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
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