FONCTIONNEMENT NEUROPSYCHOLOGIQUE DU DEPRIME. EPREUVE DE DECISION LEXICALE DANS LA DEPRESSION MAJEURE

According to the Resource Allocation Model, it is logical to think that emotional mood states modulate the allocation of capacity, most cognitive tasks require some allocation of capacity, and in many instances there is a positive correlation between effort and memory. In cognitive science, the experimental paradigm of lexical decision task is used to investigate visual words recognition and lexical access. According to the Resource Allocation Model, we postulated that depressed patients take more time to recognize items from an affective loaded list. In order to compare their behavior in lexical decision task in this study, depressed patients and healthy controls were studied. We hoped to find an interaction between the mood state of subjects and the categories (affective or neutral) of words. This kind of interaction is expected to figure among the cognitive markers of depression. Two groups of right-handed adults served as subjects in our experiment. The subjects were living in the north west region of Quebec. The first group consisted of 11 depressed patients (mean age: 40.2; SD: 6.8). All of them met the DSM III criteria for major depressive disorder and the RDC. Patients were rated using the 24-item Hamilton Depression Rating Scale (HDRS). All depressed patients were without medications. The control group was composed with 24 subjects (mean age: 32.7; SD: 7.9). We built a depressive word-list (Moodlist) and a neutral word-list (Neutral-list) and used a computer for the lexical-decision task. We noted a significant interaction [F (1,33) = 10,035, p < 0.001] between the subjects group (depression vs control) and the words category (Moodlist vs Neutral-list). This Anova revealed a principal effect of the group [F (1,33) = 15,599, p < 0.0001). The depressed patients were significatively slower than the controls and they responded with a significant difference slower to Moodlist than Neutral-list. This study indicates that the cognitive organization in depression processes information differently than the non-depressed organization.