Longitudinal analysis of the effects of genetic and family factors on attention deficit hyperactivity disorder.

Lifford, Kate Joanna. 2009. Longitudinal analysis of the effects of genetic and family factors on attention deficit hyperactivity disorder. PhD Thesis, Cardiff University.

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Abstract

Previous studies suggest that both genetic and environmental factors contribute to variation in Attention Deficit Hyperactivity Disorder (ADHD) symptoms and their continuation. Family relationship factors have also been associated with the disorder. However, whether these family relationship factors have a causal effect on ADHD symptoms is not clear. This thesis used two longitudinal community samples, to examine the effects of both genetic and family relationship factors on ADHD symptoms. The first sample included 1214 families (twins and a parent) from a population based twin register (twins aged 12-20 years). A longitudinal sub-sample of 833 families from data collected 8 years previously was also used. The second sample included 309 children (aged 11-14 years) and their parents who took part in a longitudinal study on two occasions 12 months apart. ADHD symptoms and their continuation from childhood to adolescence and young adulthood were found to be influenced by genetic factors (h2 = 64%; genetic factors explained 78% of stability), however non-shared environmental factors were also significant. Father-child rejection was the only relationship factor to significantly impact on ADHD symptoms (y = .11; beta = .15). ADHD symptoms were shown to have a negative impact upon mother-son hostility, mother-child rejection and family conflict (y = .13 to .22; beta = .19 to .24). ADHD symptoms and parent-child warmth were not associated. The association of both mother- and father-child hostility with ADHD symptoms was genetically mediated (ra = .41 to .58). Importantly, the association between mother-son hostility and boys' ADHD symptoms was environmentally mediated as well (re = .20). The findings suggest the importance of establishing whether or not environmental factors, such as family relationship factors, have causal effects on ADHD symptoms. The majority of the results in this thesis suggest that ADHD symptoms have a negative impact upon family relationship factors.

Item Type:	Thesis (PhD)
Status:	Unpublished
Schools:	Psychology
Subjects:	B Philosophy. Psychology. Religion > BF Psychology
ISBN:	9781303196966
Funders:	ESRC, MRC
Date of First Compliant Deposit:	30 March 2016
Last Modified:	12 Feb 2016 23:12
URI:	https://orca.cardiff.ac.uk/id/eprint/54507

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