Effects of comorbidity on Tourette's tic severity and quality of life

Objective The aim of this study is to gain more insight in the differential contributions of anxiety, depression and obsessive-compulsive (OC) symptom severity to quality of life (QoL) and tic severity in adults with Tourette Disorder (TD). Methods Self-reported OC symptom, anxiety and depression severity measures were used to investigate their predictive value on QoL and Tic severity in adult TD patients (N = 187), using correlation, regression, and mediation analyses. Results Tic severity has no effect on QoL. Depression severity directly reduces QoL, whereas anxiety and OC symptom severity have an indirect effect on QoL, mediated by depression severity. OC symptom severity directly affects tic severity, whereas depression and anxiety severity do not have a direct effect on tic or OC severity. Finally, anxiety severity indirectly impacts tic severity, with OC symptom severity functioning as a mediator. Conclusion In line with and extending previous studies, these findings indicate that OC symptom severity directly influences tic symptom severity whereas depression severity directly influences QoL in TD. Results imply that to improve QoL in TD patients, treatment should primarily focus on diminishing OC and depressive symptom severity rather than focusing on tic reduction