression had an increased risk of dementia (fully adjusted hazard ratio 2.69, 95% CI 1.77, 4.07).

CONCLUSIONS

Patients with major depression and diabetes had an increased risk of development of dementia compared to those with diabetes alone. These data add to recent findings showing that depression was associated with an increased risk of macrovascular and microvascular complications in patients with diabetes.

ERP based decision fusion for AD diagnosis across cohorts

As the average life expectancy increases, particularly in developing countries, prevalence of neurodegenerative diseases has also increased. This trend is especially alarming for Alzheimer's disease (AD); as there is no cure to stop or reverse the effects of AD. However, recent pharmacological advances can slow the progression of AD, but only if AD is diagnosed at early stages. We have previously introduced an ensemble of classifiers based approach for combining event related potentials obtained from different electrode locations as an effective approach for early diagnosis of AD. We further expand this approach and analyze its robustness and stability in two ways: comparing the diagnostic accuracy on hand selected and cleaned data vs. standard automated preprocessing, but more importantly, comparing the diagnostic accuracy on two different cohorts, whose data are collected under different settings: a research university lab and a community clinic.

Proteomics-derived cerebrospinal fluid markers of autopsy-confirmed Alzheimer's disease

The diagnostic performance of several candidate cerebrospinal fluid (CSF) protein biomarkers in neuropathologically confirmed Alzheimer's disease (AD), non-demented (ND) elderly controls and non-AD dementias (NADD) was assessed. Candidate markers were selected on the basis of initial two-dimensional gel electrophoresis studies or by literature review. Markers selected by the former method included apolipoprotein A-1 (ApoA1), haemopexin (HPX), transthyretin (TTR) and pigment epithelium-derived factor (PEDF), while markers identified from the literature included Abeta1-40, Abeta1-42, total tau, phosphorylated tau, alpha-1 acid glycoprotein (A1GP), haptoglobin, zinc alpha-2 glycoprotein (Z2GP) and apolipoprotein E (ApoE). Ventricular CSF concentrations of the markers were measured by enzyme-linked immunosorbent assay (ELISA). The concentrations of Abeta1-42, ApoA1, A1GP, ApoE, HPX and Z2GP differed significantly among AD, ND and NADD subjects. Logistic regression analysis for the diagnostic discrimination of AD from ND found that Abeta1-42, ApoA1 and HPX each had significant and independent associations with diagnosis. The CSF concentrations of these three markers distinguished AD from ND subjects with 84% sensitivity and 72% specificity, with 78% of subjects correctly classified. By comparison, using Abeta1-42 alone gave 79% sensitivity and 61% specificity, with 68% of subjects correctly classified. For the diagnostic discrimination of AD from NADD, only the concentration of Abeta1-42 was significantly related to diagnosis, with a sensitivity of 58%, specificity of 86% and 86% correctly classified. The results indicate that for the discrimination of AD from ND control subjects, measurement of a set of markers including Abeta1-42, ApoA1 and HPX improved diagnostic performance over that obtained by measurement of Abeta1-42 alone. For the discrimination of AD from NADD subjects, measurement of Abeta1-42 alone was superior.

Interpretation of neuropathological lesions: its limitations in medico-legal experts' reports

Aggressive or paradoxical behaviour may reflect an organic dementia. The most frequent is Alzheimer's disease, which results from an abnormal structural conformation of tubulin-associated protein (tau) and beta-amyloid protein that, respectively, aggregate in certain neurons as intracellular neurofibrillary tangles (NFTs) and in the extracellular environment as senile plaques. These lesions progress in the brain tissue according to the stages described by Braak and Braak. Staging of neurofibrillary pathology has proven anatomical and clinical correlation, which can be used in a medico-legal procedure. We report two cases demonstrating discrepancies between anatomical and clinical features, which should encourage medical expert to prudence when interpreting neuropathological reports.

Insensitivity of visual assessment of hippocampal atrophy in familial Alzheimer's disease

Medial temporal atrophy is a well-established marker for Alzheimer's disease (AD). However, due to normal variation in the size of medial temporal structures and variability in how radiologists interpret images, the use of clinical reads in establishing the presence of pathological atrophy is imprecise. A limitation of studies of magnetic resonance imaging (MRI) measures in AD is diagnostic uncertainty as it can be unknown if pre- or early-symptomatic subjects go on to develop AD and most subjects do not undergo autopsy verification of the diagnosis. In persons with or at-risk for AD due to fully-penetrant autosomal dominant mutations in the PSEN1 and APP genes, the diagnosis or future development of AD can be predicted with essentially 100% accuracy. We used this predictability to assess the ability of radiologists to detect hippocampal atrophy (HA) in persons destined to develop AD. Coronal T1-weighted MRI scans of 39 persons demented from (n = 4) or at-risk for inheriting (n = 35) PSEN1 or APP mutations were independently assessed by two radiologists and the presence or absence of HA determined. Of the 39 subjects, 26 were FAD mutation carriers. Fifteen of 28 asymptomatic at-risk persons were FAD mutation carriers and four of these were rated as having atrophy for a sensitivity of 27% and a specificity of 85%. Among seven mildly affected yet non-demented subjects, atrophy was detected in three and in the four demented subjects HA was identified in two. Our results suggest that radiologists' ability to detect HA in persons in whom the diagnosis of incipient AD is certain is sub-optimal and quantitative MRI techniques or other biological markers of the disease are needed.

Positron emission tomography and magnetic resonance imaging in the diagnosis and prediction of dementia

BACKGROUND

The diagnosis of dementia, along with the prediction of who will develop dementia, has been assisted by the development of the brain imaging techniques of magnetic resonance imaging (MRI) and positron emission tomography (PET).

METHODS

This paper reviews the brain imaging technologies of structural MRI and PET scanning as they have been applied to both the diagnosis of dementia and prediction of who will develop dementia.

RESULTS

Diagnosis has long been enhanced by the use of structural imaging techniques like MRI to rule out non-degenerative causes of disease. More recently, PET imaging with the glucose metabolic tracer [(18)F]Fluorodeoxyglucose (FDG) may be useful in providing information on the cause of dementia during life, most specifically in differentiating Alzheimer's disease from frontotemporal lobar degeneration. In addition to diagnosis, potential therapeutic advances have increased interest in prediction of dementia. Both MR and FDG-PET have shown evidence of change in brain structure and metabolism in several models of individuals at-risk for dementia, including those with mild cognitive impairment and genetic risk factors.

CONCLUSIONS

While these studies have not yet advanced to the level of prospective individual-subject predictive ability, the pattern of data emerging suggests likely candidate approaches for such studies. The advent of newer techniques such as amyloid imaging with PET and functional MRI may ultimately have relevance for both diagnosis and prediction.

Comparison of clinical and neuropathologic diagnoses of Alzheimer's disease in 3 epidemiologic samples

BACKGROUND

Studies of dementia in populations avoid many of the selection biases in clinical samples but require special evaluation and diagnostic methods to obtain high participation rates. To address this issue, we developed a unique in-home dementia assessment. We assessed validity of these assessments using neuropathologic confirmation of the clinical diagnosis in 3 epidemiologic samples.

METHODS

Subjects were 175 participants in 3 ongoing studies of dementia. Two were population based and identified dementia by cognitive screening. The third study sought volunteers via advertisements. Dementia evaluations were then conducted at the participants' residences by specially trained nurses and psychometricians. Evaluation results were interpreted, and preliminary diagnoses were assigned by a geropsychiatrist or neurologist and a psychologist. Final diagnoses were assigned by a consensus panel of neurologists, geropsychiatrists, and psychologists. We compared the clinical diagnoses with the gold-standard neuropathologic diagnoses for those participants who subsequently underwent autopsy.

RESULTS

Among the demented, the sensitivity of a clinical diagnosis of probable or possible Alzheimer's disease (AD) was 93% across the 3 studies. The rate of overall diagnostic agreement was 81%. Measures of agreement did not differ meaningfully across varying levels of dementia severity.

CONCLUSIONS

Rates of neuropathologic confirmation for clinical AD diagnoses in these studies were similar to those reported from clinic-based samples. These results support the validity of clinical diagnoses of AD from a structured in-home assessment of community dwelling and institutionalized individuals using relatively economical methods of dementia screening and assessment.

Quantitative evaluation of Alzheimer's disease

Alzheimer's disease (AD) can be definitively diagnosed only by histopathologic examination of brain tissue; the identification and differential diagnosis of AD is especially challenging in its early stages. Neuroimaging is playing an increasingly relevant role in the identification and quantification of AD in vivo, especially in the preclinical stages, when therapeutic intervention could be more effective. Neuroimaging enables quantification of brain volume loss (structural imaging), detection of early cerebral dysfunction (functional imaging), probing into the finest cerebral structures (microstructural imaging), and investigation of amyloid plaque and neurofibrillary tangle build-up (amyloid imaging). Throughout the years, several imaging tools have been developed, ranging from simple visual rating scales to sophisticated computerized algorithms. As recently revised criteria for AD require quantitative evaluation of biomarkers mostly based on imaging, this paper provides an overview of the main neuroimaging tools which might be used presently or in the future in routine clinical practice for AD diagnosis.

Cognitive impairment in older adults without dementia: clinical and pathologic outcomes in a community-based sample

This study examines clinical and neuropathologic characteristics of 37 participants in a community-based dementia series who had cognitive complaints at enrollment but did not meet dementia criteria. Participants had neuropsychological testing, were followed until death, and underwent autopsy. Twenty-four participants progressed to dementia, and their baseline characteristics were analyzed. Of the 24, 13 met criteria for neuropathologic Alzheimer disease (AD). The 13 participants who progressed to neuropathologic AD (mean intake age 78.5 +/- 7.7, mean enrollment 6.4 +/- 2.1 years) performed worse than the 11 who progressed to neuropathologic non-AD dementias (mean intake age 79.0 +/- 6.0, mean enrollment 6.0 +/- 3.2 years) on baseline Wechsler Memory Scale (WMS) delayed logical memory (3.4 +/- 2.9 vs 6.3 +/- 3.9, P = .05) and delayed visual reproduction (1.4 +/- 2.1 vs 3.1 +/- 2.7, P = .02). These observations are consistent with the view that nondemented patients with underlying AD may be more likely to present with memory than nonmemory cognitive impairment.

The neuropathology of probable Alzheimer disease and mild cognitive impairment

OBJECTIVE

Mixed pathologies are common in older persons with dementia. Little is known about mixed pathologies in probable Alzheimer disease (AD) and about the spectrum of neuropathology in mild cognitive impairment (MCI). The objective of this study was to investigate single and mixed common age-related neuropathologies in persons with probable AD and MCI.

METHODS

The study included 483 autopsied participants from the Religious Orders Study and the Rush Memory and Aging Project with probable AD (National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria), MCI (amnestic and nonamnestic), or no cognitive impairment. We excluded 41 persons with clinically possible AD and 14 with other dementias. We documented the neuropathology of AD (National Institute on Aging-Reagan criteria), macroscopic cerebral infarcts, and neocortical Lewy body (LB) disease.

RESULTS

Of 179 persons (average age, 86.9 years) with probable AD, 87.7% had pathologically confirmed AD, and 45.8% had mixed pathologies, most commonly AD with macroscopic infarcts (n = 54), followed by AD with neocortical LB disease (n = 19) and both (n = 8). Of the 134 persons with MCI, 54.4% had pathologically diagnosed AD (58.7% amnestic; 49.2% nonamnestic); 19.4% had mixed pathologies (22.7% amnestic; 15.3% nonamnestic). Macroscopic infarcts without pathologically diagnosed AD accounted for 4.5% of probable AD, 13.3% of amnestic MCI, and 18.6% of nonamnestic MCI. Pure neocortical LB disease was uncommon in all persons with cognitive impairment (<6%). Microscopic infarcts (without macroscopic infarcts) were common as a mixed pathology, but rarely accounted for a clinical diagnosis of probable AD (n = 4) or MCI (n = 3).

INTERPRETATION

Clinically diagnosed probable AD and MCI, even amnestic MCI, are pathologically heterogeneous disorders, with many persons exhibiting mixed pathologies.

Blood pressure and brain injury in older adults: findings from a community-based autopsy study

OBJECTIVES

To examine correlations between blood pressure (BP) and dementia-related pathological brain changes in a community-based autopsy sample.

DESIGN

Prospective cohort study.

SETTING

A large health maintenance organization in Seattle, Washington.

PARTICIPANTS

A cohort of 250 participants aged 65 and older and cognitively normal at time of enrollment in the Adult Changes in Thought (ACT) Study and who underwent autopsy.

MEASUREMENTS

BP and history of antihypertensive treatment were taken at enrollment. A linear regression model was used to examine the relationship between BP (systolic (SBP) and diastolic (DBP)) at enrollment and pathological changes in the cerebrum (cystic macroscopic infarcts, microinfarcts, neuritic plaques, neurofibrillary tangles, and cortical Lewy bodies).

RESULTS

The presence of more than 2 microinfarcts, but not any other pathological change, was independently associated with SBP in younger participants (65-80, n=137) but not in older participants (>80, n=91). The relative risk (RR) for more than two microinfarcts with each 10-mmHg increase in SBP was 1.15 (95% confidence interval (CI)=1.00-1.33) in the younger participants, adjusted for age at entry, sex, and time to death. This RR was particularly strong in younger participants not taking antihypertensive medications (RR=1.48, 95% CI=1.21, 1.81); significant associations were not observed in participants treated for hypertension. Findings for DBP were negative.

CONCLUSION

The association between high SBP and cerebrovascular damage in untreated older adults (65-80) suggests that adequate hypertension treatment may reduce dementia risk by minimizing microvascular injury to cerebrum.

Clinicopathological concordance in dementia diagnostics

OBJECTIVE

Accurate distinction between dementia subtypes is important for patient care and pharmacological treatment. Continuing systematic comparisons of clinical and neuropathological dementia diagnoses may provide a basis for further improvement of the diagnostic procedure. The purpose of this study was to investigate concordance between clinical dementia diagnosis and neuropathological findings in the specialized dementia care.

METHODS

Inclusion required 1) a clinical dementia disorder diagnosed at a hospital-based memory clinic and 2) a neuropathological examination within the Department of Pathology at the University Hospital in Lund, Sweden, during the years 1996-2006. A total of 176 consecutive patients fulfilled the criteria and were thus included. Clinical dementia diagnoses were obtained from the medical records and compared with the neuropathological findings.

RESULTS

The clinical and pathological dementia diagnoses were in full accordance in 86 (49%) of the patients (kappa 0.37). In an additional 24 (14%) cases, the clinical diagnosis corresponded with some but not all pathological components judged to contribute to the dementia disorder. Of the patients with clinical Alzheimer disease, 84% (46/55) had a significant Alzheimer component with or without other significant pathology at neuropathological examination. The corresponding figure for vascular dementia (VaD) was 59% (24/41), for frontotemporal dementia 74% (20/27), for combined Alzheimer and VaD 25% (4/16), and for dementia with Lewy bodies 67% (6/9).

CONCLUSIONS

This study shows that clinical dementia diagnoses do not always correspond with neuropathological changes. It stresses the importance of neuropathological examination in research and in daily clinical practice.

Frontotemporal dementia and dementia with Lewy bodies in a case-control study of Alzheimer's disease

BACKGROUND

The clinical presentations in dementia with Lewy bodies (DLB) and frontotemporal dementia (FTD) overlap considerably with that of Alzheimer's disease (AD) despite different pathological processes. Autopsy studies have also shown that multiple brain pathology occurs frequently, even in cases with a single clinical diagnosis. We aimed to determine the frequency of clinical diagnosis of FTD and DLB and the underlying pathology in a well-characterized cohort of patients with a clinical diagnosis of probable or possible AD.

METHODS

We conducted a retrospective analysis of 170 AD patients (probable AD = 83; possible AD = 87) originally enrolled in a case-control study, 27 with postmortem examination, to establish the number of cases meeting probable diagnosis for FTD and DLB, using a checklist of features compiled from their consensus criteria.

RESULTS

23/83 probable AD cases and 32/87 possible AD cases met probable criteria for another dementia, more commonly DLB than FTD. AD pathology was present in 8/15 probable AD and 8/12 possible AD cases coming to autopsy. DLB pathology was seen in four cases and FTD pathology in eight cases. In the AD cases reaching clinical diagnosis for a second dementia syndrome and coming to autopsy, a minority showed non-AD pathology only.

CONCLUSIONS

Presence of core clinical features of non-AD dementia syndromes is common in AD. Concordance between clinical and pathological diagnoses of dementia remains variable. We propose that repeat clinical examinations and structural neuroimaging will improve diagnostic accuracy. In addition, clinical diagnostic criteria for the main dementia syndromes require refinement.

Current Concepts in Vascular Cognitive Impairment and Pharmacotherapeutic Implications

Objective:

To review evolution of the vascular cognitive impairment (VCI) construct, including diagnosis, pharmacotherapeutic implications, and address challenges that will shape future developments.

Data Sources:

Literature retrieval was accessed through PubMed, from 1966 to December 2008, using the terms vascular cognitive impairment, vascular dementia, post-stroke dementia, vascular cognitive disorder, mild cognitive impairment, criteria, disease progression, outcomes, treatment, prevention, biomarkers, and neuroimaging.

Study Selection and Data Extraction:

All articles in published English identified from the data sources were evaluated for inclusion. Regarding pharmacotherapy, prospective double-blind, placebo-controlled studies were included as well as extensions or relevant post hoc analyses.

Data Synthesis:

In the 1970s, “senile dementia due to hardening of the arteries” was used to describe dementia due to vascular causes. This was a narrow view of what is now known to be a common form of cognitive impairment in older people. Multiple infarct dementia (MID) was first proposed to describe dementia attributable to multiple cerebral infarcts, followed by the vascular dementia (VaD) construct, itself meant to be an improvement over MID. The VaD construct had limitations, not the least of which was that, by the time a patient was diagnosed with VaD, the opportunity for prevention was lost. Thus arose the concept of VCI, representing a group of heterogeneous disorders that share presumed vascular causes. The importance of VCI is centered on the fact that vascular risk factors are treatable, and thus should lead to a reduction in the incidence of cognitive impairment due to vascular causes. There is evidence that treatment of hypertension can lead to a reduction in the incidence of cognitive impairment and dementia, and that treatment of VaD with acetylcholinesterase inhibitors may be beneficial.

Conclusions:

Careful attention needs to be given to controlling vascular risk factors in at-risk patients. Pharmacists should play an active role in this important area of geriatric pharmacotherapy.

EEG and MRI data fusion for early diagnosis of Alzheimer's disease

The prevalence of Alzheimer's disease (AD) is rising alarmingly as the average age of our population increases. There is no treatment to halt or slow the pathology responsible for AD, however, new drugs are promising to reduce the rate of progression. On the other hand, the efficacy of these new medications critically depends on our ability to diagnose AD at the earliest stage. Currently AD is diagnosed through longitudinal clinical evaluations, which are available only at specialized dementia clinics, hence beyond financial and geographic reach of most patients. Automated diagnosis tools that can be made available to community hospitals would therefore be very beneficial. To that end, we have previously shown that the event related potentials obtained from different scalp locations can be effectively used for early diagnosis of AD using an ensemble of classifiers based decision fusion approach. In this study, we expand our data fusion approach to include MRI based measures of regional brain atrophy. Our initial results indicate that ERPs and MRI carry complementary information, and the combination of these heterogeneous data sources using a decision fusion approach can significantly improve diagnostic accuracy.

Visual hallucinations in dementia: a prospective community-based study with autopsy

OBJECTIVE

Several studies have demonstrated that specific neuropathologic features may be associated with the presence of visual hallucinations in dementia patients, but the clinical usefulness of these studies has been limited because their subjects were selected on the basis of neuropathologic findings rather than clinical presentations. This study seeks to investigate the demographic, clinical, and neuropathologic features of community-based dementia subjects with and without visual hallucations.

DESIGN

A prospective examination of the clinical and neuropathologic correlates of visual hallucinations in community-based dementia subjects.

PARTICIPANTS

One hundred forty-eight subjects with sufficient clinical and neuropathologic data from a community-based incident dementia autopsy case series.

RESULTS

Subjects were classified according to the presence or absence of visual hallucinations and subjects with visual hallucinations (N = 27) were younger at intake and more likely to exhibit agitation, delusions, and apathy than subjects without visual hallucinations (N = 121). Subjects with visual hallucinations were also more likely than subjects without visual hallucinations to have Lewy-related pathology (LRP) (78% versus 45%). In addition, a higher frequency of visual hallucinations was observed in subjects with neocortical LRP than subjects with limbic-, amygdala-, or brainstem-predominant LRP. Although Alzheimer disease with concomitant LRP was the most common neuropathologic subtype in the visual hallucinations-positive group (59%), the frequency of subjects with Alzheimer disease pathology did not differ significantly between those with and without visual hallucinations (74% versus 62%).

CONCLUSIONS

Subjects with visual hallucinations were more likely to have concomitant postural and gait disturbance, additional neuropsychiatric symptoms, and neocortical LRP than subjects without visual hallucinations. Visual hallucinations accompanying dementia have distinct clinical and neuropathologic characteristics that are important for prognosis and clinical management.

Understanding White Matter Disease

Most strokes are covert and observed incidentally on brain scans, but their presence increases risk of overt stroke and dementia. Amyloid angiopathy, associated with Alzheimer Disease (AD) causes stroke, and when even small strokes coexist with AD, they lower the threshold for dementia. Diffuse ischemic white matter disease impairs executive functioning, information processing speed, and gait. Neuroimaging techniques, such as tissue segmentation, Diffusion Tensor Imaging, MR Spectroscopy, functional MRI and amyloid PET, probe microstructural integrity, molecular biology, and activation patterns, providing new insights into brain-behavior relationships. MR-pathological studies of periventricular hyperintensity (leukoaraiosis) in aging and dementia reveal arteriolar tortuosity, reduced vessel density, and occlusive venous collagenosis which causes venous insufficiency and vasogenic edema. Activated microglia, oligodendroglial apoptosis, clasmatodendritic astrocytosis, and upregulated hypoxia-markers are seen on immunohistochemistry. Further research is needed to understand and treat this chronic subcortical vascular disease, which is epidemic in our aging population.

Criteria for the neuropathological diagnosis of dementing disorders: routes out of the swamp?

There are several consensus criteria for both the clinical and neuropathological diagnosis of different types of dementias. The clinical diagnostic accuracy using revised research criteria and newly developed biomarkers (MRI, PET, CSF analysis, genetic markers) ranges from 65 to 96% (for Alzheimer disease) with a specificity of diagnostic criteria versus other dementias of 23-88%. Neuropathological assessment of dementing disorders using immunohistochemistry, molecular biologic and genetic methods can achieve a diagnosis/classification, based on the homogeneous definitions, harmonized inter-laboratory methods and standards for the assessment of nervous system lesions, in about 99%, without, however, being able to clarify the causes/etiology of most of these disorders. Further prospective and concerted clinicopathological studies using revised methodological and validated protocols and uniform techniques are required to establish the nature, distribution pattern and grades of lesions and; thus, to overcome the limitations of the current diagnostic framework. By data fusion this my allow their more uniform application and correlation with the clinical data in order to approach a diagnostic "gold standard", and to create generally accepted criteria for differentiating cognitive disorders from healthy brain aging. The detection of disease-specific pathologies will be indispensable to determinate the efficacy of new therapy options.

Cerebrovascular dysfunction in amyloid precursor protein transgenic mice: contribution of soluble and insoluble amyloid-beta peptide, partial restoration via gamma-secretase inhibition

The contributing effect of cerebrovascular pathology in Alzheimer's disease (AD) has become increasingly appreciated. Recent evidence suggests that amyloid-beta peptide (Abeta), the same peptide found in neuritic plaques of AD, may play a role via its vasoactive properties. Several studies have examined young Tg2576 mice expressing mutant amyloid precursor protein (APP) and having elevated levels of soluble Abeta but no cerebral amyloid angiopathy (CAA). These studies suggest but do not prove that soluble Abeta can significantly impair the cerebral circulation. Other studies examining older Tg2576 mice having extensive CAA found even greater cerebrovascular dysfunction, suggesting that CAA is likely to further impair vascular function. Herein, we examined vasodilatory responses in young and older Tg2576 mice to further assess the roles of soluble and insoluble Abeta on vessel function. We found that (1) vascular impairment was present in both young and older Tg2576 mice; (2) a strong correlation between CAA severity and vessel reactivity exists; (3) a surprisingly small amount of CAA led to marked reduction or complete loss of vessel function; 4) CAA-induced vasomotor impairment resulted from dysfunction rather than loss or disruption of vascular smooth muscle cells; and 5) acute depletion of Abeta improved vessel function in young and to a lesser degree older Tg2576 mice. These results strongly suggest that both soluble and insoluble Abeta cause cerebrovascular dysfunction, that mechanisms other than Abeta-induced alteration in vessel integrity are responsible, and that anti-Abeta therapy may have beneficial vascular effects in addition to positive effects on parenchymal amyloid.

Cerebrospinal fluid levels of tau phosphorylated at threonine 181 in patients with Alzheimer's disease and vascular dementia

In 31 patients with probable Alzheimer's disease (AD), 19 with probable vascular dementia (VaD) and 20 with Possible AD and Possible VaD, cerebrospinal fluid (CSF) tau levels hyperphosphorylated at threonine 181 (Ptau) were measured by ELISA. Thirty-six age-matched subjects were used as controls. The severity of the cognitive decline was assessed at the time of CSF analysis and after a 12-month follow-up. The groups had comparable age, degree of cognitive impairment and disease duration; these parameters were not related to P-tau levels. P-tau discriminated between demented patients and controls, but no significant difference emerged between AD and the other groups. By contrast, higher P-tau values were found to predict, independently of the clinical diagnosis, a more rapid evolution of cognitive decline. Whether these findings are due to a lack of CSF P-tau specificity or to the low reliability of clinical and radiological criteria remains unclear. P-tau may be useful in the evaluation of disease evolution, by predicting the rate of cognitive decline.

Usability of cerebrospinal fluid biomarkers in a tertiary memory clinic

AIM

Assays for cerebrospinal fluid (CSF) levels of total tau, phospho-tau protein and beta-amyloid 1-42 have been available for some years. The aim of the study was to assess the usability of these biomarkers in a mixed population of tertiary dementia referral patients in a university-based memory clinic.

METHODS

147 consecutive patients with a lumbar puncture as a part of their clinical workup were studied. A retrospective diagnosis was established based on consensus criteria without the knowledge of the CSF results.

RESULTS

When diagnosing Alzheimer's disease (AD) compared to other diagnoses, the sensitivity of a single abnormal value was between 33 and 66%. The specificity was high except when discriminating AD from amnestic mild cognitive impairment. Two or more abnormal markers further increased the specificity and decreased the sensitivity.

CONCLUSION

In a tertiary setting, abnormal CSF biomarker results may be of a diagnostic value - whereas normal results do not exclude neurodegenerative disease.

Prevalence of dementia subtypes: a 30-year retrospective survey of neuropathological reports

We investigated the distribution of neuropathologically defined dementia subtypes among individuals with dementia disorder. The neuropathological reports were studied on all patients (n=524; 55.3% females; median age 80, range 39-102 years) with clinically diagnosed dementia disorder who underwent complete autopsy including neuropathological examination within the Department of Pathology at the University Hospital in Lund, Sweden, during the years 1974-2004. The neuropathological diagnosis was Alzheimer's disease (AD) in 42.0% of the cases, vascular dementia (VaD) in 23.7%, dementia of combined Alzheimer and vascular pathology in 21.6%, and frontotemporal dementia in 4.0% of the patients. The remaining 8.8% of the patients had other dementia disorders, including combinations other than combined Alzheimer and vascular pathology. The registered prevalence of dementia subtypes depends on many variables, including referral habits, clinical and neuropathological judgments and diagnostic traditions, all of these variables potentially changing over time. This, however, does not seem to obscure the delineation of the major dementia subgroups. In this material of 30 years from Lund in the south of Sweden, AD by far dominated among dementia subtypes, while cerebrovascular pathology corresponded with the dementia disorder, either entirely or partly, in almost half of the demented patients.

Age and apoE associations with complex pathologic features in Alzheimer's disease

The risk for Alzheimer's disease (AD) is influenced by both age and ApoE status. The present study addresses the associations of age and ApoE status on complex pathologic features in AD (n=81) including coexistent cerebrovascular disease (CVD), argyrophilic grain disease (AGD), and Lewy body disease (LBD). The frequency of coexistent cerebrovascular disease increased with increasing age. Age and ApoE status were differentially associated with atherosclerosis, lacunar infarctions, and microvascular pathology. Coexistent Lewy body pathology was negatively associated with age, dropping off abruptly after age 90. The presence of an ApoE epsilon4 allele was associated with an increased frequency of coexistent LBD. Logistic regression analyses demonstrated both dependent and independent effects of age and ApoE status on the presence of coexistent Lewy body pathology in AD. While the decreasing frequency of LBD in AD after age 90 could be partly accounted for by a lower probability of an ApoE epsilon4 allele, the independent association with age suggests either 1) a survival effect, 2) decreased incidence with advancing age, or 3) both.

Dementia of the Alzheimer type

Dementia of the Alzheimer type is a progressive, fatal neurodegenerative condition characterized by deterioration in cognition and memory, progressive impairment in the ability to carry out activities of daily living, and a number of neuropsychiatric symptoms. This narrative review summarizes the literature regarding descriptive epidemiology, clinical course, and characteristic neuropathological changes of dementia of the Alzheimer type. Although there are no definitive imaging or laboratory tests, except for brain biopsy, for diagnosis, brief screening instruments and neuropsychiatric test batteries used to assess the disease are discussed. Insufficient evidence exists for the use of biomarkers in clinical practice for diagnosis or disease management, but promising discoveries are summarized. Optimal treatment requires both nonpharmacological and pharmacological interventions, yet none have been shown to modify the disease's clinical course. This review describes the current available options and summarizes promising new avenues for treatment. Issues related to the care of persons with dementia of the Alzheimer type, including caregiver burden, long-term care, and the proliferation of dementia special care units, are discussed. Although advances have been made, more research is needed to address the gaps in our understanding of the disease.

Longitudinal follow-up of late-onset Alzheimer disease families

Historically, data for genetic studies are collected at one time point. However, for diseases with late onset or with complex phenotypes, such as Alzheimer disease (AD), restricting diagnosis to a single ascertainment contact may not be sufficient. Affection status may change over time and some initial diagnoses may be inconclusive. Follow-up provides the opportunity to resolve these complications. However, to date, previous studies have not formally demonstrated that longitudinally re-contacting families is practical or productive. To update data initially collected for linkage analysis of late-onset Alzheimer disease (LOAD), we successfully re-contacted 63 of 81 (78%) multiplex families (two to 17 years after ascertainment). Clinical status changed for 73 of the 230 (32%) non-affected participants. Additionally, expanded family history identified 20 additional affected individuals to supplement the data set. Furthermore, fostering ongoing relationships with participating families helped recruit 101 affected participants into an autopsy and tissue donation program. Despite similar presentations, discordance between clinical diagnosis and neuropathologic diagnosis was observed in 28% of those with tissue diagnoses. Most of the families were successfully re-contacted, and significant refinement and supplementation of the data was achieved. We concluded that serial contact with longitudinal evaluation of families has significant implications for genetic analyses.

Positron emission tomography scans obtained for the evaluation of cognitive dysfunction

The degree of intactness of human cognitive functioning for a given individual spans a wide spectrum, ranging from normal to severely demented. The differential diagnosis for the causes of impairment along that spectrum is also wide, and often difficult to distinguish clinically, which has led to an increasing role for neuroimaging tools in that evaluation. The most frequent causes of dementia are neurodegenerative disorders, Alzheimer's disease being the most prevalent among them, and they produce significant alterations in brain metabolism, with devastating neuropathologic, clinical, social, and economic consequences. These alterations are detectable through positron emission tomography (PET), even in their earliest stages. The most commonly performed PET studies of the brain are performed with (18)F-fluorodeoxyglucose as the imaged radiopharmaceutical. Such scans have demonstrated diagnostic and prognostic utility for clinicians evaluating patients with cognitive impairment and in distinguishing among primary neurodegenerative disorders and other etiologies contributing to cognitive decline. In addition to focusing on the effects on cerebral metabolism examined with (18)F-fluorodeoxyglucose PET, some other changes occurring in the brains of cognitively impaired patients assessable with other radiotracers will be considered. As preventive and disease-modifying treatments are developed, early detection of accurately diagnosed disease processes facilitated by the use of PET has the potential to substantially impact on the enormous human toll exacted by these diseases.

Vascular cognitive impairment: current concepts and clinical developments

Vascular cognitive impairment (VCI) comprises a range of cognitive disorders related to cerebral vessel disease and has generally replaced the term multi-infarct dementia. Despite the heterogeneity of the VCI construct, some clinical patterns can be discerned, which enable subtypes, such as mixed dementia and VCI-no dementia, to be recognised. Diagnostic criteria for vascular dementia do not encompass the full range of the VCI construct, and clinical investigators now recognise the need for harmonised standards to study the many manifestations of VCI seen in daily practice and to inform the development of diagnostic criteria. Although executive dysfunction is a recognised feature of VCI, some data suggest a less exclusive role than was previously proposed. VCI might be preventable, although the evidence for this is not as complete as it is for the prevention of stroke. Future studies into specific therapies for VCI will need to consider the clinical features and outcomes carefully.

The Sun Health Research Institute Brain Donation Program: description and experience, 1987-2007

The Brain Donation Program at Sun Health Research Institute has been in continual operation since 1987, with over 1000 brains banked. The population studied primarily resides in the retirement communities of northwest metropolitan Phoenix, Arizona. The Institute is affiliated with Sun Health, a nonprofit community-owned and operated health care provider. Subjects are enrolled prospectively to allow standardized clinical assessments during life. Funding comes primarily from competitive grants. The Program has made short postmortem brain retrieval a priority, with a 2.75-h median postmortem interval for the entire collection. This maximizes the utility of the resource for molecular studies; frozen tissue from approximately 82% of all cases is suitable for RNA studies. Studies performed in-house have shown that, even with very short postmortem intervals, increasing delays in brain retrieval adversely affect RNA integrity and that cerebrospinal fluid pH increases with postmortem interval but does not predict tissue viability.

Alzheimer's disease

Alzheimer's disease is the most prevalent form of dementia. There are significant efforts underway to elucidate the pathogenesis of this disease and to find ways to lessen the impact of the symptoms. This paper summarizes current knowledge regarding the diagnosis and treatment of the disorder.