Objective: Neuropsychological, brain imaging and electrophysiological research have consistently shown a dysfunction of fronto-striato-thalamic pathways in subjects with obsessive-compulsive disorder (OCD). The functional meaning of the observed dysfunction in the pathogenesis of OCD is still debated. In the present study the hypothesis that it might be related to a hyperactive executive control is explored by means of neuropsychological and electrophysiological measures.
Methods: Multilead quantitative EEG (QEEG) characteristics and neuropsychological performance on tests exploring executive functions, attention, short-term memory and the ability to learn supraspan recurring sequences were investigated in 32 drug-free patients with DSM-IV OCD. Multilead QEEG characteristics were also investigated in 32 healthy controls, matched with patients for age, gender and handedness.
Results: A decrease of the slow alpha-band power in OCD as compared to healthy subjects was observed. A significant negative correlation between the slow alpha-band power and the time to complete a neuropsychological test exploring executive functions was found: the more reduced the slow alpha-band power, the slower the performance on this test.
Conclusions: The topographic distribution of the observed QEEG abnormalities, as well as their correlations with neuropsychological indices, suggest an increased activation of frontal networks in OC patients.
Significance: Study findings support the presence of a hyperactivity of attention/executive control mechanisms in obsessive-compulsive patients.