Gyula Demeter

Abstract
The exact nature of the neurocognitive deficit behind the clinical symptoms in obsessive-
compuslive disorder (OCD) is still unclear. There is a growing amount of evidence about the
executive system deficit in OCD, which is strongly connected to the fronto-basal loop
dysfunctions of the disorder. The theoretical background of our research on executive
functions rests on the psychometric model proposed by Miyake et al., (2000). Through latent
variable analyses, this model defines three main components of executive functions:
updating/monitoring, shifting and inhibition. In our research we assessed the executive
functions of OCD patients and healthy controls. This approach led to evidence about the
impairment of the shifting and inhibition components and to the description of the relations
between symptoms and different neuropsychological indices.
In our view the executive system deficit in OCD is strongly related to the specific prospective
memory dysfunction. This ability makes possible to retain, to recall and to execute an
intention in the appropriate time and context of the future. An important phase comes after the
realization of the intended actions: the cancellation of the successful action representations
after attaining a goal. This phase could be impaired in OCD. In this setting the goal can be
achieved by the constant monitoring of the environment or by the periodical refreshing of the
intents and strategic and automatic processes are also involved. According to our view in
OCD we face a hyperactivity of the prospective memory system resulting in constant
monitoring of the environment. We hypothesize that the impaired inhibition component of the
executive system is responsible for this hyperactivity. The patients commit significantly more
errors and slow down in the event-based prospective memory tasks’ ongoing part than the
matched control subjects. It is possible that OCD patients are unable to inactivate successfully
realized intentions and due to inhibition deficit the previous task remains on their “to execute
list”. This contributes then to the observed obsessive-compulsive behavior. The missing of the
retrieval induced forgetting effect in OCD according to our results might be explained by the
dysfunction of conflict detection processes. We have demonstrated this effect in a series of
experiments with healthy adults. It persist also in the long term if there is no additional
rehearsal and a period of nocturnal sleep is included before the recall. We think that the
inclusion and development of tasks in the cognitive behavioral therapy of patients are
essential to increase the effectiveness of inhibition mechanism and prospective memory
performance.
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