L-3,4-Dihydroxy-6-[F-18]fluorophenylalanine positron emission tomography demonstrating dopaminergic system abnormality in the brains of obsessive-compulsive disorder patients.

Aim: Obsessive-compulsive disorder (OCD) is a chronic disabling neuropsychiatric disorder. Current treatment modalities, such as pharmacological and behavioral methods, are sometimes unsatisfactory. The mesolimbic dopaminergic pathway is supposed to have a role in the pathogenesis of OCD. In this study, L-3,4-Dihydroxy-6-[F-18]fluorophenylalanine (F-18 FDOPA) positron emission tomography (PET) is exploited to investigate the possible abnormality of dopaminergic neuronal circuits in the brains of OCD patients in vivo.

Methods: The study subjects were recruited after psychological assessment and gave written informed consent to participate. The F-18 FDOPA PET scans were performed on five OCD patients and six healthy volunteers at 120 min after 185 MBq of F-18 FDOPA intravenous injection. The PET results were analyzed with the Statistical Parametric Mapping tool.

Results: Compared to the healthy subjects, the OCD brains showed increased dopaminergic metabolism in the left frontal premotor cortex (P < 0.001), along with trends toward an increase in the left posterior cingulate gyrus, the left cuneus, the left lingual gyrus, the right cuneus and precuneus, the right lingual gyrus, the right middle temporal gyrus, the left cerebellum, and the right cerebellum (P < 0.01).

Conclusion: Our observations suggest that the increased dopaminergic neuronal function in these brain areas may be implicated in the pathogenesis of OCD.