Differential cerebral metabolic changes with paroxetine treatment of obsessive-compulsive disorder vs major depression.
BACKGROUND
Serotonin reuptake inhibitors (SRIs) effectively treat both major depressive disorder (MDD) and obsessive-compulsive disorder (OCD). We compared and contrasted the functional neuroanatomical effects of SRIs in OCD and MDD as these 2 disorders occurred separately and concurrently by measuring pretreatment to posttreatment cerebral glucose metabolic changes in OCD vs MDD vs concurrent OCD + MDD.


METHODS
We obtained [(18)F]fluorodeoxyglucose positron emission tomography (PET) brain scans on 25 subjects with OCD, 25 with MDD, and 16 with concurrent OCD + MDD before and after 8 to 12 weeks of treatment with paroxetine hydrochloride. Controls (n = 16) were scanned 10 to 12 weeks apart without treatment. Treatment response was defined as a more than 25% decline in OCD symptom severity, a more than 50% decline in MDD severity, and "much improved" clinical global impression.


RESULTS
Although all patient groups received the same paroxetine dose for the same duration, regional metabolic changes differed significantly among diagnostic groups. Subjects with OCD alone showed significant metabolic decreases in the right caudate nucleus, right ventrolateral prefrontal cortex (VLPFC), bilateral orbitofrontal cortex, and thalamus that were not seen in any other group. Both the MDD and concurrent OCD + MDD groups showed metabolic decreases in the left VLPFC and increases in the right striatum. Treatment response was associated with a decrease in striatal metabolism in nondepressed OCD patients but with an increase in striatal activity in patients with OCD + MDD.


CONCLUSIONS
Brain metabolic responses to SRIs are both disorder-specific and response-specific. They vary according to the underlying pathophysiology of the patient and the degree of symptomatic improvement.
Saxena
Sanjaya
S
Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, 300 UCLA Medical Plaza, Room 2229, Los Angeles, CA 90095, USA. ssaxena@mednet.ucla.edu
Brody
Arthur L
AL
Ho
Matthew L
ML
Alborzian
Shervin
S
Maidment
Karron M
KM
Zohrabi
Narineh
N
Ho
Mai K
MK
Huang
Sung-Cheng
SC
Wu
Hsiao-Ming
HM
Baxter
Lewis R
LR
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D001921:Brain / Q000000981:diagnostic imaging / Q000187:drug effects*; D001931:Brain Mapping; D015897:Comorbidity; D003865:Major Depressive Disorder / Q000000981:diagnostic imaging / Q000188:drug therapy*; D004734:Energy Metabolism / Q000187:drug effects*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009771:Obsessive-Compulsive Disorder / Q000000981:diagnostic imaging / Q000188:drug therapy*; D017374:Paroxetine / Q000009:adverse effects / Q000627:therapeutic use*; D010555:Personality Inventory; D011859:Radiography; D014055:Tomography, Emission-Computed; D016896:Treatment Outcome
D001786:Blood Glucose; D019788:Fluorodeoxyglucose F18; D017374:Paroxetine