What does handedness reveal about ADHD? An analysis based on CPT performance

Background: Attention-deficit/hyperactivity disorder (ADHD) is a developmental disorder. Continuous performance Tests (CPTs) aid the diagnosis. Handedness is linked to disabilities. Objectives: 1-To Study the association between handedness and ADHD; 2-To verify the usefulness of the CPT in school settings; 3-To exam the relationship between handedness and CPT performance. Method: Each child was classified as right-consistent, left-consistent, or non-consistent. From the sample, 171 controls and 68 ADHDs fulfilled the inclusion criteria. The effect of handedness on the CPT was studied using a paired-sample that matched handedness by age, grade, gender, and ADHD. Results: Left-handed students had a probability of suffering from ADHD 2.88 greater than right-handers. ANOVAs on standardized scores indicated that the ADHD students exhibited higher number of errors and higher variability of reaction times as compared to the controls. Discriminant analysis indicated that these CPT parameters could discriminate ADHD from controls. Repeated ANOVAs showed a significant effect of handedness on commission errors (CE) because left-handers made more CEs than right-handers. Conclusions: 1-The association between ADHD and handedness reflects that left-handers are less lateralized and have decreased interhemispheric connections; 2-The CPT can be used to measure different attention domains in school settings; 3- Left-handers have problems in the impulsive/hyperactivity domain.