[123I]-beta-CIT SPECT imaging shows reduced brain serotonin transporter availability in drug-free depressed patients with seasonal affective disorder.
BACKGROUND
Numerous findings indicate alterations in brain serotonin systems in seasonal affective disorder (SAD). [(123)I]-2-beta-carbomethoxy-3-beta-(4-iodophenyl)-tropane ([(123)I]-beta-CIT) labels serotonin transporters (5-HTTs) in the midbrain. We performed a [(123)I]-beta-CIT single photon emission computer tomography (SPECT) study under the hypothesis of lower [(123)I]-beta-CIT binding reflecting reduced central 5-HTT availability in depressed SAD patients.


METHODS
Depressed SAD patients and healthy control subjects were investigated using [(123)I]-beta-CIT SPECT 4 hours and again 24 hours after tracer injection. Subjects had either never used psychotropic medication or had been drug-free for at least 6 months prior to the investigation. Specific-to-nondisplaceable partition coefficient (V(3)") was calculated for the thalamus-hypothalamus and the midbrain-pons; the cerebellum served as a reference region.


RESULTS
Patients showed a reduction in V(3)" in thalamus-hypothalamus (2.41+/-0.3 vs. 2.84+/-0.4; p = .026) 24 hours post tracer injection (p.i.). No difference between patients and control subjects was found in midbrain-pons (1.31+/-0.2 vs. 1.42+/-0.2; p = .39). No differences were detected in the SPECT acquisitions 4 hours p.i.


CONCLUSIONS
Depressed SAD patients showed lower specific-to-nondisplaceable [(123)I]-beta-CIT binding in the region of interest (ROI) thalamus-hypothalamus. The small size of the midbrain-pons ROI may have contributed to the failure to show a difference in this ROI as well. Similar to reduced midbrain 5-HTT availability in nonseasonal depression, depression in SAD seems to be associated with reduced 5-HTT availability to the thalamus-hypothalamus.
Willeit
M
M
Department of General Psychiatry, Vienna University, Vienna, Austria.
Praschak-Rieder
N
N
Neumeister
A
A
Pirker
W
W
Asenbaum
S
S
Vitouch
O
O
Tauscher
J
J
Hilger
E
E
Stastny
J
J
Brücke
T
T
Kasper
S
S
D000328:Adult; D001692:Biological Transport; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism*; D003042:Cocaine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D003865:Major Depressive Disorder / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016574:Seasonal Affective Disorder / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*; D015899:Tomography, Emission-Computed, Single-Photon
D012701:Serotonin; C069723:2beta-carbomethoxy-3beta-(4-iodophenyl)tropane; D003042:Cocaine