[PS-2.15] Developmental Dyslexia and comorbid motor disorder: impact of co-occurrence on cortical thickness

Biotteau, M. 1, 2 , Albaret, J. 1, 2 , Celsis, P. 1, 2 , Chauveau, N. 1, 2 , Péran, P. 1, 2 & Chaix, Y. 1, 2, 3

1 INSERM, UMR 1214 Toulouse NeuroImaging center (ToNIc), CHU Purpan, Place du Dr Baylac, F-31059 Toulouse Cedex 9, France
2 University of Toulouse III Paul Sabatier, UMR 1214 Toulouse NeuroImaging center (ToNIc), CHU Purpan, Place du Dr Baylac, F-31059 Toulouse Cedex 9, France
3 Children's Hospital, Toulouse-Purpan University Hospital, Place du Dr Baylac, F-31059 Toulouse Cedex 9, France

Motor disorders can affect about 80% of subjects with developmental dyslexia (DD) and in more of 50% of case, impairment is severe enough to meet criteria for developmental coordination disorder (DCD). Accordingly, how consider DD+DCD ? As a subgroup of DD, as a subgroup of DCD, as mix of the two, or as another disorder? The purpose of this study is to examine whether the pattern of cortical thickness (CT) for concurrent disorders is distinct from the brain alterations seen in single disorders. Fifty-five right-handed children (18?-37?) 19DD-16TAC-20DD+DCD (DSM-IV-TR criteria, MABC for motor skill, Alouette and ODEDYS for reading skill, no other additional disorder) were included into the study. CT analysis was performed to determine and compare the patterns of thickness/thinning in each disorder separately and in association. Interestingly, DD+DCD children do not cumulate the structural consequences of each disorder. We found no difference between DD and DD+DCD groups, but differences between DCD and the two others groups in parietal lobe, placing the DCD group appart from the other two. This raises the question of the status of the comorbid group, not clearly as a combination of both DD and DCD but more likely as a sub-group of DD.