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Examining the association between sluggish cognitive tempo and functional connectivity in children with ADHD: A pilot study
Adebayo B Braimah1, Jonathan A Dudley1, Jeffery Epstein2, Leanne Tamm2, and Stephen P Becker2
1Imaging Research Center, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States, 2Behavioral Medicine and Clinical Psychology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States

Synopsis

Sluggish cognitive tempo (SCT) is a behavioral phenotype characterized by excessive daydreaming that is frequently present in children with ADHD. This study examined functional connectivity in children with ADHD and high SCT, children with ADHD and low SCT, and typically developing children. Resting state fMRI data were acquired and analyzed to examine group differences as well as associations with ordinal ADHD and SCT symptom scores. Three a priori seeds were generated from NeuroSynth to investigate connectivity patterns associated with default mode, attention, and orienting domains. SCT scores were negatively associated with connectivity between attentional and medial visual areas.

Purpose

There is growing evidence that children’s attention problems are heterogeneous, with increasing interest in a sluggish cognitive tempo (SCT) phenotype characterized by excessive daydreaming, mental confusion, and slowed behavior/thinking. Approximately 40% of children with attention-deficit/hyperactivity disorder (ADHD) also experience symptoms of sluggish cognitive tempo (SCT)1. SCT refers to excessive daydreaming, mental confusion, and slowed behavior/thinking. Despite the prevalence of SCT and links to functional impairment, neural correlates remain almost entirely unexamined2. The present study examined functional connectivity in children with ADHD with and without co-occurring SCT, in addition to typically developing (TD) children with neither ADHD nor SCT.

Material & Methods

Participants (TD=22, ADHD-SCT=23, ADHD+SCT=20, age=10.03 ± 1.48 yrs, 36 males, 29 females) had SCT and ADHD symptom ratings obtained from parents (N=65), teachers (N=60), and child self-report (N=59). Participants underwent both T1w structural (TR/TE 8.052 ms, 3.68 ms, flip angle 8°, FOV 256 x 256 mm², slice thickness 1 mm, voxel size 1 x 1 x 1 mm³) and resting-state functional EPI (TR/TE 2000 ms, 30 ms, flip angle 75°, FOV 224 x 224 mm², slice thickness 3 mm, voxel size 3 x 3 x 2.8 mm³, scan duration of 600 seconds) scan acquisitions with a Philips 3T Achieva (Best, The Netherlands). Participants were instructed to keep their eyes open and look at a fixed cross (+) during the functional scan acquisition. The acquired T1w structural and functional EPIs underwent quality assurance via MRIQC3,4. Structural T1w images underwent preprocessing and surface mesh reconstruction via fmriprep3,5 and FreeSurfer6. Functional images were preprocessed with FSL’s FEAT7,8 – which included motion correction9, brain extraction10, and high pass filtering (0.1 Hz) followed by aggressive ICA-based cleanup with FSL’s FIX11–14. Volumetric functional data was then mapped to the corresponding surface mesh and registered to the HCP S1200 group average surface template using connectome workbench, ciftify15,16, and multimodal surface matching17,18. The surface mapped timeseries were then smoothed with a smoothing kernel of 4mm FWHM in addition to being demeaned. Quality control of the preprocessed functional data, and the volume-to-surface mapped functional data were assessed via visual inspection. Three seed regions of interest were obtained from NeuroSynth19 using the terms: attention, orienting, and default mode. Seeds were mapped to the HCP S1200 group average surface template using connectome workbench. We assessed group differences as well as correlations between the SCT symptom scores and seed regions of interest via dual regression20,21 and permutation testing using FSL’s PALM22,23. All analyses controlled for sex and age at scan. Multiple regression analyses also included ADHD inattention scores in the models.

Results

No group differences were found between TD, ADHD-SCT, and ADHD+SCT groups when controlling for age and sex. Parent-reported SCT symptoms were associated with decreased functional connectivity between the attention seed region and the portions of the brain centered around the pre- and post-central gyri in participants when controlling for age, sex, and parent-reported ADHD inattention symptoms (Figure 1). Teacher-reported SCT symptoms were associated with increased functional connectivity between the attention seed region and the right lateral portions of the visual pole, and decreased functional connectivity in the left lateral portion of the visual pole in participants when controlling for age, sex, and teacher-reported ADHD inattention symptoms (Figure 2). Child-reported SCT symptoms were associated with decreased functional connectivity between the attention seed region and two separate clusters. The first in the left hemisphere spanning portions of the: cuneus cortex, isthmus of the cingulate cortex, lingual gyrus, pericalcarine cortex, precuneus cortex. The second in the right hemisphere spanning portions of the: paracentral lobule, postcentral gyrus, precentral gyrus, superior frontal gyrus, superior parietal cortex (Figure 3).

Discussion & Conclusion

This study, although preliminary, is one of the first to indicate that SCT symptoms may be associated with specific functional connectivity patterns independent of ADHD symptom severity. Specifically, both teacher- and child-rated SCT scores were negatively associated with connectivity between the attention seed region and visual processing regions. Additionally, parent-rated SCT scores were negatively associated with connectivity between the attention seed region and right lateral portions of the dorsal attention network. The default mode and orienting seed regions were not shown to have any significantly different functional connectivity patterns across the brain for reported SCT scores when controlling for age, and sex. Collectively, these findings suggest that SCT may be associated with disrupted processing between attentional and visual seed regions. Future directions should include further investigation into dorsal and ventral attention network mediated functional connectivity.

Acknowledgements

This research was supported by a Cincinnati Children’s Research Foundation (CCRF) Trustee Award and the National Institute of Mental Health (NIMH; K23MH108603). The content is solely the responsibility of the authors and does not necessarily represent the official views of the CCRF or NIMH.

References

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Figures

Figure 1: Parent-rated SCT (controlling for age, sex, and parent-rated ADHD inattention symptoms) shows decreased functional connectivity between the attention seed region and the: right ccaudal anterior-cingulate cortex, right paracentral lobule, right postcentral gyrus, right posterior-cingulate cortex, fight precentral gyrus, right superior frontal gyrus, right superior parietal cortex.

Figure 2: Teacher-rated SCT (controlling for age, sex, and teacher-rated ADHD inattention symptoms) shows increased functional connectivity between the attention seed region and the: right cuneus cortex, right lateral occipital cortex, fight pericalcarine cortex, right superior parietal cortex, and decreased functional connectivity between the: left cuneus cortex, left isthmus – cingulate cortex, left lingual gyrus, left pericalcarine cortex, Left precuneus cortex.

Figure 3: Child-rated SCT symptoms (controlling for age, sex, and parent-rated ADHD inattention symptoms) shows decreased functional connectivity between the attention seed region and the: left cuneus cortex, left isthmus – cingulate cortex, left lingual gyrus, left pericalcarine cortex, left precuneus cortex, right cuneus cortex, right isthmus – cingulate cortex, right lingual gyrus, right parahippocampal gyrus, right pericalcarine cortex, right precuneus cortex.

Proc. Intl. Soc. Mag. Reson. Med. 29 (2021)
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