Biomedical subjects

L J Brant

Publications and source records attributed to L J Brant.

At least 19 recordsLinked to original sources

PubMed2001

Hormone replacement therapy and longitudinal changes in blood pressure in postmenopausal women.

BACKGROUND: The incidence of hypertension in postmenopausal women exceeds that in age-matched men. Longitudinal studies relating hormone replacement therapy (HRT) to blood pressure changes are sparse. OBJECTIVE: To investigate the association between HRT and longitudinal changes in blood pressure in postmenopausal women. DESIGN: Longitudinal observational study. SETTING: Community-dwelling volunteers. PATIENTS: 226 healthy, normotensive postmenopausal women from the Baltimore Longitudinal Study of Aging with a mean (+/-SD) age of 64 +/- 10 years were followed for 5.7 +/- 5.3 years. Seventy-seven women used both estrogen and progestin, and 149 used neither. MEASUREMENTS: Lifestyle variables, blood pressure, and traditional cardiovascular risk factors were measured at baseline and approximately every 2 years thereafter. RESULTS: Systolic blood pressure at baseline was similar in HRT users and nonusers (133.9 +/- 16.0 mm Hg vs. 132.4 +/- 14.8 mm Hg). Over time, average systolic blood pressure increased less in HRT users than nonusers, independent of other cardiovascular risk factors, physical activity, and alcohol use. For example, HRT users who were 55 years of age at their first Baltimore Longitudinal Study of Aging visit experienced a 7.6-mm Hg average increase in systolic blood pressure over 10 years; in contrast, the average increase in nonusers was 18.7 mm Hg. The lesser increase in systolic blood pressure in HRT users was more evident at older age. Diastolic blood pressure, which did not change statistically over time in either group, was not associated with HRT. CONCLUSION: Postmenopausal women taking HRT have a smaller increase in systolic blood pressure over time than those not taking HRT. This difference is intensified at older ages.

Age Factors↗

PubMed2001

Is the apoE4 allele an independent predictor of coronary events?

PURPOSE: Although the apolipoprotein E genotype epsilon4 (apoE4) has been associated with high cholesterol levels, whether it is an independent predictor of coronary events is not certain. SUBJECTS AND METHODS: We measured apoE genotypes in 730 participants in the Baltimore Longitudinal Study of Aging (421 men and 309 women, mean [+/- SD] age of 52+/-17 years) who were free of preexisting coronary heart disease. A proportional hazards regression model was used to study the association between risk factors and the occurrence of coronary events, defined as angina pectoris, documented myocardial infarction by history or major Q waves on the electrocardiogram (Minnesota Code 1:1 or 1:2), or coronary death, adjusted for other risk factors, including total plasma cholesterol level. RESULTS: The apoE4 allele was observed in 200 subjects (27%), including 183 heterozygotes and 17 homozygotes. Coronary risk factor profiles were similar in those with and without apoE4. Coronary events developed in 104 (14%) of the 730 subjects, including 77 (18%) of the 421 men during a mean follow-up of 20 years and 27 (9%) of the 309 women during a mean follow-up of 13 years. Coronary events occurred significantly more frequently in subjects with apoE4 (n = 40, 20%) than in those without this allele (64, 12%, P <0.05). In a multivariate model, apoE4 was an independent predictor of coronary events in men (risk ratio [RR]= 2.9, 95% confidence interval [CI]: 1.8 to 4.5, P<0.0001) but not in women (RR = 0.9, 95% CI: 0.4 to 1.9, P = 0.62). CONCLUSION: The apoE4 genotype is a strong independent risk factor for coronary events in men, but not women. The association does not appear to be mediated by differences in total cholesterol levels.

Adult↗

PubMed1999

The effect of gestational parity on FEV1 in a group of healthy volunteer women.

In the past, studies utilizing within-subject comparisons of small groups of pregnant women showed that forced expiratory volume in 1 s (FEV1) remained essentially unchanged during pregnancy. However, one of the findings from an epidemiological study was that women with greater number of children experienced a faster decline of FEV1. The aim of this study was to examine the effect of parity on FEV1 in a group of healthy volunteer women. To this end, cross-sectional multiple regression analyses of data from 397 healthy women participants in the Baltimore Longitudinal Study of Aging (BLSA) with a mean (range) age of 47.7 (18-92) years were performed. Similar analyses were done using the younger (50 years or less) and the older (> 50 years) subgroups. After controlling for age, height, weight, and smoking, parity as a dichotomous variable was associated with a higher FEV1 in women of child-bearing age (0.139 1; P = 0.02) but not in the older women. There was a modest link with the number of children (P = 0.05), with the first child possibly having the greatest effect on FEV1. We could not account for the effect of parity on FEV1 by the educational level, occupation, health status of the women, or by the presence of a cohort effect. Thus the nulliparous state is associated with lower FEV1 in this group of healthy adult women of child-bearing age.

Adult↗

PubMed1999

Effect of long-term caloric restriction and exercise on muscle bioenergetics and force development in rats.

We evaluated the hypothesis that long-term caloric restriction and exercise would have beneficial effects on muscle bioenergetics and performance in the rat. By themselves, each of these interventions is known to increase longevity, and bioenergetic improvements are thought to be important in this phenomenon. Accordingly, we investigated rats that underwent long-term caloric restriction and were sedentary, ad libitum-fed rats permitted to exercise by daily spontaneous wheel running (AE), and the combination of the dietary and exercise interventions (RE). Ad libitum-fed, sedentary rats comprised the control group. 31P NMR spectra of the gastrocnemius muscle (GM) were collected in vivo at rest and during two periods of electrical stimulation. Neither caloric restriction nor exercise affected the ratio of phosphocreatine to ATP or pH at rest. During the first stimulation and after recovery, the RE group had a significantly smaller decline in pH than did the other groups (P < 0.05). During the second period of stimulation, the decrease in pH was much smaller in all groups than during the first stimulation, with no differences observed among the groups. The combination of caloric restriction and exercise resulted in a significant attenuation in the decline in developed force during the second period of stimulation (P < 0.05). A biochemical correlate of this was a significantly higher concentration of citrate synthase in the GM samples from the RE rats (32.7 +/- 5.4 micromol. min-1. g-1) compared with the AE rats (17.6 +/- 5.7 micromol. min-1. g-1; P < 0.05). Our experiments thus demonstrated a synergistic effect of long-term caloric restriction and free exercise on muscle bioenergetics during electrical stimulation.

Animals↗

PubMed1998

The detection of residual serial correlation in linear mixed models.

Diggle (1988) described how the empirical semi-variogram of ordinary least squares residuals can be used to suggest an appropriate serial correlation structure in stationary linear mixed models. In this paper, this approach is extended to non-stationary models which include random effects other than intercepts, and will be applied to prostate cancer data, taken from the Baltimore Longitudinal Study of Aging. A simulation study demonstrates the effectiveness of this extended variogram for improving the covariance structure of the linear mixed model used to describe the prostate data.

Analysis of Variance↗

PubMed1998

Use of formal and informal sources of mental health care among older African-American public-housing residents.

BACKGROUND: Elderly residents of public housing have high rates of psychiatric disorders, but most of those in need of care do not use any mental health service. This study examines the use of formal and alternative informal sources of mental health care in a sample of elderly African-American public-housing residents. METHOD: Data from an epidemiological survey of six Baltimore public-housing developments for the elderly (weighted N = 818) were analysed to examine the utilization of mental health services by older African-American residents. Logistic regression analyses were used to determine correlates of using formal and informal sources by those needing mental health care. RESULTS: Thirty-five per cent of subjects needed mental health care. Less than half (47%) of those in need received any mental health care in the previous 6 months. Residents in need were more likely to use formal (38.5%) than informal sources (18.6%) for care. The strongest correlates of using formal providers were substance use disorder (OR = 15.62), Medicare insurance (OR = 10.31) and psychological distress (OR = 10.27). The strongest correlates of using informal sources were perceiving little or no support from religious/spiritual beliefs (OR = 21.65), cognitive disorder (OR = 19.71) and having a confidant (OR = 15.07). CONCLUSIONS: Contrary to elderly African-Americans in general, those in public housing rely more on formal than informal sources for mental health problems. Nevertheless, both sources fail to fill the gap between need and met need. Interventions to increase identification, referral and treatment of elderly public-housing residents in need should target general medical providers and clergy and include assertive outreach by mental health specialists.

Black or African American↗

PubMed1998

The relationship of obesity and the development of coronary heart disease to longitudinal changes in systolic blood pressure.

In an investigation of the relationship of obesity and the development of coronary heart disease (CHD) to longitudinal changes in systolic blood pressure (SBP), a sample of 1029 male participants from the Baltimore Longitudinal Study of Baltimore (BLSA), who were free of CHD at the beginning of the study, were examined with a total of 4111 examinations (mean of four examinations per person) conducted during the study period. The mean follow-up time was 8.1 years with a maximum of 16 examinations and 30.9 years of follow-up. During the follow-up period, 192 participants developed CHD, and these participants' data collected after the CHD event were excluded from the analysis. A proportional hazards regression model was used to calculate the relative risk of developing CHD for several CHD risk factors. Both simple and multiple proportional hazards regression models indicate a strong association between body mass index (BMI), cholesterol, cigarette smoking, and systolic blood pressure (SBP) with the risk of developing CHD. In addition, a linear mixed-effects model was used to examine changes in SBP measurements over time and to identify factors, including the age at first examination and time in study, that are related to that change. The results from the linear mixed-effects model analysis indicate that those in the obese group (BMI > or = 30 kg/m2) have SBP measurements that are on average 9.0 mm Hg higher than those in the normal group (20 < or = BMI < 25). Also, SPB measurements were on average 6.6 mm Hg higher in those who developed CHD during the study period than those who remained free of disease. In addition, SPB showed a quadratic relationship with time, and its patterns of change with time were different among the different age groups. Also, the relationship between changes in SBP with respect to cholesterol was dependent on time in the study as well.

Adult↗

PubMed1997

Construction of hearing percentiles in women with non-constant variance from the linear mixed-effects model.

Current age-specific reference standards for adult hearing thresholds are primarily cross-sectional in nature and vary in the degree of screening of the reference sample for noise-induced hearing loss and other hearing problems. We develop methods to construct age-specific percentiles for longitudinal data that have been modelled using the linear mixed-effects model. We apply these methods to construct percentiles of hearing level using data from a carefully screened sample of women from the Baltimore Longitudinal Study of Aging. However, the variation in the residuals and random effects from the linear mixed-effects model does not remain constant with age and frequency of the stimulus tone. In addition, the distribution of the hearing levels is not symmetric about the mean. We develop a number of methods to use the output from the linear mixed-effects model to construct percentiles that do not have constant variance. We use a transformation of the hearing levels to provide for skewness in the final percentile curves. The change in the variation of the residuals and random effects is modelled as a function of beginning age and frequency and we use this variance function to construct the hearing percentiles. We present a number of approaches. First, we use the absolute values of the population residuals to model the total deviation about the mean as a function of beginning age and frequency. Second, we model the standard deviation in the person-specific (cluster) residuals as well as the standard deviation in the estimated random effects. Finally, we use weighted least squares with the regressions on the absolute cluster residuals and absolute estimated random effects where the weights are the reciprocal of the standard deviations of their estimates.

Adolescent↗

PubMed1997

Describing the natural heterogeneity of aging using multilevel regression models.

Aging has been defined as the process of change that occurs in the individual during the course of time following the early stages of growth and development. While this process occurs in everyone, it varies from person to person. Longitudinal studies have emerged as the only method to study individual change directly and to identify factors associated with that change. Multilevel or mixed-effects regression models have proven to be a useful tool for describing the natural heterogeneity that occurs in studies of aging. These models, along with recent developments in estimation procedures and numerical techniques, have made it possible to estimate in a unified analysis the average rates of change for the study population, as well as individual deviations from these average rates. One type of multilevel models, mixed-effects models, assumes that the correlation among longitudinal measurements for an individual is due to some latent characteristics that give the individual an initial level or rate of change which is higher or lower than average. This paper discusses the application of mixed-effects models using random effects for the estimation of individual differences to aspects of human aging which have been observed over the first 35 years of the ongoing Baltimore Longitudinal Study of Aging.

Adult↗

PubMed1997

Age-associated changes in blood pressure in a longitudinal study of healthy men and women.

BACKGROUND: Current knowledge of age-associated increases in blood pressure is based primarily on unscreened population studies that may not be representative of healthy men and women. We examined longitudinal patterns of change in blood pressure in healthy male and female volunteers from the Baltimore Longitudinal Study of Aging (BLSA). METHODS: Longitudinal mixed-effects regression models are used to estimate the age-associated changes in blood pressure in 1307 men (age 17-97) and 333 women (age 18-93) who have been followed for up to 32 years (mean: 8.4 years for men and 3.4 years for women) and who have been screened for health problems or medications that affect blood pressure. RESULTS: On average, systolic pressure is relatively stable in men and women until approximately age 45, increases at 5-8 mm Hg per decade in middle age, then accelerates in men and stabilizes in women. Diastolic pressure increases at 1 mm Hg per decade at all ages in men, whereas in women the rate of change in diastolic pressure increases in middle age and then plateaus and may decline after age 70. Additional findings include: (a) BLSA cross-sectional and longitudinal findings are more similar than has been observed in studies of unscreened samples; (b) there is no evidence of a gender cross-over in this group of healthy men and women; and (c) compared to previous studies of unscreened samples, healthy BLSA men and women show a weaker association between baseline blood pressure and subsequent rate of blood pressure change. CONCLUSIONS: These findings suggest that several previously described age-associated patterns of blood pressure change partially reflect the effects of hypertension and its treatment, rather than intrinsic age changes in the blood pressure of healthy individuals.

Adolescent↗

PubMed1996

Longitudinal changes in smell identification.

BACKGROUND: Cross-sectional studies have demonstrated that olfactory function diminishes with increasing age, which may impact on the safety and quality of life of older persons. To date, however, there have been no published longitudinal studies on olfaction. The purpose of this study was to examine the influence of age and gender on smell identification over a 3-year period in a group of generally healthy men and women. METHODS: Males (n = 85) and females (n = 76) between the ages of 19 and 95 years were administered the University of Pennsylvania Smell Identification Test (SIT) over a 3-year span as part of the oral physiology component of the Baltimore Longitudinal Study of Aging. A linear mixed-effects regression model was used to determine how longitudinal changes in SIT scores differ with respect to gender, history of medical problems, and use of prescription medications. RESULTS: Over the 3-year period, SIT scores diminished progressively with increased age. Women and men in the eighth decade of life experienced a decline of greater than one SIT point per year. Females consistently performed better than males in smell identification. Similar results were obtained regardless of medical problems or medication usage. CONCLUSIONS: These results extend the conclusions of previous cross-sectional olfactory studies and indicate that smell identification deteriorates progressively with greater age. Furthermore, age-related declines in olfaction occur even in the absence of overt medical problems.

Adult↗

PubMed1996

Age- and gender-specific reference ranges for hearing level and longitudinal changes in hearing level.

This paper presents age-specific reference ranges for hearing level and change in hearing level for men and women at 500, 1000, 2000, and 4000 Hz. The percentiles are constructed from data obtained from persons in the Baltimore Longitudinal Study of Aging who were rigorously screened for otological disorders and evidence of noise-induced hearing loss. The resulting percentile curves represent norms for changes in hearing level in the absence of any known otologic disease. These percentile curves provide a reference for detecting when a person deviates from a normal pattern of change, thus helping in diagnosing problems with hearing or in monitoring hearing in occupational settings. The smoothed means and standard deviations of the hearing levels were used to construct the longitudinal percentiles. The percentiles for cross-sectional change were constructed using the skew normal distribution to allow for the percentiles to be asymmetric on either side of the median level. These percentiles are the first reference curves that (1) provide standards for hearing level changes over periods of up to 15 years, (2) account for age differences in the distribution of hearing levels, and (3) are based on data from persons who have been systematically screened for otological disorders and evidence of noise-induced hearing loss.

Adult↗

PubMed1996

Risk factors related to age-associated hearing loss in the speech frequencies.

This paper examines the relationship between several risk factors and the development of age-associated hearing loss in the speech frequencies. Hearing loss is defined as an average threshold level of 30 dB HL or greater at the frequencies of 0.5, 1, 2, and 3 kHz. Hearing thresholds from 0.5 to 8 kHz using a pulse-tone tracking procedure were collected on participants of the Baltimore Longitudinal study of Aging since 1965. A proportional hazards regression model was used to study the relationship between several risk factors that have previously been found to be associated with numerous health-related outcomes and the length of follow-up time until the occurrence of unilateral or bilateral hearing loss in a screened group of 531 men. Risk factors considered are age, blood pressure, and alcohol and cigarette consumption. After controlling for age, only systolic blood pressure showed a significant relationship with hearing loss in the speech frequencies (p < .05). Since blood pressure is a modifiable risk factor, these results suggest that preventing hypertension might contribute to an effective program for the prevention of apparent age-associated hearing loss.

Adult↗

PubMed1995

Neuroleptic use and behavioral disturbance in nursing homes: a 1-year study.

This article discusses a longitudinal study of change in disruptive behaviors among nursing home residents treated with neuroleptics compared with those not treated with neuroleptics. Observations were made of 201 participants on admission to and after 1 year in eight skilled nursing facilities. Nine disruptive behaviors were measured using the Psychogeriatric Dependency Rating Scale with nursing assistants. Neuroleptic use was documented from medication records. Odds ratios are reported for the association of behavior at baseline and use of neuroleptics on nine problem behaviors. For those who received neuroleptics during the year, there was greater change in both developing and resolving disruptive behaviors than for those not receiving neuroleptics. For both groups, restless or pacing behavior and belligerent behavior manifested by refusing instructions changed the most, both in developing and in apparently resolving. Our results show that change in disruptive behaviors occurs among nursing home residents regardless of neuroleptic use, but it occurs more frequently among those who receive neuroleptic medication. Knowledge of which disruptive behaviors are most likely to resolve or develop is important in training nursing home staff to cope with the behaviors as well as in planning interventions that may modify such behaviors.

Adult↗

PubMed1995

Gender differences in a longitudinal study of age-associated hearing loss.

Current studies are inconclusive regarding specific patterns of gender differences in age-associated hearing loss. This paper presents results from the largest and longest longitudinal study reported to date of changes in pure-tone hearing thresholds in men and women screened for otological disorders and noise-induced hearing loss. Since 1965, the Baltimore Longitudinal Study of Aging has collected hearing thresholds from 500 to 8000 Hz using a pulsed-tone tracking procedure. Mixed-effects regression models were used to estimate longitudinal patterns of change in hearing thresholds in 681 men and 416 women with no evidence of otological disease, unilateral hearing loss, or noise-induced hearing loss. The results show (1) hearing sensitivity declines more than twice as fast in men as in women at most ages and frequencies, (2) longitudinal declines in hearing sensitivity are detectable at all frequencies among men by age 30, but the age of onset of decline is later in women at most frequencies and varies by frequency in women, (3) women have more sensitive hearing than men at frequencies above 1000 Hz but men have more sensitive hearing than women at lower frequencies, (4) learning effects bias cross-sectional and short-term longitudinal studies, and (5) hearing levels and longitudinal patterns of change are highly variable, even in this highly selected group. These longitudinal findings document gender differences in hearing levels and show that age-associated hearing loss occurs even in a group with relatively low-noise occupations and with no evidence of noise-induced hearing loss.

Adult↗

PubMed1995

Preventive services for the elderly: would coverage affect utilization and costs under Medicare?

OBJECTIVES: This study was undertaken to determine whether adding a benefit for preventive services to older Medicare beneficiaries would affect utilization and costs under Medicare. METHODS: The demonstration used an experimental design, enrolling 4195 older, community-dwelling Medicare recipients. Medicare claims data for the 2 years in which the preventive visits occurred were compared for the intervention (n = 2105) and control (n = 2090) groups. Monthly allowable charges for Part A and Part B services and number of hospital discharges and ambulatory visits were compared. RESULTS: There were no significant differences in the charges between the groups owing to the intervention, although total charges were somewhat lower for the intervention group even when the cost of the intervention was included. Charges for both groups rose significantly as would be expected for an aging population. A companion paper describes a modest health benefit. CONCLUSIONS: There appears to be a modest health benefit with no negative cost impact. This finding gives an early quantitative basis for the discussion of whether to extend Medicare benefits to include a general preventive visit from a primary care clinician.

Aged↗

PubMed1992

Estimation of prostatic growth using serial prostate-specific antigen measurements in men with and without prostate disease.

Prostate growth curves were estimated from serial prostate-specific antigen (PSA) measurements on frozen sera in three groups of men: (a) 16 men with no prostatic disease by urological history and examination; (b) 20 men with a histological diagnosis of benign prostatic hyperplasia (BPH) who had undergone simple prostatectomy; and (c) 18 men with a histological diagnosis of prostate cancer. The median number of repeated PSA measurements over an 8- to 26-yr period prior to histological diagnosis or exclusion of prostate disease was eight and 11 for noncancer and cancer subjects, respectively. Predicted rates of change in PSA (PSA velocity) were linear and curvilinear for control and BPH subjects, respectively. Subjects with cancer demonstrated both a linear and an exponential phase of PSA velocity. Based on time to double PSA, we estimated the epithelial doubling time for men without prostate disease to range from 54 +/- 13 yr at age 40 to 84 +/- 13 yr at age 70. For men with BPH, doubling times ranged from 2 +/- 13 yr at age 40 to 17 +/- 5 yr at age 85. Subjects with local/regional and advanced/metastatic cancer had similar PSA doubling times of 2.4 +/- 0.6 yr and 1.8 +/- 0.2 yr, respectively. These data are consistent with what is known about prostatic growth with age in men without prostate disease and BPH, and the kinetics of prostate cancer growth. Estimates of prostatic growth rate from changes in PSA may be useful clinically in management of men with prostate disease.

Aged↗

PubMed1992

k-ratio t tests for multiple comparisons involving several treatments and a control.

We consider the problem of simultaneously comparing several treatment means with a control mean and also with one another. Following an elementary decision-theoretic Bayesian approach requiring the choice of a type-I to type-II error-seriousness ratio k, a posteriori t tests are derived for testing both treatment versus control (TvC) and treatment versus treatment (TvT) differences. These k-ratio t tests are strictly comparisonwise in nature. That is, the test applied to any TvC or TvT difference d, depends in no way at all on whether the other differences are being tested. The test for d, however, does depend on the sizes of the other differences through tG, the standardized average of the observed TvC differences, and through FT, the observed between-treatments F ratio. From these adaptive dependences on tG and FT, the critical t values can be large or small, thus avoiding the intuitive objections of under- or over-conservatism in classical comparisonwise or experimentwise level testing rules.

Bayes Theorem↗