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

TLDR

The study was designed to determine the mediating neuroanatomy of obsessive‑compulsive disorder (OCD). The short half‑life tracer oxygen‑15 labeled CO₂ was used to perform repeated PET determinations of regional cerebral blood flow in eight OCD patients during rest and symptom provocation. Provoked stimuli reliably elicited OCD symptoms and PET showed significantly increased regional cerebral blood flow in the right caudate nucleus, left anterior cingulate cortex, and bilateral orbitofrontal cortex during symptomatic states, supporting the involvement of these regions in OCD pathophysiology.

Abstract

<h3>Background:</h3> The study was designed to determine the mediating neuroanatomy of obsessive-compulsive disorder (OCD). <h3>Methods:</h3> 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. <h3>Results:</h3> Individually tailored provocative stimuli were successful in provoking OCD symptoms, in comparison with paired innocuous stimuli, as measured by selfreport on OCD analogue scales (<i>P</i>=.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 (<i>P</i>&lt;.006), left anterior cingulate cortex (<i>P</i>&lt;.045), and bilateral orbitofrontal cortex (<i>P</i>&lt;.008); increases in the left thalamus approached but did not reach statistical significance (<i>P</i>=.07). <h3>Conclusions:</h3> 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.