The purpose of this study is to assess the safety and efficacy of a customized head mold for reducing head motion during MRI scanning in young children.

Each participant completed a dedicated session for mock scanning before we acquired two sets of sMRI and fMRI scans. One scan set was collected using the head mold and the other without, and the scans were counterbalanced in order across participants. Using a specialized sMRI sequence embedded with vNAVs, we directly measured head motion during sMRI in order to more accurately evaluate the head mold's impact on structural metrics. To evaluate the feasibility and tolerability of the head mold, we concluded the scanning sessions with a brief interview that gauged participants' scanning experience and tolerance of the head mold. We investigated whether head molds would reduce head motion compared to standard scanning procedures and whether those reductions would result in improved data quality. We also tested the extent to which reductions in head motion impacted estimations of cortical volume and functional connectivity. Prior to data collection, we evaluated the noise dosage levels of the head mold condition, given the limited space available for additional hearing protection devices in the head coil while the head mold is on. We also assessed whether the head molds could balance head motion between typical and ADHD populations, and whether clinical variables such as ADHD diagnosis and trait anxiety, as determined by parent-reported dimensional measures, can predict head mold efficacy.

Inclusion Criteria:

• between ages 5 - 10
• ADHD diagnosis as determined by parent self-report

Exclusion Criteria:

• no MRI contraindications and no history of head injuries or seizures.

All data will be de-identified using standards conforming to HIPAA guidelines. Consistent with the model setup by the International Data Sharing Initiative (INDI) effort, data will be distributed via the NITRC-based Functional Connectome Project (FCP)/INDI website (http://fcon\_1000.projects.nitrc.org/ [blocked]). The following steps will be carried out to ensure that no identifying or protected health information is released:

• All imaging files will be stripped of fields containing protected health information, and date of exam will be removed
• Anatomical images will have face information removed or obscured.
• Random ID numbers will be generated and assigned to each dataset prior to release.

Legal guardians of the child participants will be asked if they consent to having their data shared publicly, as well as privately with other University of Texas at Austin researchers. If they do not consent to having their data shared, they may still participate in the study without penalty.