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Gene-environment interaction in adults' IQ scores: measures of past and present environment.

van der Sluis S, Willemsen G, de Geus EJ, Boomsma DI, Posthuma D - Behav. Genet. (2008)

Bottom Line: In younger males, higher urbanization levels were associated with slightly higher FSIQ scores.Contrary to studies in children, however, the variance attributable to additive genetic effects was stable across all levels of the moderators under study.Most results were replicated for VIQ and PIQ.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Psychology, VU University Amsterdam, Van der Boechorststraat 1, Amsterdam 1081 BT, The Netherlands. s.van.der.sluis@psy.vu.nl

ABSTRACT
Gene-environment interaction was studied in a sample of young (mean age 26 years, N = 385) and older (mean age 49 years, N = 370) adult males and females. Full scale IQ scores (FSIQ) were analyzed using biometric models in which additive genetic (A), common environmental (C), and unique environmental (E) effects were allowed to depend on environmental measures. Moderators under study were parental and partner educational level, as well as urbanization level and mean real estate price of the participants' residential area. Mean effects were observed for parental education, partner education and urbanization level. On average, FSIQ scores were roughly 5 points higher in participants with highly educated parents, compared to participants whose parents were less well educated. In older participants, IQ scores were about 2 points higher when their partners were highly educated. In younger males, higher urbanization levels were associated with slightly higher FSIQ scores. Our analyses also showed increased common environmental variation in older males whose parents were more highly educated, and increased unique environmental effects in older males living in more affluent areas. Contrary to studies in children, however, the variance attributable to additive genetic effects was stable across all levels of the moderators under study. Most results were replicated for VIQ and PIQ.

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Path diagram of the biometric model including moderation effects of the observed environmental moderator on the variances and the mean of the twin 1 and twin 2. Parameters a, c and e denote the parts of variance components A (additive genetic effects), C (common environmental effects) and E unique environmental effects) that are unrelated to the moderator, while a’, c’, and e’ denote the parts of A, C and E that depend on the moderator (i.e., the interaction terms). For the mean, parameter m denotes the intercept which is independent of the moderator, and m’ denotes the slope, which is dependent on the moderator
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Fig1: Path diagram of the biometric model including moderation effects of the observed environmental moderator on the variances and the mean of the twin 1 and twin 2. Parameters a, c and e denote the parts of variance components A (additive genetic effects), C (common environmental effects) and E unique environmental effects) that are unrelated to the moderator, while a’, c’, and e’ denote the parts of A, C and E that depend on the moderator (i.e., the interaction terms). For the mean, parameter m denotes the intercept which is independent of the moderator, and m’ denotes the slope, which is dependent on the moderator

Mentions: The full model is illustrated in Fig. 1 for a twin pair without siblings. When available, sibling data were however included in all analyses. MZ twin pairs reared together share 100% of their familial environment and 100% of their genes, so correlations between these variance components are fixed to 1. DZ twins and regular sib pairs reared together share 100% of their familial environmental and 50% of their genes on average, so correlations between these components are fixed to 1 and 0.5, respectively (Posthuma et al. 2003). In Fig. 1, the moderator is denoted as Modtw1 or Modtw2 for twin 1 and twin 2, respectively. The model includes 2 parameters for the means: an intercept (m), which is independent of the moderator, and a slope (m′), which is dependent on the moderator. For the variances, the full model included 6 parameters: the parts of A, C and E that are independent of the moderator (denoted a, c, and e), and the parts of A, C and E that depend on the moderator (denoted a′, c′, and e′). To begin with, all 8 parameters were estimated separately for males and females, and for the young and the older cohort (i.e., 32 parameters in total), which allowed us to study G × E interaction separately for young/older males/females.Fig. 1


Gene-environment interaction in adults' IQ scores: measures of past and present environment.

van der Sluis S, Willemsen G, de Geus EJ, Boomsma DI, Posthuma D - Behav. Genet. (2008)

Path diagram of the biometric model including moderation effects of the observed environmental moderator on the variances and the mean of the twin 1 and twin 2. Parameters a, c and e denote the parts of variance components A (additive genetic effects), C (common environmental effects) and E unique environmental effects) that are unrelated to the moderator, while a’, c’, and e’ denote the parts of A, C and E that depend on the moderator (i.e., the interaction terms). For the mean, parameter m denotes the intercept which is independent of the moderator, and m’ denotes the slope, which is dependent on the moderator
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2480605&req=5

Fig1: Path diagram of the biometric model including moderation effects of the observed environmental moderator on the variances and the mean of the twin 1 and twin 2. Parameters a, c and e denote the parts of variance components A (additive genetic effects), C (common environmental effects) and E unique environmental effects) that are unrelated to the moderator, while a’, c’, and e’ denote the parts of A, C and E that depend on the moderator (i.e., the interaction terms). For the mean, parameter m denotes the intercept which is independent of the moderator, and m’ denotes the slope, which is dependent on the moderator
Mentions: The full model is illustrated in Fig. 1 for a twin pair without siblings. When available, sibling data were however included in all analyses. MZ twin pairs reared together share 100% of their familial environment and 100% of their genes, so correlations between these variance components are fixed to 1. DZ twins and regular sib pairs reared together share 100% of their familial environmental and 50% of their genes on average, so correlations between these components are fixed to 1 and 0.5, respectively (Posthuma et al. 2003). In Fig. 1, the moderator is denoted as Modtw1 or Modtw2 for twin 1 and twin 2, respectively. The model includes 2 parameters for the means: an intercept (m), which is independent of the moderator, and a slope (m′), which is dependent on the moderator. For the variances, the full model included 6 parameters: the parts of A, C and E that are independent of the moderator (denoted a, c, and e), and the parts of A, C and E that depend on the moderator (denoted a′, c′, and e′). To begin with, all 8 parameters were estimated separately for males and females, and for the young and the older cohort (i.e., 32 parameters in total), which allowed us to study G × E interaction separately for young/older males/females.Fig. 1

Bottom Line: In younger males, higher urbanization levels were associated with slightly higher FSIQ scores.Contrary to studies in children, however, the variance attributable to additive genetic effects was stable across all levels of the moderators under study.Most results were replicated for VIQ and PIQ.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Psychology, VU University Amsterdam, Van der Boechorststraat 1, Amsterdam 1081 BT, The Netherlands. s.van.der.sluis@psy.vu.nl

ABSTRACT
Gene-environment interaction was studied in a sample of young (mean age 26 years, N = 385) and older (mean age 49 years, N = 370) adult males and females. Full scale IQ scores (FSIQ) were analyzed using biometric models in which additive genetic (A), common environmental (C), and unique environmental (E) effects were allowed to depend on environmental measures. Moderators under study were parental and partner educational level, as well as urbanization level and mean real estate price of the participants' residential area. Mean effects were observed for parental education, partner education and urbanization level. On average, FSIQ scores were roughly 5 points higher in participants with highly educated parents, compared to participants whose parents were less well educated. In older participants, IQ scores were about 2 points higher when their partners were highly educated. In younger males, higher urbanization levels were associated with slightly higher FSIQ scores. Our analyses also showed increased common environmental variation in older males whose parents were more highly educated, and increased unique environmental effects in older males living in more affluent areas. Contrary to studies in children, however, the variance attributable to additive genetic effects was stable across all levels of the moderators under study. Most results were replicated for VIQ and PIQ.

Show MeSH