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The genetic association between ADHD symptoms and reading difficulties: the role of inattentiveness and IQ.

Paloyelis Y, Rijsdijk F, Wood AC, Asherson P, Kuntsi J - J Abnorm Child Psychol (2010)

Bottom Line: Previous studies have documented the primarily genetic aetiology for the stronger phenotypic covariance between reading disability and ADHD inattention symptoms, compared to hyperactivity-impulsivity symptoms.We used multivariate structural equation modeling on IQ, parent and teacher ADHD ratings and parent ratings on reading difficulties from a general population sample of 1312 twins aged 7.9-10.9 years.Aetiological influences shared among all phenotypes explained 47% of the variance in reading difficulties.

View Article: PubMed Central - PubMed

Affiliation: MRC Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, UK. yannis.paloyelis@kcl.ac.uk

ABSTRACT
Previous studies have documented the primarily genetic aetiology for the stronger phenotypic covariance between reading disability and ADHD inattention symptoms, compared to hyperactivity-impulsivity symptoms. In this study, we examined to what extent this covariation could be attributed to "generalist genes" shared with general cognitive ability or to "specialist" genes which may specifically underlie processes linking inattention symptoms and reading difficulties. We used multivariate structural equation modeling on IQ, parent and teacher ADHD ratings and parent ratings on reading difficulties from a general population sample of 1312 twins aged 7.9-10.9 years. The covariance between reading difficulties and ADHD inattention symptoms was largely driven by genetic (45%) and child-specific environment (21%) factors not shared with IQ and hyperactivity-impulsivity; only 11% of the covariance was due to genetic effects common with IQ. Aetiological influences shared among all phenotypes explained 47% of the variance in reading difficulties. The current study, using a general population sample, extends previous findings by showing, first, that the shared genetic variability between reading difficulties and ADHD inattention symptoms is largely independent from genes contributing to general cognitive ability and, second, that child-specific environment factors, independent from IQ, also contribute to the covariation between reading difficulties and inattention symptoms.

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Correlated factors solution of the best fitting ACE(IQ)-AE multivariate Cholesky decomposition model presented in Fig. 1 (for twin one only). Path estimates presented as square roots are the unstandardized parameter estimates (the basis of the square root provides the standardized estimate). Bidirectional arrows between latent genetic (A1–A4) and child-specific environment (E1–E4) factors show the genetic (rg) and child-specific environment (re) correlations between them, respectively. Dotted arrows denote non-significant estimates
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Fig2: Correlated factors solution of the best fitting ACE(IQ)-AE multivariate Cholesky decomposition model presented in Fig. 1 (for twin one only). Path estimates presented as square roots are the unstandardized parameter estimates (the basis of the square root provides the standardized estimate). Bidirectional arrows between latent genetic (A1–A4) and child-specific environment (E1–E4) factors show the genetic (rg) and child-specific environment (re) correlations between them, respectively. Dotted arrows denote non-significant estimates

Mentions: Multivariate Genetic analyses A Cholesky triangular decomposition, which postulates a series of hierarchical genetic (A1–A4) and child-specific environment (E1–E4) factors, was used (Fig. 1). The order of the traits in the Cholesky model was decided a priori, with a view to estimating the aetiological influences that contribute to the covariance between reading difficulties and inattention symptoms independent of the other traits. A different ordering of the traits would produce the same fit of the model, but address different questions. The Cholesky model can be converted to the mathematically equivalent correlated factors solution (Fig. 2; Loehlin 1996), in which the order of traits is of no importance. This mathematical solution allows the estimation of the extent to which the same genes or environments contribute to the covariation between traits (i.e. the genetic and environmental correlations), irrespective of the extent to which they are shared with other traits in the model.Fig. 1


The genetic association between ADHD symptoms and reading difficulties: the role of inattentiveness and IQ.

Paloyelis Y, Rijsdijk F, Wood AC, Asherson P, Kuntsi J - J Abnorm Child Psychol (2010)

Correlated factors solution of the best fitting ACE(IQ)-AE multivariate Cholesky decomposition model presented in Fig. 1 (for twin one only). Path estimates presented as square roots are the unstandardized parameter estimates (the basis of the square root provides the standardized estimate). Bidirectional arrows between latent genetic (A1–A4) and child-specific environment (E1–E4) factors show the genetic (rg) and child-specific environment (re) correlations between them, respectively. Dotted arrows denote non-significant estimates
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2964469&req=5

Fig2: Correlated factors solution of the best fitting ACE(IQ)-AE multivariate Cholesky decomposition model presented in Fig. 1 (for twin one only). Path estimates presented as square roots are the unstandardized parameter estimates (the basis of the square root provides the standardized estimate). Bidirectional arrows between latent genetic (A1–A4) and child-specific environment (E1–E4) factors show the genetic (rg) and child-specific environment (re) correlations between them, respectively. Dotted arrows denote non-significant estimates
Mentions: Multivariate Genetic analyses A Cholesky triangular decomposition, which postulates a series of hierarchical genetic (A1–A4) and child-specific environment (E1–E4) factors, was used (Fig. 1). The order of the traits in the Cholesky model was decided a priori, with a view to estimating the aetiological influences that contribute to the covariance between reading difficulties and inattention symptoms independent of the other traits. A different ordering of the traits would produce the same fit of the model, but address different questions. The Cholesky model can be converted to the mathematically equivalent correlated factors solution (Fig. 2; Loehlin 1996), in which the order of traits is of no importance. This mathematical solution allows the estimation of the extent to which the same genes or environments contribute to the covariation between traits (i.e. the genetic and environmental correlations), irrespective of the extent to which they are shared with other traits in the model.Fig. 1

Bottom Line: Previous studies have documented the primarily genetic aetiology for the stronger phenotypic covariance between reading disability and ADHD inattention symptoms, compared to hyperactivity-impulsivity symptoms.We used multivariate structural equation modeling on IQ, parent and teacher ADHD ratings and parent ratings on reading difficulties from a general population sample of 1312 twins aged 7.9-10.9 years.Aetiological influences shared among all phenotypes explained 47% of the variance in reading difficulties.

View Article: PubMed Central - PubMed

Affiliation: MRC Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, UK. yannis.paloyelis@kcl.ac.uk

ABSTRACT
Previous studies have documented the primarily genetic aetiology for the stronger phenotypic covariance between reading disability and ADHD inattention symptoms, compared to hyperactivity-impulsivity symptoms. In this study, we examined to what extent this covariation could be attributed to "generalist genes" shared with general cognitive ability or to "specialist" genes which may specifically underlie processes linking inattention symptoms and reading difficulties. We used multivariate structural equation modeling on IQ, parent and teacher ADHD ratings and parent ratings on reading difficulties from a general population sample of 1312 twins aged 7.9-10.9 years. The covariance between reading difficulties and ADHD inattention symptoms was largely driven by genetic (45%) and child-specific environment (21%) factors not shared with IQ and hyperactivity-impulsivity; only 11% of the covariance was due to genetic effects common with IQ. Aetiological influences shared among all phenotypes explained 47% of the variance in reading difficulties. The current study, using a general population sample, extends previous findings by showing, first, that the shared genetic variability between reading difficulties and ADHD inattention symptoms is largely independent from genes contributing to general cognitive ability and, second, that child-specific environment factors, independent from IQ, also contribute to the covariation between reading difficulties and inattention symptoms.

Show MeSH
Related in: MedlinePlus