Developmental trajectories of DSM-IV symptom dimensions of ADHD and their associations with psychopathology and genetic factors

Abstract

Authors:  Henrik Larsson (1), Rezin Dilshad (1), Paul Lichtenstein (1), Edward D. Barker (2)

Objectives: Little is known about the developmental instability of the DSM-IV ADHD subtypes: the combined, the hyperactive-impulsive and the inattentive. The aim of this study was to describe the joint development of hyperactivity-impulsivity and inattention from childhood to adolescence and to study their association with externalizing and internalizing problems in early adulthood.

Method: The sample included 1 450 twin pairs born in Sweden. Parents reported on ADHD symptoms in their children at three occasions; when the twins were 8-9, 13-14, and 16-17 years old. Both parents and twins provided ratings on externalizing and internalizing problems in early adulthood, when the twins were 19-20 years old. 

Results: We found two distinct hyperactive-impulsive trajectories (low, high) and three distinct inattentive trajectories (low, increasing and high). These trajectories combined to suggest 6 developmental patterns that support early- and late-onset patterns of the three DSM-IV subtypes of ADHD. Youths characterized by high levels of hyperactivity-impulsivity and increasing/high levels of inattention from childhood to adolescence was found to be associated with an elevated risk for externalizing problems, as well as cigarette smoking and drug use in early adulthood. Quantitative genetic analyses revealed the importance of genetic factors underlying the different developmental trajectories of ADHD.  

Conclusion: These finding not only supports previous findings of a late-onset combined subtype, but may also help explaining developmental shifts in the DSM-IV subtype classification of ADHD, where youths go from a primarily hyperactive-impulsive subtype to a combined subtype.

 

(1) Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden; (2) Center for the Prevention of Youth Behavior Problems, Department of Psychology, University of Alabama, Tuscaloosa