A new clinical scale for the staging of dementia

Accurate clinical staging of dementia in older subjects has not previously been achieved despite the use of such methods as psychometric testing, behavioural rating, and various combinations of simpler psychometric and behavioural evaluations. The Clinical Dementia Rating (CRD), a global rating device, was developed for a prospective study of mild senile dementia--Alzheimer type (SDAT). Reliability, validity, and correlational data are discussed. The CRD was found to distinguish unambiguously among older subjects with a wide range of cognitive function, from healthy to severely impaired.

The Consortium to Establish a Registry for Alzheimer's Disease (CERAD). Part II. Standardization of the neuropathologic assessment of Alzheimer's disease

The Neuropathology Task Force of the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) has developed a practical and standardized neuropathology protocol for the postmortem assessment of dementia and control subjects. The protocol provides neuropathologic definitions of such terms as "definite Alzheimer's disease" (AD), "probable AD," "possible AD," and "normal brain" to indicate levels of diagnostic certainty, reduce subjective interpretation, and assure common language. To pretest the protocol, neuropathologists from 15 participating centers entered information on autopsy brains from 142 demented patients clinically diagnosed as probable AD and on eight nondemented patients. Eighty-four percent of the dementia cases fulfilled CERAD neuropathologic criteria for definite AD. As increasingly large numbers of prospectively studied dementia and control subjects are autopsied, the CERAD neuropathology protocol will help to refine diagnostic criteria, assess overlapping pathology, and lead to a better understanding of early subclinical changes of AD and normal aging.

Mild cognitive impairment represents early-stage Alzheimer disease

BACKGROUND

Mild cognitive impairment (MCI) is considered to be a transitional stage between aging and Alzheimer disease (AD).

OBJECTIVE

To determine whether MCI represents early-stage AD by examining its natural history and neuropathologic basis.

DESIGN

A prospective clinical and psychometric study of community-living elderly volunteers, both nondemented and minimally cognitively impaired, followed up for up to 9.5 years. Neuropathologic examinations were performed on participants who had undergone autopsy.

SETTING

An AD research center.

PARTICIPANTS

All participants enrolled between July 1990 and June 1997 with Clinical Dementia Rating (CDR) scores of 0 (cognitively healthy; n = 177; mean age, 78.9 years) or 0.5 (equivalent to MCI; n = 277; mean age, 76.9 years). Based on the degree of clinical confidence that MCI represented dementia of the Alzheimer type (DAT), 3 subgroups of individuals with CDR scores of 0.5 were identified: CDR 0.5/DAT, CDR 0.5/incipient DAT, and CDR 0.5/uncertain dementia.

MAIN OUTCOME MEASURE

Progression to the stage of CDR 1, which characterizes mild definite DAT.

RESULTS

Survival analysis showed that 100% of CDR 0.5/DAT participants progressed to greater dementia severity over a 9.5-year period. At 5 years, rates of progression to a score of CDR 1 (or greater) for DAT were 60.5% (95% confidence interval [CI], 50.2%-70.8%) for the CDR 0.5/DAT group, 35.7% (95% CI, 21.0%-50.3%) for the CDR 0.5/incipient DAT group, 19.9% (95% CI, 8.0%-31.8%) for the CDR 0.5/uncertain dementia group, and 6.8% (95% CI, 2.2%-11.3%) for CDR 0/controls. Progression to greater dementia severity correlated with degree of cognitive impairment at baseline. Twenty-four of the 25 participants with scores of CDR 0.5 had a neuropathologic dementing disorder, which was AD in 21 (84%).

CONCLUSIONS

Individuals currently characterized as having MCI progress steadily to greater stages of dementia severity at rates dependent on the level of cognitive impairment at entry and they almost always have the neuropathologic features of AD. We conclude that MCI generally represents early-stage AD.

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.

Cerebral amyloid deposition and diffuse plaques in "normal" aging: Evidence for presymptomatic and very mild Alzheimer's disease

The presence of senile plaques in the neocortex of apparently nondemented elderly persons often is accepted as part of "normal" aging. Alternatively, because cerebral deposition of beta-amyloid may be a key mechanism in the development of Alzheimer's disease (AD), the presence of beta-amyloid-containing plaques may represent very early AD. To examine the relationships of cognitively normal aging, very mild dementia of the Alzheimer type, and the presence of neocortical senile plaques, we performed clinicopathologic correlation in 21 longitudinally studied healthy elderly subjects (84.5 +/- 6.6 years old at death). Nine subjects had strikingly high plaque densities in the neocortex; two of these subjects died of head injury before which there was no evidence of cognitive impairment. The other seven subjects with high plaque densities had clinical evidence for very mild cognitive impairment (Clinical Dementia Rating score of 0.5) at some time during their course and mildly impaired psychometric performance at last assessment before death. The remaining 12 subjects had no clinical or psychometric impairment and had few or no neocortical AD lesions. These results suggest that senile plaques may not be part of normal aging but instead represent presymptomatic or unrecognized early symptomatic AD. The high density of senile plaques (predominately of the diffuse subtype) in the cortex of subjects just at the threshold of detectable dementia is consistent with the hypothesis that beta-amyloid deposition is an initial pathogenetic event in the development of AD.

Very mild Alzheimer's disease: informant-based clinical, psychometric, and pathologic distinction from normal aging

We compare clinicopathologic data from 10 subjects identified in the very mild stage of senile dementia of the Alzheimer type with findings from similar studies in four cognitively normal subjects. We based the diagnosis of very mild dementia in the 10 subjects on informant reports and the judgment of experienced clinicians. Deficits of some psychometric measures of memory, language, and speeded psychomotor performance were observed for these subjects. The histologic markers of Alzheimer's disease, including neurofibrillary tangles and both the "diffuse" and classic subtypes of senile plaques, were present in the neocortex in all 10 subjects but essentially were absent in the four controls. These findings indicate that even "questionable" dementia can be diagnostic for Alzheimer's disease. Furthermore, because truly normal aging may be unaccompanied by neocortical senile plaques and neurofibrillary tangles, the presence of these lesions should suggest the possibility of clinically undetected Alzheimer's disease.

Validation of clinical diagnostic criteria for Alzheimer's disease

Clinical investigations of Alzheimer's disease (AD) have been limited by diagnostic inaccuracy. We employed explicit clinical inclusion and exclusion criteria to identify subjects with senile dementia of the Alzheimer type (SDAT). In a consecutive series of 26 postmortem examinations from this sample, AD was histologically verified in all subjects and was the primary dementing illness. Seventeen of the 26 SDAT subjects had been diagnosed when only mildly demented. Two control subjects were examined neuropathologically; AD was absent in both. We conclude that research clinical diagnostic criteria for SDAT, even in its mild stage, are valid.

Psychometric differentiation of mild senile dementia of the Alzheimer type

A brief (ten-minute), easily administered battery of four psychological tests was developed to classify successfully 98% of patients with mild dementia of the Alzheimer's type and healthy older persons matched for age, sex, and social position. Only two of 84 persons (one demented, one healthy) were misclassified. The four tests are the logical memory and mental control subtests of the Wechsler Memory Scale, Form A of the Trailmaking Test, and word fluency for letters S and P.

A prospective study of cognitive function and onset of dementia in cognitively healthy elders

OBJECTIVE

To examine the earliest cognitive changes associated with the onset of dementia as well as changes associated with normal aging.

DESIGN

Longitudinal evaluation of participants with annual clinical and psychometric examinations for up to 15 1/2 years.

SETTING AND PARTICIPANTS

Elderly volunteers (n = 82) enrolled with a Clinical Dementia Rating of 0 (cognitively intact) in longitudinal studies.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Clinical Dementia Rating and results of a 1 1/2-hour psychometric battery.

RESULTS

As estimated with survival analysis, 40% of participants had a Clinical Dementia Rating greater than 0 (cognitive decline) within 12 years of enrollment; 59% of these were judged to have dementia of the Alzheimer type or incipient dementia. Participants with poorer performance on psychometric testing at enrollment were at higher risk for cognitive decline subsequently. The rate of change in psychometric performance before clinically detectable cognitive change occurred was not significantly different between those who eventually developed dementia and those who remained stable, except for performance on the Logical Memory subtest of the Wechsler Memory Scale. When subtle cognitive decline was clinically detected, however, an abrupt deterioration in performance on independently administered psychometric tests was observed.

CONCLUSIONS

Cognitively healthy elderly people maintain stable cognitive performance when measured longitudinally by both careful clinical evaluation and repeated psychometric testing. This stability is maintained unless and until they develop a dementing illness, at which time a sharp decline in performance is observed.

Reliability of the Washington University Clinical Dementia Rating

There is a growing need for methods for measuring and staging the natural history of dementia of the Alzheimer type. One instrument, designed with that purpose in mind, is the Washington University Clinical Dementia Rating. We tested its reliability using multiple clinicians in a videotape-design study, and it proved reliable under these study conditions.

Neuropathological indexes of Alzheimer's disease in demented and nondemented persons aged 80 years and older

Subjects with clinically diagnosed senile dementia of the Alzheimer type (n = 37) and healthy controls (n = 5) were assessed clinically until death. Postmortem examination of the brain was performed at age 80 years or older. The brains of all of the group with dementia (except one that was found to have a non-Alzheimer dementia) had substantial densities of neocortical senile plaques regardless of dementia severity; the control brains had very few senile plaques. In those subjects with Alzheimer's disease, moderate correlations were found between dementia duration and severity (cognitive portion of the Blessed Dementia Scale and the Sum of Boxes from the Clinical Dementia Rating) and certain neuropathological lesions, both gross and microscopic. Densities of neocortical neurofibrillary tangles were related to degree of dementia; densities of neocortical senile plaques were unrelated. We conclude that (1) neocortical senile plaque densities differentiate very old subjects with Alzheimer's disease from nondemented controls, but there is a need for more postmortem studies of older persons who are free of dementia; and (2) among the microscopic lesions studied, densities of neocortical neurofibrillary tangles were most closely related to the degree and duration of dementia.

Frequency analysis of the resting awake EEG in mild senile dementia of Alzheimer type

Spontaneous resting electroencephalograms (EEGs) were recorded from 40 subjects with senile dementia of Alzheimer type (SDAT) and 40 individually matched elderly controls at entry into a longitudinal study of SDAT. All of the demented subjects had only a mild degree of dementia, and all were still living in the community. Several measures of EEG activity were calculated, based upon the power spectra of the EEG samples from left and right occipital-to-vertex derivations. Paired t tests showed significant differences between demented and control group means for measures of theta and beta activity, but not for measures of alpha and delta activity. A significant decrease in the 'average mean frequency' in demented subjects was attributed to the combination of decreased beta and increased theta activity. The earliest changes in the resting EEG in SDAT are increased theta and decreased beta power. These changes are not identical to those reported in normal aging, in which a decrease in alpha activity accompanies the changes in theta and beta.

Untreated periodontal disease: a longitudinal study

Thirty diagnosed but untreated patients with moderate to advanced periodontal disease were examined a minimum of two times. The examination time intervals ranged between 18 and 115 months. 2. A total of 83 teeth were lost between examinations. 3. Excluding a patient who lost 25 teeth, a total of 58 teeth were lost. The adjusted tooth loss was 0.61 tooth per patient per year (or 0.36 with the elimination of 22 "hopeless" teeth). 4. The mandibular and maxillary molars had the greatest percentage of tooth loss between examinations. 5. All 29 patients completing the study had progessive increases in pocket depth during their time in the study. Increases in the mean annual pocket depths per tooth per patient varied from 0.24 millimeter per year to 2.46 millimeters per year. 6. The disto-lingual and mesio-lingual interproximal surfaces had the greatest increases in surface pocket depths. The lingual and buccal surfaces had the smallest increases in pocket depth. 7. The rate of increase in pocket depths was less in patients over 44 years of age. 8. The teeth which were lost had greater initial pocket depths and mobility scores than those which were present at both examinations. 9. There was no correlation between increases in pocket depth and changes in mobility. 10. All 29 patients showed radiographic evidence of progressive bone resorption between examinations. The posterior segments of the mouth had the largest amounts of bone loss between the first and last examinations.

Aphasia in senile dementia of the Alzheimer type

We assessed language function, using a brief clinical Aphasia Battery and psychometric measures, in 150 subjects with senile dementia of the Alzheimer type (SDAT) and 83 elderly controls. Aphasia occurred only in demented subjects, and its prevalence increased with severity of dementia. Aphasia in mildly demented subjects was associated with both an earlier age of onset and more rapid progression of SDAT than in similarly demented nonaphasics. Language dysfunction in SDAT subjects was characterized by early decline in measures of comprehension and written expression, whereas other components, including oral naming, were less profoundly affected. Performance on the verbal psychometric measures, the Sentence Repetition and the Token tests, correlated strongly with Aphasia Battery scores and declined only minimally in nonaphasics, despite increasing dementia. We conclude that aphasia is a common feature of SDAT subjects and identifies a subgroup with more rapid progression of dementia. Furthermore, it represents language-specific dysfunction beyond the global cognitive impairment of SDAT.

Mild senile dementia of Alzheimer type: research diagnostic criteria, recruitment, and description of a study population

Clinical investigations of senile dementia of the Alzheimer type require establishment of explicit clinical diagnostic criteria before histological confirmation is possible. Criteria for selection of mildly impaired subjects with senile dementia of Alzheimer type, free of other major disease, are proposed. Problems of recruitment of this select population for a longitudinal study are discussed. A study population with matched healthy control subjects has been enrolled and described. Short term follow-up has provided preliminary support for the diagnostic criteria.

Mild senile dementia of the Alzheimer type: 2. Longitudinal assessment

Forty-three subjects with mild senile dementia of the Alzheimer type (SDAT, so-called probable Alzheimer's disease) were studied longitudinally by serial administration of several tests to rate dementia. Comparison was made with 58 healthy elderly controls. The clinical diagnosis was confirmed in all 16 autopsies. At 5 years after entry into the study, the cumulative rate of nursing home placement was 73%, and of death, 30%, rising at 7 years to 84% and 44%, respectively. Four of six clinical measures of dementia were found to correlate with the natural history of SDAT. Several measures are better than a single one in carrying out longitudinal studies of the disorder.

Bovine papilloma virus contains an activator of gene expression at the distal end of the early transcription unit

Bovine papilloma virus (BPV) contains a cis-acting DNA element which can enhance transcription of distal promoters. Utilizing both direct and indirect transient transfection assays, we showed that a 59-base-pair DNA sequence from the BPV genome could activate the simian virus 40 promoter from distances exceeding 2.5 kilobases and in an orientation-independent manner. In contrast to the promoter 5'-proximal localization of other known viral activators, this element was located immediately 3' to the early polyadenylation signal in the BPV genome. Deletion of these sequences from the BPV genome inactivated the transforming ability of BPV recombinant plasmids. Orientation-independent reinsertion of this 59-base-pair sequence, or alternatively of activator DNA sequences from simian virus 40 or polyoma virus, restored the transforming activity of the BPV recombinant plasmids. Furthermore, the stable transformation frequency of the herpes simplex virus type 1 thymidine kinase gene was enhanced when linked to restriction fragments of BPV DNA which included the defined activator element. This enhancement was orientation independent with respect to the thymidine kinase promoter. The enhancement also appeared to be unrelated to the establishment of the recombinant plasmids as episomes, since in transformed cells these sequences are found linked to high-molecular-weight DNA. We propose that the enhancement of stable transformation frequencies and the activation of transcription units are in this case alternate manifestations of the same biochemical events.

The progression of personality changes in senile dementia of the Alzheimer's type

Passive, agitated, and self-centered behavioral changes were noted on initial evaluation in two-thirds, one-third, and one-third, respectively, of subjects with mild senile dementia of the Alzheimer's type (SDAT). Over a 50-month follow-up period, the percentage of patients who exhibited agitated and self-centered behaviors doubled. The percentage of subjects who demonstrated all three behavioral changes increased from 11% at entry to the study (mild SDAT) to over 50% when the dementia had reached a severe stage. The presence of personality changes at a mild stage of dementia did not predispose subjects to more rapid progression to a more advanced stage of illness.

Predictive features in mild senile dementia of the Alzheimer type

Forty-three subjects with mild senile dementia of the Alzheimer type, diagnosed and staged by clinical research criteria, were studied with clinical, psychometric, EEG, visual evoked potential, and CT measures. During the 12 months following entry into the study, 21 subjects progressed to moderate or severe dementia, 21 remained mild, and one was lost to follow-up. Many of the clinical and psychometric measures of impairment were predictive of the progression to moderate or severe dementia. Electrophysiologic and CT measures were not. In a discriminant function analysis, the scores on two measures (the digit symbol subtest of the Wechsler Adult Intelligence Scale and an Aphasia Battery) correctly predicted the stage of dementia 1 year later in 95% of the subjects.

Volumetric measurements of the cerebrospinal fluid spaces in demented subjects and controls

Forty-seven subjects 65 to 80 years of age, of whom 20 were demented and 27 were normal, were studied by computed tomography. Volumetric indices of ventricular (V%) and sulcal size (S%) were determined by pixel counts without knowledge of clinical status. V% was 5.30 (+/- 1.92) for the controls and 10.46 (+/- 4.78) for the demented subjects. S% was 6.14 (+/- 2.51) for the controls and 10.61 (+/- 3.32) for the demented subjects. In each case, differences between the two groups were significant (P less than 0.0001). When a subsample of 29 scans were analyzed using linear and volumetric measurements, the linear measurements showed less pronounced differences between the demented subjects and the controls. These findings explain the conflicting results of different investigators concerning variations in ventricular and sulcal size in dementia and normal aging.

Repression of bovine papilloma virus replication is mediated by a virally encoded trans-acting factor

Cells transformed with bovine papilloma virus type 1 mutants in the E6 or E6/7 genes are resistant to high-copy-number amplification of wild-type DNA after supertransfection. Transient and stable replication assays demonstrate this effect. If the supertransfected DNA has a mutation in a newly defined gene (M), this cellular immunity to high-copy-number replication is overcome, resulting in transient replication of the input DNA. In contrast, the resident plasmid does not participate in amplification and is maintained at a constant low copy number. Cotransformation of M- mutants and wild-type DNA into these cells leads to shutoff of replication of both genomes. Thus, M- mutants define a trans-acting negative modulator that regulates viral replication. This function is distinct from the positive factors required for replication. We propose a model that explains why the loss of E6 and E6/7 function leads to immunity of the infected cell.

The activity and signaling range of mature BMP-4 is regulated by sequential cleavage at two sites within the prodomain of the precursor

Proteolytic maturation of proBMP-4 is required to generate an active signaling molecule. We show that proBMP-4 is cleaved by furin in a sequential manner. Cleavage at a consensus furin site adjacent to the mature ligand domain allows for subsequent cleavage at an upstream nonconsensus furin site within the prodomain. BMP-4 synthesized from precursor in which the upstream site is noncleavable is less active, signals at a shorter range, and accumulates at lower levels than does BMP-4 cleaved from native precursor. Conversely, BMP-4 cleaved from precursor in which both sites are rapidly cleaved is more active and signals over a greater range. Differential use of the upstream cleavage site could provide for tissue-specific regulation of BMP-4 activity and signaling range.

Mild senile dementia of the Alzheimer type. 4. Evaluation of intervention

The design of trials of interventions intended to slow or arrest the progression of senile dementia of the Alzheimer type must be based on analysis of the natural history of the disease. Using a random coefficients statistical model, we analyzed the natural history of senile dementia of the Alzheimer type in carefully defined subjects with mild disease (n = 68) for periods of up to 10 years. Subject performance was assessed longitudinally on batteries of clinical and psychometric measures. The characteristics of these measures were analyzed relevant to their utility as outcome measures for long-term trials in patients with senile dementia of the Alzheimer type. Estimates were made of sample sizes required to show arrest, and 50% or 25% slowing in the progression of mild disease. We suggest that a clinically relevant global measure, such as the Sum of Boxes of the Clinical Dementia Rating scale, and a performance-based clinical scale or psychometric measure would be appropriate in a 12- or 24-month trial enrolling subjects with mild senile dementia of the Alzheimer type.

Long-Lived Plasma Cells in Mice and Men

Even though more than 30 years have passed since the eradication of smallpox, high titers of smallpox-specific antibodies are still detected in the blood of subjects vaccinated in childhood. In fact, smallpox-specific antibody levels are maintained in serum for more than 70 years. The generation of life-long immunity against infectious diseases such as smallpox and measles has been thoroughly documented. Although the mechanisms behind high persisting antibody titers in the absence of the causative agent are still unclear, long lived plasma cells (LLPCs) play an important role. Most of the current knowledge on LLPCs is based on experiments performed in mouse models, although the amount of data derived from human studies is increasing. As the results from mouse models are often directly extrapolated to humans, it is important to keep in mind that there are differences. These are not only the obvious such as the life span but there are also anatomical differences, for instance the adiposity of the bone marrow (BM) where LLPCs reside. Whether these differences have an effect on the function of the immune system, and in particular on LLPCs, are still unknown. In this review, we will briefly discuss current knowledge of LLPCs, comparing mice and humans.

Analysis of the prion protein gene in thalamic dementia

Thalamic degenerations or dementias are poorly understood conditions. The familial forms are (1) selective thalamic degenerations and (2) thalamic degenerations associated with multiple system atrophy. Selective thalamic degenerations share clinical and pathologic features with fatal familial insomnia, an autosomal dominant disease linked to a mutation at codon 178 of the prion protein (PrP) gene that causes the substitution of asparagine for aspartic acid (178Asn mutation). We amplified the carboxyl terminal coding region of the PrP gene from subjects with selective thalamic dementia or thalamic dementia associated with multiple system atrophy. Three of the four kindreds with selective thalamic dementia and none of the three kindreds with thalamic dementia associated with multiple system atrophy had the PrP 178Asn mutation. Thus, analysis of the PrP gene may be useful in diagnosing the subtypes of thalamic dementia. Moreover, since selective thalamic dementia with the PrP 178Asn mutation and fatal familial insomnia share clinical and histopathologic features, we propose that they are the same disease.