Come on, Come on, Do the Loco-Motion

This themed issue of Preventive Medicine comprises articles following our call for papers on Self-Transportation, Public Transportation, and Health. Prevention-wise, the logic is that using self- or public transportation is likely to increase physical activity and counter the overall trend toward obesity that most populations of the world are now experiencing. The problem is that in countries for which data are available, both the cycling fraction of road traffic and the number of miles walked are declining (Dora, 1999; Haines et al., 2000). The harvest of papers has been rewarding. They show how far we currently are in the process of assembling evidence in support of the self/public transportation and health connection, but they also reflect the deficits in the experimental evidence needed to demonstrate that improving access to public transportation and modifying the built environment to stimulate walking and biking are going to make a meaningful difference in terms of public health

International Variability in Ages at Menarche, First Livebirth, and Menopause

The occurrences and timing of reproduction-related events, such as menarche, first birth, and menopause, play major roles in a woman's life. There is a lack of comparative information on the overall patterns of the ages at and the timing between these events among different populations of the world. This study describes the variability in reproductive factors across populations in Europe, the Americas, Asia, Australia, and Africa. The study sample consisted of 18,997 women from 13 centers in 11 countries interviewed between 1979 and 1988 who comprised the control group in a World Health Organization international, multicenter case-control study of female cancers. All were surveyed with the same questionnaire and methodology. Overall, a typical woman in this study reached menarche at age 14 years and delivered her first live child 8 years later, at age 22. She was 50 years old at natural menopause and had had 36 years of reproductive life. The median ages at menarche varied across centers from 13 to 16 years. For all centers, the median age at first livebirth was 20 or more years, with the largest observed median (25 years) occurring in China. The median delay from menarche to first livebirth ranged from 5 to 11 years. Among the centers, the median age at natural menopause ranged between 49 and 52 years. In most populations, younger women had a first birth at a later age than did older women. This tendency was more accentuated in some populations. These results reveal, perhaps for the first time, the variability of reproductive histories across different populations in a large variety of geographic and cultural settings. Except for menopause, international variability is substantial for both biologically related variables (age at menarche) and culturally related variables (age at first birth). There is a generational effect, characterized by more variability of age at first birth and delay to first birth in the younger than in the older generations. Am J Epidemiol 1998;148:1195-120

Experimental approach to measuring functional food consumption for risk factor surveillance

Abstract Objective To develop and integrate the assessment of functional foods (FuF; manufactured foods with altered composition carrying a health claim) consumption into an existing risk factor surveillance system. Design FuF market research followed by an experimental FuF intake study incorporated into an ongoing community-based survey. Concurrent completion of a self-administered semi-quantitative FFQ and a self-administered, qualitative FuF frequency questionnaire (FuFFQ) followed by a face-to-face control step using FuF photographs and combined food group-based data analyses. Setting ‘Bus Santé' risk factor surveillance programme, Geneva/Switzerland. Subjects Population-based random sample of 639 residents (52 % women, aged 35-74 years) surveyed from September 2003 to April 2004. Results Local Geneva/French neighbourhood market research identified 148 FuF in five major FuF food groups which were compiled into a functional ingredient database. Prior to the face-to-face verification, 210 (33 %) individuals categorized themselves as FuF consumers, 429 (67 %) as non-consumers. The control step revealed that 70 % of the 639 participants were already familiar with the FuF concept, and thus were correctly self-categorized as FuF consumers or non-consumers. For the remaining 30 % of participants the true FuF consumption status was established, resulting in a final number of 285 FuF consumers (45 %; 12 % net increase) and 354 (55 %) non-consumers. Conclusions The developed self-administered, brief, qualitative food group-based FuF frequency check list in combination with an FFQ and a photo-assisted control step provides a flexible assessment tool for measuring FuF consumption in the context of a specific fluctuating FuF market and may be applicable to other population settings and time

Relative Contributions of Genes, Environment, and Interactions to Blood Lipid Concentrations in a General Adult Population

The authors evaluated the contributions of nine genetic (G) variants (selected from 275 single nucleotide polymorphisms in 11 reverse cholesterol transport pathway genes), five environmental (E) factors (selected from 10), and G × G, E × E, and G × E interactions in explaining population variance of blood lipid concentrations. Total cholesterol, triglycerides, and high density lipoprotein (HDL) cholesterol were measured, and low density lipoprotein (LDL) cholesterol and HDL cholesterol/LDL cholesterol ratio were calculated in a population-based random sample of 1,543 men and women in Geneva, Switzerland, aged 35-74 years in 1999-2001. Explained variances (R2) for HDL cholesterol/LDL cholesterol ratio, HDL cholesterol, and LDL cholesterol, respectively, were 34%, 33%, and 19%, decomposed into main effects of G (6%, 4%, and 5%) and E (25%, 28%, and 11%), with just 3%, 2%, and 3% due to G × G, E × E, and G × E interactions, respectively. Risk factor clustering was only moderate: 70% of study subjects had ≤3 variants, 75% had ≤2 environmental exposures, and 69% had ≤5 of both types of factors. Multiple genes with weak associations, together with more dominating environmental factors, are involved in determining blood lipid concentrations. Interactions added little explained variance. Increasing trends in hypercholesterolemia are attributable to environmental changes affecting populations as a whole. Reducing obesity and smoking and moderating alcohol intake in entire populations should remain the primary strategies for lipid contro

Association of extreme blood lipid profile phenotypic variation with 11 reverse cholesterol transport genes and 10 non-genetic cardiovascular disease risk factors

This study explored the genetic basis of the combination of extreme blood levels of HDL-C and LDL-C, a well-studied endophenotype for CVD, which has several attractive features as a target for genetic analysis: (1) the trait is moderately heritable; (2) non-genetic risk factors account for a significant but still limited portion of the phenotypic variance; (3) it is known to be moderated by a number of gene products. We exhaustively surveyed 11 candidate genes for allelic variation in a random population-based sample characterized for known CVD risk factors and blood lipid profiles. With the goal of generating specific etiological hypotheses, we compared two groups of subjects with extreme lipid phenotypes, from the same source population, using a case-control design. Cases (n=186) were subjects, within the total sample of 1708 people, who scored in the upper tertile of LDL-C and the lowest tertile of HDL-C, while controls (n=185) scored in the lowest tertile of LDL-C and the upper tertile of HDL-C. We used logistic regression and a four-tiered, systematic model building strategy with internal cross-validation and bootstrapping to investigate the relationships between the trait and 275 genetic variants in the presence of 10 non-genetic risk factors. Our results implicate a subset of nine genetic variants, spanning seven candidate genes, together with five environmental risk factors, in the etiology of extreme lipoprotein phenotypes. We propose a model involving these 14 genetic and non-genetic risk factors for evaluation in future independent studie

The ecological footprint remains a misleading metric of global sustainability

Linus Blomqvist, Barry W. Brook, Erle C. Ellis, Peter M. Kareiva, Ted Nordhaus, Michael Shellenberge

Gender differentials in the evolution of cigarette smoking habits in a general European adult population from 1993–2003

BACKGROUND: Describe the recent evolution of cigarette smoking habits by gender in Geneva, where incidence rates of lung cancer have been declining in men but increasing in women. METHODS: Continuous cross-sectional surveillance of the general adult (35–74 yrs) population of Geneva, Switzerland for 11 years (1993–2003) using a locally-validated smoking questionnaire, yielding a representative random sample of 12,271 individuals (6,164 men, 6,107 women). RESULTS: In both genders, prevalence of current cigarette smoking was stable over the 11-year period, at about one third of men and one quarter of women, even though smoking began at an earlier age in more recent years. Older men were more likely to be former smokers than older women. Younger men, but not women, tended to quit smoking at an earlier age. CONCLUSION: This continuous (1993–2003) risk factor surveillance system, unique in Europe, shows stable prevalence of smoking in both genders. However, sharp contrasts in age-specific prevalence of never and former smoking and of ages at smoking initiation indicate that smoking continues a long-term decline in men but has still not reached its peak in women

Binary classification of dyslipidemia from the waist-to-hip ratio and body mass index: a comparison of linear, logistic, and CART models

BACKGROUND: We sought to improve upon previously published statistical modeling strategies for binary classification of dyslipidemia for general population screening purposes based on the waist-to-hip circumference ratio and body mass index anthropometric measurements. METHODS: Study subjects were participants in WHO-MONICA population-based surveys conducted in two Swiss regions. Outcome variables were based on the total serum cholesterol to high density lipoprotein cholesterol ratio. The other potential predictor variables were gender, age, current cigarette smoking, and hypertension. The models investigated were: (i) linear regression; (ii) logistic classification; (iii) regression trees; (iv) classification trees (iii and iv are collectively known as "CART"). Binary classification performance of the region-specific models was externally validated by classifying the subjects from the other region. RESULTS: Waist-to-hip circumference ratio and body mass index remained modest predictors of dyslipidemia. Correct classification rates for all models were 60–80%, with marked gender differences. Gender-specific models provided only small gains in classification. The external validations provided assurance about the stability of the models. CONCLUSIONS: There were no striking differences between either the algebraic (i, ii) vs. non-algebraic (iii, iv), or the regression (i, iii) vs. classification (ii, iv) modeling approaches. Anticipated advantages of the CART vs. simple additive linear and logistic models were less than expected in this particular application with a relatively small set of predictor variables. CART models may be more useful when considering main effects and interactions between larger sets of predictor variables

Helping and Cooperation in Children with Autism

Helping and cooperation are central to human social life. Here, we report two studies investigating these social behaviors in children with autism and children with developmental delay. In the first study, both groups of children helped the experimenter attain her goals. In the second study, both groups of children cooperated with an adult, but fewer children with autism performed the tasks successfully. When the adult stopped interacting at a certain moment, children with autism produced fewer attempts to re-engage her, possibly indicating that they had not formed a shared goal/shared intentions with her. These results are discussed in terms of the prerequisite cognitive and motivational skills and propensities underlying social behavior