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Biomedical subjects

M S Albert

Publications and source records attributed to M S Albert.

At least 19 recordsLinked to original sources
PubMed1995

Age-specific incidence of Alzheimer's disease in a community population.

OBJECTIVE: To determine age-specific incidence rates of clinically diagnosed Alzheimer's disease. DESIGN: Cohort, followed a mean of 4.3 years. SETTING: East Boston, Mass. PARTICIPANTS: Of 2313 persons aged 65 years and older who were initially free of Alzheimer's disease, 1601 participated in the ascertainment of incident disease (80% of survivors), 409 declined participation, and 303 died before the end of the follow-up period. A stratified sample of 642 persons received detailed clinical evaluation. OUTCOME MEASURE: Diagnosis of new probable Alzheimer's disease through structured clinical evaluation including neurologic, neuropsychological, and psychiatric examination. Community incidence rates were computed by 5-year age groups, adjusted for gender, single year of age, length of follow-up interval, and sampling design. RESULTS: The estimated annual incidence of Alzheimer's disease in the population was 0.6% (95% confidence interval [CI], 0.3% to 0.9%) for persons aged 65 to 69 years, 1.0% (95% CI, 0.6% to 1.4%) for persons aged 70 to 74 years, 2.0% (95% CI, 1.3% to 2.7%) for persons aged 75 to 79 years, 3.3% (95% CI, 2.2% to 4.4%) for persons aged 80 to 84 years, and 8.4% (95% CI, 3.7% to 13.1%) for persons aged 85 years and older. CONCLUSIONS: The incidence of Alzheimer's disease is substantial and is approximately 14 times higher among persons older than 85 years compared with those between 65 and 69 years of age.

Age Distribution↗
PubMed1995

Behavioral and psychosocial predictors of physical performance: MacArthur studies of successful aging.

BACKGROUND: Performance-based measures of physical performance are examined for an older cohort of relatively high-functioning men and women. The influences of baseline behavioral, social, and psychological characteristics on patterns of change in performance over 2.5 years are examined. METHODS: A cohort of relatively high-functioning men and women, aged 70-79, identified in 1988 by subsampling from three community-based studies on the basis of physical and cognitive function. Baseline assessments included physical performance, sociodemographic characteristics, health status, and behavioral, social, and psychological characteristics. A summary measure of physical performance was developed from tests of balance, gait, lower body strength and coordination, and manual dexterity. In-home assessments were repeated at follow-up in 1991. RESULTS: Linear regression models were used to identify significant behavioral, social, and psychological predictors of better performance at follow-up, controlling for known sociodemographic and health status predictors. Significant, independent associations with better performance were found for participation in moderate and/or strenuous exercise activity and greater frequency of emotional support from social networks, particularly among those reporting low frequency of instrumental support. These effects remained significant independent of incident health conditions during follow-up. None of the psychological characteristics was a significant predictor. CONCLUSIONS: Maintenance of better physical performance within a high-functioning cohort is influenced by prior exercise behavior and social network emotional support. Observed patterns of both decline and improvement in performance suggest that older age is not uniformly associated with declines. Predictors of better performance identified here may offer potential for effective interventions to promote more successful aging.

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PubMed1995

Interrelationships of peak expiratory flow rate with physical and cognitive function in the elderly: MacArthur Foundation studies of aging.

BACKGROUND: Peak expiratory flow rate (PEFR) is correlated with several measures of health in the elderly, including physical and cognitive function. It is unclear, however, whether these relationships persist among the non-frail. METHODS: The Community-based Studies of the MacArthur Foundation Research Network on Successful Aging included measures of PEFR using a mini-Wright peak flow meter on a sample of 1,354 subjects selected from those aged 70-79 in three population samples. Subjects were chosen on the basis of simple measures of physical and cognitive function (high = 1192; medium = 80; low = 82), and were given a series of more detailed tests. RESULTS: Residual PEFR, adjusted for age, sex, height, weight, and smoking, was highly correlated (p < .001) with several physical performance measures, including number of steps in a tandem walk, number of seconds in a single leg stand, times to turn in a circle, write one's name, and walk 10 feet at a fast pace, foot-tapping (time per tap), and hand grip strength. The strongest association was evident for a combination of six physical function items. Residual PEFR was also correlated with cognitive performance, including tests of similarities, naming, spatial recognition, memory, and figure drawing. The strongest association was present for a combined measure. These associations persisted in analyses restricted to those in the "high" function group as well as with no history of previous myocardial infarction, stroke, or cancer. Residual PEFR also exhibited a strong independent association with urinary norepinephrine, as measured in 12-hour overnight urine specimens. This relation did not appear to be mediated by smoking or medication use.

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PubMed1995

Spectral coherence in normal adults: unrestricted principal components analysis; relation of factors to age, gender, and neuropsychologic data.

This paper demonstrates, by means of Principal Components Analysis (PCA), an objective approach to the reduction of large data sets produced by multichannel spectral coherence analyses. Coherence data, gathered from 371 normal healthy adults using Hjorth/Laplacian referencing during waking eyes-open and eyes-closed states, were analyzed by "unrestricted" PCA where neither spatial nor temporal variance was folded into among subject variance. There was substantial data reduction with our 4416 initial coherence variables for each state reduced to just 150 factors containing approximately 80% of the variance reflecting a 30 fold concentration of information content. Varimax rotation of the first 40 factors, encompassing 50% of the total variance for both states, revealed loading patterns primarily bilateral with no hemispheric bias, relationships primarily between distant single electrode pairs, (although a single electrode to multiple electrode pattern was also observed), and involvement of all spectral bands. Elemental left to right and anterior to posterior coherence patterns, often used on an a priori basis for coherence studies, were not evident among the rotated factor loading patterns. On the basis of high loadings upon extra bipolar artifact channels, 32 factors accounting for approximately 40% of the variance were identified as reflecting artifactual coherence relationships. By multiple regression the 48 non-artifactual factor scores successfully predicted subject age. In general, coherence diminished with age, which may partly explain age-related EEG desynchronization in healthy adults. Coherence factors also predicted 6 of 10 neuropsychologic variables. Gender was successfully predicted by discriminant analysis. No global interpretations about coherence and gender or neuropsychologic function were possible, i.e., almost equal numbers of factors increased as decreased in males as females. PCA derived coherence factor scores are useful for subsequent statistical analyses, but their factor loading plots of cortical coupling may require more experience to fully interpret.

Adult↗
PubMed1994

Biological magnetic resonance imaging using laser-polarized 129Xe.

As currently implemented, magnetic resonance imaging (MRI) relies on the protons of water molecules in tissue to provide the NMR signal. Protons are, however, notoriously difficult to image in some biological environments of interest, notably the lungs and lipid bilayer membranes such as those in the brain. Here we show that 129Xe gas can be used for high-resolution MRI when the nuclear-spin polarization of the atoms is increased by laser optical pumping and spin exchange. This process produces hyperpolarized 129Xe, in which the magnetization is enhanced by a factor of about 10(5). By introducing hyperpolarized 129Xe into mouse lungs we have obtained images of the lung gas space with a speed and a resolution better than those available from proton MRI or emission tomography. As xenon (a safe general anaesthetic) is rapidly and safely transferred from the lungs to blood and thence to other tissues, where it is concentrated in lipid and protein components, images of the circulatory system, the brain and other vital organs can also be obtained. Because the magnetic behaviour of 129Xe is very sensitive to its environment, and is different from that of 1H2O, MRI using hyperpolarized 129Xe should involve distinct and sensitive mechanisms for tissue contrast.

Animals↗
PubMed1994

Reliability and validity of NINCDS-ADRDA criteria for Alzheimer's disease. The National Institute of Mental Health Genetics Initiative.

OBJECTIVE: To assess interrater reliability and validity of NINCDS-ADRDA (National Institute of Neurological and Communicative Diseases and Stroke/Alzheimer's Disease and Related Disorders Association) criteria for Alzheimer's disease (AD). DESIGN: A multisite reliability and validity study in which clinicians from each site diagnosed 60 case summaries yielding a preconsensus estimate of reliability and validity. A consensus conference was conducted for each disagreement, leading to a postconsensus estimate of validity. The criterion standard was a diagnosis of AD by autopsy. SETTING: Three academic medical centers. SUBJECTS: A convenience sample of 60 detailed case summaries, 40 with AD and 20 with other dementing disorders. MAIN OUTCOME MEASURES: The kappa coefficient, sensitivity, and specificity. RESULTS: The kappa coefficient for preconsensus agreement on a diagnosis of probable or possible AD vs non-AD was 0.51; the sensitivity of a diagnosis of probable or possible AD for a pathological diagnosis of AD was 0.81, and the specificity was 0.73. The postconsensus sensitivity was 0.83, and the specificity was 0.84. CONCLUSIONS: The results support the reliability and validity of NINCDS-ADRDA criteria and show that the consensus process may improve diagnostic accuracy. The cases are reviewed with a focus on the sources of diagnostic disagreements and errors and possible changes that might improve the accuracy of the criteria.

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PubMed1994

Performance-based driving evaluation of the elderly driver: safety, reliability, and validity.

BACKGROUND: Our driving population is aging and faces increased risk for injury and death from motor vehicle crashes. Clinicians are often asked to judge the driving safety of their patients without adequate guidelines. This article describes the development of a systematic performance-based road test for measuring driving skills of elderly drivers and its correlation with cognitive measures. METHODS: This was a prospective, masked, observational study in which a driving instructor's global scores ("criterion standard") and cognitive test scores were correlated with research driving scores created by two independent research raters sitting in the back seat of the care during each driving test. A convenience sample of 30 licensed drivers with a broad range of cognitive skills, over age 60, were studied on a closed course and in traffic. RESULTS: Statistically significant correlations were observed between the "criterion standard" and closed course scores (r = .35, p < .05) and between the "criterion standard" and in-traffic scores (r = .64, p < .01). Significant correlations were obtained between in-traffic and cognitive test scores, e.g., Mini-Mental State Exam (r = .72, p < .01). Inter-rater reliability on the closed course was .84 and on the in-traffic component was .74. Internal consistency for the closed course was .78 and for in-traffic was .89. CONCLUSION: This study documented the safety, reliability, and validity of a systematic road test for elderly drivers with a range of cognitive skills. Larger studies are needed to determine the cognitive factors that independently predict driving performance.

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PubMed1994

Muscle torque changes caused by inertial exercise training.

Inertial exercise is a unique form of muscle loading with minimal data available regarding its use or efficacy. The purpose of this study was to describe a standardized clinical training program for inertial exercise using the Impulse system and to experimentally examine the influence of an inertial training program on muscle torque performance. The biceps brachii of 40 healthy subjects were pretested and posttested on the Lido Active dynamometer at 60 and 120 degrees/sec using the continuous passive motion mode. Subjects were randomly assigned to a control or training group. The training group exercised only the nondominant arm three times per week for 5 weeks on the Impulse system. Statistical analysis of peak torque measures between pretests and posttests of muscle torque was performed using a repeated measures analysis of variance design of one between-group (control vs. trained group) and three-within group (speed, arm, and movement; eccentric vs. concentric) factors. Posttraining peak torque measures for both the concentric and eccentric modes of exercise at 60 degrees/sec and for the eccentric mode at 120 degrees/sec were statistically significant at the p < .05 level. Complaints of muscle fatigue occurred during early training sessions, with no injuries and only minimal soreness reported. Inertial training appears to be an effective form of clinical muscular training that is measurable by muscle torque assessment.

Adult↗
PubMed1993

Relation of smoking and low-to-moderate alcohol consumption to change in cognitive function: a longitudinal study in a defined community of older persons.

To determine whether smoking habits and alcohol consumption are related to changes in cognitive function, the authors conducted a prospective, community-based study of persons aged 65 years and over in East Boston, Massachusetts. In 1982 and again in 1985, the subjects were given three brief tests of cognitive function: immediate memory, digit span, and a mental status questionnaire, which primarily assessed orientation. The 1,201 individuals who performed well in 1982 were included in linear regression analyses of 3-year change in performance, adjusted for age, sex, education, and income. Relative to nonsmoking, current smoking, past smoking, and pack-years were not significantly related to change in immediate memory. None was significantly related to change in orientation. Only pack-years was significantly related to normal change score in digit span (normal change score change per unit of predictor = 0.001, 95% confidence interval 0.0003-0.002). Low-to-moderate alcohol consumption during the month preceding baseline testing was not significantly related to a subsequent 3-year change in performance in two of the three tests. However, people who consumed a very small amount of alcohol had a normal change score that was 0.088 (95% confidence interval 0.015-0.160) better for digit span than did nondrinkers. This study provides evidence that the reported levels of smoking and alcohol use among older persons are not consistent or substantial predictors of the longitudinal change in cognitive function observed in a community.

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PubMed1993

Extrapyramidal signs and other neurologic findings in clinically diagnosed Alzheimer's disease. A community-based study.

The association between findings on the neurologic examination and the clinical diagnosis of Alzheimer's disease was investigated among 467 individuals from a geographically defined community population. Participants were selected by stratified random sampling based on their memory performance in a population survey of community residents 65 years of age and older. Each participant underwent a structured medical, psychiatric, neurologic, and neuropsychologic examination. Of the 467 persons examined there were 134 cases of probable Alzheimer's disease and 167 control subjects. Multiple logistic regression analysis was used to estimate the degree to which the presence of each of several neurologic examination findings affected the age- and sex-adjusted relative odds of having clinically diagnosed Alzheimer's disease. The most striking associations with the diagnosis of Alzheimer's disease were seen with various measures of extrapyramidal dysfunction. These increased relative odds were not markedly affected by excluding from the analysis cases with severe cognitive impairment. The results suggest that involvement of the extrapyramidal system is a common finding in Alzheimer's disease.

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PubMed1993

Temporal lobe regions on magnetic resonance imaging identify patients with early Alzheimer's disease.

OBJECTIVE: The goal of the study was to examine the volume of selected brain regions in a group of mildly impaired patients with Alzheimer's disease (AD). Five regions were selected for analysis, all of which have been reported to show substantial change in the majority of patients with AD at some time in the course of disease. DESIGN: Case-control study with the experimenter "blinded." SETTING: Hospital-based magnetic resonance imaging center. PARTICIPANTS: Fifteen subjects, eight patients with the diagnosis of probable dementia of the Alzheimer type made in concordance with National Institute of Neurological and Communicative Diseases and Stroke/Alzheimer's Disease and Related Disorders Association criteria and seven age-matched healthy control subjects. RESULTS: Three of the volumetric measures were significantly different between patients with AD and controls: the hippocampus, the temporal horn of the lateral ventricles, and the temporal lobe. Two of the measures did not significantly differentiate patients with AD and controls: the amygdala and the basal forebrain. A discriminant function analysis demonstrated that a linear combination of the volumes of the hippocampus and the temporal horn of the lateral ventricles differentiated 100% of the patients and controls from one another. CONCLUSIONS: The results suggest that the hippocampus and the temporal horn of the lateral ventricles may be useful as antemortem markers of AD in mildly impaired patients.

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PubMed1993

Level of education and change in cognitive function in a community population of older persons.

In a community population of persons over the age of 65, cognitive function was assessed using brief performance tests on two occasions 3 years apart. Those with fewer years of formal education consistently had greater declines in cognitive function, independently of age, birthplace, language of interview, occupation, and income. These prospective findings suggest that low educational attainment or a correlate predicts cognitive decline. It is not clear, however, whether this relation represents a direct effect of education on future cognition, whether education might be related to occurrence of a disease leading to cognitive decline in older persons, or whether education might be a surrogate for some variable not included in the study.

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PubMed1993

Cognitive performance in a high-functioning community-dwelling elderly population.

BACKGROUND: The purpose of this study was to examine the role of demographic factors as predictors of cognitive performance in a high-functioning, community-dwelling elderly population. METHODS: The study cohort consisted of 1,192 community-dwelling subjects, who were selected to represent the highest third of an elderly population with respect to physical and cognitive functioning. A neuropsychological battery, including 5 cognitive performance subtests (confrontation naming, delayed recognition span, similarities, figure-copying, and incidental delayed recall) was administered to the subjects in their homes. RESULTS: A summary measure of the 5 neuropsychological subtest scores, the total cognitive score, arrayed the study group across a broad range of difficulty, creating a near-normal distribution. Education, income, and race had statistically significant associations with the total score and the individual subtests. The effect of education was the most striking finding, explaining 30% of the variance in the total score. Education was most strongly related to the abstraction (partial R2 = .11) subtest, and least related to the memory subtests, delayed recognition (R2 = .02) and delayed recall (R2 = .01). CONCLUSIONS: Demographic factors are important predictors of cognitive performance in this high-functioning cohort. Education had the strongest influence on overall cognitive performance, and particularly notable associations with subtests that depended upon the use of previously learned materials. Longitudinal follow-up, now underway, will help to determine whether high levels of education help to maintain cognitive performance with age.

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PubMed1993

Measured versus estimated creatinine clearance in a high-functioning elderly sample: MacArthur Foundation Study of Successful Aging.

OBJECTIVE: To assess the validity of several equations for estimating creatinine clearance in a large sample of high-functioning, community-dwelling elderly. DESIGN: Serum and 12-hour urine samples were collected and assayed for creatinine using the Jaffe total chromagen method. Fifteen clearance-estimating equations were evaluated for bias, accuracy, correlation with measured clearance values, and frequency of erroneous placement into renal function categories. Stepwise regression modeling and reliability testing were performed on a split sample to construct and assess a novel creatinine-clearance-estimating equation. SETTING: New Haven, Connecticut, East Boston, Massachusetts, and a five-county region in and around Durham, North Carolina. PARTICIPANTS: A subsample of community-dwelling men and women (age range 70-79 years) from the Established Populations for Epidemiological Studies of the Elderly was screened for physical and cognitive functioning and placed into high-, medium-, and low-functioning groups (n = 1354). High-functioning respondents who provided blood and complete urine samples (n = 762) were included in the present study. RESULTS: In general, estimated creatinine clearance was more closely correlated to measured values in males than in females. Most equations underestimated creatinine clearance, with average bias ranging from -33.1 mL/min to +19.6 mL/min. Predictive accuracy ranged from 18.2 mL/min to 38.0 mL/min. Equations were variable in their erroneous placement of individuals into renal function categories. Regression modeling yielded an equation which contained novel components but failed to provide better estimates of creatinine clearance than those already available. CONCLUSIONS: The equations evaluated here provide unacceptable predictions of creatinine clearance in normally aging individuals. We advocate the use of serum drug concentration measurements when available and encourage investigation into timed urine collections of short duration as alternatives to clearance-estimating equations in the elderly.

Activities of Daily Living↗
PubMed1992

Relation of smoking and alcohol consumption to incident Alzheimer's disease.

The authors examined the effects of smoking and alcohol use in a prospective community-based study of incident Alzheimer's disease. Two in-home interviews of the total elderly population of East Boston, Massachusetts, conducted in 1982 and 1985 were used to sample individuals for clinical evaluation for Alzheimer's disease. A total of 513 persons underwent detailed clinical evaluation including neurologic, neuropsychologic, and psychiatric evaluation to diagnose Alzheimer's disease. In weighted logistic regression controlled for age, sex, and education, the estimated odds ratio of Alzheimer's disease was 0.7 (95% confidence interval 0.3-1.4) for ever smokers compared with never smokers. For 40 pack-years of smoking, the odds ratio of Alzheimer's disease was 0.8 (95% confidence interval 0.6-1.1). Consumption of 1 oz (30 ml) of alcohol per day was associated with an odds ratio of 1.1 (95% confidence interval 0.8-1.5). These results suggest that recent mild-to-moderate consumption of alcohol is not substantially related to incidence of Alzheimer's disease and that smoking does not increase risk of the disease.

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PubMed1991

Risk of death from Alzheimer's disease in a community population of older persons.

A random sample of 467 persons over age 65 years from the population of an urban US community, stratified by age, sex, and performance on a brief memory test, underwent clinical evaluation for dementing illness in 1982-1984. Of these persons, 134 had probable Alzheimer's disease, 166 had possible Alzheimer's disease, and 167 had no evidence of Alzheimer's disease. Over a median follow-up period of 4.9 years following evaluation, 165 (35%) died. Overall, persons with probable Alzheimer's disease had a relative risk of death 1.44 (95% confidence interval (Cl) 1.05-1.96) times that of the unaffected. Level of cognitive impairment and the presence of cachexia upon physical examination both strongly and independently modified risk of death. Among those with probable Alzheimer's disease, mortality for those with mild or moderate cognitive impairment and no evidence of cachexia was comparable to that of the unaffected. However, among those with probable Alzheimer's disease and either severe cognitive impairment or cachexia, the risk of death was substantially higher. Persons with probable Alzheimer's disease who had both severe cognitive impairment and clear cachexia had a risk of death 4.60 (95% Cl 1.63-13.1) times that of unaffected persons.

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