Coexistence of Tic Disorders and Combined Type of Attention Deficit/Hyperactivity Disorder: Features of Specific Cognitive Deficit

Abstract

The state of cognitive deficit in subjects with combination of attention deficit hyperactivity disorder and tic hyperkinesis is among the least studied issues. Identification of the cognitive development features in children with these disorders comorbidity will help to develop and build an adequate model of rehabilitation.Purpose of the study.To study cognitive deficits in children with tic hyperkinesis (TH) in cases of comorbidity with the combined type of attention deficit disorder (ADHD).Materials and methods.404 children aged 6–10 years with a combined type of ADHD were divided into three subgroups according to the state of monoamine activity: 1st subgroup with a combination of hypofunction of dopaminergic and hyperfunction of noradrenergic systems — 120 people, 2nd subgroup with a combination of hyperfunction of noradrenergic system with a relative dopamine balance — 136 people, 3rd subgroup with indicators of monoamines within the reference values — 148 children. The control group comprised of 90 children (54 boys and 36 girls). To diagnose the level of intellectual development, Wechsler Intelligence Scale for Children was used. In each subgroup, with the known direction of monoamine activity, the Wexler test parameters were compared among ADHD groups, both with or without TG.Results.Subtests “Picture Arrangement”, “Picture Completion” and “Block Design” turned out to be sensitive to concomitant combined type of ADHD and tics in children, reflecting, respectively, enumeration, the ability to logical thinking, visual attention and hand-eye coordination. In a case of dopamine system hypofunction in children with ADHD, the addition of tics leads to the smoothing of the biochemical imbalance by increasing the activity of dopamine and thus, results in a more effective realization of logical thinking ability. The level of visual attention in children with ADHD with the addition of TH also increases, probably due to a growth of the intensity of serotonin system activity. Finally, hand-eye coordination improves with the addition of tics in cases of a shift in the balance of dopamine and noradrenergic systems.Conclusion.The data obtained are consistent with the “frontal lobe compensation hypothesis” in the part, which describes the presence of a compensatory process when tics emerge in children with combined type of ADHD. Besides, our results expand it, suggesting that not only the prefrontal cortex but also the parietal-occipital cortex participates in the adaptive process associated with spatial synthesis and analysis of information, as well as hand-eye coordination.