Substantial genetic influence on mild mental impairment in early childhood.
We report the first major genetic study of mild mental impairment. From a representative sample of 3886 twins (1314 monozygotic, 1296 dizygotic same-sex, and 1276 dizygotic opposite-sex), the lowest 5% were selected on a composite measure of verbal and nonverbal abilities assessed by parents when the twins were 2, 3, and 4 years of age. Twin concordances for mild mental impairment were 74% for monozygotic twins, 45% for same-sex, and 36% for opposite-sex dizygotic twins, indicating substantial genetic influence. Model-fitting analyses estimated group heritability as.49, which is significantly greater than heritability for the rest of the population in early childhood. These results suggest that mild mental impairment is a good target for neuroscience research on global brain function and dysfunction.
Spinath
Frank M
FM
Department of Psychology, University of Bielefeld, Bielefeld, Germany. fspin@uni-bielefeld.de
Harlaar
Nicole
N
Ronald
Angelica
A
Plomin
Robert
R
D002675:Child, Preschool; D004200:Diseases in Twins / Q000235:genetics*; D005260:Female; D006801:Humans; D007206:Individuality; D007360:Intelligence / Q000235:genetics; D007805:Language Development Disorders / Q000175:diagnosis / Q000235:genetics; D007859:Learning Disabilities / Q000175:diagnosis / Q000235:genetics*; D008297:Male; D001523:Mental Disorders / Q000175:diagnosis / Q000235:genetics*; D009460:Neurologic Examination / Q000706:statistics & numerical data; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D011594:Psychometrics / Q000706:statistics & numerical data; D011596:Psychomotor Disorders / Q000175:diagnosis / Q000235:genetics; D015203:Reproducibility of Results; D014429:Twins, Dizygotic / Q000235:genetics / Q000523:psychology; D014430:Twins, Monozygotic / Q000235:genetics