Regional cerebral blood flow abnormalities in early-onset obsessive-compulsive disorder: An exploratory SPECT study

Objective: Recent epidemiological and clinical data suggest that obsessive- compulsive disorder (OCD) may be subtyped according the age of onset of obs essive-compulsive symptoms. The regional cerebral blood flow (rCBF) single photon emission computed tomography (SPECT) technique was used to investiga te whether the pathophysiology of OCD differs between early- and late-onset OCD subjects. Method: Resting rCBF was measured in 13 early-onset (<10 yea rs) and 13 late-onset (>12 years) adult OCD subjects and in 22 healthy cont rols. Voxel-based rCBF comparisons were performed with statistical parametr ic mapping. Results: Early-onset OCD cases showed decreased rCBF in the rig ht thalamus, left anterior cingulate cortex, and bilateral inferior prefron tal cortex relative to late-onset subjects (p <.0005, uncorrected for multi ple comparisons). Relative to controls, early-onset cases had decreased lef t anterior cingulate and right orbitofrontal rCBF, and increased rCBF in th e right cerebellum, whereas late-onset subjects showed reduced right orbito frontal rCBF and increased rCBF in the left precuneus. In early-onset subje cts only, severity of obsessive-compulsive symptoms correlated positively w ith left orbitofrontal rCBF. Conclusions: rCBF differences in frontal-subco rtical circuits between early-onset and late-onset OCD subjects were found, both in location and direction of changes. These results provide prelimina ry evidence that brain mechanisms in OCD may differ depending on the age at which symptoms are first expressed.