Brain serotonin transporter binding in depressed patients with bipolar disorder using positron emission tomography.
BACKGROUND
Depression in bipolar disorder is clinically indistinguishable from that observed in major depressive disorder. As in major depression, selective serotonin reuptake inhibitors targeting brain serotonin transporters are first-line treatments for bipolar depression. Associations of serotonin transporter promoter polymorphisms and bipolarity have been reported; however, research on alterations in serotonergic neurotransmission in bipolar depression remains scant.


OBJECTIVE
To assess in vivo brain serotonin transporter binding potential (BP(1), proportional to serotonin transporter number) in patients with bipolar depression and controls and to examine the relationship between serotonin transporter binding and genotype.


METHODS
Case-control study.


METHODS
University hospital.


METHODS
A sample of 18 medication-free patients with bipolar depression and 41 controls.


METHODS
In vivo brain serotonin transporter binding was measured using positron emission tomography and radiolabeled trans-1,2,3,5,6,10-beta-hexahydro-6-[4-(methylthio)phenyl]pyrrolo-[2,1-a]-isoquinoline ([(11)C](+)-McNeil 5652). Participants were genotyped assessing biallelic and triallelic 5-HTTLPR polymorphisms.


RESULTS
Patients with bipolar disorder had 16% to 26% lower serotonin transporter BP(1) in the midbrain, amygdala, hippocampus, thalamus, putamen, and anterior cingulate cortex. Triallelic 5-HTTLPR genotypes were unrelated to serotonin transporter BP(1).


CONCLUSIONS
Lower serotonin transporter BP(1) in bipolar depression overlaps with that observed in major depression and suggests that serotonergic dysfunction is common to depressive conditions.
Oquendo
Maria A
MA
Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA. moquendo@neuron.cpmc.columbia.edu
Hastings
Ramin S
RS
Huang
Yung-Yu
YY
Simpson
Norman
N
Ogden
R Todd
RT
Hu
Xian-Zhang
XZ
Goldman
David
D
Arango
Victoria
V
Van Heertum
Ronald L
RL
Mann
J John
JJ
Parsey
Ramin V
RV
D000293:Adolescent; D000328:Adult; D000368:Aged; D001714:Bipolar Disorder / Q000000981:diagnostic imaging / Q000378:metabolism*; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism; D002250:Carbon Radioisotopes; D016022:Case-Control Studies; D003866:Depressive Disorder / Q000000981:diagnostic imaging / Q000378:metabolism; D005260:Female; D005838:Genotype; D006801:Humans; D007546:Isoquinolines; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000706:statistics & numerical data*; D012701:Serotonin / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D014018:Tissue Distribution
D002250:Carbon Radioisotopes; D007546:Isoquinolines; D050486:Serotonin Plasma Membrane Transport Proteins; D012701:Serotonin; C058079:McN 5652