H. Gjone et al., GENETIC INFLUENCE ON PARENT-REPORTED ATTENTION-RELATED PROBLEMS IN A NORWEGIAN GENERAL-POPULATION TWIN SAMPLE, Journal of the American Academy of Child and Adolescent Psychiatry, 35(5), 1996, pp. 588-596
Objective: To assess the genetic and environmental influences on atten
tion problems in a general population twin sample and to investigate w
hether there are changes in the relative genetic influence on attentio
n problems with increasing severity. Method: Parental ratings of the C
hild Behavior Checklist were collected from five Norwegian national co
horts of same-sex twins. The sample comprises 526 identical and 389 fr
aternal pairs. Results: Considerable genetic influence on attention pr
oblems was found for both sexes and across age groups (aged 5 to 9 yea
rs and 12 to 15 years). A two-parameter model with additive genetic in
fluence and nonshared environment showed a good fit, with heritability
ranging from .73 in boys aged 5 to 9 years, to .76 in girls aged 5 to
9 years. There was no change in the relative genetic influence across
severity after accounting for the influence of cerebral palsy, epilep
sy, and low birth weight. Conclusion: The results indicate a substanti
al genetic influence on attention problems across sex, age, and severi
ty.