Phase I/IIa trial of the mammalian target of rapamycin inhibitor ridaforolimus (AP23573; MK-8669) administered orally in patients with refractory or advanced malignancies and sarcoma.

BACKGROUND: Ridaforolimus is an inhibitor of mTOR with evidence of antitumor activity in an I.V. formulation. This multicenter, open-label, 3 + 3 design nonrandomized, dose-escalation, phase I/IIa trial was conducted to determine the safety, pharmacokinetic (PK) and pharmacodynamic parameters, maximum tolerated dose, and antitumor activity of oral ridaforolimus. PATIENTS AND METHODS: Patients with metastatic or unresectable solid tumors refractory to therapy were eligible. Seven different continuous and intermittent dosing regimens were examined. RESULTS: One hundred and forty-seven patients were enrolled in this study among which 85 were patients with sarcoma. Stomatitis was the most common DLT observed. The dosing regimen, 40 mg QD × 5 days/week, provided the best combination of cumulative dose, dose density, and cumulative exposure, and was the recommended dosing regimen for subsequent clinical development. PK was nonlinear, with less than proportional increases in day-1 blood AUC0-∞ and Cmax, particularly with doses >40 mg. The terminal half-life estimate of ridaforolimus (QD × 5 40 mg) was 42.0 h, and the mean half-life ∼30-60 h. The clinical benefit rate, (complete response, partial response, or stable disease for ≥4 months was 24.5% for all patients and 27.1% for patients with sarcoma. CONCLUSION: Oral ridaforolimus had an acceptable safety profile and exhibited antitumor activity in patients with sarcoma and other malignancies. ClinicalTrials.gov Identifier NCT00112372.

Differential turnover of the subunits of ribonucleotide reductase in synchronized leukemia L1210 cells.

Ribonucleotide reductase catalyzes the rate-limiting step in the de novo synthesis of 2'-deoxyribonucleoside 5'-triphosphates that is required for DNA replication. The mammalian enzyme consists of two nonidentical protein subunits that are both required for enzyme activity. In leukemia L1210 cells, enriched in G1-phase cells by centrifugal elutriation, it was found that ribonucleotide reductase activity increased as the cells progressed to S-phase. The two subunits making up the holoenzyme did not increase coordinately. The nonheme iron subunit increased much more rapidly than the effector-binding (EB) subunit. The activity of the holoenzyme paralleled the level of the EB subunit, which was limiting. The half-lives of the holoenzyme and its subunits were determined in S-phase cells by treatment with cycloheximide. The half-lives of the holoenzyme and the nonheme iron and EB subunits, as determined by enzyme activity, were 3.5, 7.6, and 4 h, respectively. These half-lives are consistent with the data that indicate that the EB subunit is the limiting component in L1210 cells.

Ubiquitin/26S proteasome-mediated degradation of topoisomerase I as a resistance mechanism to camptothecin in tumor cells.

Camptothecin (CPT) induces down-regulation of topoisomerase I (TOP1) via an ubiquitin/26S proteasome pathway. Studies using a panel of breast and colorectal cancer cell lines as well as primary nontransformed and oncogene-transformed cells have demonstrated that CPT-induced down-regulation exhibits a high degree of heterogeneity. In general, nontransformed cells are much more proficient in CPT-induced TOP1 down-regulation than their transformed counterparts. Among the breast and colorectal cancer cell lines, there was a general correlation between the extent of CPT-induced TOP1 down-regulation and CPT resistance. The breast cancer cell line ZR-75-1, the most sensitive to CPT, was completely defective in CPT-induced TOP1 down-regulation, whereas the breast cancer cell line BT474, the least sensitive to CPT, exhibited effective CPT-induced TOP1 down-regulation. The 26S proteasome inhibitor MG132 was shown to inhibit CPT-induced down-regulation of TOP1 in BT474 cells and selectively sensitized BT474 but not ZR-75-1 cells to CPT-induced cytotoxicity and apoptosis. In the aggregate, these results suggest that CPT-induced down-regulation of TOP1 could be an important parameter for determining CPT sensitivity/resistance in tumor cells. Analysis of the levels of TOP1 cleavable complexes, SUMO-1-TOP1 conjugates, and ubiquitin-TOP1 conjugates in ZR-75-1 and BT474 cells has suggested that the heterogeneity of CPT-induced down-regulation of TOP1 in tumor cells is at least in part attributable to altered regulation of a process(es) downstream from the TOP1 cleavable complex.

Mechanisms of resistance in a human cell line exposed to sequential topoisomerase poisoning.

Camptothecins are a new class of anticancer drugs that target DNA topoisomerase I; current efforts are directed toward elucidating optimal combinations of these drugs with other antineoplastic agents. A rationale for the use of sequential therapy involving the combination of camptothecins with topoisomerase II-targeting drugs, such as etoposide, has arisen from observations of increased topoisomerase II protein levels in cell lines resistant to camptothecin. In an effort to understand potential mechanisms of resistance to this strategy, we developed a U-937 cell subline, denoted RERC, that is capable of surviving exposure to sequential topoisomerase poisoning. The RERC cells are 200-fold resistant to camptothecin, 8-fold resistant to etoposide, and 10-fold hypersensitive to cisplatin compared to the parental U-937 cells. Biochemical analyses indicate that the resistant phenotype involves alterations in both topoisomerase I and topoisomerase IIalpha. Topoisomerase I catalytic activity in the resistant cells is similar to that of the parental line but is resistant to camptothecin. Moreover, the resistant cells express a single mRNA species of topoisomerase I that codes for a mutation in codon 533. In addition, topoisomerase IIalpha protein levels are decreased 10-fold in the resistant line, coincident with a two-fold decrease in the expression of topoisomerase IIalpha mRNA. Collectively, these results indicate that resistance to sequential topoisomerase poisoning may involve a reduction in total cellular topoisomerase activity.

Risk factors for high-dose cytarabine neurotoxicity: an analysis of a cancer and leukemia group B trial in patients with acute myeloid leukemia.

PURPOSE: We analyzed pretreatment characteristics of patients with postremission acute myeloid leukemia (AML) treated with high-dose cytarabine (HIDAC) during a recent Cancer and Leukemia Group B (CALGB) trial to determine risk factors associated with HIDAC neurotoxicity. PATIENTS AND METHODS: One hundred seventy-six patients received at least one course of HIDAC as part of a CALGB protocol designed to determine the optimal dose of cytarabine (ara-C) for postremission treatment of AML. HIDAC consisted of 3 g/m2 ara-C infused over 3 hours at 12-hour intervals on days 1, 3, and 5. The pretreatment characteristics of 170 patients were available for risk analyses. RESULTS: Eighteen patients (10%) experienced neurotoxicity. Univariate analyses demonstrated associations between the occurrence of neurotoxicity and elevated serum creatinine, age, and alkaline phosphatase (AP). Multivariate analysis showed that these variables were independent risk factors. These findings were used to construct a risk model with the following parameters: creatinine greater than or equal to 1.2 mg/dL, age greater than or equal to 40 years, and AP greater than or equal to 3 x normal. Seventeen of 46 (37%) patients with two or more of these criteria developed neurotoxicity compared with one of 124 (1%) patients with one or none. The sensitivity and specificity of this model were 94% and 81%, respectively. CONCLUSION: We conclude that patients with two or more of the following parameters may be at increased risk for HIDAC neurotoxicity: (creatinine greater than or equal to 1.2 mg/dL, age greater than or equal to 40, and AP greater than or equal to 3 x normal). However, this model should be confirmed by analysis of additional groups of patients treated with HIDAC.

Increased neocortical neurofibrillary tangle density in subjects with Alzheimer disease and psychosis.

BACKGROUND: Psychosis is common in patients with Alzheimer disease. While the relationship between psychosis and clinical variables has been examined frequently, few studies have examined the relationship between psychosis and the 2 major neuropathological hallmarks of Alzheimer disease: neurofibrillary tangles and senile plaques. We characterized the occurrence of psychosis in relation to dementia severity and determined if subjects with Alzheimer disease and psychosis had a greater neurofibrillary tangle or senile plaque burden than subjects with Alzheimer disease and no psychosis. METHODS: One hundred nine subjects with Alzheimer disease were followed longitudinally with semistructured assessments in order to assign a Clinical Dementia Rating and determine whether psychosis was present. After the subjects died, their brains were obtained for histological examination. Analysis of variance was used to compare the densities of neurofibrillary tangles, total senile plaques, and cored senile plaques in subjects with psychosis vs subjects without psychosis, in several neocortical regions, the hippocampus, and the entorhinal cortex. RESULTS: Psychosis occurred commonly in Alzheimer disease, affecting 63% of subjects. The frequency of psychosis increased with increasing dementia severity. More importantly, we found that subjects with psychosis had a 2.3-fold (95% confidence interval, 1.2-3.9) greater density of neocortical neurofibrillary tangles than did subjects without psychosis. The increase was independent of dementia severity. No similar relationship with psychosis was seen for total senile plaques or cored senile plaques. CONCLUSIONS: The increase in psychosis frequency that occurs with the progression of dementia severity and the independent association between psychosis and neurofibrillary tangle density suggest the possibility that some common underlying process or processes specific to Alzheimer disease may regulate both phenomena. Arch Gen Psychiatry. 2000;57:1165-1173.

Effects of alprazolam on glucose regulation in diabetes. Results of double-blind, placebo-controlled trial.

OBJECTIVE: To determine the effects of alprazolam on glucose regulation in anxious and nonanxious patients with poor glycemic control and establish whether regulatory benefits are related to anxiolytic effects of the medication. RESEARCH DESIGN AND METHODS: Fifty-eight patients with poor glycemic control, 16 (27.6%) of whom had a symptomatic generalized anxiety disorder, were entered into a randomized, double-blind, placebo-controlled, 8-week trial using alprazolam (up to 2 mg/day) as the active agent. Generalized anxiety disorder was determined in accordance with Diagnostic and Statistical Manual of Mental Disorders criteria, and anxiety symptoms were measured using the Hopkins Symptom Checklist. Glycated hemoglobin levels were used to determine glucose regulation. Compliance behavior was assessed using glucometers and medication monitors equipped with electronic memory. RESULTS: A statistically significant reduction in glycated hemoglobin level was observed in patients treated with alprazolam compared with those receiving placebo (-1.1 vs. -0.3%, P = 0.04). This treatment effect was not a function of differences in compliance behaviors. Anxiety symptoms decreased in both alprazolam- and placebo-treated patients with generalized anxiety disorder, but reduction in glycated hemoglobin level was not dependent on alleviation of anxiety. CONCLUSIONS: A short course of alprazolam improved glucose regulation in patients with a history of poor diabetes control. This effect was not directly related to concomitant changes in anxiety. Alprazolam treatment of anxious patients with poorly controlled diabetes may result in decreased anxiety and improved glucose regulation through independent mechanisms.

Psychotic symptoms and the longitudinal course of senile dementia of the Alzheimer type.

Delusions, misidentifications and hallucinations occur frequently throughout the course of senile dementia of the Alzheimer type (SDAT). Rates of psychosis among subjects with moderate to severe SDAT range from 42% to 84% in our study group; at least half of persons with SDAT with no prior psychiatric history will display psychosis at some point during the course of dementia. Furthermore, psychotic symptoms are associated with accelerated cognitive deterioration, but not with increased mortality.

Case report of a toxic reaction from a combination of tryptophan and phenelzine.

The addition of tryptophan to a monoamine oxidase inhibitor (MAOI) has been recommended for patients failing to respond to an MAOI alone. The authors report acute behavioral and neurologic toxicity immediately after tryptophan administration in a patient taking phenelzine.

Psychopathology of very mild dementia of the Alzheimer type.

The authors describe psychiatric abnormalities, including personality and affective changes and psychotic symptoms, associated with very mild senile dementia of the Alzheimer type. The behavioral and affective changes in the subjects with very mild dementia resembled those occurring in subjects with mild dementia, but psychotic symptoms rarely occurred until the dementia had progressed to at least a mild stage.

The influence of major depression on clinical and psychometric assessment of senile dementia of the Alzheimer type.

OBJECTIVE: The performance on standard clinical and psychometric assessments of eight elderly individuals with major unipolar depression alone and seven with depression plus mild senile dementia of the Alzheimer type was compared with that of 41 nondepressed subjects suffering from very mild senile dementia of the Alzheimer type, 66 with mild senile dementia of the Alzheimer type, and 83 age-matched subjects without senile dementia. METHOD: Subjects with depression alone, depression plus mild senile dementia of the Alzheimer type, and very mild and mild senile dementia of the Alzheimer type met strict inclusionary and exclusionary criteria. A 90-minute semistructured interview, including several brief standardized clinical scales, was used to assign a Clinical Dementia Rating to each subject according to published guidelines, and each subject was given a 2-hour psychometric test battery. Data were analyzed by one-way multivariate analysis of variance to ascertain if there was an effect of group on clinical and psychometric test scores. RESULTS: The eight depressed subjects without concurrent dementia performed as well as the 83 nondepressed subjects without dementia on most clinical measures; however, their performance on most psychometric measures closely resembled that of the 41 nondepressed subjects with very mild dementia. The performance of the seven subjects with depression plus mild dementia was comparable to that of the 66 nondepressed subjects with mild dementia on most clinical and psychometric measures. CONCLUSIONS: Although depressed subjects performed as well as subjects without dementia on many clinical assessments, psychometric testing was not able to distinguish depressed subjects from those with very mild senile dementia of the Alzheimer type. This demonstrates the need for careful psychiatric evaluation before interpreting deficits on psychometric tests as indicating the presence of very mild senile dementia of the Alzheimer type.

Psychopathology in younger versus older persons with very mild and mild dementia of the Alzheimer type.

OBJECTIVE: The psychopathology associated with early-onset dementia of the Alzheimer type was investigated by comparing the prevalence of psychiatric symptoms in younger subjects (mean age = 59 years) who had very mild or mild dementia with that in older adults (mean age = 72) whose dementia was of equivalent severity. METHOD: Nondemented comparison subjects and persons with very mild or mild dementia of the Alzheimer type were recruited to participate in longitudinal studies. All subjects met strict inclusion and exclusion criteria. Information pertaining to personality changes, affective symptoms, and psychotic symptoms was included in the 90-minute semistructured, physician-administered interview, which was used to assign a clinical dementia rating according to published guidelines. The younger group were age 64 or younger and consisted of 20 nondemented subjects, 11 subjects with very mild dementia, and 18 subjects with mild dementia. The older group, described previously, were 64-83 years old and consisted of 83 nondemented subjects, 41 persons with very mild dementia, and 68 subjects with mild dementia. RESULTS: The psychopathology in the younger subjects was similar to that in the older group. Personality changes occurred in over 80% of the younger persons with very mild illness. Psychotic symptoms were present in over 40% of the younger persons with mild illness but were rare in the group with very mild dementia. CONCLUSIONS: Similar patterns of psychopathology in younger and more elderly persons with dementia of the Alzheimer type support the suggestion that these changes are direct effects of the illness on the CNS. Increased attention to documenting these noncognitive symptoms and studying various treatments is urgently needed.

Very mild senile dementia of the Alzheimer type. I. Clinical assessment.

We report a longitudinal study of 16 subjects originally enrolled in the Washington University (St Louis, Mo) Memory and Aging Project with Clinical Dementia Rating (CDR) of "questionable" dementia (CDR 0.5). A 0.5 rating was intended to characterize subjects in whom mild cognitive impairment due to senile dementia of the Alzheimer type was suspected but was insufficient in degree to warrant a diagnosis of definite dementia. Over an 84-month follow-up period, 11 of the 16 subjects either had Alzheimer's disease verified post mortem or had clinically progressed to a more advanced CDR stage in which the dementia was clearly evident. These results suggest that the CDR 0.5 stage likely represents the incipient clinical manifestation of Alzheimer's disease and that the majority of subjects with CDR 0.5 have "very mild senile dementia of the Alzheimer type." Performance on several standard clinical scales was significantly different when comparing a larger sample of controls (n = 83), subjects with CDR 0.5 (n = 41), and subjects with mild senile dementia of the Alzheimer type (score of 1; n = 68).

Reliability of the Washington University Clinical Dementia Rating.

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

Mild cognitive impairment represents early-stage Alzheimer disease.

BACKGROUND: Mild cognitive impairment (MCI) is considered to be a transitional stage between aging and Alzheimer disease (AD). OBJECTIVE: To determine whether MCI represents early-stage AD by examining its natural history and neuropathologic basis. DESIGN: A prospective clinical and psychometric study of community-living elderly volunteers, both nondemented and minimally cognitively impaired, followed up for up to 9.5 years. Neuropathologic examinations were performed on participants who had undergone autopsy. SETTING: An AD research center. PARTICIPANTS: All participants enrolled between July 1990 and June 1997 with Clinical Dementia Rating (CDR) scores of 0 (cognitively healthy; n = 177; mean age, 78.9 years) or 0.5 (equivalent to MCI; n = 277; mean age, 76.9 years). Based on the degree of clinical confidence that MCI represented dementia of the Alzheimer type (DAT), 3 subgroups of individuals with CDR scores of 0.5 were identified: CDR 0.5/DAT, CDR 0.5/incipient DAT, and CDR 0.5/uncertain dementia. MAIN OUTCOME MEASURE: Progression to the stage of CDR 1, which characterizes mild definite DAT. RESULTS: Survival analysis showed that 100% of CDR 0.5/DAT participants progressed to greater dementia severity over a 9.5-year period. At 5 years, rates of progression to a score of CDR 1 (or greater) for DAT were 60.5% (95% confidence interval [CI], 50.2%-70.8%) for the CDR 0.5/DAT group, 35.7% (95% CI, 21.0%-50.3%) for the CDR 0.5/incipient DAT group, 19.9% (95% CI, 8.0%-31.8%) for the CDR 0.5/uncertain dementia group, and 6.8% (95% CI, 2.2%-11.3%) for CDR 0/controls. Progression to greater dementia severity correlated with degree of cognitive impairment at baseline. Twenty-four of the 25 participants with scores of CDR 0.5 had a neuropathologic dementing disorder, which was AD in 21 (84%). CONCLUSIONS: Individuals currently characterized as having MCI progress steadily to greater stages of dementia severity at rates dependent on the level of cognitive impairment at entry and they almost always have the neuropathologic features of AD. We conclude that MCI generally represents early-stage AD.

Influence of age on clinical and psychometric assessment of subjects with very mild or mild dementia of the Alzheimer type.

OBJECTIVE: The influence of age on performance on clinical and psychometric assessments is examined in groups of nondemented persons and individuals with either very mild or mild dementia of the Alzheimer type (DAT). DESIGN: Initial clinical and psychometric assessments of persons enrolled in longitudinal studies of DAT and nondemented control subjects. SETTING: Alzheimer's Disease Research Center at Washington University, St Louis, Mo. PARTICIPANTS: Volunteer samples of 108 people (44 men, 64 women) with mild DAT, 61 people (30 men, 31 women) with very mild DAT, and 122 healthy nondemented people (45 men, 77 women) were recruited between 1979 and 1991. Age ranged from 54 to 87 years. Persons with confounding medical, neurologic, or psychiatric disorders were excluded. Dementia severity was staged using the Clinical Dementia Rating scale. MAIN OUTCOME MEASURES: Five brief quantitative clinical tests included in the 90-minute clinician administered protocol, as well as 14 tests included in a 2-hour psychometric test battery. RESULTS: Dementia severity affected performance on all measurements. Age did not influence performance on clinical assessments. There was a significant interaction between age and dementia severity on 10 of 14 psychometric measures. In general, older nondemented individuals performed less well than younger nondemented individuals while older mildly demented persons performed about the same as, or slightly better than, their younger counterparts. CONCLUSIONS: Age does not affect performance on brief clinical assessment instruments. However, age affects psychometric performance differently in cognitively intact persons when compared with persons with DAT. As a result, psychometric differentiation between cognitively normal and demented individuals is more difficult in older populations.

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

OBJECTIVE: To examine the earliest cognitive changes associated with the onset of dementia as well as changes associated with normal aging. DESIGN: Longitudinal evaluation of participants with annual clinical and psychometric examinations for up to 15 1/2 years. SETTING AND PARTICIPANTS: Elderly volunteers (n = 82) enrolled with a Clinical Dementia Rating of 0 (cognitively intact) in longitudinal studies. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Clinical Dementia Rating and results of a 1 1/2-hour psychometric battery. RESULTS: As estimated with survival analysis, 40% of participants had a Clinical Dementia Rating greater than 0 (cognitive decline) within 12 years of enrollment; 59% of these were judged to have dementia of the Alzheimer type or incipient dementia. Participants with poorer performance on psychometric testing at enrollment were at higher risk for cognitive decline subsequently. The rate of change in psychometric performance before clinically detectable cognitive change occurred was not significantly different between those who eventually developed dementia and those who remained stable, except for performance on the Logical Memory subtest of the Wechsler Memory Scale. When subtle cognitive decline was clinically detected, however, an abrupt deterioration in performance on independently administered psychometric tests was observed. CONCLUSIONS: Cognitively healthy elderly people maintain stable cognitive performance when measured longitudinally by both careful clinical evaluation and repeated psychometric testing. This stability is maintained unless and until they develop a dementing illness, at which time a sharp decline in performance is observed.

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

OBJECTIVE: To study differences between subjects with Alzheimer disease (AD) and cognitively intact control subjects, with respect to brain histologic markers of AD, and the relationship of those markers in the AD group to severity of dementia, age at death, sex, and apolipoprotein E genotype. SETTING: Washington University Alzheimer's Disease Research Center, St Louis, Mo. DESIGN AND SUBJECTS: Consecutive neuropathologic series of 224 prospectively studied volunteer research subjects, 186 with dementia of the Alzheimer type (DAT) or "incipient" DAT and confirmed to have AD by postmortem examination and 13 cognitively intact subjects, confirmed to lack postmortem findings of AD. MAIN OUTCOME MEASURES: Brain densities (number per square millimeter) of senile plaques and neurofibrillary tangles, extent of cerebral amyloid angiopathy, cortical Lewy bodies, and apolipoprotein E genotype. RESULTS: Neocortical neurofibrillary tangle densities were substantially correlated with dementia severity, and to a greater degree than was true for senile plaque densities. When infarcts, hemorrhages, and Parkinson disease changes coexisted with AD, neurofibrillary tangle and senile plaque densities were lower. Plaque-predominant AD was found in a greater proportion of subjects with milder than more severe dementia. Entorhinal cortical Lewy bodies were no more frequent in plaque-predominant AD than in the remaining AD cases. Increasing age at death was negatively correlated with dementia severity and densities of senile plaques and neurofibrillary tangles. The apolipoprotein E epsilon4 allele frequency was greater in AD than in control subjects but decreased with increasing age. After controlling for dementia severity, senile plaque densities were only weakly related to epsilon4 allele frequency, and only in hippocampus. However, the degree of cerebral amyloid angiopathy was clearly related to epsilon4 allele frequency. Among subjects diagnosed during life as having DAT or incipient DAT, only 7% were found to have a neuropathologic disorder other than AD causing their dementia. CONCLUSIONS: (1) The order of the strength of relationships between densities of histologic markers and dementia severity in AD is neurofibrillary tangles greater than cored senile plaques greater than total senile plaques. (2) Advanced age at death is associated with somewhat less severe dementia and fewer senile plaques and neurofibrillary tangles. (3) Plaque-predominant AD may represent a developmental stage in AD. (4) Despite a substantial effect of apolipoprotein E epsilon4 as a risk factor for AD, on decreasing the age at AD onset, and increasing the amount of cerebral amyloid angiopathy, its effect on senile plaque densities is variable and complex, being confounded with age, dementia severity, and methodologic differences. (5) Stringent clinical diagnostic criteria for DAT, even in the very mild stage, and senile plaque-based neuropathologic criteria for AD are highly accurate.

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

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