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Codevelopment of ADHD and externalizing behavior from childhood to adulthood
Author(s) -
KujaHalkola Ralf,
Lichtenstein Paul,
D'Onofrio Brian M.,
Larsson Henrik
Publication year - 2015
Publication title -
journal of child psychology and psychiatry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.652
H-Index - 211
eISSN - 1469-7610
pISSN - 0021-9630
DOI - 10.1111/jcpp.12340
Subject(s) - psychology , developmental psychology , child behavior checklist , attention deficit hyperactivity disorder , comorbidity , conduct disorder , early adulthood , trait , early childhood , twin study , young adult , association (psychology) , cohort , clinical psychology , heritability , psychiatry , genetics , biology , computer science , psychotherapist , programming language , medicine
Background Attention‐Deficit/Hyperactivity Disorder ( ADHD ) frequently co‐occurs with externalizing disorders, but a clear understanding of the etiologic underpinnings is hampered by the limited understanding of the codevelopment of the traits from childhood into early adulthood. Methods Using a birth cohort of 2600 twins, the Swedish Twin study of Child and Adolescent Development study, assessed at ages 8–9, 13–14, 16–17, and 19–20, we investigated the codevelopment of ADHD and externalizing behavior from childhood to adulthood. The analyses examined ADHD ‐like and externalizing traits, as rated by twins and their parents using the Attention Problems scale and Externalizing scale of the Child Behavior Checklist, and estimated cross‐lagged effects (one trait at one time‐point predicting the other at the next). The covariation between the traits were decomposed into stable (effects carried over from the prior time‐points) and innovative (new effects for each time‐point) sources; each source was further decomposed into additive genetics, shared and nonshared environment. Results The analysis suggested that externalizing traits in middle childhood (age 8–9) predicted ADHD ‐like traits in early adolescence (age 13–14), whereas the reverse association was nonsignificant. In contrast, ADHD ‐like traits in lateadolescence (age 16–17) predicted externalizing traits in early adulthood (age 19–20). The correlation between ADHD ‐like and externalizing traits increased over time. At all time‐points, innovative sources contributed substantially to maintained comorbidity. Genetic effects explained 67% of the covariation at each time‐point; importantly, nearly 50% of these effects were innovative. Conclusions This study challenges the belief that ADHD generally precedes externalizing behaviors; rather, change in the etiologic factors across the development is the rule. The effects were due to both new genetic and environmental factors emerging up to young adulthood. Clinicians and researchers needs to consider complex etiologic and developmental models for the comorbidity between ADHD and externalizing behaviors.