Functional Tic-Like Behaviors: A Common Comorbidity in Patients with Tourette Syndrome

Comorbid functional tic-like behaviors (FTB) have been described only rarely in patients with Tourette syndrome (TS).

We present the first large sample of patients suffering from TS and FTB to raise awareness of this clinical presentation and to guide how to differentiate one from the other.

We analyzed clinical data of 71 patients (n = 27 [38.0%] female, mean age: 21.5, range: 11-55) with TS + FTB.

In the majority of patients, FTB started abruptly on average 15 years after tic onset with "treatment-resistant" complex movements and ("coprophenomena-like") vocalizations preceded by timely related psychological stressors. Psychological evaluation revealed evidence for internal conflicts (79%), emotional dysregulation (56%), and maintaining factors (70%). About one third of patients had a positive history for further medically unexplained symptoms. Compared to a large TS sample (n = 1032), patients with TS + FTB were more likely to be female, and presented significantly more common with "coprophenomena-like" symptoms, atypical influential factors, atypical descriptions of premonitory sensations, and higher rates of comorbid obsessive-compulsive disorder and "self-injurious" behavior.

Based on our data it can be assumed that FTB is a common comorbidity in TS, similar to functional overlay in other movement disorders and epilepsy. Before classifying a patient as suffering from treatment-resistant TS, FTB should be ruled out.