Neuropathology of cognitively normal elderly

Despite general agreement about the boundaries of Alzheimer disease (AD), establishing a maximum limit for Alzheimer-type pathology in cognitively intact individuals might aid in defining more precisely the point at which Alzheimer pathology becomes clinically relevant. In this study, we examined the neuropathological changes in the brains of 39 longitudinally followed. cognitively normal elderly individuals (24 women, 15 men; age range 74-95, median 85 years). Neuropathological changes of the Alzheimer type were quantified by determining neurofibrillary tangle (NFT) staging by the method of Braak and Braak and by quantification of the abundance of diffuse, cored, and neuritic plaque burden using the scheme developed by the Consortium to Establish a Registry for Alzheimer Disease (CERAD). Vascular, Lewy body, and argyrophilic grain pathology were also assessed. We found 34 subjects (87%) with a Braak stage <IV; 32 subjects (82%) with less than moderate numbers of cored plaques and 37 subjects (95%) with less than moderate numbers of tau-positive neuritic plaques. Many subjects had moderate or frequent diffuse plaques (n = 19, 49%). By the National Institute on Aging-Reagan Institute (NIA-RI) criteria, none of our cases met criteria for high "likelihood" of AD. Four met NIA-RI criteria for intermediate "likelihood." Seven cases met CERAD criteria for possible AD. Nineteen met Khachaturian criteria for AD. Only 1 subject had neocortical Lewy bodies. Small, old infarcts were common, but no subjects had more than 2 of these and none had a single large infarction. Thus, the majority of individuals who are cognitively normal near the time of their death have minimal amounts of tau-positive neuritic pathology (Braak stage <IV and neuritic plaques <6 per x100 field in the most affected neocortical region). The few subjects with more severe AD pathology can be expected based on incidence rates of AD in the very elderly.

Synucleinopathy pathology and REM sleep behavior disorder plus dementia or parkinsonism

OBJECTIVE

To determine if synucleinopathy pathology is related to REM sleep behavior disorder (RBD) plus dementia or parkinsonism.

METHODS

The clinical and neuropathologic findings were analyzed on all autopsied cases evaluated at Mayo Clinic Rochester from January 1990 to April 2002 who were diagnosed with RBD and a neurodegenerative disorder. Ubiquitin and/or alpha-synuclein immunocytochemistry was used in all cases. The clinical and neuropathologic diagnoses were based on published criteria.

RESULTS

Fifteen cases were identified (14 men). All had clear histories of dream enactment behavior, and 10 had RBD confirmed by polysomnography. RBD preceded dementia or parkinsonism in 10 (66.7%) patients by a median of 10 (range 2 to 29) years. The clinical diagnoses included dementia with Lewy bodies (DLB) (n = 6); multiple-system atrophy (MSA) (n = 2); combined DLB, AD, and vascular dementia (n = 1); dementia (n = 1); dementia with parkinsonism (n = 1); PD (n = 1); PD with dementia (n = 1); dementia/parkinsonism/motor neuron disease (n = 1); and AD/Binswanger's disease (n = 1). The neuropathologic diagnoses were Lewy body disease (LBD) in 12 (neocortical in 11 and limbic in 1) and MSA in 3. Three also had argyrophilic grain pathology. In the LBD cases, concomitant AD pathology was present in six (one also with Binswanger's pathology, and one also with multiple subcortical infarcts).

CONCLUSION

In the setting of degenerative dementia or parkinsonism, RBD often reflects an underlying synucleinopathy.

Prevalence, costs, and treatment of Alzheimer's disease and related dementia: a managed care perspective

BACKGROUND

The number of patients with Alzheimer's disease (AD) and related dementia treated in managed care organizations (MCOs) is increasing, and this trend is expected to continue. Therefore, it is critical that MCOs develop disease management strategies for this population.

OBJECTIVE

To review the literature on the prevalence, costs, and treatment of AD and related dementia.

STUDY DESIGN

Review of published articles from MEDLINE and peer-reviewed journals.

RESULTS

Prevalence of AD and related dementia is approximately 5.7% among those aged 65 and older. Prevalence data from claims-based studies of AD in managed care are lower, ranging from 0.55% to 0.83%. Costs for formal care average $27,672 per patient annually, with long-term care being the most costly component. Annual costs for informal care are estimated to be $10,400 to $34,517 per patient. Additional costs associated with AD include lost wages and productivity of patients and caregivers and costs associated with increased morbidity of caregivers. Donepezil treatment is well tolerated and has been extensively tested and evaluated in clinical settings. Early diagnosis and treatment of AD with donepezil has been shown to slow cognitive decline in AD. Although study findings regarding the cost offsets of donepezil-treated patients to date are mixed, there is a growing body of evidence to support the inclusion of this and other therapies into an MCO's AD treatment armamentarium.

CONCLUSIONS

It is unlikely that MCOs will escape the increased prevalence and costs associated with AD. Opportunities exist through patient management programs targeted toward early diagnosis, effective use of medications, control of comorbidities, and patient and family support to partially offset these costs while providing quality patient care.

Practice parameter: diagnosis of dementia (an evidence-based review). Report of the Quality Standards Subcommittee of the American Academy of Neurology

OBJECTIVE

To update the 1994 practice parameter for the diagnosis of dementia in the elderly.

BACKGROUND

The AAN previously published a practice parameter on dementia in 1994. New research and clinical developments warrant an update of some aspects of diagnosis.

METHODS

Studies published in English from 1985 through 1999 were identified that addressed four questions: 1) Are the current criteria for the diagnosis of dementia reliable? 2) Are the current diagnostic criteria able to establish a diagnosis for the prevalent dementias in the elderly? 3) Do laboratory tests improve the accuracy of the clinical diagnosis of dementing illness? 4) What comorbidities should be evaluated in elderly patients undergoing an initial assessment for dementia?

RECOMMENDATIONS

Based on evidence in the literature, the following recommendations are made. 1) The DSM-III-R definition of dementia is reliable and should be used (Guideline). 2) The National Institute of Neurologic, Communicative Disorders and Stroke--AD and Related Disorders Association (NINCDS-ADRDA) or the Diagnostic and Statistical Manual, 3rd edition, revised (DSM-IIIR) diagnostic criteria for AD and clinical criteria for Creutzfeldt--Jakob disease (CJD) have sufficient reliability and validity and should be used (Guideline). Diagnostic criteria for vascular dementia, dementia with Lewy bodies, and frontotemporal dementia may be of use in clinical practice (Option) but have imperfect reliability and validity. 3) Structural neuroimaging with either a noncontrast CT or MR scan in the initial evaluation of patients with dementia is appropriate. Because of insufficient data on validity, no other imaging procedure is recommended (Guideline). There are currently no genetic markers recommended for routine diagnostic purposes (Guideline). The CSF 14-3-3 protein is useful for confirming or rejecting the diagnosis of CJD (Guideline). 4) Screening for depression, B(12) deficiency, and hypothyroidism should be performed (Guideline). Screening for syphilis in patients with dementia is not justified unless clinical suspicion for neurosyphilis is present (Guideline).

CONCLUSIONS

Diagnostic criteria for dementia have improved since the 1994 practice parameter. Further research is needed to improve clinical definitions of dementia and its subtypes, as well as to determine the utility of various instruments of neuroimaging, biomarkers, and genetic testing in increasing diagnostic accuracy.

An overview of common non-alzheimer dementias

Approximately 20% to 40% of dementia is caused by diseases other than Alzheimer's disease. This article reviews the major categories of non-Alzheimer dementia, including dementia associated with cerebrovascular disease, dementia associated with extrapyramidal features, and the frontotemporal dementias. Dementia associated with cerebrovascular disease is a heterogeneous condition the importance of which is often misunderstood. Dementia with Lewy bodies, the most common of the dementias associated with extrapyramidal disease, is becoming better recognized for its unique management issues. At least some of the frontotemporal dementias, which in this article encompass the progressive aphasias, have mutations in the tau gene that account for some of the phenotypic variations.

Global change assessments in anti-Alzheimer clinical drug trials

The assessment of efficacy in clinical trials in Alzheimer's disease has been a controversial area. The US Food and Drug Administration has not accepted mental status assessment as a sole determinant of efficacy because of concerns about oversensitivity and lack of direct linkage to clinical importance. Global change instruments offer a number of advantages as primary outcome measures, chief among which is a wide range of responsiveness, a property well suited for trials of 1 to 2 years. Initial investigations with global change instruments have shown encouraging validity. Reliability has been only moderate, suggesting that the methodology needs further attention. A standardized format for interview and the acceptance of a set of anchor points that better define the ratings of change are two modifications that should improve reliability. Global change instruments, if properly explained to the patients, caregivers and primary physicians, will capture the concept of clinical importance.

Association of nonsteroidal anti-inflammatory drugs and aspirin with cognitive performance in middle-aged adults

OBJECTIVES

To assess the cross-sectional association of regular use of nonsteroidal anti-inflammatory drugs (NSAIDs) or aspirin with cognitive function in 13,153 individuals, aged 48-67 years, participating in the Atherosclerosis Risk in Communities (ARIC) Study.

METHODS

Regular use of NSAIDs or aspirin was analyzed in relation to the results of three cognitive tests, the Delayed Word Recall Test, the WAIS-R Digit Symbol Subtest, and the Word Fluency Test.

RESULTS

After adjustment for covariates previously found to be associated with cognition in this sample, we found a weak negative association between current use of aspirin and poor Word Recall [OR = 0.84 (95% confidence interval: 0.68-1.04)] and poor Word Fluency [OR = 0.85 (0.70-1.03)]. We found no association between current use of aspirin and Digit Symbol score, nor did we find current NSAID use to be significantly associated with any of the cognitive tests.

CONCLUSIONS

This study suggests a modest association, at best, between NSAIDs or aspirin and better cognitive function.

Correlates of cognitive function in middle-aged adults. Atherosclerosis Risk in Communities (ARIC) Study Investigators

The Atherosclerosis Risk in Communities Study administered cognitive function tests to more than 14,000 middle-aged adults in 1990-1992. The battery included the Delayed Word Recall test, the Digit Symbol Subtest of the Wechsler Adult Intelligence Scale-Revised, and the Controlled Oral Word Association (Word Fluency) test. Test performance was correlated positively with education level, negatively with age, was better in women than in men, and better in managers/professionals compared with other occupations. After controlling for these factors, race and community, the findings most consistent for both sexes were that Delayed Word Recall was negatively associated with depressive symptoms, diabetes, and fibrinogen level; the Digit Symbol Subtest was associated with marital status, negatively associated with depressive symptoms, smoking status, fibrinogen level, and carotid intima-media thickness, and positively associated with alcohol drinking and FEV1; and the Word Fluency test was positively associated with marital status, alcohol drinking, sports participation, and FEV1. Most of these cross-sectional results were in the predicted direction and have biologic plausibility, but mean differences between extreme categories were small (generally on the order of 0.1 to 0.2 of a standard deviation). Longitudinal study is warranted to evaluate whether small differences in middle-age lead to larger, clinically meaningful deficits with aging.

Development and standardization of a new telephonic cognitive screening test: the Minnesota Cognitive Acuity Screen (MCAS)

OBJECTIVE

The aim of this study was to determine the validity and reliability of a telephonically administered cognitive screening battery, consisting of nine brief tests (orientation, attention, delayed word recall, comprehension, repetition, naming, computation, judgment, and verbal fluency), to distinguish between patients with dementia and healthy control subjects.

BACKGROUND

Existing telephonic screening instruments do not take full advantage of strategies that might increase precision.

METHODS

A total of 228 elderly individuals received a telephone assessment of cognitive function (99 mildly to moderately demented nursing home residents with an established diagnosis of dementia residing in 1 of 12 nursing facilities, and 129 community-dwelling elderly individuals who were independently screened to verify normal cognitive function).

RESULTS

Nurses and psychologists experienced in telephonic test administration typically completed the screening with each subject in less than 20 minutes. At the 100% sensitivity level, the test battery had a specificity of 87%. The post hoc optimal cut-score of the discriminant analysis yielded a sensitivity of 97.5% and a specificity of 98.5%. The split-half reliability of the test battery was 0.91. The more powerfully predictive subtests were orientation, delayed word recall, verbal fluency, computation, and judgment.

CONCLUSIONS

This telephonic screening instrument appears to have promise to distinguish, with high precision, healthy elderly individuals from those individuals with cognitive impairment. The Minnesota Cognitive Acuity Screen (MCAS) should undergo further study in unselected elderly populations to better understand its value as a screening tool.

Dietary antioxidant intake and cognitive performance in middle-aged adults. The Atherosclerosis Risk in Communities (ARIC) Study investigators

OBJECTIVE

To assess the cross-sectional association of dietary and supplemental antioxidant (carotenoids, vitamins C and E) intake with cognitive function in 12 187 individuals, aged 48-67 years, participating in the Atherosclerosis Risk in Communities (ARIC) Study.

METHODS

Dietary intake of antioxidant vitamins, as assessed by a food frequency questionnaire, and use of supplements were analysed in relation to the results of three cognitive tests, the delayed word recall test, the Wechsler adult intelligence scale, revised (WAIS-R) digit symbol subtest and the word fluency test.

RESULTS

After adjustment for covariates previously found to be associated with cognition in this sample, we found no consistent associations between dietary antioxidant vitamin intake or supplement use and any of the cognitive tests.

CONCLUSIONS

This study suggests little, if any, association between antioxidant vitamin intake and better cognitive function in middle-aged adults.

Advances in methodology and current prospects for primary drug therapies for Alzheimer's disease

There has been gratifying progress in the development of drugs for Alzheimer's disease (AD). Even though the current generation of medications, the cholinesterase inhibitors (CEIs), has produced only modest benefits, our concept of an "effective" therapy has matured considerably over this time. A less visible but equally important advance has been a quantum leap in expertise in clinical trial methodology. This chapter reviews the methodological underpinnings of clinical trials in AD: patient selection issues, key design issues, and an overview of currently available agents and the prospects for drugs of the future.

Clinical trials in Alzheimer disease: debate on the use of placebo controls

During the past 10 years, there has been a rapidly growing number of pharmaceutical industry-sponsored drug trials for treatment of Alzheimer disease (AD) and other neurodegenerative diseases. As public awareness and concerns about AD have grown, so has interest in developing drug therapies for retarding symptom progression, delaying onset, and ultimately curing the disease. Ethical debate on the use of placebo control trials in AD research has come of age in the United States with the availability of treatments approved by the Food and Drug Administration. The experts and the public agree that more effective therapies are necessary, and new therapeutic options are being developed as rapidly as possible. The arguments on each side of the debate are provocative and important but do not provide unequivocal justification for either the abandonment or the maintenance of placebo-controlled trials in all AD research. Clinical trials differ with respect to scientific and practical goals, and these factors inherently affect the ethical priorities of each study. We present these contrasting points of view to delineate some of the issues rather than to make specific recommendations other than to urge that all clinical trials in AD should be designed with careful consideration of the ethical issues surrounding the use of placebo controls. As new and more effective treatments emerge, the ethical framework for placebo use in AD studies will require frequent re-examination. To make wise choices, patients, caregivers, physicians, and ethicists (among others) must have a voice in this continuing discussion.

Nursing home placement is related to dementia progression: experience from a clinical trial. Alzheimer's Disease Cooperative Study

OBJECTIVES

To examine the relationship between nursing home placement (NHP) and measures of change in other well-established clinical disease assessments in a longitudinal study of patients with probable AD.

BACKGROUND

NHP is a common, major milestone in the natural history of AD. NHP is a readily identified event that can be accurately dated. NHP can be used in survival analyses, which are an efficient means of determining efficacy in clinical trials. NHP usually occurs in the setting of severe AD, but in cross-sectional studies, the strength of the association with disease severity has been controversial.

DESIGN/METHODS

We used data from 341 AD patients who were enrolled in a recently published clinical trial of selegiline and tocopherol. At entry, all were rated as Clinical Dementia Rating (CDR) stage 2, were community-dwelling, and had an identified caregiver. Patients were followed at 3-month intervals for 2 years. We examined the relationship between four measures of dementia severity and a measure of behavioral dysfunction and NHP. The measures included changes in CDR status, changes in activities of daily living performance, changes from baseline to last measurement in dependence level, changes from baseline to last measurement on the Blessed Dementia Rating Scale (BDRS) score, and changes from baseline to last measurement on the total score and subscales of the Behavior Rating Scale for Dementia (BRSD). Statistical models were used to assess the strength of the associations.

RESULTS

At the end of the 2-year period, 33% of patients had been institutionalized. The NHP patients did not differ at baseline from the not-NHP patients in gender, age, caregiver status, duration of illness, CDR sum of boxes, BDRS, or dependence level. The NHP patients had a lower baseline Mini-Mental State Examination score and a slightly worse BRSD total score. Patients reaching CDR3 were eight times more likely to be institutionalized than those who remained at CDR2. The change scores on all four dementia severity measures were strongly associated with NHP; the change score on the BRSD and its subscales were not. On the other hand, adverse events that included a behavioral disturbance, especially agitation, were associated with NHP.

CONCLUSION

These data show that NHP closely reflects dementia progression in the context of a clinical trial. Coupled with the high face validity of NHP as a milestone of severe dementia, NHP is a valid primary outcome measure for AD clinical trials.

Current pharmacotherapies for Alzheimer's disease

This brief overview will describe some of the current anti-Alzheimer's disease (AD) agents. The relevance of the cholinergic deficit in AD is well-established. Cholinesterase inhibitor (CEI) drugs represent the only FDA-approved primary treatment options for AD as of April 1998. Modest efficacy for AD now has been shown in well-designed clinical trials for six separate CEI agents. Only two, tacrine and donepezil, are currently on the market in the United States, but several others, including rivastigmine (ENA-713), metrifonate, and physostigmine-CR could be available by the end of 1998. Three other treatment strategies are being pursued. Estrogen replacement therapy as a treatment for AD in postmenopausal women is under active investigation. Analogously, clinical studies provide evidence that individuals using anti-inflammatory agents have a lower probability of developing AD. The success of alpha-tocopherol and selegiline in a recently conducted 2-year, double-blinded, placebo-controlled trial supports the hypothesis that oxidative stress plays a role in AD.

Inhibition and habituation: preserved mechanisms of attentional selection in aging and Alzheimer's disease

Are inhibition and habituation, processes that contribute to selective attention, impaired by aging or Alzheimer's disease (AD)? Younger adults, older adults, and adults with AD read lists of letters presented either alone or paired with distractor letters. Slower reading times for lists containing distractors relative to lists without distractors indexed concurrent interference (distraction). Slower reading times for lists in which distractors subsequently became targets relative to lists in which distractors and targets were unrelated indexed negative priming (inhibition). Faster reading times when distractors were constant in identity or location rather than random indexed repeated distractor effects (habituation). Distraction increased with aging and AD, whereas inhibition and habituation showed no age- or AD-related decline, suggesting that inhibition and habituation still function to aid attentional selection in older adults and adults with AD.

Inhibition and habituation: preserved mechanisms of attentional selection in aging and Alzheimer's disease

Are inhibition and habituation, processes that contribute to selective attention, impaired by aging or Alzheimer's disease (AD)? Younger adults, older adults, and adults with AD read lists of letters presented either alone or paired with distractor letters. Slower reading times for lists containing distractors relative to lists without distractors indexed concurrent interference (distraction). Slower reading times for lists in which distractors subsequently became targets relative to lists in which distractors and targets were unrelated indexed negative priming (inhibition). Faster reading times when distractors were constant in identity or location rather than random indexed repeated distractor effects (habituation). Distraction increased with aging and AD, whereas inhibition and habituation showed no age- or AD-related decline, suggesting that inhibition and habituation still function to aid attentional selection in older adults and adults with AD.

The initial recognition and diagnosis of dementia

Dementia is characterized by a decline in cognition, behavioral disturbances, and interference with daily functioning and independence. Diagnosis is sometimes delayed as patients or family members often misattribute obvious manifestations of cognitive decline to normal aging rather than to the onset of a degenerative disease. Many physicians do not perform mental status examinations or do not use them effectively to detect early symptoms. Clinical markers are available to decrease the difficulty in distinguishing dementia from depression and confusional states such as delirium. Alzheimer's disease (AD) is the most common form of dementia; others include rapidly progressive dementias, dementias associated with strokes and Parkinson's disease, and frontotemporal dementias. Often, AD coexists with other forms of dementia. Sensitivity to early warning signs, interviews with family members, and mental status examinations are essential to early detection of AD, and will prove useful to primary-care physicians who care for older patients.

An update on primary drug therapies for Alzheimer disease

Propelled by remarkable advances in the understanding of the pathological characteristics of Alzheimer disease (AD), the prospects for the treatment of the clinical disorder have brightened considerably in the past decade. Primary treatment is aimed at the core elements of AD: memory and other cognitive loss at the symptomatic level and the pathological characteristics of molecular, cellular, and neural systems at the biological level. Behavioral features, such as depression, delusions, anxiety, disordered sleep, and agitation, are considered secondary manifestations of AD, although these features have a major impact on the quality of life, functional effectiveness, and caregiver burden. The focus of this review is on recent developments in the primary therapy for AD.

Physiology and function of platelets from patients with Alzheimer's disease

The discovery that intact Alzheimer amyloid precursor protein is present in platelet granules, has created a great interest in the biochemistry, physiology and function of platelets of patients with Alzheimer disease (AD). In this study we monitored various biochemical and physiological parameters, such as serotonin and adenine nucleotide levels, membrane fluidity, agonist-mediated release of arachidonic acid, thromboxane formation, calcium mobilization, as well as irreversible aggregation and secretion of granule contents. Platelets of patients with AD responded poorly when stirred with weak or potent agonists on a platelet aggregometer. Although capable of agonist-mediated calcium mobilization and synthesis of thromboxanes, the aggregation response of platelets of patients with AD to thrombin and archidonate was considerably compromised. In view of the normal biochemistry and signal transduction capabilities, the compromised response of these cells to potent agonists like thrombin suggested an extrinsic defect. The present study has shown that a plasmatic factor is at least in part responsible for the functional abnormalities of AD platelets.

The Clinician Interview-Based Impression (CIBI): a clinician's global change rating scale in Alzheimer's disease

Global assessments are Food and Drug Administration-required primary outcome measures in trials of putative antidementia drugs. Global ratings are intended to provide an index of clinical importance of change that cannot be obtained from quantitative assessment measures such as mental status examinations. We examined the performance of a global assessment of change instrument, the Clinician Interview-Based Impression (CIBI), in the placebo group of a 30-week, randomized, double-blind clinical trial of tacrine in patients with Alzheimer's disease. Initially there were 184 placebo patients, of whom 125 completed the 30-week study. Descriptive statistics, correlations with changes on other assessment instruments, and test-retest reliability were determined for the CIBI. At week 30, clinicians rated more than 40% of patients on the CIBI as unchanged. The CIBI ratings were weakly but significantly correlated, in the expected direction, with change scores on the quantitative cognitive assessments. The CIBI was modestly reliable on test-retest at weeks 22 and 24 but less reliable compared with other quantitative outcome measures. Modifications of the CIBI that might improve its reliability and acceptance include (1) no restrictions on the form of the bedside mental status assessment, (2) inclusion of caregiver input, and (3) better definition of ratings on the global scale. Global instruments, if properly constructed, can provide an index of clinically important change for the assessment of dementia patients.