A longitudinal VBM study in paediatric obsessive-compulsive disorder at 2-year follow-up after cognitive behavioural therapy

Objectives: To identify neurodevelopmental differences in regional brain volume between medication-free paediatric obsessive-compulsive disorder (OCD) patients and controls at 2-year follow-up after cognitive behavioural therapy.
Methods: We assessed 17 medication-free paediatric OCD patients (mean age 13.8 years; SD = 2.8; range 8.2-19.0) and 20 controls, matched on age and gender, with T1-weighted MR scans in a repeated measures design at three time points with intervals of 6 months and 2 years. Voxel based morphometry (VBM) was used to test whole brain voxel-wise for the effects of diagnosis and time on regional grey matter (GM) and white matter volumes.
Results: GM volume of the orbitofrontal cortex showed a group × time interaction effect, driven by an increase of GM volume over the whole time period in OCD patients and a decrease in controls. When splitting the groups in two age groups (8-12 and 13-19 years) this interaction effect was only seen in the youngest age group.
Conclusions: Neuroimaging findings in paediatric OCD after 6 months of CBT in the GM volume of the orbital frontal cortex are still present at 2-year follow-up.