Apolipoprotein E epsilon 4 allele frequency in patients with Lewy body dementia, Alzheimer's disease and age-matched controls

The APOE E4 Allele Is Associated with Faster Rates of Neuroretinal Thinning in a Prospective Cohort Study of Suspect and Early Glaucoma

Purpose

Design

Participants

Methods

Main Outcome Measures

Results

Conclusions

The Effect of GBA Mutations and APOE Polymorphisms on Dementia with Lewy Bodies in Ashkenazi Jews

BACKGROUND

Glucocerebrosidase (GBA) gene mutations and APOE polymorphisms are common in dementia with Lewy bodies (DLB), however their clinical impact is only partially elucidated.

OBJECTIVE

To explore the clinical impact of mutations in the GBA gene and APOE polymorphisms separately and in combination, in a cohort of Ashkenazi Jewish (AJ) patients with DLB.

METHODS

One hundred consecutively recruited AJ patients with clinically diagnosed DLB underwent genotyping for GBA mutations and APOE polymorphisms, and performed cognitive and motor clinical assessments.

RESULTS

Thirty-two (32%) patients with DLB were carriers of GBA mutations and 33 (33%) carried an APOE ɛ4 allele. GBA mutation carriers had a younger age of onset (mean [SD] age, 67.2 years [8.9] versus 71.97 [5.91]; p = 0.03), poorer cognition as assessed by the Mini-Mental State Examination (21.41 [6.9] versus 23.97 [5.18]; p < 0.005), and more severe parkinsonism as assessed with the Unified Parkinson's Disease Rating Scale motor part III (34.41 [13.49] versus 28.38 [11.21]; p = 0.01) compared to non-carriers. There were statistically significant interactions between the two genetic factors, so that patients who carried both a mild GBA mutation and the APOE ɛ4 allele (n = 9) had more severe cognitive (p = 0.048) and motor dysfunction (p = 0.037).

CONCLUSION

We found a high frequency of both GBA mutations and the APOE ɛ4 allele among AJ patients with DLB, both of which have distinct effects on the clinical disease phenotype, separately and in combination.

Assessment of APOE in atypical parkinsonism syndromes

Atypical parkinsonism syndromes are a heterogeneous group of neurodegenerative disorders that include corticobasal degeneration (CBD), Lewy body dementia (LBD), multiple system atrophy (MSA), and progressive supranuclear palsy (PSP). The APOE ε4 allele is a well-established risk factor for Alzheimer's disease; however, the role of APOE in atypical parkinsonism syndromes remains controversial. To examine the associations of APOE ε4 and ε2 alleles with risk of developing these syndromes, a total of 991 pathologically-confirmed atypical parkinsonism cases were genotyped using the Illumina NeuroChip array. We also performed genotyping and logistic regression analyses to examine APOE frequency and associated risk in patients with Alzheimer's disease (n = 571) and Parkinson's disease (n = 348). APOE genotypes were compared to those from neurologically healthy controls (n = 591). We demonstrate that APOE ε4 and ε2 carriers have a significantly increased and decreased risk, respectively, of developing Alzheimer's disease (ε4: OR: 4.13, 95% CI: 3.23-5.26, p = 3.67 × 10^-30; ε2: OR: 0.21, 95% CI: 0.13-0.34; p = 5.39 × 10^-10) and LBD (ε4: OR: 2.94, 95% CI: 2.34-3.71, p = 6.60 × 10^-20; ε2: OR = OR: 0.39, 95% CI: 0.26-0.59; p = 6.88 × 10^-6). No significant associations with risk for CBD, MSA, or PSP were observed. We also show that APOE ε4 decreases survival in a dose-dependent manner in Alzheimer's disease and LBD. Taken together, this study does not provide evidence to implicate a role of APOE in the neuropathogenesis of CBD, MSA, or PSP. However, we confirm association of the APOE ε4 allele with increased risk for LBD, and importantly demonstrate that APOE ε2 reduces risk of this disease.

Sex-Related Differences in Rat Choroid Plexus and Cerebrospinal Fluid: A cDNA Microarray and Proteomic Analysis

The choroid plexus (CP) epithelium is a unique structure in the brain that forms an interface between the peripheral blood and the cerebrospinal fluid (CSF), which is mostly produced by the CP itself. Because the CP transcriptome is regulated by the sex hormone background, the present study compared gene/protein expression profiles in the CP and CSF from male and female rats aiming to better understand sex-related differences in CP functions and brain physiology. We used data previously obtained by cDNA microarrays to compare the CP transcriptome between male and female rats, and complemented these data with the proteomic analysis of the CSF of castrated and sham-operated males and females. Microarray analysis showed that 17 128 and 17 002 genes are expressed in the male and female CP, which allowed the functional annotation of 141 and 134 pathways, respectively. Among the most expressed genes, canonical pathways associated with mitochondrial dysfunctions and oxidative phosphorylation were the most prominent, whereas the most relevant molecular and cellular functions annotated were protein synthesis, cellular growth and proliferation, cell death and survival, molecular transport, and protein trafficking. No significant differences were found between males and females regarding these pathways. Seminal functions of the CP differentially regulated between sexes were circadian rhythm signalling, as well as several canonical pathways related to stem cell differentiation, metabolism and the barrier function of the CP. The proteomic analysis identified five down-regulated proteins in the CSF samples from male rats compared to females and seven proteins exhibiting marked variation in the CSF of gonadectomised males compared to sham animals, whereas no differences were found between sham and ovariectomised females. These data clearly show sex-related differences in CP gene expression and CSF protein composition that may impact upon neurological diseases.

APOE ε4 influences β-amyloid deposition in primary progressive aphasia and speech apraxia

BACKGROUND

Apolipoprotein E ε4 (APOE ε4) is a risk factor for β-amyloid deposition in Alzheimer's disease dementia. Its influence on β-amyloid deposition in speech and language disorders, including primary progressive aphasia (PPA), is unclear.

METHODS

One hundred thirty subjects with PPA or progressive speech apraxia underwent APOE genotyping and Pittsburgh compound B (PiB) PET scanning. The relationship between APOE ε4 and PiB status, as well as severity and regional distribution of PiB, was assessed.

RESULTS

Forty-five subjects had an APOE ε4 allele and 60 subjects were PiB-positive. The odds ratio for a subject with APOE ε4 being PiB-positive compared with a subject without APOE ε4 being PiB-positive was 10.2 (95% confidence interval, 4.4-25.5; P < .0001). The APOE ε4 allele did not influence regional PiB distribution or severity.

CONCLUSION

APOE ε4 increases the risk of β-amyloid deposition in PPA and progressive speech apraxia but does not influence regional β-amyloid distribution or severity.

Sequence variants in eukaryotic translation initiation factor 4-gamma (eIF4G1) are associated with Lewy body dementia

We recently reported a missense mutation and four variants in eukaryotic translation initiation factor 4-gamma (EIF4G1) associated with parkinsonism, dementia or both. In those with a positive family history, the mode of inheritance was autosomal dominant. Detailed neuropathologic descriptions of individuals with EIF4G1 genetic variants have not been reported. Herein, we report neuropathologic findings of three individuals from two American families with EIF4G1 variants. The patients had initial clinical presentations of dementia or parkinsonism and all had dementia at the time of autopsy. One family carried an EIF4G1 double variant, c.2056G>T (p.G686C) and c.3589C>T (p.R1197 W), and one family carried variant c.1505C>T (p.A502V). All three patients also carried at least one ε4 allele of apolipoprotein E. One individual presented with cognitive impairment without significant parkinsonism; one presented with memory problems followed by bradykinesia; and the third presented with cardinal signs of Parkinson's disease, followed more than a year later by cognitive dysfunction. Pathological examination showed diffuse cortical Lewy bodies and Lewy neurites in all patients. A small subset of Lewy bodies and Lewy neurites were immunopositive for eIF4G1. All patients had moderate to frequent non-neuritic, cortical amyloid plaques, mostly medial temporal neurofibrillary pathology (Braak neurofibrillary tangle stages of II to IV), and minimal or no TDP-43 pathology. The results suggest that in some patients variants in EIF4G1 can be associated with pathology that has a high likelihood of association with clinical features of dementia with Lewy bodies.

Diet and age interactions with regards to cholesterol regulation and brain pathogenesis

Cholesterol is an essential molecule for brain homeostasis; yet, hypercholesterolemia and its numerous complications are believed to play a role in promoting multiple aspects of brain pathogenesis. An ever increasing number of individuals in modern Western Society are regularly consuming diets high in fat which promote the development of hypercholesterolemia. Additionally, modern societies are becoming increasingly aged, causing a collision between increased hypercholesterolemia and increased aging, which will likely lead to the development of increased pathological conditions due to hypercholesterolemia, thereby promoting deleterious neurochemical and behavioral changes in the brain. Lastly, while beneficial in controlling cholesterol levels, the long-term use of statins itself may potentially promote adverse effects on brain homeostasis, although specifics on this remain largely unknown. This review will focus on linking the current understanding of diet-induced hypercholesterolemia (as well as statin use) to the development of oxidative stress, neurochemical alterations, and cognitive disturbances in the aging brain.

Proteomic identification of biomarkers in the cerebrospinal fluid in a rat model of nigrostriatal dopaminergic degeneration

We have performed proteomic analysis in the cerebrospinal fluid in an animal model of Parkinson's disease induced by axotomy of the medial forebrain bundle. In this model, the degeneration of dopaminergic neurons was completed in 14 days, with a loss of about 50% dopaminergic neurons in the substantia nigra and a loss of more than 80% dopamine terminals in the striatum, with a similar diminution of dopamine levels in both structures. Proteins were separated by 2D electrophoresis and identified by matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF). We found significant increases of haptoglobin and transthyretin along with a decrease of Apo E concentrations in the cerebrospinal fluid of axotomized animals. Changes for haptoglobin and transthyretin were further confirmed in cerebrospinal fluid and plasma by Western blotting. These results suggest that monitoring plasma levels of these signals appears to be a promising biological marker of neuronal degeneration of the nigrostriatal dopaminergic system.

Presence of an APOE4 allele results in significantly earlier onset of Parkinson's disease and a higher risk with dementia

The epsilon4 allele of the apolipoprotein E gene (APOE4) has been consistently associated with a greater risk of Alzheimer's disease (AD) as well as an earlier onset of AD. It is possible that APOE4 may also play a role in the etiology of other neurodegenerative disorders, such as Parkinson's disease (PD). APOE genotype, age of onset, disease duration, smoking history, and dementia status were collected for families with PD, yielding 324 Caucasian families with complete information. Logistic regression employing one individual per family and including age of onset and disease duration as covariates demonstrated a significantly increased risk of dementia for those individuals having inherited at least one epsilon4 allele (OR=3.37; P=0.002). Survival analyses also demonstrated a significantly earlier age of onset for those subjects with at least one epsilon4 allele (59.7 years) as compared with those homozygous for the more common epsilon3 allele (62.4 years; P=0.009). Thus, consistent with previous studies, we find evidence that the presence of an epsilon4 allele results in significantly earlier onset of PD and a greater likelihood of dementia. It appears the similarities between PD and AD may be due to an overlap in the diseases' genetic etiology.

Age, apolipoprotein E4, and the risk of HIV dementia: the Hawaii Aging with HIV Cohort

There are discrepant findings regarding the risk of HIV-associated dementia (HAD) relating to apolipoprotein E4, suggesting other factors may modulate risk. Furthermore, evidence suggests a changing phenotype of HAD in the era of highly active antiretroviral therapy (HAART), prompting a need to determine if new disease markers have emerged. In this analysis, APOE genotype was determined for 182 participants enrolled in the Hawaii Aging with HIV Cohort. After controlling for age and diabetes status, an independent risk of HAD relating to E4 was seen in older participants [OR=2.898 (1.031-8.244)] but not in younger participants [OR=0.373 (0.054-1.581)]. Several proposed mechanisms may underlie this association. Consideration of non-traditional risk factors for HAD in older HIV patients may yield new markers of disease in the era of HAART.

Progress in clinical neurosciences: Parkinson's disease with dementia and dementia with Lewy bodies

Dementia occurs in up to 30% of people with Parkinson's disease and is a major cause of disability. Pathologically, Parkinson's dementia, where dementia follows the onset of parkinsonism by at least one year, overlaps with dementia with Lewy bodies. We review the functional impact, definitions, neuropsychology, epidemiology and pathophysiology of Parkinson's dementia, dementia with Lewy bodies and their overlap. Associated psychiatric and imaging findings are also considered. Lastly, current and emerging approaches to assessment and treatment in patients with these Lewy body associated dementias are presented.

Neuroimaging in dementia with Lewy bodies: metabolism, neurochemistry, and morphology

Dementia with Lewy bodies (DLB) is recognized as one of the most common forms of neurodegenerative dementia. Neuroimaging contributes to a better understanding of the pathophysiology of DLB by examining alterations in brain metabolism, neurochemisty, and morphology in living patients. Neuroimaging can provide objective and quantifiable antemortem markers for the presence of and the progression of DLB and permits differentiation from other dementias. This article reviews current neuroimaging findings in DLB with particular attention to occipital hypometabolism, dopaminergic and cholinergic deficits, and medial temporal lobe atrophy as measured by positron emission tomography, single-photon emission computed tomography, and magnetic resonance imaging.

Clinical and neuropathological correlates of apolipoprotein E genotype in dementia with Lewy bodies

Dementia with Lewy bodies (DLB) represents the second commonest cause of dementia in the elderly following Alzheimer's disease (AD). Whilst the presence of Lewy bodies is essential, DLB shares with AD the presence of senile plaques (SP), but neurofibrillary tangles (NFT) are not a necessary feature. The apolipoprotein E (APO E) epsilon4 allele is the most consistently associated genetic risk factor for AD and has also been shown to associate with DLB. We have therefore analysed the APO E epsilon4 allele in a large series of DLB cases coming to autopsy to: (1) determine if the epsilon4 allele describes a similar risk in DLB development as in AD and (2) determine how APO E epsilon4 allele status correlates with clinical and neuropathological findings in DLB, and in AD, as an indication of the role of APO E in underlying disease biology. Both DLB and AD share an increased epsilon4 allele frequency, though in DLB the epsilon2 allele frequency is not reduced and there is a relative lack of epsilon4 homozygotes. In contrast to previous studies, no association of the epsilon4 allele with age at onset or duration of disease was found in either disorders. In DLB cases, overall a significantly shorter duration of illness was observed when compared with AD cases, though no significant effect of the epsilon4 allele on disease onset or duration was seen. The survival rate was reduced by the presence of the epsilon4 allele in DLB, as with AD. No effect on SP or NFT counts was seen with the epsilon4 allele, though DLB cases showed a lower SP burden in addition to the expected lower NFT counts. This study demonstrates that DLB shares the APO epsilon4 allele with AD as a common risk factor, but that there are differences in the way the epsilon4 allele affects the phenotypic expression of disease.

Abeta as a bioflocculant: implications for the amyloid hypothesis of Alzheimer's disease

Research into Alzheimer's disease (AD) has been guided by the view that deposits of fibrillar amyloid-beta peptide (Abeta) are neurotoxic and are largely responsible for the neurodegeneration that accompanies the disease. This 'amyloid hypothesis' has claimed support from a wide range of molecular, genetic and animal studies. We critically review these observations and highlight inconsistencies between the predictions of the amyloid hypothesis and the published data. We show that the data provide equal support for a 'bioflocculant hypothesis', which posits that Abeta is normally produced to bind neurotoxic solutes (such as metal ions), while the precipitation of Abeta into plaques may be an efficient means of presenting these toxins to phagocytes. We conclude that if the deposition of Abeta represents a physiological response to injury then therapeutic treatments aimed at reducing the availability of Abeta may hasten the disease process and associated cognitive decline in AD.

Apolipoprotein E gene in frontotemporal dementia: an association study and meta-analysis

No definite genetic risk factor of non-monogenic frontotemporal dementia (FTD) has yet been identified. Several groups have examined the potential association of FTD with the apolipoprotein E (APOE) gene, but the results are inconsistent. Our objective was to determine whether APOE is a risk factor of FTD, using the largest series of patients with FTD and controls analysed so far (94 unrelated patients and 392 age and sex-matched controls), and a meta-analysis. Homozygosity for the E2E2 genotype was significantly associated with FTD (odds ratio (OR)=11.3; P=0.033, exact test). After stratification on familial history (FH) for FTD, the OR for E2E2 was still found significant when analysing only patients with a positive FH (OR=23.8; P=0.019). The meta-analysis, using 10 case-control studies with available genotype or allele information, comprising a total of 364 FTD patients and 2671 controls, including the patients of the present study, did not reach statistical significance even if the E2E2 genotype was more frequent in patients than in controls (0.018 vs 0.006, respectively). Because of studies heterogeneity (Mantel-Haenszel statistics: P=0.004), we analysed on one hand the neuropathologically-confirmed studies, and on the other hand the clinical-based studies. In the neuropathologically-confirmed studies (Mantel-Haenszel statistics: P=ns), we found a significant increase of the E2 allele frequency in FTD patients (OR[E2 vs E3]=2.01; 95% CI=1.02-3.98; P=0.04). The same result was found in the clinical-based studies, but studies heterogeneity remained. No result was significant with the E4 allele. The E2 allele seems so to be a risk factor of FTD whereas this allele is associated with the lowest risk in Alzheimer's disease. If this finding was confirmed, it could provide new insights into the mechanisms of differential risk related to APOE in neurodegenerative diseases.

Dementia with Lewy bodies: prevalence, clinical spectrum and natural history

The article summarises history, terminology, the clinical and neuropathological diagnostic criteria, neurochemical and genetic findings, sensitivity and specificity of the clinical diagnostic criteria, prevalence, demographical data and nosology, differential diagnosis, and therapy of dementia with Lewy bodies (DLB). DLB shares clinical symptoms of Parkinson's disease and dementia of the Alzheimer-type (DAT). However, DLB is also different to PD and DAT (less tremor and asymmetry of the motor symptoms, more falls, and less favourable response to L-Dopa than PD; in contrast to DAT marked cognitive fluctuations and phases of reduced alertness, hallucinations and delirium). There are genetic similarities to DAT and PD in terms of common genetic risk factors. A genetic cause of the disease has so far not been detected. Whether or not DLB is a disease entity or an association of diseases (Lewy body disease and DAT) has so far not been elucidated. Clinical distinction from DAT and PD has clinical importance because of different therapeutic and prognostic implications. Studies are needed to standardize the treatment of motor, cognitive, psychiatric and vegetative symptoms.

Genetic susceptibility factors for Alzheimer's disease

Alzheimer's disease is the most frequent cause of dementia. Family and twin studies have suggested that genetic factors play a role in Alzheimer's disease development. Some Alzheimer's disease cases show an autosomal dominant inheritance pattern and thus allow the discovery of major disease genes. However, most Alzheimer's disease cases are sporadic. These cases are mainly due to the effects of several different genes and of interactions between genetic susceptibility factors and environmental factors. Such interactions are illustrated by the apolipoprotein E epsilon4 allele, associated with a higher risk of Alzheimer's disease. Other genetic susceptibility factors have been reported but variously confirmed in Alzheimer's disease: apolipoprotein E receptors, alpha2-macroglobulin or angiotensin I converting enzyme genes. Thus, except for a small percentage of Alzheimer's disease cases with a dominant inheritance pattern, the genetic component of the vast majority of cases is underlain by complex interactions of genetic susceptibility factors and environmental conditions.

Apolipoprotein E epsilon4 and tardive dyskinesia in a Japanese population

The findings that free radicals play a causative role in the occurrence of tardive dyskinesia (TD) and that apolipoprotein E (ApoE) 4 has decreased anti-oxidant activity suggest a potential link between TD and ApoE alleles. We, therefore, examined ApoE allelic frequencies in schizophrenic subjects with TD and non-TD. Serum samples were obtained from 333 DSM IV-diagnosed schizophrenic patients and 191 controls in Japan. The presence of TD was evaluated by research diagnostic criteria for TD. ApoE phenotypes of the serum samples were determined by polyacrylamide gel isoelectricfocusing. A total of 62 TD subjects (31 males, 31 females) were identified among all patients examined. No significant differences in ApoE allelic frequency were found between TD and non-TD groups. ApoE epsilon4 allele frequency, however, was significantly lower in the female TD group than in the male TD group. These findings do not clearly demonstrate a certain association between TD and the epsilon4 allele, but may preliminarily reveal a difference in influence of this allele on the development of TD between males and females.

The prognosis of mild cognitive impairment in the elderly

PURPOSE

To determine whether or not subtypes of intellectual functioning are suitable to predict further cognitive decline in individuals with mild cognitive impairment.

DESIGN

Naturalistic longitudinal study (mean interval 2.7 years).

PATIENTS

41 subjects with mild cognitive impairment who attended a memory clinic.

METHODS

SIDAM, CT, SPECT, and ApoE genotype.

RESULTS

At follow-up, 8 out of 41 patients (19.5%) with MCI had progressed to dementia, 8 patients (19.5%) had improved to normal levels of cognitive functioning, 25 patients (61%) had remained stable within the MCI group. At baseline the two prognostic groups differed significantly with regard to age, memory functions, orientation, and the degree of atrophy of the left medial temporal lobe on CT scan.

CONCLUSION

The majority of MCI patients in this study remained cognitively stable within the observation period. Patients with older age, poorer test performance on memory tasks and orientation deficits are at higher risk of progressive decline to dementia. CT measures of medial temporal lobe atrophy may be a sensitive parameter of group discrimination.

The Lewy body variant of Alzheimer disease

The Lewy body variant of Alzheimer disease (LBV) occupies a messy middle ground between Alzheimer disease (AD) on the one hand, and pure Lewy body diseases (Parkinson's disease or diffuse Lewy body disease), on the other. In addition to brainstem and neocortical Lewy bodies, LBV brains have enough neocortical neuritic plaques to meet diagnostic criteria for AD. However, neurofibrillary pathology in LBV is modest, since tangle densities in LBV are typically intermediate between AD and age-matched controls or pure Lewy body disease brains. Apolipoprotein E-4 is overrepresented in LBV, as it is in AD but is not in PD or diffuse Lewy body disease (DLBD). Neurologically, LBV patients often display sufficient parkinsonian signs to separate them from AD, but these findings are usually too subtle to warrant clinical diagnoses of Parkinson's disease (PD). Neuropsychological deficits in LBV include a subcortical dementia pattern similar to DLBD, and more severe global cognitive impairment reminiscent of AD.

Pathological diagnostic criteria for dementia associated with cortical Lewy bodies: review and proposal for a descriptive approach

In recent years dementia histologically characterised by the presence of cortical Lewy bodies has been increasingly recognised. There is now need for a scheme for an internationally acceptable scheme for pathological diagnosis and classification so that clinical, pathological and molecular features of disease can be correlated. Recent observations made by different groups in large patient series have used slightly different pathological criteria resulting in at least seven different diagnostic terms. In some patients the only cortical pathology is the presence of Lewy bodies, while in the majority of patients there are coexisting pathological changes which either overlap with those seen in Alzheimer's disease (AD). Cortical Lewy bodies can also be present in patients who do not have any obvious cognitive abnormality. A problem with equating studies from different groups is that different criteria have been used to define AD, so that establishing the relevance of cortical Lewy bodies themselves to cognitive decline and separating this from the contribution which may be related to the AD pathology is problematic. The lesions which appear to be of most relevance to potential cognitive decline in DLB are cortical Lewy bodies, Lewy-related neurites, senile plaques, neurofibrillary tangles, neuronal and synaptic loss, spongiform change, and cortical cholinergic deficits. It is possible to operationally classify patients with cognitive decline and cortical Lewy bodies into three main groups, Cortical Lewy body disease, Cortical Lewy body disease with plaques, and Cortical Lewy body disease with plaques and tangles. There are frequent cases which overlap these groups making operational classification difficult in practice. A descriptive classification, in which the severity of different pathological changes is rated, is easy to use in practice. As new molecular risk factors for AD or DLB are revealed they will need to be related to morphological and clinical features. A descriptive diagnostic assessment for DLB will facilitate such studies and makes no judgements as to what these relationships will be.

Apolipoprotein E gene in Parkinson's disease, Lewy body dementia and Alzheimer's disease

Apolipoprotein E (Apo E) epsilon 4 allele is a risk factor for early and late onset Alzheimer's disease. This prompted us to examine other neurophyschiatric phenotypes. Epsilon 4 allele was significantly enriched in Lewy body dementia (n = 39) but not in Parkinson's disease (n = 50) or Schizophrenia (n = 175) compared to aged non-demented controls (n = 47) and the Scottish population (n = 400). We conclude that Lewy body disease should be regarded as a variant of Alzheimer's but not Parkinson's disease.

Peripheral markers in testing pathophysiological hypotheses and diagnosing Alzheimer's disease

Alterations in amyloid precursor protein (APP) metabolism, calcium regulation, oxidative metabolism, and transduction systems have been implicated in Alzheimer's disease (AD). Limitations to the use of postmortem brain for examining molecular mechanisms underscore the need to develop a human tissue model representative of the pathophysiological processes that characterize AD. The use of peripheral tissues, particularly of cultured skin fibroblasts derived from AD patients, could complement studies of autopsy samples and provide a useful tool with which to investigate such dynamic processes as signal transduction systems, ionic homeostasis, oxidative metabolism, and APP processing. Peripheral cells as well as body fluids (i.e., plasma and CSF) could also provide peripheral biological markers for the diagnosis of AD. The criteria required for a definite diagnosis of AD presently include clinical criteria in association with histopathologic evidence obtained from biopsy or autopsy. Thus, the use of peripheral markers as a diagnostic tool, either to predict or at least to confirm a diagnosis, may be of great importance.

The genetics of dementia in late life

Recent advances in the genetics of AD and other late-life dementias have provided new insights but also have raised new queries and ethical issues. This review reflects the current state of knowledge in a rapidly evolving field. The complex relation of genes and environment to AD, VaD, and other late-life dementias suggests that the answers to these many issues will evolve through time. New issues undoubtedly will arise as additional genes are discovered and new data accrue that relate APOE and other genes to the mechanism and expression of dementing illness. The clinical relevance and applicability of such research findings will increase when effective treatments become available. Given this potential, we encourage readers to monitor new developments as they arise.

The National Institute on Aging/Alzheimer's Association recommendations on the application of apolipoprotein E genotyping to Alzheimer's disease

In a conference held in Chicago during October 1995, a working group of the National Institute of Aging (NIA) and the Alzheimer's Association (AlzA) drafted consensus recommendations on research and clinical applications of APOE genetic susceptibility testing for Alzheimer's disease (AD). The NIA/AlzA Working Group concluded that in considering future applications of APOE genotyping and other knowledge that has been gained about the genetic basis of AD, the interests of AD patients and their family members must be held paramount. The group acknowledged that a robust association exists between possession of the APOE epsilon 4 allele and the risk of late-onset AD and cited evidence that this allele is more strongly associated with AD than any other form of dementia. They recommended against the use of APOE genotyping to predict the-future development of AD in asymptomatic individuals at this time, and warned against the use of the test in isolation as the sole means for diagnosing AD. The group endorsed the concept of discretionary use of APOE genotyping as an adjunct to other AD diagnostic procedures. However, routine clinical use of the test for this purpose was not recommended at this time. Physicians were advised to weigh any potential benefits of testing against the possibility that genotype disclosure could adversely affect the insurability, employability, and social standing of AD patients and their family members. Adequate provisions for pre-test and post-test counseling and psychosocial support were advised for all future clinical and research applications of APOE genotyping. The group called for the development of improved protocols for AD genetic counseling as well as supplemental measures to assure genetic privacy for AD patients and their family members.

Frequency of the apolipoprotein E epsilon 4 allele in a case-control study of early onset Parkinson's disease

OBJECTIVES

It has been suggested that Parkinson's disease and Alzheimer's disease may share a common or at least overlapping aetiology. The prevalence of dementia among cases of Parkinson's disease is known to be greater than expected in the general population. The frequency of the apolipoprotein epsilon 4 allele in a large case-control study of early onset Parkinson's disease has been examined.

METHODS

215 patients and 212 population based controls were recruited from the Republic of Ireland between 1992 and 1994. Cases had to have disease onset at 55 years or younger and be born after 1925.

RESULTS

The frequency of the epsilon 4 allele was almost identical between cases of Parkinson's disease (14.6%) and healthy controls (13.3%). There was no relation between epsilon 4 status and disease onset, disease duration, Hoehn and Yahr score, and disease progression. The frequency of the epsilon 4 allele was not increased among 10 patients with Parkinson's disease with dementia (10.0%) compared with the other patients without dementia (14.8%). There was no association between epsilon 4 allele status and either a history of smoking, family history of dementia, or Parkinson's disease, or being born in a rural area. The odds ratio for the ApoE epsilon 4 allele associated with Parkinson's disease was 1.10 (95% confidence interval (95% CI) 0.68-1.79), adjusting for age group, sex, and residential status. The pooled odds ratio from a meta-analysis of six studies of ApoE epsilon 4 status and Parkinson's disease was 0.94 (95% CI 0.69-1.27).

CONCLUSIONS

The results from our study as well as the pooled meta-analysis exclude any important role for ApoE epsilon 4 status in the development of Parkinson's disease. Our results similarly do not support its role either in dementia associated with Parkinson's disease or disease prognosis.

Diffuse Lewy body disease without amyloid plaques in a patient homozygous for apolipoprotein E allele epsilon 4: a case report

A middle-aged woman developed extrapyramidal motor symptoms, personality and behavioral changes, and rapidly progressive dementia. Apolipoprotein E genotyping revealed that she was homozygous for the epsilon 4 allele. At autopsy, there were numerous cortical and subcortical Lewy bodies but no neuritic plaques (NPs) or neurofibrillary tangles (NFTs). This case, the first explicitly reported patient homozygous for the epsilon 4 allele having dementia of the Lewy body type (DLBT) without NPs and NFTs, reinforces the distinction between DLBT and dementia of the Alzheimer type. It calls into question the pivotal role of the epsilon 4 allele in the pathogenesis of NPs and NFTs but raises the possibility of its being an independent risk factor for the development of DLBT.

Apolipoprotein E type epsilon 4 allele frequency is increased in patients with schizophrenia

Apolipoprotein E type epsilon 4 alleles are increased in both Alzheimer's disease (AD) and cortical Lewy body dementia, while the epsilon 2 allele has been associated as a protective factor against the development of dementia in AD. We have determined APOE genotype in schizophrenic patients coming to autopsy (age range 19-95 years). The allele frequencies in this group were: epsilon 2, 6.0%; epsilon 3, 67.9%; and epsilon 4, 26.2%. Three patients (14%) were homozygous for the epsilon 4 allele. Thus, schizophrenia is associated with an increased epsilon 4 allele frequency, as compared with controls (P = 0.01), that was indistinguishable from that found in either AD or Lewy body dementia. The increased epsilon 4 allele frequency was not associated with increased age of schizophrenia patient, indicating that it was not due to the co-existence of AD.

Apolipoprotein E in the genetics and epidemiology of Alzheimer's disease

The role of apolipoprotein E (ApoE) alleles and isoforms in the etiology and pathogenesis of Alzheimer's disease is discussed. The possibility that ApoE itself is not involved in the disease pathogenesis but is merely in genetic disequilibrium with the real locus is discussed and dismissed. The data showing that the epsilon 4 allele is associated with an increased risk of developing the disease and with an earlier onset age are reviewed. The data showing that, at least in some circumstances, the epsilon 2 allele is associated with a decrease in the risk of developing the disease, and with a later onset age are also reviewed. Data from the genetic analysis of other disorders are reviewed and presented, and it is suggested that the genetic data support the notion that the role of ApoE in the etiology of the disease directly relates to beta-amyloid deposition and plaque formation. This suggestion is in concordance with the most likely mechanism for the role of beta-amyloid precursor protein gene mutations as other risk factors for the disease.

Apolipoprotein E genotype and its effect on duration and severity of early and late onset Alzheimer's disease

BACKGROUND

The apolipoprotein E (ApoE) epsilon 4 allele is associated with an increased risk of senile and probably presenile Alzheimer's disease. It is not yet clear whether the epsilon 4 allele also influences the duration/rate of progress of illness and the severity of the dementia.

METHOD

We have retrospectively examined a series of ApoE genotyped presenile and senile autopsy cases of Alzheimer's disease (AD) for length of illness and severity of pathology.

RESULTS

We find no evidence that ApoE genotype affects the rate of progress of AD, but the degree of pathology at death may be increased.

CONCLUSION

It appears that the rate of progress of AD as a whole is independent of the ApoE genotype.

Association of apolipoprotein epsilon 4 allele and neuropathologic findings in patients with dementia

Apolipoprotein E (APOE) is a lipoprotein expressed in liver and brain as one of three isoforms (APOE 2, APOE 3 and APOE 4). Recent findings suggest that the presence of APOE 4 is associated with an increased risk for both familial Alzheimer's disease and late-onset Alzheimer's disease. We extended these observations by determining the frequency of APOE alleles in patients with pathologically confirmed Alzheimer's Disease (AD), Parkinson's disease (PD), diffuse Lewy Body disease (DLBD), AD with concomitant PD pathology, demented PD patients without or with concomitant AD pathology and in schizophrenics with a progressive dementia (SCHIZ+DEM). The APOE genotype was determined by restriction digestion of polymerase chain reaction-amplified DNA isolated from frozen brain samples. The frequency of the APOE epsilon 4 allele was highest among sporadic AD and DLBD patients (0.30 and 0.38, respectively) and lowest in the SCHIZ+DEM and non-demented PD patients (0.06 and 0.1, respectively). Thus, the APOE epsilon 4 allele is over-represented selectively in patients with dementias associated with plaques and tangles and/or cortical Lewy bodies, but not in demented schizophrenics or non-demented PD patients.

The extent of amyloid deposition in brain in patients with Down's syndrome does not depend upon the apolipoprotein E genotype

The extent of deposition of amyloid beta protein (A beta) was investigated in 20 elderly patients with Down's syndrome, using the end-specific monoclonal antibodies BC05 and BA27 to detect the presence of A beta 42(43) and A beta 40 (respectively), and related to apolipoprotein E (ApoE) genotype. No significant differences in the amount of A beta deposited in the brain, either as A beta 42(43) or A beta 40, were noted in patients possessing an ApoE E4 allele, compared to those without. Patients with an ApoE E4 allele in general died at an earlier age than those with only ApoE E3 alleles, the latter in turn being outlived by those with an ApoE E2 allele. In Down's syndrome therefore, ApoE may influence the timing of onset, or the rate of progression, of disease but without affecting the type or total amount of pathology accumulated.

Apolipoprotein E epsilon 4 allele is a risk factor for familial and sporadic presenile Alzheimer's disease in both homozygote and heterozygote carriers

While apoliprotein E (ApoE) epsilon 4 allele is now a well established risk factor for familial and sporadic senile Alzheimer's disease (AD), its role in the development of the rarer presenile or early onset type is controversial. Early studies showed no association; later ones found enrichment for the epsilon 4 allele in familial or sporadic types or both. We have ApoE genotyped a series of Scottish people (n = 85) with early onset AD. We find highly significant enrichment for both homozygote and heterozygote ApoE epsilon 4 allele carriers in familial and sporadic early onset AD with a pattern closely resembling that in late onset AD.

Apolipoprotein E allelic frequencies in patients with lobar atrophy

Apolipoprotein E (ApoE) genotype was determined by polymerase chain reaction amplification and restriction digestion of DNA extracted from brain tissues of 26 patients with clinically diagnosed and pathologically verified lobar atrophy (LA) and from blood of a further 22 patients with clinical LA. Brain tissue from 50 patients with pathologically confirmed Alzheimer's disease (AD) was also examined. As has been previously reported, the ApoE E4 allele frequency was significantly increased in AD. However, no change in the frequency of ApoE alleles was found in two of the clinical and pathological forms of LA (dementia of frontal type and dementia of frontal type with motor neurone disease) although the ApoE E4 allele frequency was elevated in cases of non-fluent progressive aphasia in accordance with the presence of coincidental Alzheimer-type pathological changes.

Apolipoprotein E type epsilon 4 allele frequency is not increased in patients with sporadic inclusion-body myositis

The apolipoprotein E genotype was determined for 11 patients with sporadic inclusion-body myositis. Seven cases had the genotype epsilon 3/epsilon 3, the other four cases, epsilon 3/epsilon 4. The frequency of the epsilon 4 allele in this group of patients (0.182) was not significantly increased compared with elderly controls (0.147; n = 58), in contrast to Alzheimer's disease in which there was a significant increase (0.328; n = 67). The epsilon 2 allele was not found in any of the 11 sporadic inclusion-body myositis patients and its frequency was decreased in Alzheimer's disease. Despite certain pathological similarities that exist between inclusion body myositis and Alzheimer's disease, their association with particular apolipoprotein E genotypes is distinct.