Deficits of sustained attention in pediatric obsessive-compulsive disorder comorbid with Tic disorders

Background: Pediatric obsessive-compulsive disorder (OCD) and Tourette syndrome/chronic tics (tic disorders, TD), are associated with attention-deficit hyperactivity disorder (ADHD). Deficits in sustained attention are a core deficit in ADHD which can be captured by continuous performance tests (CPT). CPT data are used to examine deficits in sustained attention in youth with OCD, TD or both, and OCD symptom factors, to characterize the deficits in sustained attention in OCD and TD, testing the hypothesis whether comorbid OCD + TD is distinct from OCD only or TD only. Methods: A clinical registry of youth with OCD and/or TD included data on sustained attention, obtained with the Conner's CPT Test II (CPT-II). The CPT-II spans six time-blocks, capturing values for the capacity for sustained attention. The main outcome measure is the variability in the standard error (SE) of reaction time (RT) for correct responses (RT-SE), which is considered a core ADHD trait. Higher RT-SE values reflect a lack of uniformity in responses and is considered to reflect a deficit in sustained attention. Using generalized linear models (GLM), RT-SE is measured over the six time-blocks in three groups: OCD only, TD only and OCD + TS, with sex and age groups as moderators. Clinical ADHD diagnoses were contrasted between diagnostic groups while OCD dimensions (contamination-washing, aggressive-somatic, sexual-religious, counting-checking-repeating and hoarding) were tested for their effect on sustained attention. Results: Deficits in sustained attention are significantly greater in the comorbid OCD + TD compared to OCD only and TD only, with the greatest differences apparent in blocks 5 and 6 (p <.001). While sex does not moderate sustained attention deficits, the higher RT-SE in blocks 5 and 6 is only seen in the younger age group (7–11 years), but not in adolescents (12–17 years). As expected, clinical ADHD is more prevalent in youth with comorbid OCD + TS (67%) compared to OCD only (21%) or TD only (33%) (p =.0002). The hoarding group, characterized by more frequent clinical ADHD diagnoses, has higher RT-SE for time blocks 3,4,5,6 compared to non-hoarders. Participants with contamination-washing symptoms, characterized by more prevalent anxiety disorders, have higher RT-SE than those with no contamination-washing symptoms for time block 4. Conclusion: Deficits in sustained attention are associated with comorbid OCD + TD compared OCD only or TD only, evident only in a younger age group. Sustained attention deficits are also more common in youth with ADHD, OCD hoarding and OCD contamination-washing symptoms. In summary, sustained attention deficits are intrinsic to the comorbid OCD + TD group, suggesting a compounded developmental insult specific to sustained attention which tends to resolve by adolescence. A mechanistic commonality to sustained attention, tic disorders and OCD-related extinction learning may be aberrant oscillatory brain phenomena.