ADHD and hyperactivity: The influence of cognitive processing demands on gross motor activity level in children

ABSTRACT

Excessive gross motor activity is a prominent feature of children with ADHD, and accruing evidence indicates that their gross motor activity is significantly higher in situations associated with high relative to low working memory processing demands. It remains unknown, however, whether children’s gross motor activity rises to an absolute level or accelerates incrementally as a function of increasingly more difficult cognitive processing demands imposed on the limited capacity working memory (WM) system – a question of both theoretical and applied significance. The present investigation examined the activity level of 8- to 12-year-old children with ADHD (n = 36) and Typically Developing (TD) children (n = 24) during multiple experimental conditions: a control condition with no storage and negligible WM processing demands; a short-term memory (STM) storage condition; and a sequence of WM conditions that required both STM and incrementally more difficult higher-order cognitive processing. Relative to the control condition, all children, regardless of diagnostic status, exhibited higher levels of gross motor activity while engaged in WM tasks that required STM alone and STM combined with upper level cognitive processing demands, and children with ADHD were motorically more active under all WM conditions relative to TD children. The increase in activity as a consequence of cognitive demand was similar for all experimental conditions. Findings suggest that upregulation of physical movement rises and remains relatively stable to promote arousal related mechanisms when engaged in cognitive activities involving WM for all children, and to a greater extent for children with ADHD.

KEYWORDS:

• Attention-Deficit/Hyperactivity Disorder
• working memory
• gross motor activity
• cognitive processing
• central executive processes

Acknowledgments

The authors are grateful to all children and families that participated in this study, and to all research assistants that contributed to collecting and processing the data.

Research ethics committee approval information

University of Central Florida (UCF); IRB Study Number: SBE-15-11040

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

¹ STM and upper level cognitive processing both involve effortful attention – a term used to denote an individual’s voluntary/purposeful control over thoughts and emotions.

² An n-back task requires participants to identify an identical stimulus that preceded the current stimulus by “n” presentations (e.g. a, d, x, z, x represents a 2-back with x as the designated target).

³ Increased movement was not expected to correlate positively with task performance in children with ADHD as reported in past studies – the imposition of increasingly more difficult task processing demands was expected to diminish all children’s performance.

⁴ Several participants in the current study participated in two conceptually unrelated studies that examined the relative contribution of WM CE abilities to (a) general intellectual functioning (Calub et al., 2019), and (b) written expression deficits (Eckrich et al., 2019) in children with ADHD as part of a planned series of on-going investigations that are deemed completed when the n surpasses an a priori power analysis threshold.

⁵ Note: all children were able to achieve 50% or more on the set size 3 OST; no child correctly recalled 100% of the words in the 5 math problem/word list trial which rendered the creation of a 6 word list trial unnecessary.

⁶ Requiring children to engage in brief math problems in-between remembering word sets reduces the potential buildup of proactive interference (i.e. interference by previous stimuli that may impede performance on subsequent trials) by engaging the short-term memory store with an unrelated category of items (Darling & Valentine, 2005; Gardiner et al., 1972).

⁷ Note: Marginally higher levels of movement occurred at the conclusion relative to the beginning of assessment sessions for both groups (i.e., F(1,58) = 9.05, p =.004; non-significant group-by-time interaction, F(1,58) = 2.35, p =.13), but considered non-meaningful based on the significant overlap of 95% confidence intervals (pre-session 5826.16–27,966.24; post-session 6917.66–29,918.50).

⁸ IQ is inherently an unsuitable covariate even when significant between-group differences emerge because WM shares considerable variance (~57%) with FSIQ and would result in extracting WM from WM (Calub et al., 2019; Dennis et al., 2009).

⁹ A Huynh-Feldt correction was applied as recommended by Field (2013) because the Greenhouse-Geisser estimate of sphericity was >.75.

Additional information

Funding

TJD is supported by a grant of the Dutch Prins Bernhard Cultuur Fonds (no. 40021352). The funding source had no role in the study design, collection, analysis or interpretation of the data, writing the manuscript, nor the decision to submit the paper for publication.