Arithmetic performance in children with Tourette syndrome: relative contribution of cognitive and attentional factors.

The study addressed the issue of arithmetic deficiencies in children with Tourette syndrome (TS) as well as explanations for such deficiencies. A total of 47 children with TS were assigned to three subgroups based on a composite attention score from the Test of Variables of Attention (TOVA). These children, along with 17 normal controls between 8 and 16 years of age, were tested on standardized measures of IQ, attention, visuospatial ability, and arithmetic achievement. The children also were administered an experimental calculation task with two levels of structure. Children with TS scored below controls on tests of IQ, attention, and arithmetic achievement but not visuospatial ability. The TS subgroup with the greatest impairment of attention accounted for most of the differences in arithmetic achievement. Regression analysis, based on the 47 children with TS, indicated that IQ and TOVA scores were the best predictors of arithmetic achievement. Likewise, the experimental calculation task indicated that the poor performance of some children with TS could be attributed to deficient attention. Irrespective of structure, children in the TS subgroup with the greatest attentional impairment made more attention (but not visuospatial) errors than did controls on the experimental task. Thus, on both the standardized and the experimental tasks, poor arithmetic skill was found only in children with TS who had significant attentional deficits.