Intragroup differences and similarities in performance on rapid automatized naming tasks in children with ADHD symptoms, children with reading disabilities, and controls.

INTRODUCTION
Rapid automatized naming (RAN) is the ability to name, as fast as possible, symbols such as letters, digits and figures. The present study aimed to investigate intragroup performance patterns on RAN tasks in children with attention deficit hyperactivity disorder (ADHD) symptoms alone, children with reading disability (RD) alone and controls with typical development.


METHODS
A total of 216 Brazilian children between 8 to 11 years old were selected from public schools located in two Brazilian capitals, namely Porto Alegre and Belo Horizonte, to participate in the study. Mixed 3 (participant group: ADHD symptoms, RD or control group) × 3 (type of stimulus: letters, numbers or figures) ANOVAs were performed using response time and number of errors as dependent variables. Only intragroup comparisons are described in this paper.


RESULTS
The groups with ADHD symptoms and RD showed similar performance results on naming speed. There were no differences between letters and numbers within each group, but we found slower responses in figure naming compared to the other tasks for both groups. Concerning accuracy, children with ADHD symptoms showed a similar number of errors in all three tasks. These patterns were distinct from the performance of the control group.


CONCLUSION
Results suggest a shared deficit in naming speed of alphanumeric stimuli in children with ADHD symptoms and those with RD, and impairments in naming digits correctly in children with ADHD symptoms.


Introduction
Rapid automatized naming (RAN) is the ability to name, as fast as possible, visually presented familiar symbols such as letters, digits, figures or colors. 1 Several studies have revealed RAN to be a strong longitudinal predictor of reading development, especially reading fluency. [1][2][3] Furthermore, deficits in this skill are common to different neurodevelopmental disorders, such as attention deficit hyperactivity disorder (ADHD) 3,4 and reading disability (RD). 5 Performing RAN tasks requires several cognitive processes such as attentional and visual processes, integration of visual patterns and orthographic information (letters as stimuli) and recovery of phonological labels. These processes are often impaired in children with ADHD and/or RD, translating into an increased number of errors and decreased naming speed in these tasks. 4,6 Authors also claim the potential usefulness of RAN in the diagnosis of reading and attentional problems, particularly in children aged from 5 to 9. 6 There is also evidence that the development of RAN color and object may diverge from RAN letter and digit, suggesting that different cognitive processes may be involved in these different subtasks. 7 Letters and digits engage largely automated decoding processes, whereas objects and colors do not, and as such, the latter would consume more resources relating to attention. 6 In this sense, children with ADHD tend to present lower performance rates specifically on tasks composed of figures and colors compared with controls. 4,6 Within groups, adolescents and adults with ADHD have demonstrated significantly quicker naming of letters/digits compared with colors and objects; the RD group has shown significantly quicker naming of letters compared with digits, and both did not differ from object naming. 8 However, that study had some limitations: it considered only naming speed of each task as a RAN score and it did not include a control group to compare the performance of others to the pattern expected. 8 Thus, it is important to investigate the differences and similarities in performance on RAN tasks according to type of stimulus between children with ADHD and those with RD, especially due to the high comorbidity of both disorders. 6 Establishing execution performance profiles for these groups has crucial clinical relevance for both assessment and intervention designs. 5 The current study sought to compare differences in performance Performance was measured based on RT (speed) and number of errors (accuracy) in each CNS task. The scores that assess inhibition and flexibility 16 were not analyzed in the present study (for more details about the task, see van der Sluis et al. 16 ).

Results
As shown in Table 1

Discussion
The present study investigated similarities and differences between performance in different RAN tasks in participants with ADHD symptoms, participants with RD, and control children with typical development.
We discuss the results in order to provide possible explanations and directions for future investigations with RAN.
The ADHD symptoms and RD groups showed similar temporal performance in RAN tasks with letters and numbers, and lower performance with figures (when compared to letters and numbers). Children with typical development performed differently. They named letters significantly faster than numbers, and the latter faster than figures. Thus, there is probably a shared common difficulty in letter and digit (alphanumeric tasks) speeded naming in children with ADHD symptoms and those with RD, compared to control children.
The relationship between RAN and reading might be explained by the fact that both tasks require serial processing and retrieval of specific names 18 : good readers access word representations stored in the mental lexicon 19 faster and more efficiently. In this sense, rapid naming of digits and letters has a strong predictive relationship with early word recognition processes. 20 In addition, RAN interventions seem to enhance word reading speed and, consequently, improve reading fluency. 21 In children with ADHD, a deficit in executive control or failure to automatize working memory maintenance processes underlies the speed naming deficits observed in RAN tasks. In order to name a list of symbols, the child must plan, control and monitor the visual processing time for each stimulus; inhibit distractors to retrieve the representation of the next symbol; and implement sequential processing efficiently. This is probably the reason why RAN performance is also related to executive functions, especially inhibitory control, working memory and shifting. Commonly, the executive function components mentioned above are impaired in children with ADHD. 22 It can also be argued that a more general underlying cognitive process, such as processing speed, is impaired in children with ADHD symptoms and also in those with RD. Thus, the lower performance observed in naming speed in RAN tasks, especially with alphanumeric stimuli, might be explained by a common deficit in processing speed in children with RD and those with ADHD. 23,24 Concerning accuracy (number of errors), children often have more difficulty in naming figures than letters or numbers, since the former task is less common in everyday life. 25