Tourette's syndrome: [I-123]beta-CIT SPECT correlates of vocal tic severity.
OBJECTIVE
To examine in vivo the density of brain monoaminergic transporters in Tourette's syndrome (TS).


BACKGROUND
TS is a heritable neuropsychiatric disorder characterized by chronic vocal and motor tics and is often associated with obsessive-compulsive symptoms. Hyperstimulation of dopamine receptors and dysfunction of serotonergic transmission have been implicated in its pathogenesis, but direct evidence of involvement of these neurochemical systems has been limited.


METHODS
Symptom severity and the availability of presynaptic monoaminergic transporters in the basal ganglia, midbrain, and thalamus were measured using SPECT and the radioligand [I-123]2beta-carbomethoxy-3beta-(4-iodophenyl)tropane ([I-123]beta-CIT) in 10 patients with TS and in 10 age- and sex-matched normal volunteers.


RESULTS
A significant negative correlation was found between a measure of overall tic severity and beta-CIT binding in the midbrain (r = -0.73, p = 0.02) and the thalamus (r = -0.82, p < 0.01). When examined post hoc, these correlations were determined largely by vocal tic severity. No other significant correlations were found between symptom severity and beta-CIT binding in the striatum or cortex.


CONCLUSIONS
These findings indicate that serotonergic neurotransmission in the midbrain and serotonergic or noradrenergic neurotransmission in the thalamus may be important factors in the expression of TS and may suggest novel targets for treatment.
Heinz
A
A
Clinical Brain Disorders Branch, Intramural Research Program, National Institute of Mental Health, National Institutes of Health, NIMH Neuroscience Center, St. Elizabeths Hospital, Washington, DC 20032, USA.
Knable
M B
MB
Wolf
S S
SS
Jones
D W
DW
Gorey
J G
JG
Hyde
T M
TM
Weinberger
D R
DR
D000328:Adult; D003042:Cocaine / Q000031:analogs & derivatives; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008636:Mesencephalon / Q000000981:diagnostic imaging; D008875:Middle Aged; D013981:Tic Disorders / Q000000981:diagnostic imaging* / Q000209:etiology; D015899:Tomography, Emission-Computed, Single-Photon; D005879:Tourette Syndrome / Q000150:complications / Q000000981:diagnostic imaging*
D007457:Iodine Radioisotopes; C069723:2beta-carbomethoxy-3beta-(4-iodophenyl)tropane; D003042:Cocaine