Understanding the Comorbidity between Attention and Reading Disorders: Etiology, Neuropsychological Factors, and the Effects of ADHD Treatment and Reading Intervention on Attention and Reading Outcomes

Understanding the Comorbidity between Attention and Reading Disorders: Etiology, Neuropsychological Factors, and the Effects of ADHD Treatment and Reading Intervention on Attention and Reading Outcomes

First Author: Carolyn A. Denton -- Oregon Research Institute
Additional authors/chairs: 
Daniel R. Leopold; Greg Roberts; Leanne Tamm; Discussant
Keywords: Attention, Reading disability
Abstract / Summary: 

Attention Deficit/Hyperactivity Disorder (ADHD) and reading disabilities (RD) are common childhood disorders, and they frequently co-occur. The purpose of this symposium is to integrate findings from basic and intervention research to better understand ADHD/RD comorbidity. The first paper will focus on etiological and neuropsychological underpinnings and functional impairment in ADHD/RD comorbidity. Three presentations of intervention research will further explore the relationship between attention and reading. The first describes the effects of intensive reading intervention on attention in middle school students. The next two papers are based on a study contrasting the effects of ADHD intervention (medication + parent training), intensive reading instruction, and their combination for children with comorbid ADHD/RD. The first reports the impact of adding ADHD treatment on response to reading intervention for children with ADHD/RD, and the second reports the effects of the three treatments on reading comprehension for this population. The discussant, Erik Willcutt, will integrate findings across the papers.

Symposium Papers: 

Twin studies of comorbidity between reading disability and ADHD

First Author/Chair:Daniel R. Leopold -- University of Colorado Boulder
Additional authors/chairs: 
Erik Willcutt ; John C. DeFries ; Sally J. Wadsworth ; Bruce Pennington ; Janice M. Keenan ; Richard K. Olson

Reading disability (RD) and attention-deficit/hyperactivity disorder (ADHD) frequently co-occur, but the etiological and neuropsychological underpinnings and functional consequences of this comorbidity are not well understood.

As part of their participation in the Colorado Learning Disabilities Research Center twin study, twins with ADHD alone (N = 275), RD alone (N = 325), both RD and ADHD (N = 150), and a control sample without RD or ADHD (N = 900) completed an extensive battery of measures of neuropsychological functioning and functional impairment. Phenotypic and behavioral genetic analyses were conducted to examine the shared and unique risk factors for RD and ADHD and the consequences of their co-occurrence.

RD and ADHD co-occur more frequently than expected by chance due to shared genetic influences. Further, the comorbid group exhibited greater impairment in multiple domains than groups with either disorder alone, including higher rates of academic, social, and global impairment. Genetically mediated weaknesses in cognitive processing speed and response variability accounted for most of the covariance between RD and ADHD and helped to explain the higher levels of functional impairment in the comorbid group, whereas other neuropsychological weaknesses were uniquely associated with RD (phonological decoding, vocabulary, and naming speed) and ADHD (response inhibition).

Shared genetic influences on measures of cognitive efficiency such as processing speed and response variability may lead to frequent comorbidity between RD and ADHD and increased functional impairment in individuals with both disorders. Additional research is needed to determine the potential treatment implications for individuals with both RD and ADHD.

The Impact of Intensive Reading Intervention on Level of Attention in Middle School Students

First Author/Chair:Greg Roberts -- University of Texas at Austin
Additional authors/chairs: 
Jack M. Fletcher; Sharon Vaughn

Purpose: The purpose of the study was to estimate the impact of reading intervention on ratings of student attention over time.

Method: We used extant data from a longitudinal randomized study of a response-based reading intervention to fit a multiple-indicator, multilevel growth model. The sample at randomization was 54% male, 18% limited English proficient, 85% eligible for free or reduced-price lunch, 58% African American, and 32% Hispanic. Reading ability was measured by using the Woodcock-Johnson III Tests of Achievement. Attention was measured by using the Strengths and Weaknesses of ADHD Symptoms and Normal Behavior Scale.

Results: Intensive, response-based reading intervention over 3 years improved reading achievement and behavioral attention in middle school struggling readers, with treatment directly affecting reading, which in turn influenced attention. In the business-as-usual condition, there was no relation between improved reading and attention.

Conclusions: The results are consistent with a correlated liabilities model of comorbidity. The results do not align with the inattention-as-cause hypothesis, which predicts that reading intervention should not affect attention. The findings do not support, but do not necessarily preclude, the phenocopy hypothesis. The results are especially pertinent for older students who may be inattentive partly because of years of struggling with reading.

Does Concurrent Treatment with Medication and Parent Training Improve Response to Reading Intervention in Poor Readers with ADHD?

First Author/Chair:Leanne Tamm -- Cincinnati Children's Hospital Medical Center
Additional authors/chairs: 
Carolyn A. Denton; Jeff Epstein; Chris Schatschneider

Purpose: Up to 40% of children with Attention-Deficit/Hyperactivity Disorder (ADHD) also have reading difficulties or disabilities (RD). In this study, we investigate the relative efficacy of intensive reading intervention and ADHD interventions on reading fluency outcomes in students with both RD and ADHD, and whether treating ADHD symptoms concurrently with medication and parent training enhances response to reading intervention.

Method: Children (n=214) in grades 2-5 diagnosed with ADHD and word-reading deficits (≤25th percentile on Woodcock-Johnson III Letter-Word Identification or Word Attack or Basic Reading Skills) were randomly assigned to receive 1) intensive reading intervention, 2) medication and parent training, or 3) both, for 16 weeks. The Test of Word Reading Efficiency (TOWRE) Sight Word Efficiency (SWE) and Phonemic Decoding Efficiency (PDE) subtests were administered to assess reading fluency. Mixed model analyses compared fluency scores across the three intervention conditions.

Results: A significant main effect was observed for PDE (p=.02), and a marginally significant effect was observed for SWE (p=.06) Efficiency. For PDE, the combined intervention group (Hedges g=.21) and reading intervention group (Hedges g=.34) improved reading fluency more than the group that received medication and parent training alone, but did not differ from one another (Hedges g=.12).

Conclusions: Not surprisingly, interventions specifically targeting reading skills impact reading fluency more than those targeting ADHD behaviors. Concomitant ADHD treatment in addition to reading intervention was not superior to reading intervention alone for reading fluency outcomes. Students with significant word-reading difficulties and ADHD require specific interventions targeting reading skills to address reading fluency.

The Effects of ADHD Treatment, Intensive Reading Intervention, and Their Combination on the Reading Comprehension of Children with Comorbid ADHD and Word-Reading Difficulties

First Author/Chair:Carolyn Denton -- University of Texas Health Science Center at Houston
Additional authors/chairs: 
Leanne Tamm; Chris Schatschneider; Jeff Epstein

Purpose: Up to 38% of children with reading difficulties (RD) also have Attention-Deficit/Hyperactivity Disorder (ADHD; DuPaul et al., 2013). In this study, we compared the effects of ADHD treatment alone (medication + parent training), RD treatment alone (intensive reading intervention), and their combination on the reading comprehension growth of children with both ADHD and word-level RDs.

Method: Children (n=214) in grades 2-5 with ADHD and word-reading deficits were randomly assigned to receive 1) only RD treatment (RD group), 2) only ADHD treatment (ADHD group), or 3) both (Combined group), for 16 weeks. Children were assessed at baseline and posttest with the Test of Sentence Reading Efficiency and Comprehension (TOSREC) and WIAT III Reading Comprehension. Mixed model analyses compared outcomes in the treatment conditions.

Results: There were no significant group differences on the TOSREC. On WIAT comprehension, the ADHD group had significantly better outcomes than the RD group (p=.008; g=.30). Although the ADHD group outperformed the Combined group and the Combined group outperformed the RD group, these differences were not significant.

Conclusions: In children with comorbid ADHD and RD, sentence-level comprehension was not differentially impacted by the type of intervention provided. In contrast, the combination of ADHD medication and parent training was significantly more effective than intensive reading intervention in improving children’s comprehension of connected text. This finding may be related to the roles of attention and self-regulation in reading comprehension, processes typically impaired in children with ADHD that may have been impacted by the ADHD treatment.

Discussion of Paper Findings about ADHD/RD Comorbidity

First Author/Chair:Discussant Erik Willcutt

Erik Willcutt will integrate findings across the four spoken papers with current knowledge and theory related to the comorbidity between ADHD and Reading Disabilities.