Objective: To examine the relationship between tic symptom severity and amplitude of low frequency fluctuation (ALFF) brain functioning of the first-episode Tourette syndrome through resting-state functional magnetic resonance imaging (fMRI).
Method: Sixteen subjects were all recruited from the outpatient department of pediatrics, Beijing Anding Hospital, Capital Medical University and were all first-episode Tourette syndrome patients [male: 13, female: 3; age: 6-16 years; mean age: (11.00 ± 2.92) years]; mean education time: (5.06 ± 2.86) years; course: 14-104 months; mean (48.44 ± 25.00) months; scores of YGTSS at baseline: tic severity score: 37.88 ± 5.39; global damage score: 25.63 ± 12.63. All the subjects experienced resting-state fMRI scans and ALFF were calculated in three frequency ranges: 0.01-0.1 Hz, 0.01-0.027 Hz and 0.027-0.073 Hz. First-episode Tourette syndrome patients and 16 gender, age, and education-matched normal controls experienced resting-state fMRI scans. Correlation analysis was performed in between the amplitude of low frequency fluctuation (ALFF) and the severity of tic symptom. P < 0.05 and k value ≥ 10 were considered to be of significance.
Result: In tic symptom patients, tic severity (total tic scores of YGTSS) was positively correlated with the ALFF values in the orbital part of left superior frontal gyrus (0.01-0.1 Hz:r = 0.83,0.027-0.073 Hz:r = 0.91, P < 0.05, respectively), right middle frontal gyrus (0.01-0.027 Hz:r = 0.85,0.027-0.073 Hz:r = 0.57, P < 0.05, respectively ) and orbital part of left middle frontal gyrus (0.01-0.027 Hz:r = 0.64, P < 0.05). Tic severity was negatively correlated with the ALFF values in the right calcarine fissure and surrounding cortex (0.01-0.1 Hz:r = -0.65,0.01-0.027 Hz:r = -0.69, P < 0.05, respectively ) and the left calcarine fissure and surrounding cortex (0.027-0.073 Hz:r = -0.81, P < 0.05).
Conclusion: Tic symptom severity of the first-episode Tourette syndrome is associated with abnormal brain activity patterns of specific brain areas.