GENETIC INFLUENCE ON PARENT-REPORTED ATTENTION-RELATED PROBLEMS IN A NORWEGIAN GENERAL-POPULATION TWIN SAMPLE

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.