title: An fMRI study in monozygotic twins discordant for obsessive-compulsive symptoms.
abstract: To examine neurobiological changes underlying obsessive-compulsive symptoms (OCS) we examined intrapair differences in behavior and fMRI brain activation in monozygotic twins discordant for OCS, using a Tower of London planning paradigm. Despite only mild evidence for impairment at the behavioral level, twins with OCS showed significantly decreased brain activation during planning in dorsolateral prefrontal cortex, thalamus pulvinar, and inferior parietal cortex. These findings are consistent with the hypothesis of disturbed cortico-striato-thalamo-cortical (CSTC) circuitry underlying OCS. In contrast to previous studies in patients with obsessive-compulsive disorder (OCD) we did not find robust evidence for reduced responsiveness in striatal brain regions. Together, these findings suggest that neurobiological mechanisms underlying OCS of environmental origin partly overlap with neurobiological changes in patients with OCD, where the disorder is likely caused by a combination of genetic and environmental influences. A difference between genetical and environmental etiologies may relate to the amount of reduced striatal responsiveness.
authors.affiliation: Department of Biological Psychology, Vrije Universiteit Amsterdam, van der Boechorststraat 1, 1081 BT Amsterdam, The Netherlands.
authors.forename: Anouk
authors.initials: A
authors.lastname: den Braber
authors.forename: Dennis van 't
authors.initials: Dv
authors.lastname: Ent
authors.forename: Gabriëlla A M
authors.initials: GA
authors.lastname: Blokland
authors.forename: Daniël S
authors.initials: DS
authors.lastname: van Grootheest
authors.forename: Danielle C
authors.initials: DC
authors.lastname: Cath
authors.forename: Dick J
authors.initials: DJ
authors.lastname: Veltman
authors.forename: Michiel B
authors.initials: MB
authors.lastname: de Ruiter
authors.forename: Dorret I
authors.initials: DI
authors.lastname: Boomsma
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology; D003627:Data Interpretation, Statistical; D004777:Environment; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D009434:Neural Pathways / Q000473:pathology; D009483:Neuropsychological Tests; D009771:Obsessive-Compulsive Disorder / Q000235:genetics* / Q000473:pathology* / Q000523:psychology; D011597:Psychomotor Performance / Q000502:physiology; D014430:Twins, Monozygotic