Working memory profile differs in dyslexia with or without associated developmental coordination disorder.

Maziero, S. 1, 2 , Tallet, J. 2 , Bellocchi, S. . 3 , Jover, M. 4 , Chaix, Y. 2, 5 & Jucla, M. . 1

1 Octogone-Lordat, University of Toulouse, France
2 ToNIC, Toulouse NeuroImaging Center, Toulouse University, Inserm, UPS, France
3 Epsylon Research Unit EA 4556 Paul-Valéry University, Montpellier 3 France
4 Aix Marseille Université, PSYCLE, Aix-en- Provence, France
5 Hôpital des Enfants, Centre Hospitalier Universitaire de Toulouse ; CHU Purpan, Toulouse, France

Verbal working memory impairment is frequently reported in developmental dyslexia (DD). In the visuospatial domain, results are inconsistent. We postulate that an associated developmental coordination disorder (DCD) might impact the working memory profile of dyslexic children. We performed an exploratory cluster analysis on phonological (PWM) and visuospatial working memory (VSWM) performance (digit span and Wechsler block-tapping task) in 47 children with isolated DD, 27 children with DD and co-occurrent DCD, 22 children with isolated DCD, 42 typically achieving children (TA) from 7;6 to 12;6 years old. None of them presented with a developmental language disorder or attention deficit/hyperactivity disorder. The analysis lead to four clusters. Cluster A included children with impaired PWM but preserved VSWM comprising a majority of DD-only children. Cluster B included children with impaired abilities in VSWM and poor performance in PWM predominantly counting DCD-only and DD+DCD children. Two other clusters include children with about (cluster C - children from the four subgroups) or above (cluster D - mainly TA children) the expected average. These results shed light on the influence of comorbidity on children with DD as DD-only children have expected PWM weakness without VSWM difficulties whereas DD+DCD children?s memory profile resembles that of DCD-only children.