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.

Children’s Behavioral Styles at Age 3 Are Linked to Their Adult Personality Traits at Age 26

Children’s Behavioral Styles at Age 3 Are Linked to Their Adult Personality Traits at Age 26
Avshalom Caspi et al.; 2003


Abstract

We observed 1,000 3-year-old children who exhibited five temperament types: Undercontrolled, Inhibited, Confident, Reserved, and Well-adjusted. Twenty-three years later, we reexamined 96% of the children as adults, using multiple methods of comprehensive personality assessment, including both self- and informant-reports. These longitudinal data provide the longest and strongest evidence to date that children’s early-emerging behavioral styles can foretell their characteristic behaviors,  thoughts, and feelings as adults, pointing to the foundations of  the human personality in the early years of life.

Childhood IQ and adult mental disorders: a test of the cognitive reserve hypothesis.

Childhood IQ and adult mental disorders: a test of the cognitive reserve hypothesis.
Koenen KC et al.; 2009
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2705657/



Abstract

Objective

Cognitive reserve has been proposed as important in the etiology of neuropsychiatric disorders. However, tests of the association between premorbid IQ and adult mental disorders other than schizophrenia have been limited and inconclusive. The authors tested the hypothesis that low childhood IQ is associated with increased risk and severity of adult mental disorders.

Method

Participants were members of a representative 1972-1973 birth cohort of 1,037 males and females in Dunedin, New Zealand, who were followed up to age 32 with 96% retention. WISC-R IQ was assessed at ages 7, 9, and 11. Research diagnoses of DSM mental disorders were made at ages 18, 21, 26, and 32.

Results

Lower childhood IQ was associated with increased risk of developing schizophrenia spectrum disorder, adult depression, and adult anxiety. Lower childhood IQ was also associated with greater comorbidity and with persistence of depression; the association with persistence of generalized anxiety disorder was nearly significant. Higher childhood IQ predicted increased risk of adult mania.

Conclusions

Lower cognitive reserve, as reflected by childhood IQ, is an antecedent of several common psychiatric disorders and also predicts persistence and comorbidity. Thus, many patients who seek mental health treatment may have lower cognitive ability; this should be considered in prevention and treatment planning.

The Nature and Nurture of High IQ

The Nature and Nurture of High IQ
An Extended Sensitive Period for Intellectual Development
Angela M Brant et al.; August 2013
Psychological Science


Abstract

IQ predicts many measures of life success, as well as trajectories of brain development. Prolonged cortical thickening observed in individuals with high IQ might reflect an extended period of synaptogenesis and high environmental sensitivity or plasticity. We tested this hypothesis by examining the timing of changes in the magnitude of genetic and environmental influences on IQ as a function of IQ score. We found that individuals with high IQ show high environmental influence on IQ into adolescence (resembling younger children), whereas individuals with low IQ show high heritability of IQ in adolescence (resembling adults), a pattern consistent with an extended sensitive period for intellectual development in more-intelligent individuals. The pattern held across a cross-sectional sample of almost 11,000 twin pairs and a longitudinal sample of twins, biological siblings, and adoptive siblings.

Who, What, Where, When (and Maybe Even Why)? How the Experience of Sexual Reward Connects Sexual Desire, Preference, and Performance

Who, What, Where, When (and Maybe Even Why)? How the Experience of Sexual Reward Connects Sexual Desire, Preference, and Performance
James G Pfaus et al.; 2012
http://www.recherche.ouvaton.org/telechargement/pfaus_2012.pdf


Abstract

Although sexual behavior is controlled by hormonal and neurochemical actions in the brain , sexual experience induces a degree of plasticity that allows animals to form instrumental and Pavlovian associations that predict sexual outcomes, thereby directing the strength of sexual responding. This review describes how experience with sexual reward strengthens the development of sexual behavior and induces sexually-conditioned place and partner preferences in rats. In both male and female rats, early sexual experience with partners scented with a neutral or even noxious odor induces a preference for scented partners in subsequent choice tests. Those preferences can also be induced by injections of morphine or oxytocin paired with a male rat’s first exposure to scented females, indicating that pharmacological activation of opioid or oxytocin receptors can‘‘stand in’’for the sexual reward-related neurochemical processes normally activated by sexual stimulation. Conversely, conditioned place or partner preferences can be blocked by the opioid receptor antagonist naloxone. A somatosensory cue (a rodent jacket) paired with sexual reward comes to elicit sexual arousal in male rats, such that paired rats with the jacket off show dramatic copulatory deficits. We propose that endogenous opioid activation forms the basis of sexual reward, which also sensitizes hypothalamic and mesolimbic dopamine systems in the presence of cues that predict sexual reward. Those systems act to focus attention on ,and activate goal directed behavior toward, reward-related stimuli. Thus, a critical period exists during an individual’s early sexual experience that creates a‘‘love map’’or Gestalt of features, movements, feelings, and interpersonal interactions associated with sexual reward.

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"It is becoming increasingly clear that there is a critical period of sexual behavior development that forms around an individual’s first experiences with sexual arousal and desire, masturbation, orgasm, and sexual intercourse itself. During this period, the sensory and motor mechanics of the behavior become integrated and crystallized along with the development of preferences for ideal activities and physical features of a partner."

How People Make Their Own Environments: A Theory of Genotype --> Environment Effects

How People Make Their Own Environments: A  Theory of Genotype --> Environment Effects
Sandra Scarr and Kathleen McCartney; 1983
http://defiant.ssc.uwo.ca/undergraduate/psych3440g/readings/Scarr198scar_mc.pdf


Abstract

We propose a theory of development in which experience is directed by genotypes. Genotypic differences are proposed to affect phenotypic differences, both directly and through experience, via 3 kinds of genotype --> environment effects: a passive kind, through environments provided by biologically related parents; an evocative kind, through responses elicited by individuals from others; and an active kind, through the selection of different environments by different people. The theory adapts the 3 kinds of genotype-environment correlations proposed by Plomin,  DeFries, and Loehlin in a developmental model that is used to explain results from studies of deprivation, intervention, twins, and families.

Heritability of Verbal and Performance Intelligence in a Pediatric Longitudinal Sample

Heritability of Verbal and Performance Intelligence in a Pediatric Longitudinal Sample
Inge L C van Soelen et al.; 2011
http://www.tweelingenregister.org/nederlands/verslaggeving/NTR-publicaties_2011/Soelen_TRHG_2011.pdf


Abstract

The longitudinal stability of IQ is well-documented as is its increasing heritability with age. In a longitudinal twin study, we addressed the question to what extent heritability and stability differ for full scale (FSIQ), verbal (VIQ), and performance IQ (PIQ) in childhood (age 9–11 years), and early adolescence (age 12–14 years). Genetic and environmental influences and correlations over time were evaluated in an extended twin design, including Dutch twins and their siblings. Intelligence was measured by the Wechsler Intelligence Scale for children — Third version (WISC III). Heritability in childhood was 34% for FSIQ, 37% for VIQ, and 64% for PIQ, and increased up to 65%, 51%, and 72% in early adolescence. The influence of common environment decreased between childhood and early adolescence from explaining 43% of the phenotypic variance for FSIQ to 18% and from 42% for VIQ to 26%. For PIQ common environmental influences did not play a role, either in childhood or in early adolescence. The stability in FSIQ and VIQ across the 3-year interval (rp) was .72 for both measures and was explained by genetic and common environmental correlations across time (FSIQ, rg = .96, rc= 1.0; VIQ, rg=.78, rc= 1.0). Stability of PIQ (rp=.56) was lower and was explained by genetic influences (rg= .90). These results confirm the robust findings of increased heritability of general cognitive abilities during the transition from childhood to adolescence. Interestingly, results for PIQ differ from those for FSIQ and VIQ, in that no significant contribution of environment shared by siblings from the same family was detected.

Energetic demand of multiple dependents and the evolution of slow human growth

Energetic demand of multiple dependents and the evolution of slow human growth
Michael Gurven and Robert Walker; 2006
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1560216/


Abstract

This study investigates the consequences of the human foraging niche and multiple dependent offspring on the optimal growth trajectory of humans. We test the hypothesis that the human pattern of slow human growth between age at weaning and puberty helps defer the compound energetic demand on parents with multiple dependents, by using growth and demographic data from two foraging societies, the Ache of eastern Paraguay and the Dobe Ju/'hoansi of Botswana and Namibia. We run simulations of observed and potential growth trajectories among sub-adults and their consequent energetic demands on parents given profiles of fertility, mortality, consumption and production. We find that either sub-adult production or food subsidies from other people must substantially increase in order to compensate for the dramatic increase in energetic demand on parents if offspring were to grow faster at younger ages. Our conclusion is that slow human growth followed by a rapid adolescent growth spurt may have facilitated rising human fertility rates and greater investments in neural capital.


Fig.1.:  

A post-genomic view of behavioral development and adaptation to the environment

A post-genomic view of behavioral development and adaptation to the environment
Peter LaFreniere and Kevin Mac Donald; 2013


Abstract

Recent advances in molecular genetics are reviewed that have major implications for the biobehavioral sciences and for understanding how organisms adapt to their environments at both phylogenetic and ontogenic levels. From a post-genomics perspective, the environment is as crucial as the DNA sequence for constructing the phenotype, and as a source of information in trying to predict phenotypes. The review is organized with respect to five basic processes by which phenotypes adapt to both recurrent and novel environmental challenges, with an emphasis on the data for humans: 1) developmental plasticity, 2) epigenetic mechanisms, 3) genotypeenvironment correlations, 4) gene x environment interactions, and 5) domain-general psychological mechanisms.