1. Brain regional α-[11C]methyl-L-tryptophan trapping in medication-free patients with obsessive-compulsive disorder.
- Author
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Berney A, Leyton M, Gravel P, Sibon I, Sookman D, Rosa Neto P, Diksic M, Nakai A, Pinard G, Todorov C, Okazawa H, Blier P, Nordahl TE, and Benkelfat C
- Subjects
- Adolescent, Adult, Case-Control Studies, Caudate Nucleus metabolism, Female, Hippocampus metabolism, Humans, Magnetic Resonance Imaging, Male, Middle Aged, Positron-Emission Tomography, Temporal Lobe metabolism, Tryptophan metabolism, Young Adult, Brain metabolism, Obsessive-Compulsive Disorder metabolism, Tryptophan analogs & derivatives
- Abstract
Context: The hypothesis of a serotonin (5-hydroxytryptamine [5-HT]) dysfunction in obsessive-compulsive disorder (OCD) stems largely from the clinical efficacy of 5-HT reuptake inhibitors. Serotonergic abnormalities in the unmedicated symptomatic state, however, remain to be fully characterized., Objective: To investigate brain regional 5-HT synthesis, as indexed by positron emission tomography and the α-[(11)C]methyl-L-tryptophan trapping constant (K*), in treatment-free adults meeting criteria for OCD., Design: Between-group comparison., Setting: Department of Psychiatry and Montreal Neurological Institute, McGill University, and Department of Psychology, McGill University Health Centre, Quebec, Canada., Participants: Twenty-one medication-free patients with OCD (15 men with a mean [SD] age of 33.2 [9.3] years and 6 women with a mean [SD] age of 35.8 [7.1] years) and 21 healthy controls matched for age and sex (15 men with a mean [SD] age of 32.9 [10.1] years and 6 women with a mean [SD] age of 36.5.5 [8.6] years). Main Outcome Measure The α-[(11)C]methyl-L-tryptophan brain trapping constant K*, which was analyzed with Statistical Parametric Mapping (SPM8) and with proportional normalization (extent threshold of 100 voxels with a peak threshold of P ≤ .005)., Results: Compared with healthy controls, the patients with OCD exhibited significantly greater α-[(11)C]methyl-L-tryptophan trapping in the right hippocampus and left temporal gyrus (Brodmann area 20). In the larger subsample of all men, these same differences were also evident, as well as higher K* values in the caudate nucleus. Individual differences in symptom severity correlated positively with K* values sampled from the caudate and temporal lobe of the patients with OCD, respectively. There were no regions where the patients exhibited abnormally low K* values. Volumetric analyses found no morphometric alterations that would account for the group differences., Conclusion: The results support previous reports of greater striatal and temporal lobe activity in patients with OCD than in healthy controls and suggest that these disturbances include a serotonergic component. Previously reported glucose metabolic disturbances in OCD involving the orbitofrontal and cingulate cortices, in comparison, might reflect postsynaptic changes in the serotonergic system.
- Published
- 2011
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