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Funded by a programme grant from the Medical Research Council
The Twins Early Development Study (TEDS) focuses on the early development of the three most common psychological problems in childhood: Communication disorders, mild mental impairment and behaviour problems. The TEDS twins were assessed longitudinally at 2, 3, 4, 7 and 9 years of age in order to investigate genetic and environmental contributions to change and continuity in language and cognitive development; it is multivariate in order to examine the origins of co-morbidity; and it uses a large sample in order to study abnormal development in the context of normal development. The twins were identified from birth records of twins born in the UK in 1994-96. More than 15,000 pairs of twins have been enrolled in TEDS and the participating families are representative of the UK. At 7 and 9 years, children are assessed for language and cognitive development and behaviour problems and teachers also assess behaviour problems as well as academic achievement. One set of findings is that the same genes largely contribute to both language and cognitive problems and the same genes affect normal and abnormal development, a result that suggests that general impairment may be a better target for genetic research than specific language impairment independent of nonverbal cognitive problems. DNA has been obtained so far for more than 5000 pairs, which is used in molecular genetics research to identify specific genes involved in normal and abnormal development. Current studies include language impairment, hyperactivity, autistic spectrum disorders, antisocial behaviour, reading, writing and maths.In future, TEDS plans to continue its research through online activities and assessments completed by twins, parents and teachers.