Symptom Provocation of Obsessive-Compulsive Symptoms in Tourette Disorder and its Neural Correlates

It is known that Tourette Syndrome (TS) is often accompanied by obsessive-compulsive disorder (OCD) and there do exist a lot of similarities among symptoms such as tics and obsessive-compulsive symptoms (OCS; Bhikram, Crawley, Arnold, Abi-Jaoude, and Sandor, 2020).

Symptom provocation while participants underwent fMRI was used in order to identify its neural substrates (Bhikram et al., 2020). Symptom provoking pictures concerning washing, checking, and symmetry in addition to neutral and disgust pictures were used. There were three different participan groups created for comparison, These were TS with severe/moderate OCS, TS with absent/mild OCS, and healthy control participants.

The paradigm that the investigators used was found to be effective in inducing subjective anxiety of higher magnitude in TS as compared to healthy controls In the conditions with symptom provocation. Higher subjective anxiety was not found in the neutral and disgust conditions (Bhikram et al., 2020).

Within the group of TS participants, there was found a negative relationship among OCS severity and activation in brain areas such as the supramarginal gyrus, precuneus, and visual processing areas, which was found to be common in all symptom provocation conditions. Furthermore, for exept the provocation condition concerning washing, there were found negative relationships among OCS severity and activation of the precentral gyrus, SMA, and IFG to be found across all provocation conditions. 

The severity of tics was only related to activation of the anterior cingulate cortex concerning the symmetry symptom provocation condition (Bhikram et al., 2020).