Tourette syndrome and obsessive-compulsive disorder: event-related brain potentials show similar mechanisms [correction of mechansims] of frontal inhibition but dissimilar target evaluation processes.
OBJECTIVE
Tourette Syndrome (TS) and Obsessive-Compulsive Disorders (OCD) share many clinical similarities and show a strong comorbidity. Current theories view a frontal-striatal dysfunction as the underlying cause of many clinical aspects of both disorders. This study sought to investigate mechanisms of conceptual integration and attention in both disorders. We hypothesized that the processing of stimuli with interfering aspects would be altered in a similar way while attentional mechanisms could differ.


METHODS
Event-related brain potentials (ERPs) were recorded in a modified STROOP-paradigm in groups of TS and OCD patients and in a control group. The paradigm involved the presentation of color words in a range of different colors. The subjects had to respond to words of matching word content and color and to ignore mismatching stimuli.


RESULTS
Incongruent stimuli elicited a frontal negative component ("N450") which was enhanced in amplitude and prolonged in latency in both patient groups. Matching stimuli evoked enhanced N2 and P3b components representing target evaluation mechanisms. The OCD group alone displayed a larger P3b amplitude in comparison to both other groups.


CONCLUSIONS
The data are interpreted to indicate that frontal inhibitory mechanisms are altered alike in TS and OCD. In contrast, only the OCD group showed evidence for aberrant target evaluation.
Department of Neuropsychology, Otto-von-Guericke Universität, Magdeburg, Germany. johannes.soenke@mh-hannover.de
Sönke
S
Johannes
Bernardina M
BM
Wieringa
Wido
W
Nager
Dominik
D
Rada
Kirsten R
KR
Müller-Vahl
Hinderk M
HM
Emrich
Reinhard
R
Dengler
Thomas F
TF
Münte
Detlef
D
Dietrich
D000293:Adolescent; D000328:Adult; D005071:Evoked Potentials; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009771:Obsessive-Compulsive Disorder / Q000503:physiopathology*; D005879:Tourette Syndrome / Q000503:physiopathology*