Time Reproduction Deficits at Young Adult Follow-Up in Childhood ADHD: The Role of Persistence of Disorder and Executive Functioning

ABSTRACT

No studies have examined if time reproduction deficits exist in children with attention deficit hyperactivity disorder (ADHD) by adulthood. We followed 131 ADHD and 71 community control (CC) cases for 20+ years to young adulthood at which time they were given a time reproduction task. The ADHD group made smaller time reproductions and showed greater variability of errors at the longer durations compared to CC cases, whether ADHD was still present or not at follow-up. Nonverbal working memory and design fluency tests were related to timing errors while anxiety and depression were not. Childhood ADHD is associated with timing deficits at adult follow-up.

Conflict of Interest Declaration

The authors have no conflicts of interest relevant to this article to disclose.

Data Sharing Statement

The data that support the findings of this study are available from the corresponding author, RAB, upon reasonable request.

Financial Disclosure Statement

Dr. Barkley has received consulting fees from Takeda Pharmaceutical Co. and Shire Pharmaceutical Co., book, video, and newsletter royalties from Guilford Publications, Premier Educational Seminars, Inc., and the American Psychological Association Press, a podcast fee from AptusHealth.com, and CE course royalties from Premier Educational Seminars, Inc., ContEdCourses.com, and J&KSeminars.com. Dr. Fischer has no financial relationships to disclose.

Sources of Support

The longitudinal study and related data used here are based on research supported by grant (MH42181) from the National Institute of Mental Health to the first author. The opinions expressed herein do not necessarily represent those of the Institute.

Notes

1. Controlling for differences in IQ in such research may be self-defeating in the evaluation of ADHD as an independent variable since the disorder has a reliable and meaningful negative association with IQ with which it shares about 6%–10% of the variance (Tillman, Bohlin, Sorenson, & Lundervold, 2009). This relationship is through shared genetic and developmental etiological influences (Rommel, Rijsdijk, Greven, Asherson, & Kuntsi, 2015) and to some extent (4%–46%) may be mediated by EF components related to both variables (Tillman et al., 2009). Thus, IQ differences between ADHD and control groups are not merely a consequence of confounding or errors/bias in participant selection that is to be statistically controlled. Doing so removes meaningful variance from the independent variable of interest (ADHD) (Miller & Chapman, 2001) and so unnecessarily and erroneously reduces potential group differences on the dependent variables of interest resulting in meaningless or unrealistic residuals.

Additional information

Funding

This work was supported by the National Institute of Mental Health: [grant number MH 42181].