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January 1994

Regional Cerebral Blood Flow Measured During Symptom Provocation in Obsessive-Compulsive Disorder Using Oxygen 15—Labeled Carbon Dioxide and Positron Emission Tomography

Author Affiliations

From the Departments of Psychiatry (Drs Rauch, Jenike, Baer, Breiter, and Savage) and Radiology (Drs Rauch, Alpert, Breiter, and Fischman) and Division of Nuclear Medicine/Positron Emission Tomography Laboratory (Drs Rauch, Alpert, and Fischman), Massachusetts General Hospital and Harvard Medical School, Boston.

Arch Gen Psychiatry. 1994;51(1):62-70. doi:10.1001/archpsyc.1994.03950010062008

Background:  The study was designed to determine the mediating neuroanatomy of obsessive-compulsive disorder (OCD).

Methods:  The short half-life tracer oxygen 15—labeled carbon dioxide was used to allow for repeated positron emission tomographic determinations of regional cerebral blood flow on each of eight patients with OCD during a resting and a provoked (symptomatic) state.

Results:  Individually tailored provocative stimuli were successful in provoking OCD symptoms, in comparison with paired innocuous stimuli, as measured by selfreport on OCD analogue scales (P=.002). Omnibus subtraction images demonstrated a statistically significant increase in relative regional cerebral blood flow during the OCD symptomatic state vs the resting state in right caudate nucleus (P<.006), left anterior cingulate cortex (P<.045), and bilateral orbitofrontal cortex (P<.008); increases in the left thalamus approached but did not reach statistical significance (P=.07).

Conclusions:  These findings are consistent with results of previous functional neuroimaging studies and contemporary neurocircuitry models of OCD. The data further implicate orbitofrontal cortex, caudate nucleus, and anterior cigulate cortex in the pathophysiology of OCD and in mediating OCD symptoms.

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