Patients with Tourette syndrome (TS) frequently indicate that they show tics as a way of coping with uncomfortable feelings. These feelings are referred to as premonitory desires because they are interpreted as an impulse to act. Recent efforts to create therapies to minimize tic manifestation in persons with TS have focused on premonitory desires. For a study, researchers sought to determine how GABA and glutamate levels in the right primary sensorimotor cortex (SM1), supplementary motor area (SMA), and insular cortex (insula) affected tic and urged intensity in children with TS.

GABA+ (GABA + macromolecules) and Glx (glutamate + glutamine) levels in the right SM1, SMA, and insula were measured by edited magnetic resonance spectroscopy in 68 children with TS (MAge=10.59, SDAge=1.33) and 41 usually developing control individuals (MAge=10.26, SDAge=2.21). They began by comparing GABA+ and Glx levels in these brain areas between groups. They then investigated the relationship between regional GABA+ and Glx levels and urge and tic severity.

GABA+ and Glx levels in the right SM1, SMA, and insula of children with TS and normally developing control individuals were comparable. Lower levels of SMA GABA+ in children with TS were linked to more intense and frequent premonitory cravings. GABA+ and Glx levels were not linked to tic severity. The findings lent credence to the function of GABAergic neurotransmission within the SMA in children with TS experiencing premonitory desires.