part a) Follow-up brain imaging study in obsessive-compulsive disorder;part b) Frontal-striatal and limbic circuits in Tourette and OCD, a brain imaging study

Obsessive-compulsive disorder (OCD) is a common and chronic neuropsychiatric
condition that is characterized by intrusive anxiety-provoking thoughts
(obsessions) and time-consuming ritualistic behaviours (compulsions).
Tourette's syndrome is a movement disorders that is characterized by motor and
vocal tics. OCD and Tourette share phenomenological and neurobiological
characteristics. OCD is characterized by increased limbic and ventral
prefrontal-striatal activity at rest and in response to emotional cues as well
as decreased dorsal prefrontal-striatal activity correlating with impaired
executive performance. The hypothesis has been put forward that altered dorsal
prefrontal-striatal function contributes to decreased inhibition of the limbic
response during processing of emotions. Based on the results derived from the
original project (described in protocol version 2) we have better insight in
the structural and functional brain abnormalities in OCD. However 2 important
questions remain: 1) do these abnormalities persist after symptom reduction /
remission? and 2) how specific are these abnormalities?

Aims:
a) Understand persistence and/or plasticity of the brain correlates
b) Understand specificity of the brain correlates

Questions:
a) Which neural correlates of OCD are state dependent and thus normalized after
successful treatment?
b) Which neural correlates of OCD are specific and which correlates are shared
with related disorders, e.g. Tourette*s syndrome?

part a)
Follow-up measurement after naturalistic follow-up in OCD patients and healthy
controls:
- psychiatric and neuropsychological assessment (2 hours)
- MRI scan session (1 hour), including a) T1-weigthed structural scan (3*); b)
resting state fMRI scan (5*); c) diffusion tensor imaging (10*); d) glutamate
magnetospectroscopy (MRS) (20*); and e) functional MRI scan during the response
inhibition (10*)


part b)
Addition of clinical control group (TS patients) and their matched healthy
controls:
- psychiatric and neuropsychological assessment (2 hours)
- MRI scan session (1 hour), including a) T1-weigthed structural scan (3*); b)
resting state fMRI scan (5*); c) diffusion tensor imaging (10*); d) glutamate
magnetospectroscopy (MRS) (20*); and e) functional MRI scan during the response
inhibition (10*)

Repetitive transcranial magnetic stimulation (rTMS) will be used to temporarily
enhance the excitability of the dorsal prefrontal cortex in patients and, in
contrast, to temporarily reduce dorsal responsiveness in healthy controls.

The experiment costs
- 2 hours psychiatric assessment (including questionnaires)
- 1 hour MRI scan session

Half of the patients already participated in the extended version of the
protocol and thus exactly know what they can expect.

Main concern is the claustrophobic nature of the MR environment. By excluding
extreme claustrophobic participants and by proper guiding of the participants
during the experiment, we have the experience that participants can easily
fulfill the protocol.