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Genetic influences on mechanically‐assessed activity level in children
Author(s) -
Wood Alexis C.,
Saudino Kimberly J.,
Rogers Hannah,
Asherson Philip,
Kuntsi Jonna
Publication year - 2007
Publication title -
journal of child psychology and psychiatry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.652
H-Index - 211
eISSN - 1469-7610
pISSN - 0021-9630
DOI - 10.1111/j.1469-7610.2007.01739.x
Subject(s) - heritability , psychology , impulsivity , twin study , developmental psychology , population , attention deficit hyperactivity disorder , cognition , temperament , correlation , clinical psychology , personality , psychiatry , demography , social psychology , evolutionary biology , geometry , mathematics , sociology , biology
Background: Activity level is an important component of children's temperament, as well as being part of the core symptom domain of hyperactivity‐impulsivity within attention deficit hyperactivity disorder (ADHD). Yet it is poorly understood, due partly to limitations on parent and teacher ratings, which are typically used as measurements of these symptoms. Methods: We aimed to study the etiology of objectively‐measured activity level across two situations, using actigraphs. A population‐based sample of 463 7–9‐year‐old twin pairs were assessed individually both when apart undergoing laboratory‐based cognitive testing and when together during a break in testing. Results: Heritability of activity level was estimated as 24% during the test session and at 30% during the break in testing. Shared environmental influences accounted for 27% of the variance in activity level during the test session and 42% of activity level measured during the break. A genetic correlation of 1.0 indicated that the same genes influenced activity level across the two situations, justifying the use of a composite measure of the two situations. This produced a heritability estimate of 36%. Conclusions: Objectively‐measured activity level shows a moderate degree of genetic influence, with a common set of genes influencing activity level across situations. This supports the use of actigraphs as an additional source of information in studies that aim to improve phenotype definition for molecular genetic studies of activity level and ADHD.