Date of Award

Summer 8-1-2025

Document Type

Dissertation

Degree Name

Doctor of Psychology (PsyD)

Department

Psychology

First Advisor

Elizabeth O'Laughlin

Second Advisor

Thomas Johnson

Third Advisor

Virgil Sheets

Abstract

Research suggests that a high intelligence quotient (IQ) may contribute to the underdiagnosis and misdiagnosis of Attention-Deficit/Hyperactivity Disorder (ADHD) in children. High IQ may allow children to compensate for executive functioning-related deficits inherent in ADHD and/or may influence behaviors such as high activity level or not following rules that mimic ADHD symptoms. To gain a better understanding of the relationship between IQ and ADHD, the present study aimed to investigate how high IQ impacts symptoms of inattention and hyperactivity as well as outcomes related to academic performance, emotional regulation, and peer relationships in children. The study utilized archival data from 263 children (ages 6-12) who were evaluated for ADHD at a Midwest university-based ADHD clinic. Data collected included parent and teacher ratings on behavior ratings scales and child performance on a measure of intellectual ability. Contrary to hypotheses, the current study did not find support for reduced ratings of inattention, hyperactivity, and academic impairment for children with high IQ and ADHD compared to children with average IQ and ADHD in a clinical sample, although ratings of academic impairment trended in the expected direction. Findings revealed some support for a moderation effect of IQ on the relationship between emotional dysregulation and peer impairment; the relationship between emotional dysregulation and peer impairment was stronger at lower IQ levels and weaker at higher IQ levels. Results suggest that factors in addition to emotional dysregulation contribute to peer impairment for children with higher IQ. Considering clinical implications, greater understanding of how IQ impacts presentation of ADHD symptoms and outcomes could influence the process by which clinicians integrate and interpret assessment data.

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