Elevated putamen D(2) receptor binding potential in major depression with motor retardation: an [11C]raclopride positron emission tomography study.
OBJECTIVE
Several antidepressants raise striatal dopamine, but the role of striatal dopamine during major depressive episodes is unclear. Striatal [(11)C]raclopride binding potential measured with positron emission tomography is an index of D(2) type receptors and is sensitive to extracellular dopamine levels (higher D(2) binding potential occurs when dopamine is lower). It was hypothesized that putamen D(2) binding potential would be higher during major depressive episodes featuring motor retardation.


METHODS
Drug-free, nonsmoking subjects experiencing a major depressive episode (N=21) underwent [(11)C]raclopride PET imaging as did 21 healthy age-matched comparison subjects. Motor retardation was measured with the finger tapping test.


RESULTS
The depressed subjects exhibiting motor retardation had significantly higher D(2) binding potential in both the left and right putamen than did healthy subjects, and putamen D(2) binding potential correlated significantly with motor speed in the depressed subjects.


CONCLUSIONS
The results argue that extracellular dopamine is lower in subjects experiencing a major depressive episode that features motor retardation. This depression subtype should preferentially benefit from dopamine-increasing medications and should be targeted in future clinical trials of dopamine reuptake inhibitors.
Meyer
Jeffrey H
JH
College (Clarke) Site, Centre for Addiction and Mental Health and Department of Psychiatry, University of Toronto, 250 College St., Toronto, Ontario M5T 1R8, Canada. jeff.meyer@camhpet.ca
McNeely
Heather E
HE
Sagrati
Sandra
S
Boovariwala
Anahita
A
Martin
Krystle
K
Verhoeff
N Paul L G
NP
Wilson
Alan A
AA
Houle
Sylvain
S
D000328:Adult; D000367:Age Factors; D002250:Carbon Radioisotopes; D003342:Corpus Striatum / Q000000981:diagnostic imaging / Q000378:metabolism; D003865:Major Depressive Disorder / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism; D005260:Female; D007839:Functional Laterality; D006719:Homovanillic Acid / Q000134:cerebrospinal fluid; D006801:Humans; D008297:Male; D019957:Motor Skills Disorders / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism; D009483:Neuropsychological Tests; D049268:Positron-Emission Tomography / Q000706:statistics & numerical data*; D011699:Putamen / Q000000981:diagnostic imaging / Q000378:metabolism*; D020891:Raclopride / Q000378:metabolism; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D012737:Sex Factors
D002250:Carbon Radioisotopes; D017448:Receptors, Dopamine D2; D020891:Raclopride; D004298:Dopamine; D006719:Homovanillic Acid