title: Adolescent self-report of emotional and behavioral problems: interactions of genetic factors with sex and age.
abstract: OBJECTIVE
  The aim of the current study was to investigate the sex and age effects on the mean levels and the genetic architecture of adolescent self-reported emotional and behavioral problems.
  
  
  METHODS
  Survey data on psychopathology as assessed by the Youth Self Report (YSR; Achenbach & Rescorla, 2001) were collected in a large sample of Dutch adolescent twins and their non-twin siblings (6381 twins and 1195 siblings from 3511 families) aged 12 to 20 years. Sex and age effects on the levels of emotional and behavioral problems and on the genetic architecture were investigated using genetic structural equation modeling.
  
  
  RESULTS
  For all syndrome scales of the YSR (except for Aggressive Behavior) and for the broadband scales Internalizing and Externalizing sex-differences in mean levels were found. Females score higher than males on Internalizing problems and its subscales (Anxious/Depressed and Withdrawn/Depressed), while males score higher than females on Externalizing behavior and its subscale Rule-Breaking. Age-effects on mean levels vary in strength and direction by syndrome and sex. An increase in problems with increasing age was seen for Anxiety/Depressed, while a decrease was observed for Somatic Complaints, Aggressive Behavior, and Social and Thought Problems. Significant genotype interactions with age and with sex were found for most scales of the YSR. These effects vary in strength and direction, resulting in differences in genetic architecture between males and females and developmental changes in genetic architecture throughout adolescence. For example the heritability for Anxious/Depressed and Withdrawn/Depressed behavior increases and the heritability of Externalizing behavior decreases throughout adolescence.
  
  
  CONCLUSIONS
  Age and sex are found to be important moderators of both mean levels and the heritability of self-reported adolescent emotional and behavioral problems. Differences between adolescents in YSR syndrome and broadband scales are accounted for by genetic and non-shared environmental influences. We observed no influence of shared environment in this large sample. Clinical implications of the age and sex effects on the genetic architecture are discussed.
authors.affiliation: Department of Biological Psychology, VU University, Amsterdam, the Netherlands.
authors.forename: Meike
authors.initials: M
authors.lastname: Bartels
authors.forename: Niels
authors.initials: N
authors.lastname: van de Aa
authors.forename: Catherina E M
authors.initials: CE
authors.lastname: van Beijsterveldt
authors.forename: Christel M
authors.initials: CM
authors.lastname: Middeldorp
authors.forename: Dorret I
authors.initials: DI
authors.lastname: Boomsma