Episodic memory assessment: effects of sex and age on performance and response time during a continuous recognition task

Introduction

Continuous recognition tasks (CRTs) assess episodic memory (EM), the central functional disturbance in Alzheimer's disease and several related disorders. The online MemTrax computerized CRT provides a platform for screening and assessment that is engaging and can be repeated frequently. MemTrax presents complex visual stimuli, which require complex involvement of the lateral and medial temporal lobes and can be completed in less than 2 min. Results include number of correct recognitions (HITs), recognition failures (MISSes = 1-HITs), correct rejections (CRs), false alarms (FAs = 1-CRs), total correct (TC = HITs + CRs), and response times (RTs) for each HIT and FA. Prior analyses of MemTrax CRT data show no effects of sex but an effect of age on performance. The number of HITs corresponds to faster RT-HITs more closely than TC, and CRs do not relate to RT-HITs. RT-HITs show a typical skewed distribution, and cumulative RT-HITs fit a negative survival curve (RevEx). Thus, this study aimed to define precisely the effects of sex and age on HITS, CRs, RT-HITs, and the dynamics of RTs in an engaged population.

Methods

MemTrax CRT online data on 18,255 individuals was analyzed for sex, age, and distributions of HITs, CRs, MISSes, FAs, TC, and relationships to both RT-HITs and RT-FAs.

Results

HITs corresponded more closely to RT-HITs than did TC because CRs did not relate to RT-HITs. RT-FAs had a broader distribution than RT-HITs and were faster than RT-HITs in about half of the sample, slower in the other half. Performance metrics for men and women were the same. HITs declined with age as RT-HITs increased. CRs also decreased with age and RT-FAs increased, but with no correlation. The group over aged 50 years had RT-HITs distributions slower than under 50 years. For both age ranges, the RevEx model explained more than 99% of the variance in RT-HITs.

Discussion

The dichotomy of HITs and CRs suggests opposing cognitive strategies: (1) less certainty about recognitions, in association with slower RT-HITs and lower HIT percentages suggests recognition difficulty, leading to more MISSes, and (2) decreased CRs (more FAs) but faster RTs to HITs and FAs, suggesting overly quick decisions leading to errors. MemTrax CRT performance provides an indication of EM (HITs and RT-HITs may relate to function of the temporal lobe), executive function (FAs may relate to function of the frontal lobe), processing speed (RTs), cognitive ability, and age-related changes. This CRT provides potential clinical screening utility for early Alzheimer's disease and other conditions affecting EM, other cognitive functions, and more accurate impairment assessment to track changes over time.

Toward digitally screening and profiling AD: A GAMLSS approach of MemTrax in China

PURPOSES

To establish a normative range of MemTrax (MTx) metrics in the Chinese population.

METHODS

The correct response percentage (MTx-%C) and mean response time (MTx-RT) were obtained and the composite scores (MTx-Cp) calculated. Generalized additive models for location, shape and scale (GAMLSS) were applied to create percentile curves and evaluate goodness of fit, and the speed-accuracy trade-off was investigated.

RESULTS

26,633 subjects, including 13,771 (51.71%) men participated in this study. Age- and education-specific percentiles of the metrics were generated. Q tests and worm plots indicated adequate fit for models of MTx-RT and MTx-Cp. Models of MTx-%C for the low and intermediate education fit acceptably, but not well enough for a high level of education. A significant speed-accuracy trade-off was observed for MTx-%C from 72 to 94.

CONCLUSIONS

GAMLSS is a reliable method to generate smoothed age- and education-specific percentile curves of MTx metrics, which may be adopted for mass screening and follow-ups addressing Alzheimer's disease or other cognitive diseases.

HIGHLIGHTS

GAMLSS was applied to establish nonlinear percentile curves of cognitive decline. Subjects with a high level of education demonstrate a later onset and slower decline of cognition. Speed-accuracy trade-off effects were observed in a subgroup with moderate accuracy. MemTrax can be used as a mass-screen instrument for active cognition health management advice.

Posttraumatic Stress Disorder-Associated Cognitive Deficits on the Repeatable Battery for the Assessment of Neuropsychological Status in a Veteran Population

Background

Posttraumatic stress disorder (PTSD) is a frequent problem of veterans receiving care and is often associated with cognitive deficits. The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) is a well-validated cognitive screening measure often used in the US Department of Veterans Affairs (VA), particularly in neurorehabilitation settings. However, the influence of PTSD on RBANS performance is unclear, particularly within a heterogeneous VA outpatient population in which PTSD and traumatic brain injury (TBI) may not be the primary focus of care.

Methods

Participants included 153 veterans with complex deployment-related health problems, including a diagnosis of PTSD (n = 98) and a history of TBI (n = 92). All veterans completed a targeted cognitive battery that included the Wechsler Test of Adult Reading, the Wechsler Adults Intelligence Scale, measure assessing processing speed, attention, and cognitive flexibility, and RBANS.

Results

A diagnosis of PTSD was associated with worse performance on the Story Recall subtest of the RBANS, but not on any other cognitive measures. A diagnosis of mild TBI, or co-occurring PTSD and TBI did not predict cognitive performance on any measures.

Conclusions

The RBANS best captured cognitive deficits associated with PTSD compared with a history of mild TBI or co-occurring mild TBI and PTSD. These findings may provide insight into the interpretation and attribution of cognitive deficits in the veteran population.

Treatment of Alzheimer's Disease: Trazodone, Sleep, Serotonin, Norepinephrine, and Future Directions

In this issue, an article by La et al. provides evidence that trazodone delayed cognitive decline in 25 participants with Alzheimer's disease (AD), mild cognitive impairment, or normal cognition. For participants considered to have AD pathology, trazodone non-users declined at a rate 2.4 times greater than those taking trazodone for sleep over a 4-year period. In the analysis of sleep complaints, the relationship between trazodone, a widely used medication for sleep problems in the elderly, and cognition was associated with subjective improvement of sleep disruption. Due to the design of the study, it was not possible to prove that the benefit of slowing cognitive decline was due specifically to the improvement in sleep. However, trazodone uniquely improves the deeper phases of slow-wave sleep. Other sedative medications are generally associated with worse cognitive function over time, and they do not improve sleep characteristics as does trazodone. Trazodone has a variety of effects on several monoaminergic mechanisms: a potent serotonin 5-HT2A and α1-adrenergic receptor antagonist, a weak serotonin reuptake inhibitor, and a weak antihistamine or histamine H1 receptor inverse agonist. Because of the potential importance of this finding, further discussion is provided on the roles that trazodone may play in the modulation of monoamines, cognition, and the development of AD. If trazodone really does provide such a dramatic slowing in the development of dementia associated with AD, a great deal more research on trazodone is needed, including environmental and behavioral factors related to improvement of sleep, energy management, and neuroplasticity.

Findings from the National Memory Screening Day program

OBJECTIVES

To report experience with a large, nation-wide public memory screening program.

DESIGN

Descriptive study of community-dwelling elderly adults.

SETTING

Local community sites (48 sites agreed to provide data) throughout the United States participating in National Memory Screening Day in November 2010.

PARTICIPANTS

Of 4,369 reported participants, 3,064 had complete data records and are included in this report.

MEASUREMENTS

Participants completed a questionnaire that included basic demographic information and a question about subjective memory concerns. Each site selected one of seven validated cognitive screening tests: Mini-Cog, General Practitioner assessment of Cognition, Memory Impairment Screen, Kokmen Short Test of Mental Status, Mini-Mental State Examination, Montreal Cognitive Assessment, Saint Louis University Mental Status Examination.

RESULTS

Overall, 11.7% failed one of the seven screening tests. As expected, failure rates were higher in older and less-educated participants (P's < .05). Subjective memory concerns were associated with a 40% greater failure rate for persons of similar age and education but no memory concerns (odds ratio = 1.4, 95% confidence interval = 1.07-1.78), although only 11.9% of those who reported memory concerns (75% of all participants) had detectible memory problems.

CONCLUSION

Screening for cognitive impairment in community settings yielded results consistent with expected effects of age and education. The event attracted a large proportion of individuals with memory concerns; 88.1% were told that they did not have memory problems detectible with the tests used. Further studies are needed to assess how participants respond to and use screening information, whether this information ultimately influences decision-making or outcomes, and whether memory screening programs outside healthcare settings have public health value.

Challenges to be overcome using population-based sampling methods to recruit veterans for a study of post-traumatic stress disorder and traumatic brain injury

Background

Many investigators are interested in recruiting veterans from recent conflicts in Afghanistan and Iraq with Traumatic Brain Injury (TBI) and/or Post Traumatic Stress Disorder (PTSD). Researchers pursuing such studies may experience problems in recruiting sufficient numbers unless effective strategies are used. Currently, there is very little information on recruitment strategies for individuals with TBI and/or PTSD. It is known that groups of patients with medical conditions may be less likely to volunteer for clinical research. This study investigated the feasibility of recruiting veterans returning from recent military conflicts— Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF) - using a population-based sampling method.

Methods

Individuals were sampled from a previous epidemiological study. Three study sites focused on recruiting survey respondents (n = 445) who lived within a 60 mile radius of one of the sites.

Results

Overall, the successful recruitment of veterans using a population-based sampling method was dependent on the ability to contact potential participants following mass mailing. Study enrollment of participants with probable TBI and/or PTSD had a recruitment yield (enrolled/total identified) of 5.4%. We were able to contact 146 individuals, representing a contact rate of 33%. Sixty-six of the individuals contacted were screened. The major reasons for not screening included a stated lack of interest in the study (n = 37), a failure to answer screening calls after initial contact (n = 30), and an unwillingness or inability to travel to a study site (n = 10). Based on the phone screening, 36 veterans were eligible for the study. Twenty-four veterans were enrolled, (recruitment yield = 5.4%) and twelve were not enrolled for a variety of reasons.

Conclusions

Our experience with a population-based sampling method for recruitment of recent combat veterans illustrates the challenges encountered, particularly contacting and screening potential participants. The screening and enrollment data will help guide recruitment for future studies using population-based methods.

Ethics review as a catalyst for progress

There are several points where ethical decision-making has become paralyzed and inefficient as the field of Alzheimer's disease study has advanced. The focus of this review is to highlight these points and several lines of research that can inform ethical decision-making. The goal is to identify barriers and to move toward solutions. Examples of other fields of study that can be particularly useful for innovative ways to study effective ethical decision-making include implementation science and neuroscience of decision-making, as well as therapeutic investigations of other domains such as the human biology and psychology.

Formoterol, a long-acting β2 adrenergic agonist, improves cognitive function and promotes dendritic complexity in a mouse model of Down syndrome

BACKGROUND

Down syndrome is associated with significant failure in cognitive function. Our previous investigation revealed age-dependent degeneration of locus coeruleus, a major player in contextual learning, in the Ts65Dn mouse model of Down syndrome. We studied whether drugs already available for use in humans can be used to improve cognitive function in these mice.

METHODS

We studied the status of β adrenergic signaling in the dentate gyrus of the Ts65Dn mouse model of Down syndrome. Furthermore, we used fear conditioning to study learning and memory in these mice. Postmortem analyses included the analysis of synaptic density, dendritic arborization, and neurogenesis.

RESULTS

We found significant atrophy of dentate gyrus and failure of β adrenergic signaling in the hippocampus of Ts65Dn mice. Our behavioral analyses revealed that formoterol, a long-acting β2 adrenergic receptor agonist, caused significant improvement in the cognitive function in Ts65Dn mice. Postmortem analyses revealed that the use of formoterol was associated with a significant improvement in the synaptic density and increased complexity of newly born dentate granule neurons in the hippocampus of Ts65Dn mice.

CONCLUSIONS

Our data suggest that targeting β2 adrenergic receptors is an effective strategy for restoring synaptic plasticity and cognitive function in these mice. Considering its widespread use in humans and positive effects on cognition in Ts65Dn mice, formoterol or similar β2 adrenergic receptor agonists with ability to cross the blood brain barrier might be attractive candidates for clinical trials to improve cognitive function in individuals with Down syndrome.

MR spectroscopy for assessment of memantine treatment in mild to moderate Alzheimer dementia

OBJECTIVES

Magnetic Resonance Spectroscopy (MRS) may provide a precise and reliable assessment of the extent and severity of neural tissue loss caused by various diseases. In particular, the N-Acetyl Aspartate (NAA) and Creatine (Cr) ratio has been found to be an indicator of the degree of neuronal loss in Alzheimer's disease (AD). Memantine is thought to benefit the AD brain by stabilizing the NMDA receptors on neurons in turn reducing excitotoxicity. Despite its effectiveness in treating moderate to severe AD, memantine has not had similar success in the treatment of mildly demented AD patients. The objective of this study was to test whether memantine would slow or prevent the loss of neurons in mild to moderate AD patients.

METHODS

A double-blind placebo-controlled study was designed to measure the effect of a year-long course of memantine in patients with a probable AD diagnosis with mild to moderate dementia. The primary outcome measure was stipulated to be change in MRS NAA/Cr ratio in inferior parietal cortex in memantine relative to the placebo treatment condition. The secondary outcome measures were changes in cognitive and function scale scores.

RESULTS

This pilot study failed to demonstrate a benefit of memantine on the primary outcome measure, the inferior parietal NAA/Cr ratio, or the secondary outcome measures.

CONCLUSIONS

More studies are needed to determine the effect of memantine on regions of the brain significantly affected by AD pathology.

Spatial test for agricultural pesticide "blow-in" effect on prevalence of Parkinson's disease

The current study used Department of Veteran's Affairs (VA) clinical records, State of California pesticide application records, spatial maps of distribution of Parkinson's disease patients, and pesticide applications to determine if there was evidence for "blow-in" of pesticides as a factor in explaining the prevalence of Central Valley Parkinson's disease. The results did not support the hypothesis of increasing prevalence of Parkinsonism attributable to wind drift.

Use of a VA pharmacy database to screen for areas at high risk for disease: Parkinson's disease and exposure to pesticides

The purpose of this study was to assess whether pharmacy database information from US Department of Veterans Affairs (VA) medical centers could be used to screen for areas of higher Parkinson's disease prevalence in patients exposed to pesticides. The authors used pharmacy data sets and compared the use of antiparkinsonian medications at 2 VA medical centers in California: one in Palo Alto, near the ocean, and one in Fresno, downwind from extensively farmed parts of the Central Valley. They found that patients at Fresno had higher odds ratios (1.5-1.8) for the use of Parkinson's disease medications than patients at Palo Alto. These data are consistent with the observations of prior epidemiologic studies and suggest that VA pharmacy databases can prioritize locations for further epidemiologic research. However, a thorough exploration of alternative explanations is needed to reach definitive conclusions regarding the findings suggested by this method.

Measuring cognition in advanced Alzheimer's disease for clinical trials

Measurement of cognitive dysfunction and treatment response in the early stages of Alzheimer's disease (AD) has used such scales as the Mini-Mental State Examination (MMSE) and the AD Assessment Scale (ADAS). With the exception of clinical rating scales, however, there are only a few objective measures of cognition for tracking progression in advanced AD. Given renewed interest in potential therapies for advanced AD, objective measures of cognition are important for the adequate evaluation of change due to AD progression or therapy. Several cognitive measures for advanced AD are reviewed. One measure, the Severe Impairment Battery (SIB) is reviewed in detail. Preliminary analyses from a trial of memantine show significant change on the SIB in memory (p < 0.001) and visuospatial functions (p < 0.02) over six-months with a trend for language and praxis. Data from a donepezil trial also highlight the importance of accurate assessment in advanced AD.

Modeling the time-course of Alzheimer dementia

Alzheimer's disease (AD) progresses from a preclinical period, through a middle phase of cognitive deterioration, to a late, profound state. The temporal progression of disability can be modeled with a horologic (time-based) function using "time-index" (TI) intervals (day- or year-units) to quantify an individual's disability across multiple cognitive and functional domains relative to a reference AD population. Clinicians and researchers can use TI quantification to assess dementia severity and initial therapy benefits. Rate of progression and confidence intervals require at least two successive measurements. Rate of progression measures can be used to support diagnosis and to investigate disease-course-modifying therapies.

"Preclinical" AD revisited: neuropathology of cognitively normal older adults

OBJECTIVE

To classify neuropathologic alterations in the brains of nondemented older adults using current sets of criteria for AD.

BACKGROUND

AD neuropathologic alterations are found in the brains of some nondemented elderly subjects and suggest the possibility of presymptomatic AD. Three sets of guidelines have been developed to classify AD using senile plaques, neuritic plaques, and neurofibrillary tangles (NFT).

METHODS

Neuropathologic changes in 59 older adults followed longitudinally with a standard battery of mental status measures were investigated using Khachaturian, Consortium to Establish a Registry for Alzheimer's Disease (CERAD), and National Institute on Aging-Reagan Institute (NIA-RI) guidelines. AD neuropathologic markers were evaluated in neocortical and allocortical regions. Cases were categorized as neuropathologically "normal" or "AD-like" and compared for possible mental status differences.

RESULTS

Between 11 and 49% of cases met one or more of the three classifications of AD. With adjustments for multiple comparisons, only NFT in hippocampal CA1 region were associated with autopsy age, suggesting that this may represent a pathologic process associated with normal brain aging. Using the NIA-RI guidelines, subjects in the AD-like group performed less well on the immediate paragraph recall and word-list delayed recall than their counterparts who did not meet these guidelines.

CONCLUSIONS

These data indicate that the prevalence of "preclinical" AD in our population is relatively low based on the NIA-RI classification. Although many subjects had AD-like changes based on CERAD and Khachaturian guidelines, they exhibited no differences in mental performance, suggesting that the aging brain may be able to withstand such structural changes without meaningful impact on mental functioning.

Modelling mini mental state examination changes in Alzheimer's disease

The Mini Mental State Examination (MMSE) is widely used to measure dementia severity in Alzheimer's disease patients. While changes over time in the MMSE due to dementia have been studied, the relationship between MMSE scores and the duration of disease course is less well understood. Using the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) data, we modelled change in MMSE as a function of time for this population. For this purpose we used the interval between consecutive MMSE assessments as the time factor. We also investigated the impact of sex, education and age at testing on the resulting model. Analyses showed that Alzheimer's disease progression over time (ADP) can be modelled using a cubic or a logarithmic function of MMSE score. From these curves ADP can be obtained as a function of MMSE. These models demonstrate that there are different rates of change for various ranges of the MMSE. Additional analyses suggest that patient factors affect rates of ADP, younger patients and more educated patients progress more rapidly, while sex has little impact on ADP. Such estimations of disease course are useful when comparing different populations for both clinical and research purposes.

Single SPECT measures of cerebral cortical perfusion reflect time-index estimation of dementia severity in Alzheimer's disease

To determine the relationship between cerebral cortical blood flow loss and the temporal development of the dementia in Alzheimer's disease (AD), SPECT was studied in a cross section of AD patients with a broad range of impairment.

METHODS

Thirty patients with a diagnosis of probable AD had their mini-mental state examination scores transformed into time-index values to give an estimation of dementia severity relative to the developmental time course. SPECT images were obtained using 99mTc-ethyl cysteinate dimer and a 3-head camera. Cortical surface perfusion was analyzed, including modified Talairach standardization, to obtain cortical elements from the convexity (each representing about 0.25 cm2 at the surface, 6.6-mm cortical depth) referenced to the mean perfusion of the full greater cerebellar hemisphere. These element ratios were analyzed (individually and by averages of estimated Brodmann's areas and brain regions) using linear regression with the time-index value.

RESULTS

For individual posterotemporal and inferoparietal Brodmann's areas (21, 22 and 39, 40, respectively) the correlation coefficients between cortical perfusion ratios and dementia severity ranged between -0.67 and -0.78 (P < 0.001). Perfusion ratios from these regions declined 2.5%-4.2% for each estimated year of progression. Prefrontal area perfusion showed less association with severity. Perfusion in primary cortical regions had no significant association with dementia severity.

CONCLUSION

Cerebral cortical perfusion loss is temporally related to development of dementia. The spatial pattern of high, significant correlations between cortical perfusion and dementia severity shows a regional distribution that corresponds closely to the distribution of AD pathology described in autopsy studies.

Neuropil threads are collinear with MAP2 immunostaining in neuronal dendrites of Alzheimer brain

Alzheimer disease (AD) neuropathology includes neuropil threads (NTs) and neurofibrillary tangles (NFTs). In tangle-bearing neurons, the normal cytoskeleton is severely disrupted and replaced with paired helical filament (PHF) aggregates of aberrantly phosphorylated microtubule-associated protein tau. In this study, double-label immunocytochemistry was used to clarify the relationship between the appearance of neurofibrillary pathology (NTs and NFTs) and the loss of normal cytoskeletal components, such as microtubule-associated protein 2 (MAP2) in 13 AD cases and 6 nondemented elderly control individuals. Brain areas examined included neocortex (cingulate, motor, and inferior parietal cortices), hippocampus, and entorhinal cortex. In mildly affected neurons, PHF-1 immunostained NTs were found in dendrites, frequently at dendritic branch points, and were adjacent to MAP2 immunostaining. In more severely affected neurons, the PHF-1 immunoreactivity occupied distinct dendritic segments and appeared to displace MAP2. Interspersed MAP2 immunopositive dendritic segments were often beaded in appearance. In all instances where dendrites with NTs could be traced back to the soma, the soma also contained PHF-1 immunostained fibrils in various stages of NFT formation. The results suggest that PHFs gradually displace normal microtubules in dendrites, and cause degeneration of dendritic segments between NTs.

Seizures in patients receiving concomitant antimuscarinics and acetylcholinesterase inhibitor

Seizures occurred in two patients with probable Alzheimer's disease who were receiving long-term treatment with metrifonate, an irreversible acetylcholinesterase inhibitor. In both patients seizures were associated with discontinuation of short-term agents with high antimuscarinic properties. Hence, abrupt discontinuation of antimuscarinics or anticholinergics with high antimuscarinic properties in patients receiving long-term acetylcholinesterase inhibition therapy may be associated with a reduction of seizure threshold. With increasing administration of acetylcholinesterase inhibitors for patients with Alzheimer's disease, practitioners should be aware of the potential for drug-drug interactions and other complications. In general, it is good medical practice to avoid concomitant administration with centrally acting anticholinergic agents.

Pharmacokinetics, pharmacodynamics, and safety of metrifonate in patients with Alzheimer's disease

Metrifonate is converted nonenzymatically to 2.2, dimethyl dichlorovinyl phosphate (DDVP), an inhibitor of acetylcholinesterase (AChE). This 21-day, randomized, double-blind, placebo-controlled trial of metrifonate in patients with Alzheimer's disease (n = 27) evaluated four doses, each administered orally once daily. All patients received a loading dose (LD) for 6 days followed by a maintenance dose (MD) for 15 days. The treatment groups were: panel 1, LD = 1.5 mg/kg (75-135 mg), MD = 0.25 mg/kg (12.5-25 mg); panel 2, LD = 2.5 mg/kg (125-225 mg), MD = 0.40 mg/kg (20-35 mg); panel 3, LD = 4.0 mg/kg (200-335 mg), MD = 0.65 mg/kg (30-60 mg); and panel 4, LD = 4.0 mg/kg (200-335 mg), MD = 1.0 mg/kg (50-90 mg). All metrifonate doses were well tolerated. Most adverse events were mild to moderate in intensity, gastrointestinal in nature, and transient. Mean area under the concentration-time curve (AUC) and maximum concentration (Cmax) for both metrifonate and DDVP increased in relation to dose. Metrifonate and DDVP had similar, largely dose-independent mean values for time to Cmax (tmax) and half-life (t1/2). There was little or no accumulation of either metrifonate or DDVP with long-term administration. After 21 days of treatment, mean percent erythrocyte AChE inhibition was 14%, 35%, 66%, 77%, and 82% for placebo and panels 1 through 4, respectively. Cognitive improvement was observed with the two highest metrifonate doses. These results reflect favorable safety and pharmacokinetic profiles for the use of metrifonate in the treatment of Alzheimer's disease.

Comparison of neuropathologic criteria for the diagnosis of Alzheimer's disease

The National Institute on Aging and Reagan Institute (NIA-RI) criteria, and other neuropathologic criteria for Alzheimer's disease (AD), were compared with the clinical diagnosis of dementia in a well defined population of Catholic sisters. The 47-participant subset examined in this study were college educated and lacked complicating conditions such as brain infarcts or diffuse Lewy body disease. Sixteen participants had a clinical diagnosis of dementia. The NIA-RI criteria imply a perfect correlation between neuritic plaque (NP) density and neurofibrillary tangle distribution. However, NP density often did not coincide with tangle distribution. As a result, it was not possible to categorize many of the participants using the NIA-RI guidelines. The 'high likelihood' category of the NIA-RI criteria for AD research settings (neocortical Braak stage and frequent neocortical NP) had relatively high specificity (90% of nondemented participants did not meet this criteria). However, only half of the demented participants were in this category. Neuropathologic criteria requiring the presence of neocortical tangles (rather than neocortical Braak stage) had relatively high sensitivity, accounting for 87-94% of participants with dementia, but also included 32-35% of nondemented participants. Criteria based on neocortical NP or senile plaques had 100% sensitivity, but a majority of nondemented participants also met these criteria. The results support consideration of both tangles and NP for the neuropathologic diagnosis of AD, but indicate that refinement of the NIA-RI criteria is necessary. A possible refinement is suggested for further consideration.

Age, education, and changes in the Mini-Mental State Exam scores of older women: findings from the Nun Study

OBJECTIVE

To describe the relationship of Mini-Mental State Exam (MMSE) scores and changes over time in MMSE scores to age and education in a population of older women.

DESIGN

A prospective study of a defined population.

SETTING

Various motherhouses and church-run health care facilities in the Eastern, Midwestern, and Southern regions of the United States.

PARTICIPANTS

Catholic sisters (nuns) participating in the Nun Study, a study of aging and Alzheimer's Disease. The 678 participants were 75 to 102 years old (mean 83.3, standard deviation 5.5, median 82.3) at the time of the first functional assessment. Second assessments were obtained an average of 1.6 years later on 575 survivors.

MEASUREMENTS

The outcome variables were MMSE scores at the first assessment (Time-one), and MMSE scores at the second assessment (Time-two). The independent variables were age at Time-one, and education (bachelor's degree or no bachelor's degree).

RESULTS

Time-one MMSE scores decreased with age at Time-one. The decrease in MMSE scores with age was less in sisters with bachelor's degrees than in sisters without bachelor's degrees. The changes in MMSE scores had a "U-shaped" relationship with Time-one score, where the greatest declines occurred in sisters with intermediate Time-one scores. Stratified analysis by age, education, and Time-one MMSE scores of 20 or greater because of the small numbers of sisters with Time-one scores less than 20. In sisters with Time-one MMSE scores in the categories 20 to 23, 24 to 26, or 27 to 30, older ages at Time-one were associated with greater decline in those with bachelor's degrees, but not in those without bachelor's degrees. Also, lower education was associated with greater decline in sisters aged 75 to 84 years at Time-one, but this education effect disappeared or reversed in sisters who were 85 years of age or older at Time-one.

CONCLUSIONS

Cognitive function as measured by the MMSE decreased with age at Time-one, most steeply as a function of age in those without bachelor's degrees. Cognitive function declined over 1.6 years within individuals, and the extent of decline increased with age in the sisters with bachelor's degrees. The extent of decline varied with age and education in an interactive manner, which may have been attributable to a hardy survivor effect in lower educated sisters. It may be necessary to consider such interactions whenever changes in function are studied, particularly when analyses are stratified by the initial level of function.

Temporal quantification of Alzheimer's disease severity: 'time index' model

A fundamental issue in the clinical and neuropathological assessment of Alzheimer's disease patients is quantification of dementia severity progression. Several methods have been advanced for the purpose of staging dementia with various sensitivities at different phases of the disease, but no mathematical function has been developed to link these measures to a physical continuum. Using a dynamic method for quantifying illness severity, change in severity over time was referenced to a cumulative temporal index, a physical dimension. Data from 33 patients with probable Alzheimer's disease with at least 2 successive assessments on three 50-point scales measuring cognitive, behavioral, and daily living skills were used to determine rate of change. 'Fuzzylogic' smoothing of the data, integration over time, and least-squares regression were used to derive a cubic polynomial function to calculate a severity measure in which 'days of illness' was estimated from the severity score. This method can be used to improve the comparability of performance across various mental status tests, and to link measures of very early phases of preclinical dementia and late profound dementia phases. This method also provides a description of an 'average' time course for any population from which the index is derived.

Psychotropic drug use in relation to psychiatric symptoms in community-living persons with Alzheimer's disease

We attempted to determine the relationship between psychiatric symptoms and psychotropic drug use in persons with Alzheimer's disease based on a multicenter patient registry of 671 community-living persons diagnosed with the disease by published criteria. Logistic regression was performed to determine which symptoms were associated psychotropic use after controlling for age, sex, and Mini-Mental Status Examination (MMSE) score. At least one psychotropic drug was reported by 31% of patients, and 66% had at least one psychiatric symptom. Antipsychotics were associated with a lower MMSE score (odds ratio = 0.92, 95% confidence interval 0.88-0.97), emotional lability (OR = 4.52, 95% CI 1.69-11.94), and hallucinations (OR = 6.54, 95% CI 2.99-14.26). Antidepressants were associated with depressive symptoms (OR = 5.8, 95% CI 2.61-13.46), and benzodiazepines with a lower MMSE score (OR = 0.93, 95% CI 0.90-0.97). Community-living persons with Alzheimer's disease are frequently prescribed psychotropic drugs; however, more than 50% of patients with a psychiatric symptom did not report taking one of these agents. This suggests that alternative therapies and no treatment are also prevalent.

Anticonvulsants attenuate amyloid beta-peptide neurotoxicity, Ca2+ deregulation, and cytoskeletal pathology

Increasing evidence supports the involvement of amyloid beta-peptide (A beta) and an excitotoxic mechanism of neuronal injury in the pathogenesis of Alzheimer's disease. However, approaches aimed at preventing A beta toxicity and neurofibrillary degeneration are undeveloped. We now report that anticonvulsants (carbamazepine, phenytoin, and valproic acid) can protect cultured rat hippocampal neurons against A beta- and glutamate-induced injury. Each of the anticonvulsants attenuated the elevation of intracellular free calcium levels [(Ca2+)i] elicited by A beta or glutamate suggesting that their neuroprotective mechanism of action involved stabilization of [Ca2+]i. These compounds were effective at clinically relevant concentrations (carbamazepine, 100 nM-10 microM; phenytoin, 100 nM-1 microM; valproic acid, 100 nM-100 microM). The anticonvulsants suppressed glutamate-induced alterations in tau and buiquitin immunoreactivities. Compounds that stabilize [Ca2+]i may afford protection against the kinds of insults believed to underlie neuronal injury in Alzheimer's disease.

Psychopathology associated with Alzheimer's disease and related disorders

BACKGROUND

This study compared the occurrence of psychiatric symptoms in a large group of community-residing participants enrolled in an Alzheimer's disease patient registry who met clinical diagnostic criteria for Alzheimer's disease or multi-infarct dementia, as well as mixed Alzheimer's disease and multi-infarct dementia.

METHODS

Psychiatric morbidity observed from a psychiatric examination of 514 patients with Alzheimer's disease, 135 patients with multi-infarct dementia, and 86 cases with mixed dementia was analyzed using analysis of variance comparing symptoms across groups and chi-square test for differences in frequency of occurrence. Associations between pairs of symptoms were also reported.

RESULTS

The frequency of occurrence and patterns of psychiatric problems were similar in patients with Alzheimer's disease and multi-infarct dementia. Agitation was the most frequent symptom, followed by depression, apathy, and behavioral disorders. Patients with mixed dementia had significantly more psychopathology.

CONCLUSION

This study demonstrated that significant psychopathology occurs in individuals with Alzheimer's disease or multi-infarct dementia. The high levels of symptoms in mixed dementia suggest that the two conditions have a synergistic effect on behavioral problems. The prevalence of multiple symptoms is higher than previously reported.

Delayed late component of visual global field power in probable Alzheimer's disease

A substantial literature shows that late components of visual evoked potentials (VEPs) are delayed in at least some forms of dementia in the elderly. The late-component delay is selective in that earlier components are not affected. More recent work with better defined clinical groups suggests that the selective late-component delay may be characteristic of Alzheimer's disease (AD) rather than an inevitable feature of dementia in general. To overcome problems in traditional VEP component latency measurement the present study uses reference-free Global Field Power (GFP) analysis to more objectively define VEP components and finds that the GFP peak corresponding to the late P2 component of the flash VEP is delayed in a probable AD group but not in a demented unlikely AD group, relative to age-equivalent healthy controls. The late-component delay is again found to be selective in that the GFP peak corresponding to the earlier P1 component of the flash VEP does not differ between groups. These findings further strengthen the evidence for electrocortical changes in the visual system of AD patients.

Drug use patterns of persons with Alzheimer's disease and related disorders living in the community

OBJECTIVE

To describe drug use patterns by persons with Alzheimer's disease, multi-infarct dementia, and mixed Alzheimer's disease and multi-infarct dementia.

DESIGN

Multicenter, patient registry.

SETTING

Community-living persons evaluated in primary care, geriatric, and Alzheimer ambulatory settings.

PARTICIPANTS

Of the 930 persons in three diagnostic categories, there were 671 with probable or possible Alzheimer's disease by NINCDS/ADRDA criteria or Alzheimer's disease by DSM-III-R criteria, 162 multi-infarct cases by DSM-III-R criteria, and 97 mixed cases by DSM-III-R criteria. In each diagnostic category, 65% were women, and the majority were 70 years or older.

MEASUREMENTS

The average number of all prescription and non-prescription drugs and selected therapeutic categories by age, sex, diagnosis, and mini-mental status score at the time of diagnosis or evaluation.

RESULTS

Alzheimer patients average 2.3 drugs compared with multi-infarct (4.3; P < 0.0001) and mixed (3.7; P = 0.002) patients, and their pattern of drug use was different when stratified by therapeutic categories and drug classes. Drug use increased with age, and women used significantly more drugs than men in all three diagnostic categories. Women with Alzheimer's disease used significantly more cardiovascular drugs than men with Alzheimer's disease (P < 0.05). The lower the mini-mental status score in patients with any dementia, the greater the mean number of central nervous system agents used. The higher the mini-mental status score in a patient with multi-infarct or mixed dementia, the greater the use of cardiovascular drugs.

CONCLUSION

Drug use by Alzheimer patients was lower than in multi-infarct and mixed patients, primarily due to a lower prevalence of cardiovascular drugs.

Sex differences in the psychiatric manifestations of Alzheimer's disease

OBJECTIVE

To test the null hypothesis, ie, that there are no gender differences in psychiatric problems manifest in patients with Alzheimer's disease.

DESIGN

Survey.

SETTING

Patients living in the community and evaluated at Alzheimer's disease and geriatric outpatient programs.

PATIENTS

Three hundred twenty-eight women and 186 men clinically diagnosed with Alzheimer's disease using NINCDS/ADRDA or DSM-III-R criteria.

MEASUREMENTS

Psychiatric signs and symptoms recorded following a psychiatric interview, including the Hamilton Depression Rating Scale.

RESULTS

Approximately two-thirds of both men and women had psychiatric problems, but women had significantly more multiple symptoms. When pairs of symptoms were analyzed for independence, agitation was only significantly associated with paranoia in men, whereas in women agitation was significantly associated with most other psychiatric problems.

CONCLUSION

The higher prevalence of multiple psychiatric problems in women may be due to many factors, including sociodemographic influences, physician bias, and/or other differences between men and women. The finding of a different pattern of association of symptoms with agitation in men and women deserves replication.

Functional status and clinical findings in patients with Alzheimer's disease

We analyzed the association of clinical findings with impaired functional status, i.e., activities of daily living (ADLs), in a sample of 240 patients diagnosed with Alzheimer's disease by NINCDS/ADRDA or DSM-III-R criteria. Logistic regression models were used to determine independent predictors of both the number of ADL impairments and number of ADL impairments characterized as moderate to severe. Two psychiatric problems, behavioral disorders and apathy, as well as a history of hypertension were significantly associated with ADL impairment independent of age, sex, race, and cognitive impairment. Behavioral disorders and apathy were also significantly associated with moderate to severe ADL impairment, but hypertension was not significant at this level.

Human serum stimulates Alzheimer markers in cultured hippocampal neurons

The mechanism for promoting the distinct types of lesions in the Alzheimer disease (AD) brain and other changes outside the brain is unknown. We examined neurons in culture, unprotected by glia or a blood-brain barrier, to determine if exposure to serum from Alzheimer patients would affect markers for Alzheimer brain lesions. Rat hippocampal neurons were first grown for 4 days in a new serum-free culture medium, then exposed for 24 hr to human sera. Sera from 12 AD patients or their spouses increased four molecular markers characteristic of Alzheimer senile plaques and neurofibrillary tangles: Alz-50, beta-amyloid (beta/A4), MAP2, and ubiquitin, each with their expected cytologic distributions. Sera from ten young adults produced significantly less stimulation. By quantitative immunofluorescence, neuronal exposure to the elderly human sera produced 1.8- to 2.5-fold increases in mean fluorescent area/cell for each of these four markers relative to no serum exposure. As controls, an unrelated neuronal marker, enolase, was unaffected and fetal bovine serum did not stimulate immunoreactivity. Neuron viability and somal area were unaffected at 24 hours. The MAP2 increases were dose dependent with negligible effect at 2% serum and maximum effect at 10% serum after 24 hr. The MAP2 increase was greater after 48 hr of exposure than 24 hr and negligible at 2 hr. This stimulation of AD markers by human serum suggests that the genesis of both neuronal plaques and tangles may arise from access of toxic serum factors to susceptible neurons and/or failure to detoxify these factors.

Severe family violence and Alzheimer's disease: prevalence and risk factors

This study describes the prevalence of violence and the putative risk factors for violence in 184 Alzheimer patients and their primary caregivers living in the community. Analysis of the severe violence subscale of the Conflict Tactics Scale indicated that 15.8% of patients had been violent in the year since diagnosis. A total of 5.4% of caregivers reported being violent toward the patient. The overall prevalence of violence was 17.4%. The variables most associated with violence were caregiver depression and living arrangement.

Are there clinical differences between familial and nonfamilial Alzheimer's disease?

OBJECTIVE

The purpose of the study was to determine whether there are differences in clinical characteristics in two groups of patients with Alzheimer's disease, those reported to have a family history of dementia and those without a family history of dementia.

METHOD

Using a data set from an Alzheimer's disease patient registry, funded as part of a National Institute on Aging cooperative agreement, the authors made comparisons of sociodemographic and clinical variables in a group of 462 patients with Alzheimer's disease, 172 reported to have at least one first-degree relative with dementia and 290 classified with no family history.

RESULTS

Patients with a presumptive family history differed from those without a family history in two ways: the course of dementia was described as having a fast rather than a slow progression from onset of symptoms to diagnosis, and caregivers reported a higher prevalence of family history of psychiatric disorders. There were no significant differences in age at onset, duration, female gender, aphasia and apraxia, handedness, family history of Down's syndrome, or number of children, brothers, and sisters.

CONCLUSIONS

The association of faster course and family history of psychiatric disorders in the patients with a family history of dementia is consistent with the hypothesis of heterogeneity, but the overall results could also be explained by a genetic-environmental model of Alzheimer's disease.

An empirical evaluation of the Global Deterioration Scale for staging Alzheimer's disease

OBJECTIVE

Although the Global Deterioration Scale has been widely used since its publication in 1982, its stages are based on implicit assumptions about the linearity, temporality, and interdependence of cognitive, functional, and behavioral impairment in Alzheimer's disease. The authors evaluated the validity of these assumptions and tested the hypothesis that psychopathology and functional impairment would occur in earlier stages than the Global Deterioration Scale predicts.

METHOD

The analyses were based on data on 324 patients with Alzheimer's disease who were selected from a registry of such patients. Data analyses included 1) descriptive statistics on the frequency of psychiatric symptoms and difficulties with activities of daily living and 2) logistic regression, with symptoms and functional impairment as independent variables, to test for significant changes in patients' status between stages of the Global Deterioration Scale.

RESULTS

More than 50% of the patients at stage 2 displayed psychopathology, and 32% had two or more symptoms. The significant increase in psychiatric symptoms occurred between stages 3 and 4, not between stages 5 and 6 as predicted by the Global Deterioration Scale. Impairment in functional status was observed at all stages, and significant increases occurred between stages 3 and 4 as well as between stages 5 and 6.

CONCLUSIONS

Psychiatric symptoms and functional impairment occur earlier than predicted by the Global Deterioration Scale, and the rate of change is also different from that specified in the scale. Separate scales to describe cognitive, clinical, and functional status may be the best way to describe the illness until better multidimensional instruments are developed.

Assessing Alzheimer severity with a global clinical scale

Diagnosis of dementia needs to be complemented by precise determination of disease severity across the broad spectrum of disease progression. The Mini-Mental State Exam (MMS), the Activities-of-Daily-Living assessment (ADL) and the Clinical Dementia Rating scale (CDR) were modified for direct comparability and administered to 112 outpatients and 45 nursing home residents with a range of dementia severity from mild to profound. The scales showed the highest correlations for the probable Alzheimer's disease patient group (62) (Global Assessment of Dementia; GAD vs. ADL: r = 0.91; Extended Mini-Mental Assessment; EMA vs. GAD: r = 0.91; ADL vs. EMA: r = 0.86). For these patients, scores on the individual scales tended to be similar. Disparity among the three scores for individual cases was associated with the presence of comorbidities. The high correlations and correspondence among these scales demonstrate their reliability, validity, and utility in the assessment of dementia severity. The use of an average of these measures, with their increased precision, may give a more accurate indication of dementia severity over a broader range of impairment.

Electrocortical mapping, MRI, and neuropsychological measures: evidence of Alzheimer's disease in the presence of vascular lesions

We report here a case study of a 76-year-old woman with a high school education, whose presenting psychiatric symptomatology indicated dementia of unknown etiology. Neuropsychological test results were consistent with AD, but diagnosis was complicated by an MRI showing a large right hemisphere cortical infarct and scattered subcortical changes leading to a diagnosis of possible AD. Electrocortical mapping showed the right hemisphere infarct, and gave independent evidence suggestive of AD in the relatively intact left hemisphere. This case demonstrates the utility of multidimensional assessment as an aid to differential diagnosis.

Visual evoked potentials in dementia: selective delay of flash P2 in probable Alzheimer's disease

The flash visual evoked potential P2 component is delayed in etiologically mixed groups of demented patients compared to healthy controls or nondemented patients. This study compared patients meeting both DSM-III-R criteria for dementia and NINCDS-ADRDA criteria for probable Alzheimer's disease (AD) with healthy elderly controls and found the P2 delay in the probable AD group. Additional comparisons found no evidence of a P2 delay in demented unlikely AD patients. These results suggest that earlier findings of a delayed P2 in etiologically mixed demented groups may have been due to inclusion of AD patients.

Visual response latencies in temporal lobe structures as a function of stimulus information load

In a monkey performing a visual delayed matching-to-sample task, units and visual evoked potentials (VEPs) were sampled from the inferior bank of the superior temporal sulcus (STS; Areas TEa and IPa), the hippocampus, and the presubiculum. VEP latencies indicated that flash information--signaling the imminent presentation of a color sample to be retained--reached the presubiculum and the hippocampus substantially earlier than the STS. In contrast, color sample VEP latencies did not differ between sites, arriving at all sites appreciably later than flash VEPs. Unit data indicated generally excitatory responses to both stimuli at all sites and net inhibition during the interstimulus interval separating flash from sample. As with VEPs, unit latencies to flash were shorter than to sample stimuli. The alerting flash data imply activation of the hippocampus occurring before activation of the STS cortex, whereas the coincident arrival of color sample information suggests temporal synchronization between these structures.

Visual response latencies in temporal lobe structures as a function of stimulus information load

In a monkey performing a visual delayed matching-to-sample task, units and visual evoked potentials (VEPs) were sampled from the inferior bank of the superior temporal sulcus (STS; Areas TEa and IPa), the hippocampus, and the presubiculum. VEP latencies indicated that flash information--signaling the imminent presentation of a color sample to be retained--reached the presubiculum and the hippocampus substantially earlier than the STS. In contrast, color sample VEP latencies did not differ between sites, arriving at all sites appreciably later than flash VEPs. Unit data indicated generally excitatory responses to both stimuli at all sites and net inhibition during the interstimulus interval separating flash from sample. As with VEPs, unit latencies to flash were shorter than to sample stimuli. The alerting flash data imply activation of the hippocampus occurring before activation of the STS cortex, whereas the coincident arrival of color sample information suggests temporal synchronization between these structures.

Alzheimer patient evaluation and the mini-mental state: item characteristic curve analysis

To develop a tool for precisely assessing dementia severity, items should be selected according to their relationship to the overall progression of the disease. Using an item characteristic curve analysis (ICC), items were examined from the Folstein Mini-Mental State Exam (MMSE), a useful clinical tool for evaluating dementia. MMSE data were available for 86 patients who met DSM-III criteria for primary degenerative dementia -- possible or probable Alzheimer's disease (AD). A logistic regression analysis of the probability of correct performance on an item, given the total MMSE score, yielded statistics for difficulty and discrimination. These statistics were interpreted respectively as indicators of the point in the progression of the illness at which the mental function tested by that item is lost and the rapidity of that loss. The data indicated a systematic progression of the development of symptoms in AD related to decline of memory function. Temporal orientation was lost before spatial and object orientation, and recollection of words was lost before ability to repeat them. ICC can help to delineate the loss of mental functions during the course of AD.

Cerebral glucose metabolic patterns in Alzheimer's disease. Effect of gender and age at dementia onset

No previous study of Alzheimer's disease has, to our knowledge, assessed the effect of both age at dementia onset and gender on cerebral glucose metabolic patterns. To this end, we used positron emission tomography (fludeoxyglucose F 18 method) to study 24 patients with clinical diagnoses of probable Alzheimer's disease. Comparisons of the 13 patients with early-onset dementia (less than 65 years of age) with the 11 patients with late-onset dementia (greater than 65 years of age) revealed significantly lower left parietal metabolic ratios (left posterior parietal region divided by the hemispheric average) in the early-onset group. The metabolic ratio of posterior parietal cortex divided by the relatively disease-stable average of caudate and thalamus also separated patients with early-onset dementia from those with late-onset dementia, but not men from women. Further comparisons between sexes showed that, in all brain regions studied, the 9 postmenopausal women had higher nonweighted mean metabolic rates than the 15 men from the same age group, with hemispheric sex differences of 9% on the right and 7% on the left. These results demonstrate decreased parietal ratios in early-onset dementia of Alzheimer's disease, independent of a gender effect.

Advances in Alzheimer therapy: cholinesterase inhibitors

After a decade of intense study of cholinergic therapies for Alzheimer's disease, three conditions in this field are apparent: 1) The potential that cholinergic agents will ameliorate the memory dysfunction of Alzheimer patients (as 1-dopa benefits Parkinson patients) is still a stimulus for research. 2) Cholinergic neuropharmacology and its impact on the therapy of memory disorders associated with cholinergic dysfunction needs to be further characterized and understood. 3) While there is still a search for a symptomatic treatment for AD, the path to find a treatment for the Alzheimer disease process must first pass through a phase of basic research to find the cause of Alzheimer's disease. At the meeting, there was an undercurrent of concern that the cholinergic deficit is too severe to be treated, that the cholinergic systems are too complex to respond to a pharmacologic therapy and that too many other systems are involved in Alzheimer's disease for a cholinergic treatment to be successful. However, this concern was balanced by the evidence of basic scientific experiments which indicate that the central cholinergic system mediating memory can be positively manipulated in animal lesion preparations and Alzheimer tissue. Also there were reports that improved pharmacological approaches and psychological measures are being developed. It appears that Alzheimer therapy is at the stage that cancer chemotherapy was 20 years ago: the promising agents cause nausea without producing clear effects but the basic laboratory studies strongly suggest that substantial benefits are possible and several agents have shown encouraging results. Meanwhile, patients and scientists are becoming increasingly interested in the field.(ABSTRACT TRUNCATED AT 250 WORDS)

Neuropsychological "systems efficiency" and positron emission tomography

Positron emission tomography (PET) has dramatically improved our ability to examine the functioning of the living brain. PET studies of neural pathways of the major sensory modalities--auditory, visual, somatosensory--have confirmed many traditional neuropsychological concepts, such as cross-lateral representation and regional functioning to particular primary sensory cortical areas. Other PET studies have used radioisotopes to examine relationships between radiopharmaceutical agents and neurobehavioral functioning in both normal and neuropathological states. In some areas, PET methodology requires further refinement. For example, effort should be made to develop the technology to do multiple scans within a short time frame; statistical procedures to examine relationships between neuropsychological tasks and the activity or presence of radiopharmaceutical agents in multiple sites; adequate controls for experimental error; and activation paradigms controlling the nonspecific effects of simple arousal. PET activation models of cognition suggest that a "systems efficiency" approach to assessing neuropsychological test performance involving both serial and parallel processing would be useful. These developments will improve empirical methodology and our understanding of brain-behavior relationships.

Clinical characterization of Alzheimer's disease: reliability of 'age at onset' and a new descriptor, 'age at shift'

To determine the interrater reliability of clinical descriptors for Alzheimer's disease (AD), we assessed the degree of agreement among four clinicians who rated 21 patients during a longitudinal study. Despite variability in response patterns, degree of agreement for determining age at onset of dementia was statistically significant (P less than 0.005). We also found significant agreement (P less than 0.0001) among three clinicians for the clinical descriptor, "age at shift" from questionable to probable AD, according to the National Institutes of Health Consensus Criteria. These data demonstrate that both retrospective and prospective descriptors can be reliably determined in the clinical assessment of AD.