Numerical and calculation abilities in children with ADHD.

The aim of this study is to investigate the specific numerical and calculation abilities of 28 children with ADHD without comorbid mathematical learning disabilities (LD) raging from the first to the fifth grade of primary school and to examine the stability or the development of the arithmetic profile during school age. Our results showed that a high percentage of ADHD children have severe difficulties on numerical and calculation abilities, particularly on counting and arithmetical facts, and these percentages increase with age. Whereas younger children have more problems in lexical processes, for older children, mental calculation and counting processes are particularly difficult. The older students had statistically worse performance than younger students in the two measures of time (i.e., mental calculation time and counting time), indicating automatization deficits. This study underlines the importance for teachers to take into account individual arithmetic profiles of children with ADHD and enhanced the specific difficulties through education.