Late-Life Depression (LLD) is characterized by deficits in cognitive control. We investigated the effect of LLD on a subset of cognitive control functions, the Cognitive Action Control (CAC), distinguishing on-line and adaptive control.
We compared LLD subjects (n = 31) and Healthy Controls (HC, n = 31) on their performance in a Simon task. The online congruency effect and adaptive effect were compared for reaction times (RT) and accuracy rates between the groups using mixed models. We applied distributional analyses of RT to differentiate the strength of impulsive action selection and the proficiency of selective action suppression. Finally, we measured correlations between the performances on the task and clinical scores of the LLD group.
LLD had increased error rates in congruent trials compared to HC. Conversely, the adaptive CAC was equivalent between the groups. Distributional analyses showed that the fastest actions were less led by pertinent information in LLD. This phenomenon was found exclusively for congruent trials preceded by non-congruent trials. On the other hand, LLD patients, when they take time, were better than HC to suppress selectively non-relevant information. No difference was observed for adaptation to the preceding condition. No association between behavioral measurements and clinical scores were found.
Our results suggest that LLD participants have a specific cognitive disturbance of CAC, showing less facilitation than HC in congruent situations. We propose that this originates in a difficulty in LLD patients in disengaging their attention from conflict situations, which is consistent with a biased CAC to aversive stimuli in depression.

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