Lifecourse infectious origins of sexual inequalities in central adiposity

Common Childhood Viruses and Pubertal Timing: The LEGACY Girls Study

Earlier pubertal development is only partially explained by childhood body mass index; the role of other factors, such as childhood infections, is less understood. Using data from the LEGACY Girls Study (North America, 2011-2016), we prospectively examined the associations between childhood viral infections (cytomegalovirus (CMV), Epstein-Barr virus (EBV), herpes simplex virus (HSV) 1, HSV2) and pubertal timing. We measured exposures based on seropositivity in premenarcheal girls (n = 490). Breast and pubic hair development were classified based on mother-reported Tanner Stage (TS) (TS2+ compared with TS1), adjusting for age, body mass index, and sociodemographic factors. The average age at first blood draw was 9.8 years (standard deviation, 1.9 years). The prevalences were 31% CMV+, 37% EBV+, 14% HSV1+, 0.4% HSV2+, and 16% for both CMV+/EBV+ coinfection. CMV+ infection without coinfection was associated with developing breasts an average of 7 months earlier (hazard ratio (HR) = 2.12, 95% confidence interval (CI): 1.32, 3.40). CMV infection without coinfection and HSV1 and/or HSV2 infection were associated with developing pubic hair 9 months later (HR = 0.41, 95% CI: 0.24, 0.71, and HR = 0.42, 95% CI: 0.22, 0.81, respectively). Infection was not associated with menarche. If replicated in larger cohorts with blood collection prior to any breast development, this study supports the hypothesis that childhood infections might play a role in altering pubertal timing.

Influence of Childhood Adversity and Infection on Timing of Menarche in a Multiethnic Sample of Women

Childhood adversities (CAs) and infections may affect the timing of reproductive development. We examined the associations of indicators of CAs and exposure to tonsillitis and infectious mononucleosis (mono) with age at menarche. A multiethnic cohort of 400 women (ages 40–64 years) reported exposure to parental maltreatment and maladjustment during childhood and any diagnosis of tonsillitis and/or mono; infections primarily acquired in early life and adolescence, respectively. We used linear and relative risk regression models to examine the associations of indicators of CAs individually and cumulatively, and history of tonsillitis/mono with an average age at menarche and early onset of menarche (<12 years of age). In multivariable models, histories of mental illness in the household (RR = 1.44, 95% CI: 1.01–2.06), and tonsillitis diagnosis (RR = 1.67, 95% CI: 1.20–2.33) were associated with early menarche (<12 years), and with an earlier average age at menarche by 7.1 months (95% CI: −1.15, −0.02) and 8.8 months (95% CI: −1.26, −0.20), respectively. Other adversities indicators, cumulative adversities, and mono were not statistically associated with menarcheal timing. These findings provided some support for the growing evidence that early life experiences may influence the reproductive development in girls.

Early childhood infections and body mass index in adolescence

BACKGROUND

The incidence of childhood overweight and obesity is rising. It is hypothesized that infections in early childhood are associated with being overweight. This study investigated the association between the number of symptomatic infections or antibiotic prescriptions in the first 3 years of life and body mass index (BMI) in adolescence.

SUBJECTS

The current study is part of the Prevention and Incidence of Asthma and Mite Allergy population-based birth cohort study. Weight and height were measured by trained research staff at ages 12 and 16 years. The 3015 active participants at age 18 years were asked for informed consent for general practitioner (GP) data collection and 1519 gave written informed consent. Studied exposures include (1) GP-diagnosed infections, (2) antibiotic prescriptions, and (3) parent-reported infections in the first 3 years of life. Generalized estimating equation analysis was used to determine the association between each of these exposures and BMI z-score.

RESULTS

Exposure data and BMI measurement in adolescence were available for 622 participants. The frequencies of GP-diagnosed infections and antibiotic prescriptions were not associated with BMI z-score in adolescence with estimates being 0.14 (95% CI -0.09-0.37) and 0.10 (95% CI -0.14-0.34) for the highest exposure categories, respectively. Having ≥6 parent-reported infections up to age 3 years was associated with a 0.23 (95% CI 0.01-0.44) higher BMI z-score compared to <2 parent-reported infections.

CONCLUSIONS

For all infectious disease measures an increase in BMI z-score for the highest childhood exposure to infectious disease was observed, although only statistically significant for parent-reported infections. These results do not show an evident link with infection severity, but suggest a possible cumulative effect of repeated symptomatic infections on overweight development.

Is early life exposure to polyomaviruses and herpesviruses associated with obesity indices and metabolic traits in childhood?

BACKGROUND

Evidence for an infectious origin of obesity is emerging. We explored whether common viruses were associated with obesity and metabolic traits.

METHODS

We used cross-sectional (n = 674) and prospective (n = 440) data from children participating at the 4 and 6 years of age follow-up in the Rhea birth cohort. Presence of IgG antibodies to ten polyomaviruses (BKPyV, JCPyV, KIPyV, WUPyV, HPyV6, HPyV7, TSPyV, MCPyV, HPyV9, and HPyV10) and four herpesviruses (EBV, CMV, HSV-1, and HSV-2) were measured at age 4. Body mass index, waist circumference, and skinfold thickness were measured at age 4 and 6. Data on serum lipids, leptin, and adiponectin were also available. Multivariable linear regression models were used to explore the associations.

RESULTS

At 4 years of age, seroprevalence to polyomaviruses ranged from 21.0% for HPyV9 to 82.0% for HPyV10. Seroprevalence for EBV, CMV, HSV-1, and HSV-2 was 53.0%, 26.0%, 3.6%, and 1.5% respectively. BKPyV seropositivity was associated with lower BMI SD score at age 4 [-0.21 (95% CI: -0.39, -0.03)] and 6 [-0.27 (95% CI:-0.48, -0.05)], waist circumference at age 4 [-1.12 cm (95% CI: -2.10, -0.15)] and 6 [-1.73 cm (95% CI: -3.33, -0.12)], sum of four skinfolds [-2.97 mm (95% CI: -5.70, -0.24)], and leptin levels at age 4 [ratio of geometric means, 0.83 (95% CI: 0.70, 0.98)]. CMV seropositivity was associated with higher BMI SD score at age 4 [0.28 (95% CI: 0.11, 0.45)] and 6 [0.24 (95% CI: 0.03, 0.45)] and sum of four skinfolds at age 6 [4.75 mm (95% CI: 0.67, 8.83)]. Having "2-3 herpesviruses infections" (versus "0 herpesvirus infections") was associated with higher BMI SD score [0.32, (95% CI: 0.12, 0.53)], waist circumference [1.22 cm (95% CI: 0.13, 2.31)], and sum of four skinfolds [3.26 mm (95% CI: 0.18, 6.35)] at age 4. Polyomaviruses burden was not associated with outcomes.

CONCLUSIONS

A higher herpesviruses burden and CMV seropositivity were associated with obesity traits in childhood.

Viral Infections and Obesity

PURPOSE OF REVIEW

Obesity is a multifactorial disease that is now endemic throughout most of the world. Although addressing proximate causes of obesity (excess energy intake and reduced energy expenditure) have been longstanding global health priorities, the problem has continued to worsen at the global level.

RECENT FINDINGS

Numerous microbial agents cause obesity in various experimental models-a phenomena known as infectobesity. Several of the same agents alter metabolic function in human cells and are associated with human obesity or metabolic dysfunction in humans. We address the evidence for a role in the genesis of obesity for viral agents in five broad categories: adenoviridae, herpesviridae, phages, transmissible spongiform encephalopathies (slow virus), and other encephalitides and hepatitides. Despite the importance of this topic area, there are many persistent knowledge gaps that need to be resolved. We discuss factors motivating further research and recommend that future infectobesity investigation should be more comprehensive, leveraged, interventional, and patient-centered.

Associations between excessive adiposity and seroprevalence of herpes simplex virus type 1 and type 2 among US adults: a population-based age-period-cohort analysis

OBJECTIVES

Evidence on the association between herpes simplex virus (HSV) and excessive adiposity, such as obesity (body mass index ≥30 kg/m2) and abdominal obesity (waist circumference (WC) >102 or 88 cm), has been inconsistent. We sought to examine whether age-period-cohort (APC) effects could explain for the observed heterogeneities.

DESIGN

Population-based cross-sectional study.

PARTICIPANTS

Adults aged 20-49 years with available serological data in the National Health and Nutrition Examination Survey (NHANES) in 1999-2012.

EXPOSURE MEASURES

Obesity and abdominal obesity.

RESULTS

In men, excessive adiposity was generally not associated with HSV1 or HSV2 (all p>0.05); however, there were positive correlations between HSV seroprevalence and excessive adiposity in certain age and birth cohort groups. Based on APC analysis, abdominally obese men aged 30-40 years showed a nearly 20% increase in risk for HSV1 seropositivity (adjusted prevalence ratio (aPR)=1.18; 95% CI 1.10 to 1.27) as compared with abdominally non-obese men of the same age; there was no such association in men of other age groups. Also, men of a large WC who were born before 1962 or after 1979 had a 28% higher risk for HSV2 seropositivity than those of a normal WC in the same birth cohorts (aPR=1.28, 95% CI 1.17 to 1.54); yet the association did not hold for men in other cohorts (aPR=0.86, 95% CI 0.64 to 1.17). In women, a large WC was correlated with a minimally increased HSV1 seroprevalence (aPR=1.07, 95% CI 1.01 to 1.13) but not with HSV2 seropositivity (aPR=1.13; 95% CI 0.99 to 1.28). Likewise, there were strong associations between abdominal obesity and HSV2 seropositivity in subgroups of women participating in the earliest survey cycle (aPR=1.41, 95% CI 1.12 to 1.78) but not in other survey periods (aPR=0.94, 95% CI 0.85 to 1.03).

CONCLUSIONS

There was no consistent evidence for strong associations between HSV seropositivity and excessive adiposity in adults. APC analysis results further cautioned the generalisability of previous reports based on 1 or 2 cycles of survey data.

Infection and pubertal timing: a systematic review

The decline in age of pubertal timing has serious public health implications ranging from psychosocial adjustment problems to a possible increase in reproductive cancers. One biologically plausible explanation for the decline is a decrease in exposures to infections. To systematically review studies that assess the role of infection in pubertal timing, Medline, Web of Science and EMBASE were systematically searched and retrieved studies were reviewed for eligibility. Eligible studies examined the association between infections, including microbial exposures, and physical pubertal characteristics (breast, genitalia and pubic hair development) or age at menarche. We excluded studies that were published in a language other than English, focused on precocious puberty, were case studies, and/or included youth with autoimmune diseases. We report on study design, population characteristics, measurement of infection and puberty and the main effects of infection on pubertal development. Based on our search terms we identified 1372 unique articles, of which only 15 human and five animal studies met our eligibility criteria. Not all studies examined all outcomes. Infection was associated with later breast development (4/4 human studies), with less consistent evidence for genitalia and pubic hair development. Seven studies assessed age at menarche with inconsistent findings (three supporting later, four no association). We conclude that a small but consistent literature supports that infection is associated with later breast development; the evidence for other pubertal events and age at menarche is less clear. Where fewer childhood infections coincide with the rise in incidence of hormone-related cancers.

Social Patterning in Adiposity in Adolescence: Prospective Observations from the Chinese Birth Cohort ''Children of 1997''

INTRODUCTION

Low early life socio-economic position is more strongly associated with adiposity among women than men. We examined whether the sex difference of social patterning in general and central adiposity exists before adulthood.

METHODS

In Hong Kong's "Children of 1997" birth cohort, we used multivariable regression to examine the association of parental education, a marker of early life socio-economic position, with body mass index (BMI) (n = 7252, 88% follow-up) and waist-height ratio (n = 5636, 68% follow-up), at 14 years.

RESULTS

Parental education of Grade 9 or below, compared to Grade 12 or above, was associated with higher waist-height ratio z-score particularly in girls (0.30, 95% confidence interval (CI) 0.19, 0.41) compared to boys (0.12, 95% CI 0.02, 0.22) (p for sex interaction = 0.02). Lower parental education was associated with greater BMI z-score in adolescents of locally born mothers, but not adolescents of migrant mothers, with no difference by sex.

CONCLUSIONS

Different social patterning in different markers of adiposity may imply different sociological and biological mediating pathways. A stronger association between low early life socio-economic position and waist-height ratio in adolescent girls may indicate sex-specific influences of SEP related early life exposures on central adiposity.

Infection-Related Hospitalization in Childhood and Adult Metabolic Outcomes

BACKGROUND AND OBJECTIVES

Identifying childhood determinants of adult cardiometabolic disease would facilitate early-life interventions. There are few longitudinal data on the contribution of childhood infections. Therefore, we investigated whether hospitalization with childhood infection is associated with adult anthropometric and metabolic outcomes in a large, well-phenotyped longitudinal cohort.

METHODS

A total of 1376 subjects from the Cardiovascular Risk in Young Finns Study, aged 3 to 9 years at baseline (1980), who had lifetime data from birth onward on infection-related hospitalization (IRH) had repeated assessments through childhood and adolescence and at least once in adulthood (age 30-45 years in 2001-2011). Early childhood (<5 years), childhood/adolescence (5-18 years), adult (>18 years), and total lifetime IRHs were related to adiposity, BMI, and metabolic syndrome in adulthood. Analyses were adjusted for childhood and adulthood risk factors and potential confounders.

RESULTS

Early-childhood IRH correlated with adverse adult but not childhood metabolic variables: increased BMI (P = .02) and metabolic syndrome (risk ratio: 1.56; 95% confidence interval: 1.03-2.35; P = .03), adjusted for age, gender, birth weight, childhood BMI and other risk factors, and family income. The age at which differences in adult BMI became persistent was related to age of IRH in childhood. The greatest increase in adult BMI occurred in those with >1 childhood IRH.

CONCLUSIONS

Childhood IRH was independently associated with adverse adult metabolic variables. This finding suggests that infections and/or their treatment in childhood may contribute to causal pathways leading to adult cardiometabolic diseases.

Obesity and association with area of residence, gender and socio-economic factors in Algerian and Tunisian adults

INTRODUCTION

The epidemiological transition has resulted in a major increase in the prevalence of obesity in North Africa. This study investigated differences in obesity and its association with area of residence, gender and socio-economic position among adults in Algeria and Tunisia, two countries with socio-economic and socio-cultural similarities.

METHODS

Cross-sectional studies used stratified, three-level, clustered samples of 35-70 year old adults in Algeria, (women n = 2741, men n = 2004) and Tunisia (women n = 2964, men n = 2379). Thinness was defined as Body Mass Index (BMI) = weight/height <18.5 kg/m(2), obesity as BMI ≥30, and abdominal obesity as waist circumference/height ≥0.6. Associations with area of residence, gender, age, education, profession and household welfare were assessed.

RESULTS

Prevalence of thinness was very low except among men in Algeria (7.3% C.I.[5.9-8.7]). Prevalence of obesity among women was high in Algeria (30.1% C.I.[27.8-32.4]) and Tunisia (37.0% C.I.[34.4-39.6]). It was less so among men (9.1% C.I.[7.1-11.0] and 13.3% C.I.[11.2-15.4]).The results were similar for abdominal obesity. In both countries women were much more obesity-prone than men: the women versus men obesity Odds-Ratio was 4.3 C.I.[3.4-5.5] in Algeria and 3.8 C.I.[3.1-4.7] in Tunisia. Obesity was more prevalent in urban versus rural areas in Tunisia, but not in Algeria (e.g. for women, urban versus rural Odds-Ratio was 2.4 C.I.[1.9-3.1] in Tunisia and only 1.2 C.I.[1.0-5.5] in Algeria). Obesity increased with household welfare, but more markedly in Tunisia, especially among women. Nevertheless, in both countries, even in the lowest quintile of welfare, a fifth of the women were obese.

CONCLUSION

The prevention of obesity, especially in women, is a public health issue in both countries, but there were differences in the patterning of obesity according to area of residence and socio-economic position. These specificities must be taken into account in the management of obesity inequalities.

Can infections cause Alzheimer's disease?

Late-onset Alzheimer's disease (AD) is the most prevalent cause of dementia among older adults, yet more than a century of research has not determined why this disease develops. One prevailing hypothesis is that late-onset AD is caused by infectious pathogens, an idea widely studied in both humans and experimental animal models. This review examines the infectious AD etiology hypothesis and summarizes existing evidence associating infectious agents with AD in humans. The various mechanisms through which different clinical and subclinical infections could cause or promote the progression of AD are considered, as is the concordance between putative infectious agents and the epidemiology of AD. We searched the PubMed, Web of Science, and EBSCO databases for research articles pertaining to infections and AD and systematically reviewed the evidence linking specific infectious pathogens to AD. The evidence compiled from the literature linking AD to an infectious cause is inconclusive, but the amount of evidence suggestive of an association is too substantial to ignore. Epidemiologic, clinical, and basic science studies that could improve on current understanding of the associations between AD and infections and possibly uncover ways to control this highly prevalent and debilitating disease are suggested.