Association of estrogen receptor-alpha genotypes with body mass index in normal healthy postmenopausal Caucasian women

Several lines of evidence suggest the importance of the estrogen receptor (ER) in determining body mass index (BMI). Our purpose was to investigate whether genetic polymorphisms at the restriction enzyme PvuII site of the ER-alpha gene locus are associated with BMI variation. Data on BMI, age, and ER-alpha genotypes were obtained from 108 healthy midwestern U.S. postmenopausal Caucasian women. The study subjects were unrelated and aged 65 yr and over (mean age +/- SD, 73.4 +/- 5.1 yr), with an average BMI of 25.25 (SD, 4.04). The ER-alpha genotypes were obtained by PCR followed by restriction enzyme PvuII digestion. We found that in our study subjects the ER-alpha genotypes are significantly associated with BMI (by ANOVA, P = 0.04), explaining about 6.2% of the BMI variation in our study sample. The allelic effects of this locus on BMI are approximately additive. In our sample, individuals of the PP and Pp genotypes have, respectively, 11.4% and 4.8% higher BMI than individuals of the pp genotype. There is a significant ER-alpha genotype by age interaction, so that in our sample PP individuals tend to gain weight with age, whereas Pp and pp individuals tend to lose weight with age. Therefore, the ER-alpha polymorphisms are associated with BMI variation in healthy postmenopausal Caucasian women aged 65 yr and over. Our result is consistent with some recent findings suggesting the potential effects of the ER on BMI. The importance of the ER-alpha genotypes in other populations and other age groups needs to be demonstrated. Although the results of the ER-alpha genotype by age interaction are obtained here from cross-sectional data, direct confirmation may come from longitudinal studies in which individuals are measured multiple times over several years. The importance of the ER-alpha genotypes on BMI should be confirmed by further studies using methods robust to the potential problem of population substructuring that may confound the conclusions of population association studies.     

Weight, weight change, mortality in a random sample of older community-dwelling women

OBJECTIVE: To evaluate the relationship between measured weight, weight change, and 6-year mortality risk in a random sample of 648 community-dwelling women aged 65 and older from Baltimore, Maryland. MEASUREMENTS: Data were collected using a standardized questionnaire and administered in person by trained interviewers. Questionnaires were completed annually from 1984 to 1986, and body weight was measured at each interview. Weight was defined as body mass index (BMI) of low (< 23 kg/m2), average (> or = 23 kg/m2 to < or = 28 kg/m2), and high (> 28 kg/m2). Four mutually exclusive categories of weight change of at least 4.5% in BMI over the three annual interviews were developed to describe all possible weight change patterns: weight gain, weight loss, no change, and weight cycling. RESULTS: During the follow-up period, 106 women (16%) died. Women with low baseline BMI, regardless of weight change, and those who lost weight, regardless of baseline BMI had increased mortality risk. Women with average baseline BMI and weight loss had a very high mortality risk (hazard ratio (HR) 3.84, 95% Confidence interval (CI) 2.14-6.89). Women who weight cycled had increased mortality risk at low and high baseline weights, and a nonsignificant increased risk at average baseline weight (P = .069). Analyses were adjusted for age, education, smoking, alcohol usage, and pre-existing illness and included an interaction between weight change and baseline BMI. CONCLUSIONS: These results suggest that white, older, community-dwelling women are at an increased risk of mortality if they are underweight, lose weight, or weight cycle.     

The influence of aging on pharyngeal collapsibility during sleep

BACKGROUND: Aging increases vulnerability to obstructive sleep apnea (OSA), but the underlying mechanisms remain unclear. Recent data in awake healthy volunteers show a decrease in the genioglossus negative pressure reflex and anatomic compromise with increasing age, suggesting an age-related predisposition to pharyngeal collapse. However, aging effects on pharyngeal collapsibility have not been studied extensively during sleep. We tested the hypotheses that upper airway closing pressure (PCLOSE) and the increase in pharyngeal resistance during sleep (primary outcomes) as well as measures of arousal threshold (secondary outcomes) increase with age. METHODS: We studied 21 healthy individuals (8 women [mean (+/- SD) age, 36 +/- 18 years] and 13 men [mean age, 41 +/- 23 years]) who were between 18 and 75 years of age. During overnight polysomnography, we measured nasal pressure (PMASK) and epiglottic pressure (Pepi) during stage 2 sleep before and after airway occlusion (external valve) until arousal. PCLOSE was defined as the pressure at which PMASK plateaued despite further decreases in PEPI. RESULTS: Increasing age was correlated with both pharyngeal collapsibility ([PCLOSE] r = 0.69; p < 0.01) and an increase in pharyngeal resistance during sleep (r = 0.56; p < 0.01) independent of body mass index (BMI) and gender. There was no evidence for an effect of age on arousal threshold after airway occlusion during stage 2 sleep. CONCLUSIONS: Older age is associated with increased pharyngeal airway collapsibility during sleep independent of gender and BMI. These data may at least partially explain the mechanisms underlying the predisposition for pharyngeal collapse in the elderly.     

Pregnancy weight gain from 1960s to 2000 in Finland

OBJECTIVE: To study secular trends in average pregnancy weight gain between the 1960s and 2000 in Finland, and whether the changes were related to body mass index (BMI), age or parity. DESIGN: Three cross-sectional population surveys in Finland from three different periods. SUBJECTS: Women who were pregnant in Helsinki in the period 1954-1963 (N=2262), or in Tampere in the period 1985-1986 (N=1771) or in 2000-2001 (N=371). MEASUREMENTS: Pregnancy weight gain was determined from self-reported prepregnancy weight and measured weights during pregnancy. RESULTS: The mean age and prepregnancy BMI of all pregnant women increased between the 1960s and 2000 (from 26.5 to 29.6 y, from 21.9 to 23.7 kg/m(2)). The mean pregnancy weight gain, adjusted for mother's age, BMI and parity, increased from the 1960s to the mid-1980s from 13.2 to 14.3 kg. The increase was observed in all BMI categories. Compared to the 1960 cohort, the proportion of women with a pregnancy weight gain of less than 10 kg decreased and the proportion of women with a weight gain of 15 kg or more increased in the 1980 cohort. After the mid-1980s, the average pregnancy weight gain remained the same. In all cohorts, overweight women gained least weight during pregnancy, but age and parity were not associated with BMI and parity-/age-adjusted pregnancy weight gain. Higher pregnancy weight gain was associated with higher mean child's birthweight and higher proportion of high birthweight babies in all cohorts. CONCLUSIONS: The mean pregnancy weight gain has increased since the 1960s, which may be of importance with regard to the development of later obesity. Factors other than changes in prepregnancy BMI, age and parity must explain the increased pregnancy weight gain over time.     

Prospectively measured levels of serum follicle-stimulating hormone, estradiol, and the dimeric inhibins during the menopausal transition in a population-based cohort of women

The aims of this study were: 1) to describe, in relation to the date of final menses, the average hormone levels of women in the years before and after this date and to determine the extent to which these average levels were dependent on age and body mass index (BMI); and 2) to determine the degree of tracking in residual hormone levels [i.e., the extent to which individuals above (below) the mean for their age or time relative to final menstrual period (FMP) and BMI remain above (below) the mean as time progresses]. Serial levels of serum FSH, circulating estradiol (E2), and the dimeric inhibins (INH) A and B were measured annually in 150 women who experienced a natural menopause during 6 years of follow-up. Means of the log-transformed hormonal levels were analyzed as a double-logistic function of time relative to FMP, as well as age and BMI and correlations between repeated hormonal levels, were measured. Mean FSH levels started to increase from about 2 years before the FMP, increased most rapidly about 10 months before the FMP, and had virtually plateaued by 2 years after the FMP. FSH levels were, on average, 3% greater for each year of age and 2% lower for each kg/m2 of BMI. After adjusting for time relative to the FMP, logFSH showed modest tracking. Age-adjusted values of logFSH were moderately correlated across time, and much of this tracking was explained by the actual timing of a woman's FMP. Mean E2 levels started to decrease about 2 years before the FMP, decreased most rapidly around the time of the FMP, and had virtually plateaued by 2 years after the FMP. E2 levels were lower, on average, by about 9% per year of age, and residual values showed weak tracking. Levels of both INHA and INHB decreased, on average, in the years before the FMP and were undetectable (INHA, < 10 pg/mL; INHB, < 25 pg/mL) in the majority of women by the time of the FMP and in almost all women by 4 years post-FMP. Significant negative correlations between log serum FSH and log E2 (r = -0.73) and log INHA (r = -0.41) and log INHB (r = -0.36) were observed. It is concluded that substantial changes in reproductive hormone levels occur within 1-2 yr on each side of the FMP, that falling concentrations of E2 and the INH contribute to the rising concentrations of FSH, and that there is no single reliable hormonal marker of menopausal status for an individual woman.     

Contribution of several candidate gene polymorphisms in the determination of adiposity changes: results from the Québec Family Study

BACKGROUND: Several candidate genes have been associated with obesity, but very few studies have tested more than one gene simultaneously. METHODS: In this study, 15 polymorphisms in 10 candidate genes of obesity were tested for association with changes in adiposity measured over a period of 6-10 years in a maximum of 332 adult subjects with a wide range of adiposity (17.5or=40 years). RESULTS: In the whole sample, the variance in age-related adiposity changes explained by the candidate gene polymorphisms ranged from 3.1% (BMI, P<0.05) to 8.5% (fat mass (FM), P相似文献   

Changes in nocturnal melatonin secretion in perimenopausal women: correlation with endogenous estrogen concentrations

Although age-related decrease in melatonin secretion in humans and animals is well documented, there is a paucity of data on the precise changes in melatonin secretion that occur during the perimenopausal period. The present study was designed to measure changes in nocturnal melatonin and to characterize the role played by estrogen in controlling nocturnal melatonin secretion in perimenopausal women. Nocturnal serum melatonin concentrations were determined every 2 hr in 46 premenopausal women, 44 postmenopausal women, and 11 premenopausal women with uterine leiomyoma scheduled for hysterectomy and bilateral salpingo-oophorectomy. Nocturnal serum melatonin secretion in premenopausal women declined moderately from 17 to 45 years of age, and increased during the period from 46 to 50 years of age. Among postmenopausal women, a steep, age-related decline in nocturnal melatonin secretion was found for up to 15 years postmenopause, followed by an extremely gradual decline thereafter. A significant negative correlation was observed between the peak serum melatonin concentration and the serum 17 beta-estradiol concentration in premenopausal women aged 40-50 years (r = -0.661, P<0.0005). Daily oral administration of conjugated estrogen (0.625 mg) to postmenopausal women suppressed nocturnal melatonin secretion (P<0.005). A low estrogen state, induced by oophorectomy of premenopausal women with uterine leiomyoma led to an increase in nocturnal melatonin secretion (P<0.0001). Our findings suggest that transient elevated nocturnal melatonin secretion during menopause may be related to the existence of a low estrogen environment. The age-related decrease in melatonin secretion observed in other conditions is most likely attributable to other age-related factors.     

The relationship of childhood to adult blood pressure: longitudinal study of juvenile hypertension in Lithuania

OBJECTIVE: To assess changes in blood pressure from childhood to adulthood and the ability to predict adult blood pressure. DESIGN: Longitudinal study of a cohort of children with baseline data and a follow-up survey after 20 years. SETTING: Epidemiological survey of schoolchildren and subsequent inhabitants of Kaunas, a town in Lithuania. PARTICIPANTS: The children came from 15 schools and accounted for 25% of all 12- and 13-year-old children born in 1964 in Kaunas. The first survey (n = 1082) was carried out in 1977. The same population was re-examined in 1997 (n = 505). Data from 217 men and 288 women, who participated in both the first and the most recent surveys, is presented. MAIN OUTCOME MEASURES: Systolic and diastolic blood pressure at the age of 32-33 years. RESULTS: In the 20 years between the two surveys blood pressure increased more in men than in women. Statistically significant correlation between childhood and adult blood pressure levels was estimated (for systolic blood pressure r=0.40 in men and r=0.24 in women; for diastolic blood pressure r=0.14 in men and r=0.34 in women). Stepwise regression analysis of the data showed that the best predictors of adult blood pressure were the initial childhood blood pressure levels and change in BMI during the 20-year period for both men and women. Other factors were less predictive. CONCLUSIONS: Childhood blood pressure is related to adult levels and, together with changes in body mass index, is a significant predictor of adult blood pressure.     

Leptin and norepinephrine plasma concentrations during glucose loading in normotensive and hypertensive obese women

We performed this study to investigate whether changes in plasma glucose, insulin, and norepinephrine concentrations during an oral glucose tolerance test (OGTT) are associated with changes in plasma leptin levels in normotensive and hypertensive obese women. Plasma insulin, glucose, norepinephrine, and leptin concentrations were evaluated at the baseline and during OGTT in normotensive women (NT-Ob, N = 24, mean age 38.3 ± 1.8 years, body mass index [BMI] 37.9 ± 1.1 kg/m²) and hypertensive (HT-Ob, N = 25, mean age 37.7 ± 1.9 years, BMI 39.4 ± 1.3 kg/m²) obese women, and in a group of normal-weight women (controls, N = 20, mean age 38.3 ± 1.3 years, BMI 23.1 ± 0.4 kg/m²). The OGTT caused a significant increase in plasma leptin concentrations in both NT-Ob and HT-Ob groups, whereas no such change was detectable in control subjects. Area under curve (AUC) for plasma leptin showed a direct correlation with norepinephrine AUC in both NT-Ob (r = 0.73, P = .001) and HT-Ob (r = 0.74, P = .001) group, which was still detectable in multivariate analysis (P = .014 and P = .017, respectively). Our study confirms that glucose loading increases circulating leptin concentrations in obese women, and demonstrates the existance of an association between leptin and norepinephrine changes during OGTT in both normotensive and hypertensive obese women. We hypothesize that this association may reflect the lack of leptin suppression by catecholamines or a direct leptin-induced sympathoactivation. These findings suggest that leptin could be relevant in the regulation of blood pressure in obese women.     

Visceral fat and prevalence of hypertension among African Americans and Hispanic Americans: findings from the IRAS family study

BackgroundWe examined the relationship between visceral adipose tissue (VAT), independent of overall adiposity, and prevalent hypertension among adults enrolled in the Insulin Resistance Atherosclerosis (IRAS) Family Study. We also examined the role of insulin sensitivity (S(I)) upon hypertension. This was a cross-sectional epidemiological study in which African-American and Hispanic-American families were recruited from three clinical sites. The main outcome measure was prevalent hypertension, as defined by standardized protocol.MethodsThe relationship between VAT and prevalent hypertension was examined in adjusted marginal models among 1,582 participants. All continuous variables were standardized.ResultsA significant VAT by gender interaction prompted separate analyses for VAT according to gender. Further adjustment for S(I) was performed to determine its potential roles in the VAT-hypertension relationship. The mean age (s.d.) of the sample was 41.3 (13.8) years, with a mean body mass index (BMI) (s.d.) of 28.7 (6.0) kg/m(2). Women comprised 58.5% of the sample (N = 925), and Hispanic Americans comprised 69.2% of the sample (N = 1,095). One in five participants (21.2%) had prevalent hypertension. In women, VAT was significantly associated with hypertension, independent of BMI (odds ratio (OR) = 1.49, P = 0.006). African-American women demonstrated increased odds of prevalent hypertension compared to Hispanic-American women (OR = 3.08, P < 0.001). Among men, VAT was not associated with hypertension independent of BMI, and BMI explained a significant amount of the variation in hypertension.ConclusionsA significant relationship may exist between VAT and hypertension among women, but not among men. The relationship between VAT and hypertension in women was not associated with insulin resistance.American Journal of Hypertension (2008). doi:10.1038/ajh.2008.213American Journal of Hypertension (2008); 21, 8, 910-916. doi:10.1038/ajh.2008.213.     

Longitudinal body composition changes in old men and women: interrelationships with worsening disability

BACKGROUND: Few studies have evaluated prospectively age-related body composition changes and their relationships with worsening disability in the elderly population. METHODS: Ninety-seven women and 62 men aged 71.4+/-2.2 and 71.6+/-2.2 years, respectively, at baseline underwent dual-energy x-ray absorptiometry determinations at baseline and at 2- and 5.5-year follow-up intervals to measure total body and leg fat (FM) and total, appendicular, and leg fat-free mass (FFM). Height, weight, body mass index (BMI), and waist circumference (as well as reported disabilities using a four-level scale) were evaluated at baseline and at 2- and 5.5-year follow-up. RESULTS: In both sexes, total FM did not change significantly, while total, appendicular, and leg FFM significantly decreased over the study follow-up. In men and women losing weight, BMI, total and leg FM, and total, appendicular, and leg FFM significantly decreased. In weight-stable men and women, appendicular and leg FFM significantly decreased and BMI, waist circumference, and total FM significantly increased. Men lost significantly more total, appendicular, and leg FFM than did women, irrespective of whether they maintained or lost weight. Over the follow-up period, 43.3% of women and 43.5% of men declined in one or more levels of reported disability. We evaluated the effect of age, baseline BMI, FM, FFM, number of diseases, baseline 6-minute walking test, categories of weight change, total, appendicular, or leg FFM changes, total FM and waist changes on the probability of a decline in one or more levels of reported disability score over the follow-up period, taking into account sex. Patients losing appendicular and leg FFM were 2.15 and 2.53 times, respectively, more likely to report increased disability than were patients without FFM loss. CONCLUSIONS: Reduction in appendicular or leg FFM was the main predictor of decline in one or more levels of reported disability in older men and women, and accounted for about a 2-fold increase in risk.     

Lifetime dietary change and its relation to increase in weight in Spanish women

INTRODUCTION: Changes in dietary patterns and a decrease in physical activity have occurred in Western countries. These are factors in the variation in body composition observed in populations, characterized by a progressive accumulation of fat with age and a consequent increase in the risk of suffering from common chronic illnesses such as obesity, cardiovascular disease and cancer. OBJECTIVE: To investigate weight gain throughout the life-cycle and its relation to modifications in dietary patterns, analyzing the causes of these modifications and their implications for patterns of adult overweight and obesity. DESIGN: Cross-sectional sample of Spanish women from a socio-economically disadvantaged class. SUBJECTS: 1037 healthy perimenopausal women (age: 45-65 y). MEASUREMENTS: Juvenile body mass index (BMI), current BMI, food frequency questionnaire, retrospective food habits. RESULTS AND CONCLUSIONS: Of these women, 48.8% had changed their dietary habits during their lifetime. A change in diet due to migration or marriage occurred at approximately 20 years of age and was characterized by an increased frequency of consumption of foods rich in protein and complex carbohydrates, while a change due to illness occurred at around 50 years of age and was characterized by a decrease in the consumption of these types of food. The change in dietary behavior due to migration was associated with weight gain. Weight gain was also inversely associated with BMI during youth; women who in their youth had a BMI<18.5 kg/m2 gained an average of 21.4 kg, compared with those with a BMI>27 kg/m2 in their youth, who gained an average of 5.4 kg. International Journal of Obesity (2000)24, 14-19     

Body mass index and waist circumference correlate to the same degree with insulin-mediated glucose uptake

To compare the relationship between insulin-mediated glucose uptake (IMGU) and excess adiposity as determined by measurement of either body mass index (BMI) or waist circumference (WC), IMGU was quantified by determining the steady-state plasma glucose (SSPG) concentration with the insulin suppression test and the relationship between the SSPG concentration and BMI or WC evaluated in a study of 208 healthy individuals (128 women/80 men). The results indicated that BMI and WC were correlated (P < .001) to a similar degree in both men (r = 0.90) and women (r = 0.86). Steady-state plasma glucose and both indices of excess adiposity were also significantly correlated (P < .001) to an essentially identical extent in men (r values of 0.71 vs 0.70) and women (r values of 0.54 vs 0.53). When the population was divided into tertiles on the basis of SSPG concentrations, 96% of those in the most insulin-resistant tertile were identified as being overweight/obese by BMI criteria and 84% as abdominally obese by WC criteria. However, a substantial number of those in the most insulin-sensitive tertile also demonstrated excess adiposity as defined by either BMI (45%) or WC (33%). To summarize, (1) BMI and WC correlate closely within an individual and equally well with IMGU, and (2) BMI is as effective as WC in identifying insulin-resistant individuals.     

Weight development over time in parous women--the SPAWN study--15 years follow-up

BACKGROUND: Weight gain is common after pregnancy. Most studies suggest that weight gain associated with a pregnancy is between 0.5 and 3.8 kg up to 2.5 y of follow-up. However, 73% of the female patients at our obesity clinic identified pregnancy as an important trigger for marked weight retention. The majority retained more than 10 kg after each pregnancy. The aim of this study was to examine long-term weight development after pregnancy in a 15 y follow-up of women who took part in the Stockholm Pregnancy And Women's Nutrition (SPAWN) study. METHOD AND SUBJECTS: The SPAWN study is a long-term follow-up study of women who delivered children in 1984-85 in Stockholm (n=2342). A total of 1423 participants (response rate=61%) completed questionnaires, which covered eating behaviour and exercise, demographic information including social situation and status and details of the pregnancy before, during and up to 1 y after pregnancy. After 15 y, these women were invited to take part in the follow-up study. Anthropometric measurements and the same questionnaire data were collected from the 563 women who participated (response rate=40%). The sample was divided into two main groups: those who were normal weight before pregnancy and remained normal weight, and those who were normal weight before pregnancy and had become overweight at 15 y follow-up. RESULTS: Those women who became overweight had a higher pre-pregnant body mass index (BMI) (22.3+/-1.5 vs 20.5+/-1.6 kg/m(2), P<0.001), gained more weight during pregnancy (16.3+/-4.3 vs 13.6+/-3.7 kg, P<0.001) and had retained more at 1 y follow-up. The women who became overweight had a steeper weight trajectory gaining more from 1 y follow-up to 15 y follow-up (11.1+/-6.5 vs 4.5+/-6.5 kg, P<0.001), with a higher BMI at 15 y follow-up of 27.5+/-2.6 vs 22.5+/-2.3 5 kg/m(2) (P<0.001). However, differences between those who became overweight and those who did not could not be explained by age, number of children and various socioeconomic factors. Features of pregnancy that did differ between the two groups were breastfeeding and smoking cessation. However, women who became overweight had lower lactation scores than women who remained normal weight. Relatively more subjects of the group that became overweight stopped smoking during pregnancy. DISCUSSION: Pregnancy is a vulnerability factor for some women to become overweight. This study attempted to identify those factors that place initially normal weight women on a steeper weight trajectory as a result of pregnancy. Demographic, behavioural, physical and psychological characteristics only partly explain the weight gain observed at 15 y follow-up. Further research is required to investigate the relative role of these characteristics in predicting postpregnancy weight development.     

The relationship between body mass index and per cent body fat in the severely obese

BacKGROUND: International standards define clinical obesity according to body mass index (BMI) without reference to age and gender. Recent studies among adults in the normal to mildly obese BMI ranges have shown that the relationship between BMI and per cent body fat (% fat) differs by age and gender. The extent to which age and gender affect the relationship between BMI and % fat among more severely obese individuals is less known. AIM: The aim was to examine the age-gender association between measured BMI and % fat from a large cohort of adults, including a large number of severely obese subjects (1862 with a BMI > or = 35 kg/m(2)). METHODS: BMI was computed from measured height and weight, and % fat was estimated from bioelectrical impedance in 3068 adults. Two impedance equations, the Sun equation and the Heath equation (specific to severe obesity), were used to calculate % fat. RESULTS: Average age for 991 men and 2077 women was 46 +/- 15 vs. 44 +/- 14 years respectively (p = 0.0003). The average BMI was 36 +/- 9 kg/m(2) for men and 39 +/- 10 kg/m(2) for women (p < 0.0001), with a combined gender BMI range of 19-74 kg/m(2). Using the Sun equation, average % fat was 31 +/- 8 vs. 46 +/- 8% (p < 0.0001) for all men and women respectively. With the Sun equation, age-adjusted Spearman correlations between all BMI and % fat values were r = 0.80 and r = 0.83 for men and women, respectively, but only 0.60 (n = 479) and 0.61 (n = 1383) in severely obese participants (BMI > or = 35 kg/m(2)). Using the Heath equation, only for participants with BMI > or = 35 kg/m(2), the age-adjusted Spearman correlations improved to r = 0.82 (n = 479) and r = 0.70 (n = 1383) for men and women respectively. Finally, by combining the Sun equation for subjects with BMI < 35 kg/m(2) and the Heath equation for those with BMI > or = 35 kg/m(2), correlations improved to 0.89 for men and 0.87 for women. Using these combined equations, the relationship between BMI and % fat was best fit as a linear function for men and curvilinear function (both p < 0.001) for women across the range of BMI. The % fat was approximately 10% higher for any BMI value among women vs. men even among the severely obese (p < 0.0001). CONCLUSIONS: These data that include a large cohort of severely obese individuals demonstrated a linear association between BMI and % fat for men and a curvilinear association between BMI and % fat for women when Sun and Heath equations were combined. Assuming disease risk is driven by adiposity, this study suggests a need to further explore the appropriateness of gender-specific BMI cutpoints for clinical risk assessment due to the marked difference in the BMI-per cent fat relation observed in men and women across the entire range of BMI.     

Differential determinants of men's and women's everyday physical activity in later life

OBJECTIVES: The present study of a representative sample of older adults quantified everyday physical activity (EPA) by having participants wear actigraphs. Our objectives were to examine whether poor health may partly explain why older adults become less physically active with advancing age and whether gender might moderate the extent to which health status predicts EPA. METHODS: We performed multiple regression analyses on a sample of older, community-dwelling adults (aged 80-98 years, N = 198; women = 63.1%). RESULTS: The results imply that age-related declines in EPA may be partially accounted for by health (in men) and by living arrangements (in women). DISCUSSION: We consider reasons why poorer health might erode EPA for men (but not women) and why living alone might erode EPA for women (but not men).     

Longitudinal study on the role of body size in premenopausal breast cancer

BACKGROUND: A high body mass index (BMI) has been related to a reduced risk of breast cancer in premenopausal women. The mechanisms underlying this association have not been elucidated. METHODS: We explored whether factors affecting ovulation may explain the inverse association between BMI (calculated as weight in kilograms divided by the square of height in meters) and breast cancer in 113,130 premenopausal participants in the Nurses' Health Study II. During 1,225,520 person-years of prospective follow-up between 1989 and 2003, 1398 incident cases of invasive breast cancer were diagnosed. Weight, height, ovulatory infertility, menstrual cycle patterns, and a multitude of covariates were assessed throughout follow-up. Cox proportional hazards regression was used to compute hazard ratios and 95% confidence intervals (CIs). RESULTS: We observed a significant linear inverse trend between current BMI and breast cancer incidence (P<.001) that was not explained by menstrual cycle characteristics or infertility due to an ovulatory disorder (covariate-adjusted hazard ratio for breast cancer in women with a BMI > or =30 vs 20.0-22.4, 0.81; 95% CI, 0.68-0.96). We found BMI at age 18 years to be the strongest predictor of breast cancer incidence (covariate-adjusted hazard ratio for breast cancer in women with a BMI at age 18 years > or =27.5 vs 20.0-22.4, 0.57; 95% CI, 0.41-0.81). CONCLUSIONS: Body size during the early phases of adult life seems to be particularly important in the development of premenopausal breast cancer. Factors other than anovulation are likely to mediate the protection conferred by a high BMI.     

An apparently anomalous relationship between insulin and C-peptide concentrations in their initial response to intravenous glucose.

Intravenous glucose tolerance tests (IVGTTs) with determination of plasma glucose, insulin, and C-peptide concentrations were performed in 136 men and 154 women. It was found that in 4% of men and 12% of women the plasma concentration of insulin exceeded that of C-peptide during the initial response to glucose. Subjects exhibiting this phenomenon had lower fasting and post-glucose C-peptide concentrations than those who did not; however, there were no statistically significant differences in glucose or insulin concentrations. The phenomenon was age-related, being absent from individuals aged 35 years and under, while in older age groups it appeared to be more prevalent in women than in men, suggesting an additional effect of menopause. However, in three follow-up IVGTTs performed in a subgroup of postmenopausal women over a period of 18 months, the phenomenon failed to recur in any of the individuals who first exhibited it, although it did occur in others. Our observations suggest the existence of an age-related but intermittent decrease in pancreatic insulin secretion, which does not lead to any significant change in plasma insulin concentrations, possibly as a result of reduced hepatic uptake of insulin. One consequence appears to be an excess of insulin over C-peptide during the early part of the IVGTT, which is probably related to the different distributional kinetics of the two peptides.     

A cross-sectional analysis of age and sex patterns in grip strength, tooth loss, near vision and hearing levels in Chinese aged 50-74 years

By focusing on four health variables, handgrip strength, near visual acuity, tooth loss and hearing level, this study examined the different patterns of age-related changes in these variables in Chinese aged from 50 to 74 years, as well as explored the relationship among the variables in a cross-sectional sample of 2006 individuals. The data exhibited high quality with a low missing rate of under 5% in any age groups for each variable. Effects of age and sex on the changes in the four health variables were assessed using multiple regression models with age and sex interactions included. Upon the highly significant effects of age on all four measurements, we observed substantially higher grip strength for men who, however, exhibited a faster age-related decline than for women. No sex difference or age-sex interaction was found in the number of teeth lost. Near visual acuity displayed a faster age-related decline in women than in men but neither the overall sex difference nor age-sex interaction reached statistical significance. For hearing function, while no sex difference was found at middle frequency, women had better sensitivity at high frequency and men were more sensitive at low frequency. Multivariate analysis did not support an age-related common mechanism underlying the four health variables.     

Aging, cohorts, and verbal ability

OBJECTIVES: Age-related differences in cognitive abilities observed in cross-sectional samples of individuals varying in age may in part be spurious due to the effects of cohort differences in schooling and related factors. This study examined the effects of aging on cognitive function controlling for any and all differences in cohort-based social experiences of different age groups. METHODS: We examined age-related patterns in a measure of verbal ability using 14 repeated cross-sectional surveys from the General Social Survey (GSS) over a 24-year period. RESULTS: The raw GSS data show the expected age-related growth and decline in vocabulary knowledge, but these age differences are reduced when adjusted for cohort differences. There is evidence of small age-related patterns in vocabulary knowledge within cohorts, but the curvilinear contributions of aging to variation in verbal scores account for less than one-third of 1% of the variance in vocabulary knowledge, once cohort is controlled. Cohort differences in schooling contribute substantially to this effect. DISCUSSION: Within-age-group variation in vocabulary knowledge is vastly more important than age differences per se, and the complexities of the relationship of verbal skills to historical differences in the experience of schooling present an interesting avenue for future research.