Attention deficit hyperactivity disorder and dyslexia: a history of overlap

Transtorno do déficit de atenção e hiperatividade e dislexia: a história de uma superposição

EDITORIAL

Attention deficit hyperactivity disorder and dyslexia: a history of overlap

Transtorno do déficit de atenção e hiperatividade e dislexia: a história de uma superposição

Alexandra Prufer de Queiroz Campos Araujo

Professora-associada de Neuropediatria, Faculdade de Medicina, Universidade Federal do Rio de Janeiro

^{Correspondence}

Attention deficit hyperactivity disorder (ADHD) is a frequent disorder like dyslexia. The ADHD worldwide-pooled prevalence is 5.29%¹ and for dyslexia the prevalence ranges from 6 to 9%². Co-morbidity among those two disorders is found in more than a third of ADHD³. Furthermore, dyslexia is much more frequent in children with ADHD, up to six times more, as it is among children without ADHD⁴.

Overlap here may be more than just the simple case of two common problems occurring by chance in the same person. Both developmental disorders arise from multiple cognitive deficits. Common underlying features may be contributing to the high co-morbidity between these disorders. There are propositions that dyslexia might be related to underlying deficits in attention shifting⁵.

The study published in the current issue of Arquivos de Neuro-Psiquiatria by Miranda et al.⁶ contributes to this field. With the aim of investigating the performance parameters of children with dyslexia (32), children with ADHD (52) and control children (475), using the Conners' Continuous Performance Test, they found some overlapping as both show failure in inhibitory control.

Children with ADHD displayed specific deficits compared with the Control Group: a failure in attention (omission error), a failure in inhibitory control (commission error), inconsistency in the response rate (standard error of the reaction time), intra-participant variability, higher level of impulsiveness (perseverations), and poor vigilance (change in the inter-stimulus interval).

Those with dyslexia had more errors due to failures in the inhibitory control (commission errors), more variable and anticipatory responses (perseverations), and less response consistency as the test progressed compared to the Control Group.

Comparing both developmental disorders, children with ADHD displayed higher attention deficits (higher omission errors), highly variable reaction times, frequent inattention, higher rate of anticipatory responses (perseverations), and less consistent reaction times with longer stimulus intervals.

In summary, Miranda et al.⁶ advance in understanding the differences and similarities of both disorders in children, as put forward by Dhar et al. in adults with dyslexia as compared to those with ADHD⁷.

Conflict of interest

There is no conflict of interest to declare.

Received 19 December 2011

Accepted 26 December 2011

• 1. Polanczyk G, de Lima MS, Horta BL, Biederman J, Rohde LA. The worldwide prevalence of ADHD: a systematic review and metaregression analysis. Am J Psychiatry 2007;164:942-948.
• 2. Shaywitz SE, Shaywitz BA, Fletcher JM, Escobar MD. Prevalence of reading disability in boys and girls. Results of the Connecticut Longitudinal Study. JAMA 1990;264:998-1002.
• 3. Langberg JM, Vaughn AJ, Brinkman WB, Froehlich T, Epstein JN. Clinical utility of the Vanderbilt ADHD Rating Scale for ruling out comorbid learning disorders. Pediatrics 2010;126:1033-1038.
• 4. Yoshimasu K, Barbaresi WJ, Colligan RC, et al. Gender, attention-deficit/hyperactivity disorder, and reading disability in a population-based birth cohort. Pediatrics 2010;126:788-795.
• 5. Lallier M, Tainturier MJ, Dering B, Donnadieu S, Valdois S, Thierry G. Behavioral and ERP evidence for amodal sluggish attentional shifting in developmental dyslexia. Neuropsychologia 2010;48:4125-4135.
• 6. Miranda MC, Barbosa T, Muszkat M, et al. Performance patterns in Conners' CPTamong children with attention deficit hyperactivity disorder and dyslexia. Arq Neuropsiquiatr 2012;70:91-96.
• 7. Dhar M, Been PH, Minderaa RB, Althaus M. Information processing differences and similarities in adults with dyslexia and adults with attention deficit hyperactivity disorder during a Continuous Performance Test: a study of cortical potentials. Neuropsychologia 2010;48:3045-3056.

Publication Dates

• Publication in this collection
  31 Jan 2012
• Date of issue
  Feb 2012