Functional genomics in inborn errors of immunity

Inborn errors of immunity (IEI) comprise a diverse spectrum of 485 disorders as recognized by the International Union of Immunological Societies Committee on Inborn Error of Immunity in 2022. While IEI are monogenic by definition, they illuminate various pathways involved in the pathogenesis of polygenic immune dysregulation as in autoimmune or autoinflammatory syndromes, or in more common infectious diseases that may not have a significant genetic basis. Rapid improvement in genomic technologies has been the main driver of the accelerated rate of discovery of IEI and has led to the development of innovative treatment strategies. In this review, we will explore various facets of IEI, delving into the distinctions between PIDD and PIRD. We will examine how Mendelian inheritance patterns contribute to these disorders and discuss advancements in functional genomics that aid in characterizing new IEI. Additionally, we will explore how emerging genomic tools help to characterize new IEI as well as how they are paving the way for innovative treatment approaches for managing and potentially curing these complex immune conditions.

Population Diversity at the Single-Cell Level

Population-scale single-cell genomics is a transformative approach for unraveling the intricate links between genetic and cellular variation. This approach is facilitated by cutting-edge experimental methodologies, including the development of high-throughput single-cell multiomics and advances in multiplexed environmental and genetic perturbations. Examining the effects of natural or synthetic genetic variants across cellular contexts provides insights into the mutual influence of genetics and the environment in shaping cellular heterogeneity. The development of computational methodologies further enables detailed quantitative analysis of molecular variation, offering an opportunity to examine the respective roles of stochastic, intercellular, and interindividual variation. Future opportunities lie in leveraging long-read sequencing, refining disease-relevant cellular models, and embracing predictive and generative machine learning models. These advancements hold the potential for a deeper understanding of the genetic architecture of human molecular traits, which in turn has important implications for understanding the genetic causes of human disease. Expected final online publication date for the Annual Review of Genomics and Human Genetics, Volume 25 is August 2024. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Presence of inclusions positive for polyglycine containing protein, FMRpolyG, indicates that repeat-associated non-AUG translation plays a role in fragile X-associated primary ovarian insufficiency

STUDY QUESTION

Does repeat-associated non-AUG (RAN) translation play a role in fragile X-associated primary ovarian insufficiency (FXPOI), leading to the presence of polyglycine containing protein (FMRpolyG)-positive inclusions in ovarian tissue?

SUMMARY ANSWER

Ovaries of a woman with FXPOI and of an Fmr1 premutation (PM) mouse model (exCGG-KI) contain intranuclear inclusions that stain positive for both FMRpolyG and ubiquitin.

WHAT IS KNOWN ALREADY

Women who carry the FMR1 PM are at 20-fold increased risk to develop primary ovarian insufficiency (FXPOI). A toxic RNA gain-of-function has been suggested as the underlying mechanism since the PM results in increased levels of mRNA containing an expanded repeat, but reduced protein levels of fragile X mental retardation protein (FMRP). Recently, RAN translation has been shown to occur from FMR1 mRNA that contains PM repeat expansions, leading to FMRpolyG inclusions in brain and non-CNS tissues of fragile X-associated tremor/ataxia syndrome (FXTAS) patients.

STUDY DESIGN, SIZE, DURATION

Ovaries of a woman with FXPOI and women without PM (controls), and ovaries from wild-type and exCGG-KI mice were analyzed by immunohistochemistry for the presence of inclusions that stained for ubiquitin and FMRpolyG . The ovaries from wild-type and exCGG-KI mice were further characterized for the number of follicles, Fmr1 mRNA levels and FMRP protein expression. The presence of inclusions was also analyzed in pituitaries of a man with FXTAS and the exCGG-KI mice.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Human ovaries from a woman with FXPOI and two control subjects and pituitaries from a man with FXTAS and a control subjects were fixed in 4% formalin. Ovaries and pituitaries of wild-type and exCGG mice were fixed in Bouin's fluid or 4% paraformaldehyde. Immunohistochemistry was performed on the human and mouse samples using FMRpolyG, ubiquitin and Fmrp antibodies. Fmr1 mRNA and protein expression were determined in mouse ovaries by quantitative RT-PCR and Western blot analysis. Follicle numbers in mouse ovaries were determined in serial sections by microscopy.

MAIN RESULTS AND THE ROLE OF CHANCE

FMRpolyG-positive inclusions were present in ovarian stromal cells of a woman with FXPOI but not in the ovaries of control subjects. The FMRpolyG-positive inclusions colocalized with ubiquitin-positive inclusions. Similar inclusions were also observed in the pituitary of a man with FXTAS but not in control subjects. Similarly, ovaries of 40-week-old exCGG-KI mice, but not wild-type mice, contained numerous inclusions in the stromal cells that stained for both FMRpolyG- and ubiquitin, while the ovaries of 20-week-old exCGG-KI contained fewer inclusions. At 40 weeks ovarian Fmr1 mRNA expression was increased by 5-fold in exCGG-KI mice compared with wild-type mice, while Fmrp expression was reduced by 2-fold. With respect to ovarian function in exCGG-KI mice: (i) although the number of healthy growing follicles did not differ between wild-type and exCGG-KI mice, the number of atretic large antral follicles was increased by nearly 9-fold in 40-week old exCGG-KI mice (P < 0.001); (ii) at 40 weeks of age only 50% of exCGG-KI mice had recent ovulations compared with 89% in wild-type mice (P = 0.07) and (iii) those exCGG-KI mice with recent ovulations tended to have a reduced number of fresh corpora lutea (4.8 ± 1.74 versus 8.50 ± 0.98, exCGG-KI versus wild-type mice, respectively, P = 0.07).

LIMITATIONS, REASONS FOR CAUTION

Although FMRpolyG-positive inclusions were detected in ovaries of both a woman with FXPOI and a mouse model of the FMR1 PM, we only analyzed one ovary from a FXPOI subject. Caution is needed to extrapolate these results to all women with the FMR1 PM. Furthermore, the functional consequence of FMRpolyG-positive inclusions in the ovaries for reproduction remains to be determined.

WIDER IMPLICATIONS OF THE FINDINGS

Our results suggest that a dysfunctional hypothalamic-pituitary-gonadal-axis may contribute to FXPOI in FMR1 PM carriers.

STUDY FUNDING/COMPETING INTERESTS

This study was supported by grants from NFXF, ZonMW, the Netherlands Brain Foundation and NIH. The authors have no conflict of interest to declare.

Life events and personality predicting loneliness among centenarians: findings from the Georgia Centenarian Study

Regarding the purpose of this study, the researchers analyzed the roles that both life events (life-time positive events and life-time negative events) and personality (Neuroticism, Extraversion, Trust, Competence, and Ideas) played in participants of the Georgia Centenarian Study. The researchers analyzed these variables to determine whether they predicted loneliness. Analyses indicated that life-time negative events significantly predicted loneliness. In essence, the higher was the number of life-time negative life events, the higher was the loneliness score. Moreover, Neuroticism, Competence, and Ideas were all significant predictors of loneliness. The higher was the level of Neuroticism and intellectual curiosity, the higher was the level of loneliness, whereas the lower was the level of Competence, the higher was the level of loneliness. In addition, both life-time positive and life-time negative life events were significant predictors of Neuroticism. The higher was the number of life-time positive events, the lower was the level of Neuroticism, and the higher was the number of life-time negative events, the greater was the level of Neuroticism. These results indicated that life-time negative events indirectly affect loneliness via Neuroticism. Last, our results indicated that the Competence facet mediated the relationship between lifetime negative life events and loneliness. Life-time negative life events significantly affected centenarians' perceived competence, and Competence in turn significantly affected the centenarians' loneliness. These results as a whole not only add to our understanding of the link between personality and loneliness, but also provide new insight into how life events predict loneliness.

Multidimensional predictors of fatigue among octogenarians and centenarians

BACKGROUND

Fatigue is a common and frequently observed complaint among older adults. However, knowledge about the nature and correlates of fatigue in old age is very limited.

OBJECTIVE

This study examined the relationship of functional indicators, psychological and situational factors and fatigue for 210 octogenarians and centenarians from the Georgia Centenarian Study.

METHODS

Three indicators of functional capacity (self-rated health, instrumental activities of daily living, physical activities of daily living), two indicators of psychological well-being (positive and negative affect), two indicators of situational factors (social network and social support), and a multidimensional fatigue scale were used. Blocked multiple regression analyses were computed to examine significant factors related to fatigue. In addition, multi-group analysis in structural equation modeling was used to investigate residential differences (i.e., long-term care facilities vs. private homes) in the relationship between significant factors and fatigue.

RESULTS

Blocked multiple regression analyses indicated that two indicators of functional capacity, self-rated health and instrumental activities of daily living, both positive and negative affect, and social support were significant predictors of fatigue among oldest-old adults. The multiple group analysis in structural equation modeling revealed a significant difference among oldest-old adults based on residential status.

CONCLUSION

The results suggest that we should not consider fatigue as merely an unpleasant physical symptom, but rather adopt a perspective that different factors such as psychosocial aspects can influence fatigue in advanced later life.

Cognitive performance in centenarians and the oldest old: norms from the Georgia Centenarian Study

We present normative data from a large population-based sample of centenarians for several brief, global neurocognitive tasks amenable for frail elders. Comparative data from octogenarians are included. A total of 244 centenarians and 80 octogenarians from Phase III of the Georgia Centenarian Study were administered the Mini-Mental Status Examination, Severe Impairment Battery, and Behavioral Dyscontrol Scale. Centenarians (age 98-107) were stratified into three age cohorts (98-99, 100-101, 102-107), octogenarians into two 5- year cohorts (80-84, 85-89). Highly significant differences were observed between groups on all measures, with greater variation and dispersion in performance among centenarians, as well as stronger associations between age and performance. Descriptive statistics and normative ranges (unweighted and population-weighted) are provided by age cohort. Additional statistics are provided by education level. While most previous centenarian studies have used convenience samples, ours is population-based and likely more valid for comparison in applied settings. Results suggest centenarians look different than do even the oldest age range of most normative aging datasets (e.g., 85-90). Results support using global measures of neurocognition to describe cognitive status in the oldest old, and we provide normative comparisons to do so.

Predicting happiness among centenarians

BACKGROUND

Happiness is believed to evolve from the comparison of current circumstances relative to past achievement. However, gerontological literature on happiness in extreme old age has been limited.

OBJECTIVE

The purpose of this study was to determine how perceptions of health, social provisions, and economics link past satisfaction with life to current feelings of happiness among persons living to 100 years of age and beyond.

METHODS

A total of 158 centenarians from the Georgia Centenarian Study were included to conduct the investigation. Items reflecting congruence and happiness from the Life Satisfaction Index were used to evaluate a model of happiness. Pathways between congruence, perceived economic security, subjective health, perceived social provisions, and happiness were analyzed using structural equation modeling.

RESULTS

Congruence emerged as a key predictor of happiness. Furthermore, congruence predicted perceived economic security and subjective health, whereas perceived economic security had a strong influence on subjective health status.

CONCLUSION

It appears that past satisfaction with life influences how centenarians frame subjective evaluations of health status and economic security. Furthermore, past satisfaction with life is directly associated with present happiness. This presents implications relative to understanding how perception of resources may enhance quality of life among persons who live exceptionally long lives.

Family history and adaptation among centenarians and octogenarians

BACKGROUND

The purpose of this study was to analyze various 'family history' variables (i.e. childhood health, financial situation while growing up, living with grandparents before age 17, and number of children) among participants of the Georgia Centenarian Study.

OBJECTIVE

To determine whether family history variables predict critical outcome areas such as cognitive functioning, activities of daily living, mental health, and economic dependence.

METHODS

A total of 318 older adults (236 centenarians and 82 octogenarians) were assessed with regard to their mental status, ADL (activities of daily living) functioning, depression, family history, loneliness, and perceived economic status.

RESULTS

Analyses indicated that the number of children significantly predicted the ability to engage in activities of daily living and loneliness. In essence, the more children, the higher the activities of the daily living score and the lower the loneliness scores. In addition, childhood health significantly predicted loneliness. The poorer one's health in childhood, the higher the loneliness scores.

CONCLUSION

The results of this study confirm the importance of distal family history variables on present-day functioning.

Depression among centenarians and the oldest old: contributions of cognition and personality

BACKGROUND

An estimated 20% of adults over the age of 55 experience clinical mental disorders such as depression and anxiety. For older adults, mental health concerns are often undetected, concomitant with physical challenges, and ultimately go untreated. These realities have significant implications for older adults' day-to-day functioning, particularly among the oldest old.

OBJECTIVE

The present study examined the ability of cognition and personality in explaining depression within a sample of octogenarians and centenarians.

METHODS

Participants were assessed during the most recent cross-sectional data collection of the Georgia Centenarian Study. The final eligible sample included 76 octogenarians (mean: 84.25 years, SD: 2.82; range: 81-90) and 158 centenarians and near centenarians (mean: 99.82 years, SD: 1.72; range: 98-109).

RESULTS

Hierarchical regression analyses were conducted to examine the relation between key variables and depressive symptoms in the two age groups. Blocks entered into the analyses included: demographics (i.e. age group, residential status, sex, and ethnicity) and functioning, memory and problem-solving ability, and personality (i.e. extraversion and neuroticism). Models differed for octogenarians and centenarians. Decreased problem-solving ability was related to greater depressive symptoms among octogenarians. For centenarians, institutional residence and increased neurotic tendencies were related to greater depressive symptoms.

CONCLUSION

Study findings demonstrate the need to examine a variety of factors which influence mental health in later life and to consider the unique contexts and differential experiences of octogenarians and centenarians.

Distal and proximal resource influences on economic dependency among the oldest old

BACKGROUND

As exceptional survivors, centenarians may have characteristics that reduce their dependency on family and community support systems despite the expectation that their extreme age creates a burden on those systems. The Georgia Centenarian Study obtained information about assistance for income, medical care, and caregiving of all types for a sample of centenarians and octogenarians. Previous studies have not established which characteristics may contribute to economic dependency among the oldest old.

OBJECTIVE

To identify distal and proximal resource influences on economic dependency, considering past lifestyle, proximal health, economic resources, personality, and coping behavior.

METHODS

Analysis sample sizes ranged from 109 to 138 octogenarians and centenarians. Blockwise multiple regressions predicted whether they received income assistance, number of medical care events, number of caregiving types, and total caregiving hours.

RESULTS

Past life style, gender, ethnicity, socioeconomic status, functional health, and coping were not related to economic dependency. With the exception of the number of types of care, centenarians were not more dependent than octogenarians. Cognitive ability had the strongest effects for medical care and caregiving services. 'Extraversion', 'ideas', 'neuroticism', and 'competence' personality factors had significant effects for caregiving types and total hours of care received.

CONCLUSION

Monitoring and intervention to maintain cognitive ability are critical practices for autonomy and reduced economic dependency among the oldest old. Psychological resources are more important influences on social support than functional health and other proximal economic resources.

Social resources and longevity: findings from the Georgia centenarian study

BACKGROUND

As the proportion of adults aged 85 and older increases, investigations of resources essential for adapting to the challenges of aging are required.

OBJECTIVE

To comprehensively investigate the social resources of cognitively intact centenarians participating in the Georgia Centenarian Study and the association between these resources and residence status.

METHODS

Two widely used measures of social resources were investigated among participants living in private homes, personal care facilities, and nursing homes. Logistic regression was used to determine significant predictors of nursing home residence.

RESULTS

Differences in levels of social resources were found between centenarians and octogenarians, and among centenarians in different living situations. Analyses revealed differential findings between self- and proxy reports. Controlling for education, activities of daily living, and financial ability to meet needs, only one of the two social resources measures significantly reduced the odds of nursing home residence.

CONCLUSION

The findings of this study add to the existing literature on one of the basic adaptive resources (social resources) for centenarians. Whether a more specific assessment of network contact is employed, or a more global assessment is used, differences in these constructs exist between centenarians and octogenarians, among centenarians in differing living conditions, and across types of informants. Researchers examining the different resources that may contribute to extraordinary longevity and positive adaptation may find it essential to differentiate between the oldest old and centenarians, and to account for differences based upon measure, reporter type, and centenarian residence status.

Clinical and neuropathologic variation in neuronal intermediate filament inclusion disease

BACKGROUND

Recently described neuronal intermediate filament inclusion disease (NIFID) shows considerable clinical heterogeneity.

OBJECTIVE

To assess the spectrum of the clinical and neuropathological features in 10 NIFID cases.

METHODS

Retrospective chart and comprehensive neuropathological review of these NIFID cases was conducted.

RESULTS

The mean age at onset was 40.8 (range 23 to 56) years, mean disease duration was 4.5 (range 2.7 to 13) years, and mean age at death was 45.3 (range 28 to 61) years. The most common presenting symptoms were behavioral and personality changes in 7 of 10 cases and, less often, memory loss, cognitive impairment, language deficits, and motor weakness. Extrapyramidal features were present in 8 of 10 patients. Language impairment, perseveration, executive dysfunction, hyperreflexia, and primitive reflexes were frequent signs, whereas a minority had buccofacial apraxia, supranuclear ophthalmoplegia, upper motor neuron disease (MND), and limb dystonia. Frontotemporal and caudate atrophy were common. Histologic changes were extensive in many cortical areas, deep gray matter, cerebellum, and spinal cord. The hallmark lesions of NIFID were unique neuronal IF inclusions detected most robustly by antibodies to neurofilament triplet proteins and alpha-internexin.

CONCLUSION

NIFID is a neuropathologically distinct, clinically heterogeneous variant of frontotemporal dementia (FTD) that may include parkinsonism or MND. Neuronal IF inclusions are the neuropathological signatures of NIFID that distinguish it from all other FTD variants including FTD with MND and FTD tauopathies.

Plasma testosterone levels in Alzheimer and Parkinson diseases

BACKGROUND

Testosterone deficiency, a treatable condition commonly seen in aging men, has been linked to Parkinson disease (PD) and Alzheimer disease (AD). In normal subjects, low testosterone levels are associated with cognitive and neuropsychiatric symptoms, yet the relationship between testosterone levels and cognitive function in PD and AD remains unclear.

OBJECTIVE

To examine the relationship of testosterone levels to age and cognitive function in PD and AD.

METHODS

Plasma testosterone levels were determined in men enrolled in a clinical registry of subjects with PD and AD, and neuropsychological testing was performed on subjects who consented. Testosterone levels in men with PD were compared with those in men with AD. In both groups, the relationship between testosterone levels and neuropsychological test scores was analyzed, adjusting for age and education.

RESULTS

Linear regression analysis revealed that testosterone levels decreased with age in male PD patients (p < 0.03) and male AD patients (p < 0.07). The rate of decline was similar for the two groups. In PD patients, lower testosterone levels were associated with poorer performance on Trails B Seconds (p < 0.02).

CONCLUSIONS

There is a similar age-related decline in plasma testosterone levels in men with either PD or AD. Previously described associations between low testosterone levels and frontal lobe dysfunction in normal aged men, together with these results, suggest that the hormonal deficiency may act as a "second hit" to impair cognitive function in neurodegenerative disease.

Complications of gamma knife surgery for Parkinson disease

BACKGROUND

Many medical centers throughout the world offer radiosurgery with the gamma knife (GK) for pallidotomy and thalamotomy as a safe and effective alternative to radiofrequency ablative surgery and deep brain stimulation for Parkinson disease (PD). The reported incidence of significant complications varies considerably, and the long-term complication rate remains unknown.

DESIGN

We describe 8 patients seen during an 8-month period referred for complications of GK surgery for PD.

RESULTS

Of the 8 patients, 1 died as a result of complications, including dysphagia and aspiration pneumonia. Other complications included hemiplegia, homonymous visual field deficit, hand weakness, dysarthria, hypophonia, aphasia, arm and face numbness, and pseudobulbar laughter. In all patients, lesions were significantly off target.

CONCLUSIONS

The 8 patients with PD seen in referral at our center for complications of GK surgery highlight a spectrum of potential problems associated with this procedure. These include lesion accuracy and size and the delayed development of neurological complications secondary to radiation necrosis. Gamma knife surgery may have a higher complication rate than has been previously appreciated due to delayed onset and underreporting. We believe that the risk-benefit ratio of the GK will require further scrutiny when considering pallidotomy or thalamotomy in patients with PD. Physicians using this technique should carefully follow up patients postoperatively for delayed complications, and fully inform patients of these potential risks.

Apolipoprotein E and age at onset of Alzheimer's disease in African American patients

The authors examined whether the APOE-epsilon4 allele is associated with an earlier age at onset of AD in 71 African American patients with probable AD. The authors found a linear dose effect in which each copy of the epsilon4 allele was associated with a 3.6-year earlier onset of AD, indicating a dose-dependent relationship between APOE-epsilon4 and age at onset of AD in African Americans.

Tau-associated neuropathology in ganglion cell tumours increases with patient age but appears unrelated to ApoE genotype

Ganglion cell tumours, including gangliogliomas and gangliocytomas, are low grade neoplasms with a mature neuronal component. Ganglion cells within these lesions occasionally exhibit neurodegenerative changes including neurofibrillary tangles (NFT) similar to those in Alzheimer's disease. The frequency and spectrum of degenerative pathology in these lesions have not been defined, nor has their relation to patient age or factors such as apolipoprotein E (ApoE) genotype that predispose to Alzheimer's disease. We studied 72 ganglion cell tumours (61 gangliogliomas, 11 gangliocytomas) from patients 7 months to 72-years-old. Haematoxylin and eosin (H&E), silver stains (Hirano method) and immunohistochemistry for tau, alpha-synuclein and beta-amyloid were performed on formalin-fixed, paraffin-embedded tissue from surgical specimens. Tau-and silver-positive NFT and neuropil threads (NPT) were present in four of 26 ganglion cell tumours from patients over 30-years-old (ages 31, 38, 50, and 58 years). Neuronal granulovacuolar degeneration (GVD) was noted in five of 26 tumours from patients over 30-years-old (mean, 48 years). NFT, NPT, and GVD were not seen in ganglion cell tumours from patients under 30-years-old[0/46]. Cytoplasmic argentophilic bodies distinct from NFT were present in five of 26 tumours from patients over 30-years-old and in two of 46 under 30 years. Neither alpha-synuclein positive neuronal inclusions nor beta-amyloid immunoreactivity was noted in ganglion cell tumours from any age group. The distribution of ApoE genotypes was similar among those tumours that contained tau-associated neuropathology and those that did not. Neurodegenerative changes are uncommon in ganglion cell tumours, but increase in frequency with patient age. GVD, tau-positive NFT and NPT, and argentophilic bodies occur more often in ganglion cell tumours from patients over 30-yrs-old, but do not appear to be associated with a specific ApoE genotype.

The role of neuropeptide Y in the progesterone-induced luteinizing hormone-releasing hormone surge in vivo in ovariectomized female rhesus monkeys

Progesterone induces a LHRH surge in estrogen-primed ovariectomized rhesus monkeys, with a concomitant increase in the pulse frequency of neuropeptide Y (NPY) release. However, the role for NPY in the positive feedback action of progesterone on LHRH release in primates is unknown. The present study examines the effect of an antisense oligodeoxynucleotide for NPY messenger RNA (AS NPY) on the progesterone-induced LHRH surge in vivo using push-pull perfusion. The AS NPY was directly infused into the stalk-median eminence (S-ME), whereas perfusates were collected for assessment of LHRH release. For a control, a scrambled oligodeoxynucleotide was infused. The results indicate that 1) the scrambled oligodeoxynucleotide did not interfere with the progesterone-induced LHRH surge, 2) whereas AS NPY blocked the progesterone-induced increase in LHRH release, and 3) no LHRH surges were induced by oil as a control for progesterone, but the AS NPY also reduced LHRH release in oil controls. These data suggest that 1) AS NPY infusion into the S-ME results in reduction in LHRH release; and 2) NPY release in the S-ME is important for the positive feedback effects of progesterone on LHRH release in estrogen-primed ovariectomized monkeys.

The utility of apolipoprotein E genotyping in the diagnosis of Alzheimer disease in a community-based case series

CONTEXT

A recent collaborative study found that apolipoprotein E (APOE) genotype, in conjunction with the clinical diagnosis of Alzheimer disease (AD), was useful in improving diagnostic specificity (correctly not diagnosing AD) relative to the clinical diagnosis alone. Since these samples are particularly enriched with patients with AD and the APOE epsilon4 allele, results may not be generalizable to patients seen in the general medical community.

OBJECTIVE

To evaluate the diagnostic utility of the APOE genotype in diagnosing AD in a community-based case series from the largest health maintenance organization in an urban area.

DESIGN

We examined the effect of including APOE genotype on the diagnosis of AD in a community-based case series of patients presenting with memory complaints.

PATIENTS

Clinical and neuropathologic diagnoses and APOE genotype were obtained from 132 patients who underwent evaluation for dementia and subsequent autopsy.

MAIN OUTCOME MEASURES

Sensitivity, specificity, and positive and negative predictive values given various combinations of clinical diagnoses and the presence of an APOE epsilon4 allele.

RESULTS

Of the 132 patients, 94 had neuropathologically confirmed AD, yielding a prevalence of 71%. The clinical diagnosis alone yielded a sensitivity of 84%, an estimated specificity of 50%, and positive and negative predictive values of 81% and 56%, respectively. The presence of an epsilon4 allele alone was associated with an estimated sensitivity of 59%, specificity of 71%, and positive and negative predictive values of 83% and 41%, respectively. Using the presence of clinical AD and an epsilon4 allele decreased the sensitivity to 49% and increased the specificity to 84%. The positive and negative predictive values were 88% and 40%, respectively. Alternatively, the clinical diagnosis of AD or the presence of an epsilon4 allele in individuals not meeting clinical criteria for AD increases the estimated sensitivity to 94% but decreases the specificity to 37%. The positive and negative predictive values were 79% and 70%, respectively. The changes in the sensitivity and specificity for the combined tests relative to clinical diagnosis alone offset each other. For lower prevalence communities, the positive predictive value will be much lower than those observed herein.

CONCLUSIONS

Our findings do not support the use of APOE genotyping alone in the diagnosis of AD in the general medical community. Although the presence of an epsilon4 allele in older persons with clinical AD increased the probability of having AD and the absence of an epsilon4 allele in this group decreased the probability of having AD, the association is not strong enough in the differential diagnosis of non-Alzheimer dementia and AD.

Progression of regional neuropathology in Alzheimer disease and normal elderly: findings from the Nun study

Although diffuse plaques in the neocortex may represent an early stage in the evolution of neuritic plaques, plaques in the striatum and cerebellum retain their predominantly diffuse nature in Alzheimer disease (AD), regardless of disease duration. We had the opportunity to explore the progression of these regional features by using autopsy brain specimens from 15 cognitively normal and five AD subjects, all Catholic sisters enrolled in the Nun Study, a longitudinal study on aging and AD. Neuropathologic changes were assessed in the temporal cortex, striatum, and cerebellum without knowledge of clinical status. We found diffuse plaques in the striatum in six (40%) and cerebellar plaques in none of the brains from the non-demented subjects. Striatal plaques were present in all five and cerebellar plaques in four of the five AD cases. In the 20 cases overall, the presence of striatal plaques generally paralleled the occurrence of neuritic plaques in neocortex and correlated with lower scores on several neuropsychologic tests assessing memory. Our findings suggest that striatal diffuse plaques occur relatively early in the progression of AD pathology and coincide with neocortical pathology and cognitive changes. Thus, it is unlikely that temporal factors alone account for regional differences in progression of AD neuropathology.

Comparison of Lewy body variant of Alzheimer's disease with pure Alzheimer's disease: Consortium to Establish a Registry for Alzheimer's Disease, Part XIX

OBJECTIVE

To compare the clinical, neuropsychological, and neuropathologic findings in patients with AD alone with those in patients with the Lewy body variant of AD (LBV).

BACKGROUND

Prior studies indicate that patients with LBV not only have distinct clinical and neuropsychological differences from those with AD alone, but have a poorer prognosis with shorter survival time.

METHODS

The authors evaluated 74 patients with autopsy-confirmed AD alone and 27 patients with LBV, and compared demographic characteristics and clinical, neuropsychological, and neuropathologic findings.

RESULTS

The two groups of patients were equivalent with respect to age at time of entry into the study, years of education, and sex. Two or more extrapyramidal clinical manifestations were found in 44% of patients with LBV, compared with 16% of patients with AD alone (p = 0.02). Duration of survival after entry into the study was similar in both groups, with a mean survival of 3.6 (+/-2.1) years for AD alone versus 3.8 (+/-1.9) years for LBV. Of the various neuropsychological tests administered at the last Consortium to Establish a Registry for Alzheimer's Disease evaluation, only delayed recall of a learned word list was significantly different in the two groups, with 32% of patients with LBV versus 15% of patients with AD alone recalling any items (p = 0.04). Neuropathologic findings confirmed those of previous studies and showed that neurofibrillary tangles were significantly less frequent in the neocortex of patients with LBV than in those with AD alone.

CONCLUSION

Compared with patients with AD alone, those with LBV had a greater frequency of extrapyramidal manifestations, somewhat better recall on a selected memory task at their final evaluation, and a significantly lower frequency of neocortical neurofibrillary tangles at autopsy. There were no differences between the two groups, however, in survival time from entry into the study.

Tau pathology in a family with dementia and a P301L mutation in tau

Familial forms of frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) have recently been associated with coding region and intronic mutations in the tau gene. Here we report our findings on 2 affected siblings from a family with early-onset dementia, characterized by extensive tau pathology and a Pro to Leu mutation at codon 301 of tau. The proband, a 55-year-old woman, and her 63-year-old brother died after a progressive dementing illness clinically diagnosed as Alzheimer disease. Their mother, 2 sisters, maternal aunt and uncle, and several cousins were also affected. Autopsy in both cases revealed frontotemporal atrophy and degeneration of basal ganglia and substantia nigra. Sequencing of exon 10 of the tau gene revealed a C to T transition at codon 301, resulting in a Pro to Leu substitution. Widespread neuronal and glial inclusions, neuropil threads, and astrocytic plaques similar to those seen in corticobasal degeneration were labeled with a battery of antibodies to phosphorylation-dependent and phosphorylation-independent epitopes spanning the entire tau sequence. Isolated tau filaments had the morphology of narrow twisted ribbons. Sarkosyl-insoluble tau exhibited 2 major bands of 64 and 68 kDa and a minor 72 kDa band, similar to the pattern seen in a familial tauopathy associated with an intronic tau mutation. These pathological tau bands predominantly contained the subset of tau isoforms with 4 microtubule-binding repeats selectively affected by the P301L missense mutation. Our findings emphasize the phenotypic and genetic heterogeneity of tauopathies and highlight intriguing links between FTDP-17 and other neurodegenerative diseases.

Neurofibrillary pathology in Alzheimer disease with Lewy bodies: two subgroups

BACKGROUND

While NFT frequency is reportedly reduced in AD+DLB, we often encounter abundant neocortical NFTs in such cases and decided to investigate this discrepancy.

OBJECTIVE

To compare neurofibrillary tangle (NFT) frequency in Alzheimer disease with concomitant dementia with Lewy bodies (AD+DLB) with NFT frequency in "pure" AD.

METHODS

Neurofibrillary tangle frequency, as well as regional staging of neurofibrillary degeneration modified from Braak, was scored in 160 autopsy cases of primary dementia (80 AD+DLB cases and 80 pure AD cases).

RESULTS

Neurofibrillary tangle and modified Braak scores were lower in AD+DLB, as reported previously. Yet, neocortical NFT scores assumed markedly different patterns in the 2 groups (P = .001). In pure AD, NFT scores of "frequent" were predominant: more cases exhibited frequent than moderate or sparse NFTs. In AD+DLB, the distribution of NFT scores was bimodal: NFTs were either frequent or few to absent. Neocortical NFT scores in the AD+DLB group tended to parallel the severity of other types of tau cytopathology (neuropil threads and tau-positive plaque neurites).

CONCLUSIONS

Cases of AD+DLB may be divided into 2 subgroups based on the extent of neocortical neurofibrillary pathology. These findings could have implications for disease pathogenesis and treatment.

Cerebral infarcts in patients with autopsy-proven Alzheimer's disease: CERAD, part XVIII. Consortium to Establish a Registry for Alzheimer's Disease

OBJECTIVE

To study the relation between cerebral infarction and clinical and neuropsychologic manifestations in patients with autopsy-proven Alzheimer's disease (AD) enrolled in the Consortium to Establish a Registry for Alzheimer's Disease (CERAD).

BACKGROUND

Prior studies report that subjects with neuropathologic evidence of AD and concomitant brain infarcts had poorer cognitive function and higher frequency of dementia than those with AD alone.

METHODS

Clinical and neuropsychologic manifestations of dementia were studied in 74 subjects with neuropathologic findings of AD alone and 32 with AD and concomitant cerebral infarcts or lacunar lesions.

RESULTS

The 32 patients with both AD and vascular lesions were significantly older at time of death (median age, 81 years) than the 74 patients with AD alone (76 years; p = 0.02). At the final follow-up visit, the severity of the dementia was greater in AD patients with vascular lesions (median Clinical Dementia Rating [CDR] = 3) than in those with AD alone (CDR = 2; p = 0.03). Patients with AD and vascular lesions performed significantly worse on verbal fluency, Boston Naming, and Mini-Mental State Examination (MMSE) tests. No differences between the groups were observed, however, in the semiquantitative measures of frequency of neuritic plaques or neurofibrillary tangles.

CONCLUSIONS

The clinical-neuropathologic correlations in CERAD patients generally confirm those in prior studies, indicating that the presence of cerebral infarction in patients with AD is associated with greater overall severity of clinical dementia and poorer performance on specific tests of language and cognitive function.

Clinicopathologic studies in cognitively healthy aging and Alzheimer's disease: relation of histologic markers to dementia severity, age, sex, and apolipoprotein E genotype

OBJECTIVE

To study differences between subjects with Alzheimer disease (AD) and cognitively intact control subjects, with respect to brain histologic markers of AD, and the relationship of those markers in the AD group to severity of dementia, age at death, sex, and apolipoprotein E genotype.

SETTING

Washington University Alzheimer's Disease Research Center, St Louis, Mo.

DESIGN AND SUBJECTS

Consecutive neuropathologic series of 224 prospectively studied volunteer research subjects, 186 with dementia of the Alzheimer type (DAT) or "incipient" DAT and confirmed to have AD by postmortem examination and 13 cognitively intact subjects, confirmed to lack postmortem findings of AD.

MAIN OUTCOME MEASURES

Brain densities (number per square millimeter) of senile plaques and neurofibrillary tangles, extent of cerebral amyloid angiopathy, cortical Lewy bodies, and apolipoprotein E genotype.

RESULTS

Neocortical neurofibrillary tangle densities were substantially correlated with dementia severity, and to a greater degree than was true for senile plaque densities. When infarcts, hemorrhages, and Parkinson disease changes coexisted with AD, neurofibrillary tangle and senile plaque densities were lower. Plaque-predominant AD was found in a greater proportion of subjects with milder than more severe dementia. Entorhinal cortical Lewy bodies were no more frequent in plaque-predominant AD than in the remaining AD cases. Increasing age at death was negatively correlated with dementia severity and densities of senile plaques and neurofibrillary tangles. The apolipoprotein E epsilon4 allele frequency was greater in AD than in control subjects but decreased with increasing age. After controlling for dementia severity, senile plaque densities were only weakly related to epsilon4 allele frequency, and only in hippocampus. However, the degree of cerebral amyloid angiopathy was clearly related to epsilon4 allele frequency. Among subjects diagnosed during life as having DAT or incipient DAT, only 7% were found to have a neuropathologic disorder other than AD causing their dementia.

CONCLUSIONS

(1) The order of the strength of relationships between densities of histologic markers and dementia severity in AD is neurofibrillary tangles greater than cored senile plaques greater than total senile plaques. (2) Advanced age at death is associated with somewhat less severe dementia and fewer senile plaques and neurofibrillary tangles. (3) Plaque-predominant AD may represent a developmental stage in AD. (4) Despite a substantial effect of apolipoprotein E epsilon4 as a risk factor for AD, on decreasing the age at AD onset, and increasing the amount of cerebral amyloid angiopathy, its effect on senile plaque densities is variable and complex, being confounded with age, dementia severity, and methodologic differences. (5) Stringent clinical diagnostic criteria for DAT, even in the very mild stage, and senile plaque-based neuropathologic criteria for AD are highly accurate.

Diffuse plaques in the striatum in Alzheimer disease (AD): relationship to the striatal mosaic and selected neuropeptide markers

Although neuritic and diffuse plaques generally coexist in Alzheimer disease (AD) neocortex, the predominance of diffuse plaques in the striatum prompted us to explore the potential influence of striatal features such as the striatal mosaic on beta-amyloid (A beta) deposition. Using double immunohistochemistry with an antibody to A beta in combination with antibodies to met-enkephalin or somatostatin, we investigated the relationship between diffuse plaques and neuropeptide distribution in the dorsal striatum. This relationship was examined in "pure" AD cases as well as in AD cases with coexisting Parkinson disease (PD) pathology, i.e. nigral degeneration and Lewy bodies at any site (AD + PD). Despite the presence of numerous A beta-positive diffuse plaques in both groups, the mosaic pattern, as exemplified by met-enkephalin-immunoreactive patches, was preserved. No obvious association was observed between the plaques and met-enkephalin-positive patches or somatostatin-immunoreactive neurons. Tyrosine hydroxylase immunoreactivity in the matrix was, however, diminished in AD + PD, most likely reflecting the nigral degeneration in these cases. Overall, these observations suggest that neostriatal A beta deposition in AD is not influenced by environmental factors associated with the striatal mosaic.

Apolipoprotein E genotypes in a neuropathological series from the Consortium to Establish a Registry for Alzheimer's Disease

We evaluated the sensitivity, specificity, and predictive value of the apolipoprotein E (ApoE) epsilon4 allele for the neuropathological diagnosis of Alzheimer disease (AD) in a clinical series of well-characterized AD patients and controls followed longitudinally in the multicenter study of the Consortium to Establish a Registry for Alzheimer's Disease (CERAD). In the 162 patients for whom autopsy and ApoE genotype data were available, the clinical diagnosis of AD was verified as the primary cause of dementia in 139 cases (139 of 162, or 86%). The sensitivity and specificity of the epsilon4 allele for AD were both 83%. The positive predictive value of the epsilon4 allele was very high at 97% (115 of 119); whereas, the negative predictive value was 44% (19 of 43), providing no useful information for diagnosis of AD when the epsilon4 allele is not present. Of the cases where AD was not considered the primary or sole cause of dementia (n = 23), 6 cases exhibited concomitant neuropathological findings of definite or probable AD and 2 of these 6 cases had at least one epsilon4 allele. These multicenter data extend previous observations reported from smaller case series of single laboratories and demonstrate that once the clinical diagnosis of AD is established, the presence of an epsilon4 allele reliably predicts the ultimate CERAD neuropathological diagnosis of AD. The findings also suggest that ApoE genotype information is useful clinically in bolstering diagnostic confidence when an epsilon4 allele is present and in identifying a group of patients for whom additional diagnostic evaluations may be warranted when the epsilon4 allele is absent.

Corticobasal degeneration: neuropathologic and clinical heterogeneity

We investigated clinical and neuropathologic heterogeneity and apolipoprotein E (apoE) genotype in 11 cases of neuropathologically diagnosed corticobasal degeneration (CBD). Although seven of the 11 patients presented with unilateral limb dysfunction, the remaining four patients had less typical presentations including memory loss, behavioral changes, and difficulties with speech or gait. All 11 patients eventually developed extrapyramidal signs as well as cortical features, most commonly apraxia. At autopsy, the brains of seven of the 11 patients exhibited predominant neuronal loss and gliosis of perirolandic cortex; degeneration of more rostral frontal cortex was observed in three of the four patients with atypical clinical presentations. All cases displayed ballooned neurons, tau-positive neuronal and glial inclusions, threads and grains, and nigral degeneration. Six of the 11 cases manifested overlapping neuropathologic features of one or more disorders, including Alzheimer's disease (AD), progressive supranuclear palsy (PSP), Parkinson's disease (PD), and hippocampal sclerosis. Interestingly, these six patients all exhibited memory loss early in the course of their illness. The 11 CBD cases exhibited increased frequency (0.32) of the epsilon 4 allele of apoE, relative to control populations; the frequency remained elevated (0.25) even when the three cases with concomitant AD were excluded. Beta-amyloid (A beta) deposition in hippocampus or cortex was present in five of the seven cases with an epsilon 4 genotype. These observations indicate that CBD is a pathologically and clinically heterogeneous disorder with substantial overlap with other neurodegenerative disorders.

Astrocyte-apolipoprotein E associations in senile plaques in Alzheimer disease and vascular lesions: a regional immunohistochemical study

While apolipoprotein E (ApoE) and beta-amyloid (A beta) co-localize in senile plaques in cortex and cerebellum in Alzheimer disease (AD), the A beta-positive, predominantly diffuse plaques in the striatum do not exhibit ApoE immunoreactivity regardless of disease duration. As astrocytes are a major source of ApoE in the brain, we investigated potential regional differences in the ability of astrocytes to produce ApoE that might affect A beta processing and the progression of AD pathology. Using antibodies to ApoE, glial fibrillary acidic protein (GFAP), and A beta, we compared the pattern of immunoreactivity in senile plaques in AD autopsy tissue with that of reactive astrocytes surrounding subacute and old infarcts in both AD and non-AD cases. We found GFAP and ApoE immunoreactivity, but not A beta label in cell bodies and processes of reactive astrocytes in zones of infarction within cerebral cortex, striatum, and cerebellum, indicating that astrocytes are capable of upregulating ApoE within these 3 regions. In contrast, while astrocytes surrounded many neocortical neuritic plaques in AD, these GFAP-positive cells failed to label with ApoE; instead. ApoE label within plaques paralleled that of A beta. As expected, neither the ApoE-negative diffuse plaques of the striatum nor the ApoE-immunopositive diffuse plaques of the cerebellum were clearly associated with GFAP-immunoreactive astrocytes. The apparent absence of ApoE label in cortical plaque-associated astrocytes may signify a regulatory mechanism affecting ApoE synthesis and secretion, influenced by binding of ApoE to fibrillar amyloid within the plaques, neuritic changes, or other factors.

beta-Amyloid (A beta) deposition in the brains of aged orangutans

While aged monkeys of several species show cerebral amyloid deposition in senile plaques and blood vessels similar to that seen in human aging and Alzheimer's disease (AD), studies of great apes have been limited. Using histological and immunohistochemical methods, we examined the brains of four orangutans aged 10, 28, 31, and 36 years. We encountered sparse beta-amyloid (A beta)-immunoreactive, silver-negative plaque-like structures in the brains of the three older apes. The 36-year-old orangutan also evidenced small A beta-positive deposits in subcortical white matter and sparse vascular amyloid deposition, primarily in meningeal vessels. Neurofibrillary tangles were not detected on silver stains or on tau or ubiquitin immunohistochemistry. Many of the A beta-positive plaque-like deposits in the orangutans were apolipoprotein E-immunoreactive, as we have previously reported in aged rhesus monkeys and an aged chimpanzee. Also, paralleling our earlier findings in these nonhuman primates, A beta 40 in plaques was more prominent in the orangutan than is typically seen in human aging, AD, and Down syndrome. These intriguing species differences may provide clues to the mechanisms of amyloid deposition and the development of neuropathologic changes in AD.

Abeta1-40 but not Abeta1-42 levels in cortex correlate with apolipoprotein E epsilon4 allele dosage in sporadic Alzheimer's disease

Apolipoprotein E (ApoE) epsilon4 allele is established to be a risk factor for the development of late-onset Alzheimer's disease (AD) which is associated with increased frequency of senile plaques and extent of amyloid angiopathy. In a recent report, we demonstrated that ApoE epsilon4 dosage correlates with an increase in A beta1-40 but not A beta1-42/43-immunoreactive plaques. In the present study, we sought to confirm this relationship at a biochemical level by using a sensitive ELISA to measure the amounts of A beta1-42/43 and A beta1-40 in cerebral cortex in 36 cases of sporadic AD. We found that dosage of ApoE epsilon4 allele correlated significantly with cortical A beta1-40 levels, while levels of A beta1-42 showed no significant association with genotype. These results parallel our immunohistochemical findings and suggest that A beta1-40 may play a key role in the pathogenesis of late-onset sporadic AD.

A beta40 is a major form of beta-amyloid in nonhuman primates

Because aged nonhuman primates show beta-amyloid (A beta) deposition in senile plaques and blood vessels similar to that seen in human aging and AD, we used C-terminal specific antibodies to A beta40 and A beta42 to investigate A beta peptide length in the brains of 11 aged rhesus monkeys and a 59-year-old chimpanzee. In contrast to AD, where the earliest and most prominent form of A beta in senile plaques is A beta42, in the monkey, A beta40-positive plaques predominated. The ratio of A beta40:A beta42-positive plaques averaged 2.08 in the monkey, as compared to a mean ratio of 0.37 in 68 human AD subjects (p < 0.001). A beta40 was also more prominent in the chimpanzee than in humans. Possible explanations for these findings include species differences in the cleavage of A beta from the amyloid precursor protein or in the activity of a putative carboxy peptidase forming A beta40 from A beta42 in situ.

Abeta-peptide length and apolipoprotein E genotype in Alzheimer's disease

Apolipoprotein E (ApoE) epsilon4 allele, a risk factor for the development of Alzheimer's disease (AD), is associated with increased amyloid deposition. We examined cerebral cortex in 68 AD cases using antibodies to beta-amyloid (Abeta) peptides of different length (Abeta1-40 and Abeta1-42) and found that the increased plaque frequency observed with epsilon4 genotypes may be largely attributed to an increase in Abeta1-40-positive plaques. Indeed, both the number of Abeta1-40-positive plaques, as well as the ratio of Abeta1-40/Abeta1-42-positive plaques, increased with epsilon4 dosage. In contrast, the frequency of Abeta1-42-immunoreactive plaques was similar for epsilon3/epsilon3, epsilon3/epsilon4, and epsilon4/epsilon4 genotypes. ApoE may influence Abeta1 length by facilitating Abeta1-40 deposition onto Abeta1-42-seeded plaques or by modulating the activity of a putative carboxypeptidase that forms Abeta1-40 from Abeta1-42 in situ.

Alzheimer's disease with and without coexisting Parkinson's disease changes: apolipoprotein E genotype and neuropathologic correlates

The frequency of the apolipoprotein E (ApoE) epsilon 4 allele and its relationship with coexistent Parkinson's disease (PD) neuropathology in Alzheimer's disease (AD) have not been extensively explored. We determined ApoE genotype in 100 dementia patients with neuropathologically confirmed AD with and without concomitant Parkinson's disease (PD) changes (nigral degeneration and Lewy bodies at various sites). Fifty "AD+PD" patients were matched closely with 50 "pure AD" patients for age, sex, and duration of dementia. We found identical overrepresentation of the epsilon 4 allele in the two groups: 72% of the patients in each group had at least one ApoE epsilon 4 allele, compared with approximately 25% in the general population (p < 0.005) and in our institutional autopsy population (p < 0.001). Age at onset varied inversely with epsilon 4 allele dosage in men but not in women in both the AD and the AD+PD groups. As with amyloid deposition and plaque frequency in AD, we observed an association between epsilon 4 dosage and PD-related changes. Specifically, the severity of ubiquitin-positive neuritic change in CA2/3 of the hippocampus, but not the frequency of cortical Lewy bodies, varied significantly with epsilon 4 dosage in the AD+PD cases.

Regional variation in the distribution of apolipoprotein E and A beta in Alzheimer's disease

While the epsilon 4 allele of apolipoprotein E (ApoE) has been identified as a risk factor in Alzheimer's disease (AD), the mechanism by which this risk is conveyed is not understood. Immunohistochemical studies demonstrating ApoE-A beta colocalization in senile plaques, neurofibrillary tangles, and blood vessels and in vitro studies of ApoE-A beta interactions suggest that ApoE plays a role in amyloid processing and/or fibrillogenesis. We examined the ApoE-A beta association in diffuse and neuritic plaques in the neocortex, striatum, and cerebellum, and determined the ApoE genotype in 100 brains derived from dementia patients with neuropathologically confirmed AD. As expected, the epsilon 4 allele was overrepresented in AD patients compared with patients without neurological disease (p < 0.001). ApoE-positive plaque counts in neocortex were higher in epsilon 4/4 individuals than in individuals with other genotypes (p < 0.0005). Overall, in the 100 cases, ApoE-positive plaques were less frequent than A beta-positive plaques in contiguous sections (p < 0.0001). In all cases, A beta-positive diffuse plaques in the striatum failed to label with ApoE antibody, whereas the majority of cerebellar diffuse plaques showed A beta-ApoE colocalization. Possible explanations for these discrepancies include regional variation in amyloid processing and fibrillogenesis, varying stages of plaque evolution, and technical considerations.

Ubiquitin-positive CA2/3 neurites in hippocampus coexist with cortical Lewy bodies

We investigated CA2/3 ubiquitin-immunoreactive neurites in 120 cases of diverse neurodegenerative diseases. This neuritic change occurred in 25 of 30 cases of Alzheimer's disease (AD) with coexistent Parkinson's disease (PD) changes, as well as two cases of PD and two cases of progressive supranuclear palsy. All 29 cases with neuritic change showed cortical Lewy bodies. Neuritic change was absent in 86 cases of neurodegenerative diseases without Lewy bodies, including 66 cases of pure AD. Thus, ubiquitin-immunoreactive CA2/3 neurites and cortical Lewy bodies, frequently coexist; this association appears to be independent of the presence or absence of coexistent pathologies, eg, AD. Moreover, in and of itself, nigral degeneration without Lewy bodies, such as that encountered in other (non-PD) movement disorders, apparently is not associated with CA2/3 neuritic change.

Apolipoprotein E genotype in diverse neurodegenerative disorders

While the apolipoprotein E (ApoE) epsilon 4 allele is a recognized risk factor for Alzheimer's disease (AD), an association of epsilon 4 with other neurodegenerative diseases (NDs) has not been extensively explored. We examined 51 cases of neuropathologically confirmed ND. After eliminating 18 cases exhibiting pathology sufficient to warrant an additional diagnosis of AD, three disorders characterized by tau-related cytoskeletal pathology, i.e., Pick's disease, corticobasal degeneration, and progressive supra-nuclear palsy, showed increased epsilon 4 frequencies. Since the number of cases within each category was small, these increased epsilon 4 frequencies were not statistically significant. beta-Amyloid (beta A4) immunoreactive diffuse plaques were observed in many of these cases. While we cannot eliminate the possibility that these patients were destined to develop AD, these changes may merely reflect an independent association of epsilon 4 with amyloid deposition. These preliminary data affirm the need for further study of well-characterized cases to explore the relationship of ApoE to cytoskeletal pathology and ND.

The Consortium to Establish a Registry for Alzheimer's Disease (CERAD). Part X. Neuropathology confirmation of the clinical diagnosis of Alzheimer's disease

This report summarizes the neuropathologic findings in the first 106 autopsies of CERAD (Consortium to Establish a Registry for Alzheimer's Disease) dementia patients diagnosed clinically as having Alzheimer's disease (AD). In 92 (87%) of the 106 cases, neuropathologists confirmed Alzheimer's disease (AD) as the primary dementing illness. Coexistent Parkinson's disease (PD) changes were present in 19 (21%) and vascular lesions of varying nature and size in 26 (28%) of these 92 AD cases. The 14 cases in which AD was not interpreted as the primary dementing illness can be divided into four major subgroups based on their neuropathology findings: PD and related pathology (n = 5), hippocampal sclerosis (n = 3), miscellaneous neurodegenerative and other disorders (n = 3), and no significant changes (n = 3). Despite the relatively high level of clinical diagnostic accuracy, further refinement of assessment batteries may facilitate distinction of non-AD dementias from AD.

The CERAD experience, Part VIII: Neuroimaging-neuropathology correlates of temporal lobe changes in Alzheimer's disease

We compared premortem neuroimaging findings with neuropathologic evidence of temporal lobe atrophy in 20 patients with Alzheimer's disease (AD) confirmed by autopsy. There were significant correlations between temporal horn enlargement observed by neuroimaging and hippocampal atrophy at autopsy, and between the overall cerebral atrophy severity on neuroimaging and scores on the Mini-Mental State Examination. This report confirms previous studies correlating temporal lobe atrophy on neuroimaging with a clinical diagnosis of AD, although more precise neuroimaging techniques are needed for use in multicenter studies of AD.

Neuropathology and apolipoprotein E profile of aged chimpanzees: implications for Alzheimer disease

Neuropathological findings in three aged chimpanzees were compared with those in rhesus monkeys and individuals with Alzheimer disease. Senile plaques and blood vessels were immunoreactive for amyloid beta-protein and apolipoprotein E (apoE) in the nonhuman primates, recapitulating findings in human aging and Alzheimer disease. Neurofibrillary tangles, another hallmark of Alzheimer disease, were absent. PCR/restriction-enzyme analysis in chimpanzees revealed an APOE profile similar to the human APOE type 4 allele associated with an increased risk of Alzheimer disease. These findings militate against the hypothesis that the absence of APOE type 3 allele predisposes to neurofibrillary tangle formation and support the value of aged primates for exploring mechanisms of amyloid processing and the role of apoE.

Progressive supranuclear palsy: neuropathologic and clinical heterogeneity

To investigate potential heterogeneity in progressive supranuclear palsy (PSP), we examined 13 patients with neuropathologically diagnosed PSP. The clinical diagnosis of PSP was made in eight of these individuals, whereas probable AD was the primary diagnosis in the remaining five. In addition to PSP neuropathology, seven of the 13 patients (54%) showed concomitant pathologic changes of Alzheimer's disease (AD), Parkinson's disease (PD), or both disorders. These observations indicate that AD and PD changes coexist with PSP neuropathology in a substantive proportion of patients and provide further evidence of clinical and neuropathologic heterogeneity in neurodegenerative disorders. Moreover, our results suggest that PSP may be underdiagnosed and deserves more prominence in the differential diagnosis of dementing illness.

Apolipoprotein E4 and beta amyloid in senile plaques and cerebral blood vessels of aged rhesus monkeys

Recent studies of late onset familial and sporadic Alzheimer's disease (AD) show a genetic disequilibrium between inheritance of the epsilon 4 allele of the apolipoprotein E (ApoE) gene and development of AD. beta-Amyloid (A beta)-positive senile plaques and blood vessels in AD are immunoreactive for ApoE, suggesting that ApoE plays a role in amyloid deposition. We examined the brains of nine rhesus monkeys (Macaca mulatta) to determine the immunohistochemical distribution of ApoE and to investigate the association of ApoE with A beta in this species. Antibodies to ApoE and A beta labeled senile plaques and vessels in the brains of aged monkeys, indicating cross-species homogeneity of the association of these two proteins. Polymerase chain reaction/restriction enzyme analysis of the ApoE epsilon 3/epsilon 4 allelic site (residue 112) in the rhesus monkey revealed that the rhesus has an arginine at this site like the human epsilon 4 allele, the cynomolgus monkey, baboon, cow, pig, mouse, and rat but unlike the human epsilon 3 allele and the rabbit. These results emphasize the value of aged nonhuman primates as animal models for A beta deposition and ApoE4-A beta interactions in AD and aging.

Interlaboratory comparison of neuropathology assessments in Alzheimer's disease: a study of the Consortium to Establish a Registry for Alzheimer's Disease (CERAD)

Concerns about intercenter variation in methods and interpretation prompted CERAD investigators to examine standardization of the neuropathological assessment of Alzheimer's disease (AD). Contiguous frontal lobe sections derived from autopsy brains of eight patients clinically diagnosed as having probable AD and two cognitively normal individuals were distributed to 24 neuropathologists from 18 medical centers in the United States and Canada. Using their routine staining method(s), neuropathologists determined the rank order of severity of AD neuropathology in these cases, as well as semiquantitative and quantitative senile plaque and neurofibrillary tangle frequencies. Ranking of the ten cases revealed 75% inter-rater reliability among the 24 raters. Semiquantitative analyses showed reasonable inter-rater agreement, whereas quantitative measures yielded significant differences between raters for plaque and tangle counts (p < 0.0001). These differences reflected variation in stain sensitivity, staining technique (even when the same stain was used), and interpretation of the histological findings. Ratings on the cases with the highest proportions of diffuse plaques showed the greatest dependence upon stain sensitivity and variability in interpretation. This study indicates that greater attention to quality improvement is needed for the neuropathological evaluation of AD, particularly when pooling data in multicenter studies such as CERAD.

Mitochondrial DNA variants observed in Alzheimer disease and Parkinson disease patients

Mitochondrial DNA (mtDNA) variants associated with Alzheimer disease (AD) and Parkinson disease (PD) were sought by restriction endonuclease analysis in a cohort of 71 late-onset Caucasian patients. A tRNA(Gln) gene variant at nucleotide pair (np) 4336 that altered a moderately conserved nucleotide was present in 9/173 (5.2%) of the patients surveyed but in only 0.7% of the general Caucasian controls. One of these patients harbored an additional novel 12S rRNA 5-nucleotide insertion at np 956-965, while a second had a missense variant at np 3397 that converted a highly conserved methionine to a valine. This latter mutation was also found in an independent AD + PD patient, as was a heteroplasmic 16S rRNA variant at np 3196. Additional studies will be required to determine the significance, if any, of these mutations.

Amyloid precursor protein (APP) in the striatum in Alzheimer's disease: an immunohistochemical study

Increasing recognition of diffuse plaques has raised questions about the differences between diffuse and neuritic plaques, particularly in regard to the role of amyloid precursor protein (APP) processing in their formation. To address this issue, corpus striatum (containing almost exclusively diffuse plaques) and cerebral cortex (containing an admixture of plaque types) from patients with Alzheimer's disease (AD) were examined immunohistochemically with antibodies to domain-specific sites of APP (N-terminal, C-terminal, beta A4-related, isoform-specific, and other epitopes). Striatal plaques labeled strongly with beta A4 antibodies as did cortical plaques in AD and the occasional diffuse plaques in cortex from nondemented elderly controls. Weak labeling of some cortical neuritic plaques but not diffuse plaques was observed with antibodies directed against other APP epitopes. Electron microscopy of diffuse plaque-rich striatum in AD cases revealed only rare degenerating neurites without apparent fibrillar amyloid; no changes were noted in the plaque-free striatum of controls. These results suggest that antibodies to beta A4 recognize not only fibrillar amyloid of neuritic plaques but also antigenic determinants of diffuse plaques which lack fibrillar amyloid. Furthermore, the finding that antibodies to non-A4 domains of APP labeled only cortical but not striatal plaques suggests that APP processing mechanisms in cortical and striatal tissues may differ.

Heterogeneity in Alzheimer's disease: progression rate segregated by distinct neuropsychological and cerebral metabolic profiles

In an attempt to define possible subgroups of Alzheimer's disease, 21 patients satisfying current clinical diagnostic criteria for this disorder were divided on the basis of progression rates of symptoms. Thirteen patients with relatively rapid intellectual deterioration did not differ from eight patients showing slow progression with respect to global intellectual performance, sex, or age at onset of symptoms. Neuropsychological testing revealed that although the two groups were indistinguishable in verbal or visuospatial functions associated with the parietotemporal cortex, the more rapidly deteriorating group had significantly greater impairment in executive functions attributed to the frontal lobe. PET scans showed equivalent reductions in glucose metabolism in the parietotemporal cortex, but patients with relatively fast progression had significantly greater hypometabolism frontally. These results suggest an association between relatively severe frontal lobe involvement and a rapid clinical course that might have important implications for the development of treatment strategies for patients with Alzheimer's disease.

Prostaglandin E2 mediates the stimulatory effect of methoxamine on in vivo luteinizing hormone-releasing hormone (LH-RH) release in the ovariectomized female rhesus monkey

Previously, we found that noradrenergic input through alpha 1-receptors modulates pulsatile release of luteinizing hormone-releasing hormone (LH-RH) in ovariectomized rhesus monkeys in the absence of estrogen. In the present study, the role of prostaglandin E2 (PGE2) in mediating alpha-adrenergic stimulation of LH-RH release is investigated. In the first experiment the effects of the alpha 1-adrenergic agonist methoxamine (MTX) on LH-RH and PGE2 release were examined. Push-pull perfusion of the stalk-median eminence (S-ME) was performed in conscious, ovariectomized monkeys, and perfusate samples were collected on ice. MTX (10(-5) M) was infused into the S-ME through the push cannula for 10 min at 90-min intervals, and LH-RH and PGE2 in aliquots of the same perfusate samples were measured by radioimmunoassay. Infusion of MTX significantly stimulated LH-RH release (n = 12; P less than 0.01) and PGE2 release (P less than 0.05). In the second experiment, the effect of PGE2 infusion on LH-RH release was tested. PGE2 (10(-7) M) was infused using the same protocol as above, and LH-RH was measured in the perfusates. Infusion of PGE2 through the push cannula significantly stimulated LH-RH release (n = 23; P less than 0.05). These results suggest that the stimulatory effect of MTX on LH-RH release is at least partly mediated by PGE2, since MTX stimulated not only LH-RH but also PGE2 release, and since PGE2 itself stimulated LH-RH release. Therefore, PGE2 may be an important endogenous mediator of alpha 1-adrenergic input stimulating pulsatile LH-RH release.(ABSTRACT TRUNCATED AT 250 WORDS)

The alpha-1-adrenergic neuronal system is involved in the pulsatile release of luteinizing hormone-releasing hormone in the ovariectomized female rhesus monkey

It has been postulated that catecholamines are integral to the control of LHRH release. In the present study, the roles of adrenergic and dopaminergic receptors in the control of pulsatile LHRH release are examined. The effects of prazosin (an alpha 1-antagonist), rauwolscine (an alpha 2-antagonist), propranolol (a beta-antagonist), haloperidol (a dopamine antagonist), SCH23390 (a D1 antagonist), and LY163502 (a D2 agonist), on in vivo LHRH release in the stalk-median eminence were tested in ovariectomized female rhesus monkeys using push-pull perfusion. Prazosin caused a significant suppression of the LHRH release. This was primarily due to a significant suppression of LHRH pulse amplitude, but not pulse frequency, i.e. the interpulse interval was not affected by the administration of prazosin. In contrast to prazosin, none of the other adrenergic or dopaminergic drugs had significant effects on LHRH release. We conclude from these results that (1) the stimulatory effects of norepinephrine (NE) and/or epinephrine on pulsatile LHRH release are mediated by alpha 1-adrenergic receptors but not alpha 2- or beta-adrenergic receptors, and (2) dopaminergic receptors do not appear to be involved in pulsatile LHRH release in ovariectomized rhesus monkeys.