Functional impairment is a core symptom of Alzheimer's disease. The most accurate indicator of functional impairment is the decline in performance of Activities of Daily Living (ADL). Several scales have been used to measure ADL in geriatric and Alzheimer's disease (AD) populations including the Disability Assessment for Dementia (DAD). The key to making a correct differential diagnosis between benign cognitive impairment and dementia is the detection of a decline in functioning. The instrumental ADL (IADL) relevant items of the DAD could provide crucial guidance in the diagnosis of early stage AD for primary care physicians. It is anticipated that the role of primary care physicians, already essential for the management of the AD patient, will expand to include the diagnosis of earlier cases and the prescription of cholinergic drugs as treatment. ADL assessment tools such as the DAD may help their tasks.

Staging methodologies are an essential tool in the assessment of disease severity in progressive dementing illness. Several different instruments have been developed for this purpose. One of the most widely used methodologies is the Global Deterioration Scale/Functional Assessment Staging (GDS/FAST) system. This system has been studied extensively and proven to be reliable and valid for staging dementia in Alzheimer's disease (AD) in diverse settings. One of the major advantages of this system is that it spans, demarcates, and describes the entire course of normal aging and progressive AD until the final substages of the disease process. Other advantages include: (a) greatly enhanced ability to track the longitudinal course of AD, (b) improved clinicopathologic observations of AD interrelationships, and (c) enhanced diagnostic, differential diagnostic, and prognostic information. This article presents a brief overview of the GDS/FAST staging system.

Global staging measures for dementia of the Alzheimer type (DAT) assess the influence of cognitive loss on the ability to conduct everyday activities and represent the “ultimate test” of efficacy for antidementia drug trials. They provide information about clinically meaningful function and behavior and are less affected by the “floor” and “ceiling” effects commonly associated with psychometric test. The Washington University Clinical Dementia Rating (CDR) is a global scale developed to clinically denote the presence of DAT and stage its severity. The clinical protocol incorporates semistructured interviews with the patient and informant to obtain information necessary to rate the subject's cognitive performance in six domains: memory, orientation, judgment and problem solving, community affairs, home and hobbies, and personal care. The CDR has been standardized for multicenter use, including the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) and the Alzheimer's Disease Cooperative Study, and interrater reliability has been established. Criterion validity for both the global CDR and scores on individual domains has been demonstrated, and the CDR also has been validated neuropathologically, particularly for the presence or absence of dementia. Standardized training protocols are available. Although not well suited as a brief screening tool for population surveys of dementia because the protocol depends on sufficient time to conduct interviews, the CDR has become widely accepted in the clinical setting as a reliable and valid global assessment measure for DAT.

Whitehouse: In the USA, the Agency for Healthcare Policy and Research has recently issued guidelines for early recognition and assessment of dementia, which I think this group should aim to incorporate in its deliberations. Interestingly, to assess patient function, they selected an instrument from the literature called the FAQ, which as far as I am aware, is not widely known by people in the field. Would anyone like to comment on this test? These guidelines will influence GPs, because they will be made aware of the recommendations by government information leaflets.

Our topic was functional and global evaluations. We discussed the scales per se versus the concept of evaluation. In terms of usefulness for the primary care physician, we concluded that the concept of evaluating functional and global impairment was important, but due to time constraints on general practitioners (GPs), the use of ratings scales was impractical. However, we believed that for those of us with research interests, the rating scales and their psychometric properties are crucial.

There is compelling evidence for the early involvement of the hippocampal formation in the natural history of Alzheimer's disease (AD). The evidence comes from recent neuropathology, neuropsychology, and neuroimaging studies. AD-type histopathologic changes limited to the hippocampus have been described and may be seen in normal aging subjects. The sites of maximal neuronal loss in the hippocampal formation are in the CA1, subiculum, and entorhinal cortex. Minimally cognitively impaired (MCI) individuals (defined by ratings of functional capacity and psychiatric symptomatology) exhibit a neuropsychological profile that is distinct from that of the unimpaired elderly. Pathologic evidence suggests that most of these cases already have AD brain changes accentuated in the hippocampal region, and our own longitudinal studies reveal that 70% of this group develop dementia within a 4-year period. We have developed a negative-angle axial view designed to cut parallel to the anterior-posterior plane of the hippocampus. Using this modified axial plane of section in conjunction with computed tomography (CT) and magnetic resonance imaging (MRI), we estimated the prevalence of hippocampal atrophy in normal aging and across severity levels of cognitively impaired elderly patients. Longitudinal study shows that hippocompal atrophy is a sensitive and specific predictor of future AD for patients with MCI. MRI volume study of AD patients, controls, and MCI patients shows specific hippocampal volume loss in MCI. We conclude that the atrophic changes associated with early AD can be visualized using qualitative techniques and are readily quantifiable with volumetry. This article is not intended to be comprehensive, but to provide an overview of some of the structural neuroimaging data from our laboratory.

In a prospective study of more than 200 cases of dementia and 119 controls, annual technetium-99m–hexamethyl-propylene amineoxime (99m Tc-HMPAO) single-photon emission computed tomography (SPECT) and annual medial temporal lobe (MTL) oriented X-ray computed tomography (CT) have been used to evaluate the diagnostic potential of functional and structural neuroimaging in the differential diagnosis of dementia. Some subjects have had up to 7 annual evaluations. So far, of 151 who have died, 143 (95%) have come to necropsy. Histology is known for 118, of whom 80 had Alzheimer's disease (AD), 24 had other “non-AD” dementias, and 14 controls with no cognitive deficit in life also had no significant central nervous system pathology. To compare the findings in the dementias with the profile of stuctural and functional imaging in the cognitively normal elderly, scan data from 105 living, elderly controls without cognitive deficit have also been included in the analysis. All clinical diagnoses were according to National Institute of Neurological and Communicable Disease and Stroke—Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) and the Diagnostic and Statistical Manual of Mental Disorders (3rd ed., rev.; DSM-III-R) criteria, and all histopathological diagnoses according to the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) criteria. Early data from this cohort have suggested that the combination of both MTL atrophy seen on CT with parietotemporal hypoperfusion on SPECT may predict the pathology of AD. The diagnostic sensitivity, specificity, accuracy, and positive and negative predictive values of the NINCDS-ADRDA and DSM-III-R criteria could be assessed in this cohort against the gold standard of histopathology. The diagnostic potential of CT evidence of MTL atrophy alone, SPECT evidence of parietotemporal hypoperfusion alone, and the combination of both of these scan changes in the same individual could then be compared against the diagnostic accuracy of clinical operational criteria in the pathologically confirmed cases. Furthermore, all of these modalities could be compared with the diagnostic accuracy of apolipoprotein E4 (Apo E4) genotyping to predict AD in the histopathologically confirmed cohort. In this population, NINCDS “probable-AD” was 100% specific, 49% sensitive, and 66% accurate; “possible-AD” was only 61% specific, but 93% sensitive and 77% accurate; and the combination of both “probable-AD” and “possible-AD was 61% specific, 96% sensitive, and 85% accurate. DSM-III-R criteria were 51% sensitive, 97% specific, and 66% accurate. In the same cases and including the 105 living, elderly controls, the diagnostic accuracy of the Oxford Project to Investigate Memory and Aging (OPTIMA) scanning criteria showed CT alone to be 85% sensitive, 78% specific, and 80% accurate; SPECT alone had 89% sensitivity, 80% specificity, and 83% accuracy; and the combination of the two was 80% sensitive, 93% specific, and 88% accurate. The Apo E4 genotype was 74% sensitive but yielded 40% false positives in the histologically confirmed series. The diagnostic accuracy afforded by this method of CT and SPECT used alone is better than that of any established clinical criteria and reveals that the combination of MTL atrophy and parietotemporal hypoperfusion is common in AD, much less common in other dementias, and rare in normal controls. In the NINCDS-ADRDA criteria “possible-AD” cases, the combination of CT and SPECT findings alone were better in all diagnostic indices than the presence of Apo E4 alone in predicting AD. The frequent occurrence of MTL atrophy in AD and also in other “non-AD” dementias later in the course of the disease suggests the concept of medial temporal lobe dementia. This could explain some of the overlap of clinical profiles in the dementias, particularly as the dementia progresses, making clinical differential diagnosis difficult. In this context, the use of SPECT can significantly enhance specificity.

High-resolution single-photon emission computed tomography (SPECT) with brain-retained technetium-99m (99mTc)–labeled tracers may be used for 3-dimensional measurements of regional cerebral blood flow (rCBF). This article summarizes important findings in SPECT studies of Alzheimer's disease (AD). There are three distinct potential applications of SPECT in diagnosing AD: (a) as a diagnostic adjunct in patients with mild cognitive or behavioral symptoms, suggesting a possible dementia disorder; (b) as a diagnostic adjunct for demented patients in whom the history, physical examination, and laboratory studies are in agreement with a diagnosis of probable AD; and (c) for determining the relative contributions of degenerative and vascular pathology to the clinical picture in demented patients with mixed disease. A clinical diagnosis of probable AD is associated with focal perfusion deficits as measured by SPECT. Characteristically, hypoperfusion is observed in the frontal and temporoparietal association areas, whereas other brain regions are relatively spared. The changes are present in the early phases of AD. The topography of rCBF deficits displays a marked heterogeneity among patients and correlates with cognitive profiles. In patients with mild cognitive complaints, the presence of focal hypoperfusion on SPECT may increase the accuracy of the diagnosis by confirming the presence of brain disease. In patients with probable AD, the presence of temporoparietal rCBF deficits on SPECT increases the accuracy of the clinical diagnosis, in particular when associated with medial temporal lobe atrophy on cranial X-ray computed tomography (CT). The role of SPECT in diagnosing patients with mixed disease remains to be clarified.

In vivo functional brain imaging provides an opportunity to quantify and localize functional deficits associated with Alzheimer's disease (AD), in relation to dementia severity and heterogeneous cognitive profiles. Such imaging also provides a basis for distinguishing AD from other causes of dementia and for making an early diagnosis of disease. One imaging modality that can elucidate AD is positron emission tomography (PET), which is used to measure regional cerebral metabolic rates for glucose (rCMRglc) and regional cerebral blood flow (rCBF). Resting-state measurements with PET, when related to cognitive profiles in longitudinal studies, indicate that specific cognitive defects are preceded and predicted by reductions in rCMRglc in regions subserving the cognitive functions tested. Metabolic reductions and right/left metabolic asymmetries can be used to convert a “possible” to a “probable” diagnosis of AD by the National Institute of Neurological and Communicative Disorders and Stroke–Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) criteria. Furthermore, discriminant analyses of PET metabolic patterns can identify patients at risk for AD with mild memory deficits as having probable AD. In the future, stimulation PET studies should augment the power of this discriminant analysis.

Electroencephalography is the only diagnostic instrument directly reflecting cortical neuronal functioning, and it remains an important clinical tool in the diagnosis and differential diagnosis of Alzheimer's disease (AD). Although a normal EEG is found in many patients with mild AD, a pathological EEG is an important finding, because such a result is not in line with differential diagnoses such as depression or pseudodementia within a dissociative disorder. The vast majority of patients with moderate to servere AD have a pathological EEG. A normal EEG in this patient group is more in line with subcortical dementia or frontal lobe degeneration than with AD. Compared to SPECT or routine structural brain imaging (cCT, MRT), EEG has a comparable diagnosis sensitivity and a higher specificity. For monitoring changes of brain function by serial recordings (e.g., during therapy with antidementia drugs), EEG is the best available method.

Roses: I reviewed Professor Smith's and Dr. Jobst's data with them at Oxford, and we are really not concluding anything very different. The tests of state used in their study, in this case the computed tomographic (CT) scan, work on essentially all patients with Alzheimer's disease (AD), no matter what their ApoE genotype. The positive predictor value of an E4 in the 60% or 75% of patients with AD who have a positive E4 is 97%, but for those 35% or so who are negative, the test has no value at all. So, in comparing its diagnostic usefulness, there will always be a proportion of patients for whom the test has no value.

Before I start reviewing this workshop, I would just like to draw your attention to Screening for Cognitive Impairment in General Practice—Towards a Consensus. This is a document that was prepared as a result of an Alzheimer's Disease International (ADI) workshop in Buenos Aires in 1995. ADI is now expanding its Medical and Research Board and would like to invite experts from the International Psychogeriatric Association to be on the advisory panel. The collective role of this ADI advisory panel will be to offer expert advice on all aspects of Alzheimer's disease (AD) management to family carers of individuals with this condition. I hope you will be able to participate in this important initiative.

Currently used criteria for neuropathological diagnosis of Alzheimer's disease (AD) allow only the distinction of fully developed AD or ill-defined cases with less severe pathologic alterations. There is a need for a staging procedure that is able to supplement the currently used criteria, to allow for sufficient differentiation between the initial and intermediate stages of the illness, and to provide a characterization of the degree of involvement in the brain tissue of “nondemented, age-related controls.” The destructive process underlying AD is characterized by a typical distribution pattern of brain changes that is specific with respect to area, lamina, and even cell type. The most conspicuous change is the progressive deposition of abnormal proteins, both between and within the nerve cells. Conventional staining methods to identify these deposits lack sensitivity and specificity. Silver methods (specifically the Gallyas silver-iodide technique for neurofibrillary changes and the Campbell-Switzer silver-pyridin technique for brain amyloid) are by far the best suited to diagnostic work. They are inexpensive, simple to use, and far more reliable. This article describes the patterns of staining typically found with each of these techniques in the brains of patients with progressively severe AD and describes how the specific changes observed can be used as a staging system for diagnostic purposes.

The Consortium to Establish a Registry for Alzheimer's Disease (CERAD), a multicenter longitudinal study, has worked to establish standardized instruments for the evaluation of individuals clinically diagnosed as having Alzheimer's disease (AD). Since its formation in 1986, clinical neuropsychological, neuroimaging, and neuropathology assessment batteries have been developed. The neuropathology protocol not only establishes levels of certainty for the diagnosis of AD, but also facilitates correlations with clinical, genetic, and other data. We find a high rate of diagnostic accuracy: the clinical diagnosis of AD was confirmed in 176 of 201 (87.6%) CERAD dementia subjects. Coexistent vascular lesions, usually infarcts, were found in 32% of these confirmed AD cases, and 23% had coexisting Parkinson's disease (PD) changes (nigral degeneration and Lewy bodies at any site). In the remaining 25 cases (12.4%), neuropathologists attributed the primary cause of dementia to other conditions. In studies comparing neuropathology protocols for AD, several groups have found that the CERAD diagnosis most closely correlates with measures of dementia severity, such as the Mini-Mental State Examination (MMSE). Others have adopted the CERAD neuropathology protocol for multicenter brain banking, citing its relative simplicity and adaptability among laboratories, the experience of many AD centers with the protocol, and its application to other dementing conditions. The CERAD data set and batteries are increasingly used for a wide array of clinical, neuropathological, and genetic studies.

Reisberg: I would like to summarize very briefly. In the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) study, one third of patients with Alzheimer's disease (AD) had concomitant cerebral vascular disease. This finding supports the original work of Tomlinson and Blessed, who indicated a similar percentage of patients with AD also had mixed cerebral vascular disease upon neuropathologic examination.

Within our workshop we discussed neuropathological assessments in different cultures and countries, evaluation of dementia type, and availability of autopsy. We agreed that evaluation of dementia cases should not be limited to the use of diagnostic criteria; but neuropathologic assessment should be utilized where appropriate. We agreed that it is vital to communicate this concept to general practitioners (GPs) and physicians working in nursing homes, where there is often a high proportion of dementia patients. When neuropathologic assessments are conducted correctly, they provide both quantitative and qualitative information about cell and tissue damage. The assessment should preferably be performed by a neuropathologist in order that a diagnosis plus an estimation of disease severity and extent can be made.

Positive predictive value (PPV) estimates how often a particular test predicts the eventual diagnosis, and it is the basis of any test that attempts to establish a diagnosis. Calculating the PPV depends directly on the entrance criteria for considering the diagnosis and the exit criteria of the generally accepted “gold standard” for establishing the ultimate diagnosis. For a relatively common disease such as AD, the practical usefulness of a diagnostic test also relates to the stage of the disease at which the test can be applied. An accurate and predictive test only has practical value when it can be used early in the course of the disease. Apolipoprotein E (Apo E) is the first genetic locus identified as a susceptibility polymorphism for a common complex disease using positional or candidate cloning strategies. There are three common alleles (ε2 to ε4) and six possible genotypes; about 30% of the population carries an ε4 allele, each additional copy of which is associated with an increased risk of AD and earlier age of onset distribution. In patients with cognitive impairment of the Alzheimer type, who have been diagnosed with possible or probable AD, the presence of an Apo E-ε4 allele is likely in more than 50% of patients for whom the PPV is greater than 97%. Apo E genotyping is the only diagnostic adjunct that has been subjected to rigorous measurements of specificity, sensitivity, PPV, and NPV. In the past, testing of dementia patients was directed at “ruling out” other treatable causes. Results from the initial studies of the PPV of Apo E genotyping for AD showed that the PPV of Apo E genotyping was greater than 97%. The paradigm for AD diagnosis is changing. Apo E genotyping can provide useful diagnostic information and that accuracy will improve as other susceptibility genetic risk factors are identified.

Alzheimer's disease (AD) is histopathologically characterized by the presence of numerous neurons with neurofibrillary tangles of paired helical filaments (PHF) in the neocortex, particularly the hippocampus. The major protein subunit of PHF, which also accumulate as neuropil threads and dystrophic neurites of the neuritic (senile) plaques, is the microtubule-associated protein τ. τ in AD brain is abnormally hyperphosphorylated. In addition to hyperphosphorylation, some of the AD τ is also ubiquitinated. The level of τ in AD brain is elevated severalfold, and this increase is in the form of the abnormally phospholylated τ. The levels of conjugated ubiquitin are also increased severalfold in AD brain. The cerbrospinal fluid (CSF) levels of both τ and ubiquitin are elevated in AD. However, some of the normal elderly and non-AD neurological control cases also show elevated levels of these two proteins in the CSF. At present, it is not clear whether the overlap in CSF τ or ubiquitin values between AD and the control groups is due to some unknown heterogeneity of AD, inclusion of presymptomatic AD cases in the control group, or lack of specificity of the CSF elevation of these markers to AD. Thus, until the results of prospective studies on many patients with AD and normal controls become available, the CSF τ and ubiquitin levels can be used only as additional tools in the psychometric and clinical diagnosis of AD.

This article describes the results of studies conducted to determine the usefulness of reflex changes as markers of disease severity in Alzheimer's disease (AD). Standardized and quantified muscle stretch reflexes, cutaneous, reflexes, and developmental (primitive) reflexes were studied in normal older adults, in individuals with mild memory impairment, and in patients with AD, in all clinical severity stages as assessed with the Global Deterioration Scale (GDS), the Mini-Mental State Examination (MMSE), and the Functional Assessment Staging (FAST) procedure. Changes in frequency and intensity of these individual reflex variables, as well as of variables consisting of combinations of these individual reflexes, appeared to be sensitive indicators of the progression of AD. These neurological reflex variables showed high Pearson correlations with the GDS (.72), the MMSE (.74), and the FAST (.80). Standardized quantified neurological reflex measures are useful as noncognitive, education-independent, and culture-independent markers of the course of AD.

To determine the association between cognitive dysfunction and motor behavior in older adults, 41 cognitively normal elderly (NL), 25 nondemented patients exhibiting mild cognitive impairment (MI) and at risk for future decline to dementia, and 25 patients with mild (early) Alzheimer's disease (AD) were examined using a wide array of motor/psychomotor and cognitive assessments. The three groups were recruited from an aging and dementia research center and were composed of well-characterized physically healthy volunteers, with similar ages and gender distributions. The outcome measures included 16 motor/psychomotor tests categorized a priori into gross, fine, and complex, as well as eight cognitive tests of memory and language. Relative to the NL group, MI individuals performed poorly on cognitive, fine, and complex motor measures but not on gross motor tests; AD patients performed worse on cognitive and all motor domains. Differences in complex motor function persisted after adjustment for performance on cognitive and on less complex motor tests. Classification analyses showed similar accuracies in discriminating NL from MI and NL from AD cases for both complex motor (79% and 92% accuracy, respectively) and cognitive tests (80% and 93% accuracy, respectively). Less complex motor tests produced poorer accuracies. Among nondemented subjects, education correlated with several cognitive scores but no motor scores. These results indicate that motor impairment is an important aspect of cognitive decline in older adults. Motor/psychomotor assessments were found to be comparably sensitive to traditional tests of cognitive function in identifying persons affected by the earliest stages of AD pathology and may improve identification of at-risk nondemented elderly, especially among diversely educated individuals.