Increasing Heritability of BMI and Stronger Associations With the FTO Gene Over Childhood

Increasing Heritability of BMI and Stronger Associations With the FTO Gene Over Childhood
Clair M A Haworth et al; 2008
http://onlinelibrary.wiley.com/doi/10.1038/oby.2008.434/full


Abstract

The growing evidence of health risks associated with the rise in childhood obesity adds to the urgency of understanding the determinants of BMI. Twin analyses on repeated assessments of BMI in a longitudinal sample of >7,000 children indicated that the genetic influence on BMI becomes progressively stronger, with heritability increasing from 0.48 at age 4 to 0.78 at age 11. In the same large twin sample, the association between a common variant in the FTO gene and BMI increased in parallel with the rise in heritability, going from R² < 0.001 at age 4 to R² = 0.01 at age 11. These findings suggest that expression of FTO may become stronger throughout childhood. Increases in heritability may also be due to children increasingly selecting environments correlated with their genetic propensities.

Body mass index across midlife and cognitive change in late life

Body mass index across midlife and cognitive change in late life
Dahl AK et al., 2012


Abstract
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Background: 

High midlife body mass index (BMI) has been linked to a greater risk of dementia in late life, but few have studied the effect of BMI across midlife on cognitive abilities and cognitive change in a dementia-free sample. 

Methods:

We investigated the association between BMI, measured twice across midlife (mean age 40 and 61 years, respectively), and cognitive change in four domains across two decades in the Swedish Adoption/Twin Study of Aging.

Results:

Latent growth curve models fitted to data from 657 non-demented participants showed that persons who were overweight/obese in early midlife had significantly lower cognitive performance across domains in late life and significantly steeper decline in perceptual speed, adjusting for cardio-metabolic factors. Both underweight and overweight/obesity in late midlife were associated with lower cognitive abilities in late life. However, the association between underweight and low cognitive abilities did not remain significant when weight decline between early and late midlife was controlled for.

Conclusion:

There is a negative effect on cognitive abilities later in life related to being overweight/obese across midlife. Moreover, weight decline across midlife rather than low weight in late midlife per se was associated with low cognitive abilities. Weight patterns across midlife may be prodromal markers of late life cognitive health.
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Body Mass Index, Change in Body Mass Index, and Survival in Old and Very Old Persons

Body Mass Index, Change in Body Mass Index, and Survival in Old and Very Old Persons

Dahl AK et al., 2013


Abstract

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OBJECTIVES:

To examine how body mass index (BMI) and change in BMI are associated with mortality in old (70-79) and very old (≥80) individuals.

DESIGN:

Pooled data from three multidisciplinary prospective population-based studies: OCTO-twin, Gender, and NONA.

SETTING:

Sweden.

PARTICIPANTS:

Eight hundred eighty-two individuals aged 70 to 95.

MEASUREMENTS:

BMI was calculated from measured height and weight as kg/m² . Information about survival status and time of death was obtained from the Swedish Civil Registration System.

RESULTS:

Mortality hazard was 20% lower for the overweight group than the normal-underweight group (relative risk (RR) = 0.80, P = .011), and the mortality hazard for the obese group did not differ significantly from that of the normal-underweight group (RR = 0.93, P = .603), independent of age, education, and multimorbidity. Furthermore, mortality hazard was 65% higher for the BMI loss group than for the BMI stable group (RR = 1.65, P < .001) and 53% higher for the BMI gain group than for the BMI stable group (RR = 1.53, P = .001). Age moderated the BMI change differences. That is, the higher mortality risks associated with BMI loss and gain were less severe in very old age.

CONCLUSION:

Old persons who were overweight had a lower mortality risk than old persons who were of normal weight, even after controlling for weight change and multimorbidity. Persons who increased or decreased in BMI had a greater mortality risk than those who had a stable BMI, particularly those aged 70 to 79. This study lends further support to the belief that the World Health Organization guidelines for BMI are overly restrictive in old age.

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Being Overweight in Midlife Is Associated With Lower Cognitive Ability and Steeper Cognitive Decline in Late Life

Being Overweight in Midlife Is Associated With Lower Cognitive Ability and Steeper Cognitive Decline in Late Life
Anna Dahl et al., 2010
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2796876/


Abstract

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Background

Although an increasing body of evidence links being overweight in midlife with an increased risk for dementia in late life, no studies have examined the association between being overweight in midlife and cognitive ability in late life. Our aim was to examine the association between being overweight in midlife as measured by body mass index (BMI) and cognitive ability assessed over time.

Methods

Participants in the Swedish Adoption/Twin Study Aging were derived from a population-based sample. The participants completed baseline surveys in 1963 or 1973 (mean age 41.6 years, range 25–63 years). The surveys included questions about height, weight, diseases, and lifestyle factors. Beginning in 1986, the same individuals were assessed on neuropsychological tests every 3 years (except in 1995) until 2002. During the study period, 781 individuals who were 50 years and older (60% women) had at least one complete neuropsychological assessment. A composite score of general cognitive ability was derived from the cognitive test battery for each measurement occasion.

Results

Latent growth curve models adjusted for twinness showed that persons with higher midlife BMI scores had significantly lower general cognitive ability and significantly steeper longitudinal decline than their thinner counterparts. The association did not change substantially when persons who developed dementia during the study period were excluded from the analysis.

Conclusions

Higher midlife BMI scores precede lower general cognitive ability and steeper cognitive decline in both men and women. The association does not seem to be mediated by an increased risk for dementia.

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Association of adolescent obesity and lifetime nulliparity

Association of adolescent obesity and lifetime nulliparity – SWAN, the study of women's health across the nation

Alex J Polotzky et al., 2011

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2891509/


Abstract

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Objective

To evaluate whether adolescent obesity is associated with difficulties for becoming pregnant later in life.

Design

Cross-sectional analysis of baseline data from a longitudinal cohort

Setting

Multiethnic, community-based observational study of US women

Patient(s)

3154 midlife women

Main Outcome Measure(s)

Lifetime nulliparity and lifetime nulligravidity

Result(s)

527 women (16.7%) women had never delivered a baby. Participants were categorized by self-reported high school body mass index (BMI): underweight (< 18.5 kg/m²), normal (18.5 to 24.9 kg/m²), overweight (25-29.9 kg/m²), and obese (> 30 kg/m²). The prevalence of lifetime nulliparity increased progressively across the high school BMI categories: 12.7%, 16.7%, 19.2%, and 30.9%, respectively (p<0.001). Multivariable logistic regression analysis confirmed that women who were obese adolescents had significantly higher odds of remaining childless as compared to normal weight women (odds ratio [OR] 2.84, 95% confidence intervals [CI] 1.59 to 5.10) after adjusting for adult BMI, history of non-gestational amenorrhea, marital status, ethnicity, study site, and measures of socioeconomic status. Furthermore, adolescent obesity was associated with lifetime nulligravidity (OR 3.93, 95% CI 2.12 to 7.26).

Conclusion(s)

Adolescent obesity is associated with lifetime nulliparity and nulligravidity in midlife U.S. women.

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[There seems to be a connection between high sugar diets and obesity. Maybe these diets also cause a lowered fertility in women.] 

Sucrose Exposure in Early Life Alters Adult Motivation and Weight Gain

Sucrose Exposure in Early Life Alters Adult Motivation and Weight Gain
Christianne R M Frazier et al., 2008
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0003221


Abstract

The cause of the current increase in obesity in westernized nations is poorly understood but is frequently attributed to a ‘thrifty genotype,’ an evolutionary predisposition to store calories in times of plenty to protect against future scarcity. In modern, industrialized environments that provide a ready, uninterrupted supply of energy-rich foods at low cost, this genetic predisposition is hypothesized to lead to obesity. Children are also exposed to this ‘obesogenic’ environment; however, whether such early dietary experience has developmental effects and contributes to adult vulnerability to obesity is unknown. Using mice, we tested the hypothesis that dietary experience during childhood and adolescence affects adult obesity risk. We gave mice unlimited or no access to sucrose for a short period post-weaning and measured sucrose-seeking, food consumption, and weight gain in adulthood. Unlimited access to sucrose early in life reduced sucrose-seeking when work was required to obtain it. When high-sugar/high-fat dietary options were made freely-available, however, the sucrose-exposed mice gained more weight than mice without early sucrose exposure. These results suggest that early, unlimited exposure to sucrose reduces motivation to acquire sucrose but promotes weight gain in adulthood when the cost of acquiring palatable, energy dense foods is low. This study demonstrates that early post-weaning experience can modify the expression of a ‘thrifty genotype’ and alter an adult animal's response to its environment, a finding consistent with evidence of pre- and peri-natal programming of adult obesity risk by maternal nutritional status. Our findings suggest the window for developmental effects of diet may extend into childhood, an observation with potentially important implications for both research and public policy in addressing the rising incidence of obesity.

[Maybe a low-sugar diet in childhood is a good way to prevent obesity in the adult life.]