Impaired response inhibition during a stop-signal task in children with Tourette syndrome is related to ADHD symptoms: A functional magnetic resonance imaging study

Abstract

Objectives: Tourette syndrome (TS) is characterised by the presence of sudden, rapid movements and vocalizations (tics). The nature of tics suggests impairments in inhibitory control. However, findings of impaired inhibitory control have so far been inconsistent, possibly due to small sample sizes, wide age ranges, or not taking medication use or attention-deficit/hyperactivity disorder (ADHD) comorbidity into account. Methods: We investigated group differences in response inhibition using an fMRI-based stopsignal task in 103 8 to 12-year-old children (n ¼ 51 with TS, of whom n ¼ 28 without comorbid ADHD [TS À ADHD] and n ¼ 23 with comorbid ADHD [TS þ ADHD]; and n ¼ 52 healthy controls), and related these measures to tic and ADHD severity. Results: We observed an impaired response inhibition performance in children with TS þ ADHD, but not in those with TS À ADHD, relative to healthy controls, as evidenced by a slower stop-signal reaction time, slower mean reaction times, and larger variability of reaction times. Dimensional analyses implicated ADHD severity as the driving force in these findings. Neural activation during failed inhibition was stronger in the inferior frontal gyrus and temporal and parietal areas in TS þ ADHD compared to healthy controls. Conclusions: Impaired inhibitory performance and increased neural activity in TS appear to manifest predominantly in relation to ADHD symptomatology.

Acute and Long-Term Effects of an Internet-Based, Self-Help Comprehensive Behavioral Intervention for Children and Teens with Tic Disorders with Comorbid Attention Deficit Hyperactivity Disorder, or Obsessive Compulsive Disorder: A Reanalysis of Data from a Randomized Controlled Trial

“…These results suggest that comorbid ADHD was associated with greater disability than TD alone. Our findings are consistent with previous studies indicating that co-existing ADHD often causes more psychosocial impairment for children and adolescents with TD than the severity of the tics themselves [ 8 , 13 , 16 ].…”

“…These two studies showed that CBIT may promote neurocognitive changes and normalization of deficits in cortico-striato-thalamo-cortical circuits in individuals with TD, which may account for our findings of an improvement in inattention, psychosomatic, anxiety and impulsivity-hyperactivity symptoms. As ADHD and TD share both common and different brain regions [ 11 , 13 , 36 ], it is conceivable that the improvements on the CRPS-R scores may be related to the positive effects of the core therapeutic techniques of CBIT; namely, tic awareness training, stress management and tic suppression by implementing habit reversal skills. These techniques may have a positive effect on certain neurological circuits associated with the impaired inhibitory performance and with attentional and sensory regulation mechanisms underlying both ADHD and TD [ 9 , 13 ].…”

“…As ADHD and TD share both common and different brain regions [ 11 , 13 , 36 ], it is conceivable that the improvements on the CRPS-R scores may be related to the positive effects of the core therapeutic techniques of CBIT; namely, tic awareness training, stress management and tic suppression by implementing habit reversal skills. These techniques may have a positive effect on certain neurological circuits associated with the impaired inhibitory performance and with attentional and sensory regulation mechanisms underlying both ADHD and TD [ 9 , 13 ].…”

“…Studies have indicated that comorbid ADHD places a greater burden on response inhibition in children and teens with TD than do tics, and contributes the most to the increased incidence of school problems, social difficulties, and the presence of other emotional disorders [ 13 , 14 ]. However, a meta-analysis showed that poor verbal and motor inhibition, inattention, and poor impulse control may be part and parcel of TD, even in the absence of any comorbid disorder [ 7 , 15 ].…”

Inhibitory Control in Children with Tourette Syndrome Is Impaired in Everyday Life but Intact during a Stop Signal Task

“…Despite the association between TS and disinhibition, other studies have pointed to the opposite pattern, namely, an increased IC in TS. We previously found children with TS to be equal or superior regarding response inhibition to typically developing controls when inhibiting fast, impulsive actions [13], with another study demonstrating the increased activation of prefrontal areas in children with TS during tasks that require IC [14]. Together, these results support the hypothesis that children with TS develop neuroplastic compensatory mechanisms due to the ongoing suppression of tics [15,16].…”