Phasic dysfunction of dopamine transmission in Tourette's syndrome evaluated with 99mTc TRODAT-1 imaging.
This study investigated the complex dysregulation of the dopaminergic neurotransmitter system in Tourette's syndrome (TS) patients challenged with methylphenidate (MPH). Eight drug-naïve male patients (aged 21-25 years) who met DSM-IV criteria for TS and had a mean disease severity of 25 on the Yale Global Tic Severity Scale were recruited. Brain (99m)TC TRODAT-1 dopamine transporter (DAT) single photon emission computed tomography (SPECT) was performed 5 days before, and 2 h after 10 mg of orally administered MPH. Eight age-matched healthy males served as controls. Repeated measures analysis of variance was used to measure differences in DAT-binding ratios before and after MPH challenge between the TS patients and controls. The DAT-binding ratios decreased significantly after MPH treatment in both groups. However, a significant interaction between group and MPH effects was found only in the right caudate, which was mainly due to a smaller decline of the DAT-binding ratio after MPH in the TS group than in the controls. Such a distinction was not found in the other striatal sub-regions in the two groups. No correlation, however, was observed between the tic severity score and DAT-binding ratio measured from the whole striatum or its sub-regions. The observed change in the DAT-binding ratio might indicate a functional abnormality of the dopaminergic system in the right caudate nucleus of TS patients. Future studies exploring dopamine transmission are thus needed to understand the pathophysiology of TS.
Yeh
Chin-Bin
CB
Department of Psychiatry, Tri-Service General Hospital, National Defense Medical School, Taipei, Taiwan, ROC.
Lee
Chung-Shian
CS
Ma
Kuo-Hsing
KH
Lee
Meei-Shyuan
MS
Chang
Chia-Jung
CJ
Huang
Wen-Sheng
WS
D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism; D002421:Caudate Nucleus / Q000000981:diagnostic imaging / Q000378:metabolism; D000697:Central Nervous System Stimulants / Q000627:therapeutic use; D004298:Dopamine / Q000378:metabolism*; D006801:Humans; D008297:Male; D008774:Methylphenidate / Q000627:therapeutic use; D015609:Organotechnetium Compounds; D011699:Putamen / Q000000981:diagnostic imaging / Q000378:metabolism; D019275:Radiopharmaceuticals; D015899:Tomography, Emission-Computed, Single-Photon; D005879:Tourette Syndrome / Q000175:diagnosis / Q000188:drug therapy / Q000378:metabolism; D014326:Tropanes
D000697:Central Nervous System Stimulants; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D014326:Tropanes; C104196:technetium Tc 99m TRODAT-1; D008774:Methylphenidate; D004298:Dopamine