Emotional reactivity to valence-loaded stimuli are related to treatment response of neurocognitive therapy.

Emotional Context Insensitivity (ECI) is a psychological feature observed in depressed patients characterized by a decreased emotional reactivity when presented to positive- and negative valence-loaded stimuli. Given that fronto-cingulate-limbic circuits are implicated in abnormal reactivity to valence-loaded stimuli, neurocognitive treatments engaging the prefrontal cortex may be able to modulate this emotional blunting observed in MDD. Therefore, our goal was to evaluate emotional reactivity in depressed patients before and after a combination of neurocognitive interventions that engage the prefrontal cortex (cognitive control training and/or transcranial direct current stimulation). In line with the premises of the ECI framework, before the start of the antidepressant intervention, patients showed blunted emotional reactivity after exposure to negative valence-loaded stimuli. This emotional reactivity pattern changed after 9 sessions of the intervention: positive affect decreased and negative affect increased after watching a series of negative valence-loaded stimuli (i.e. images). Interestingly, higher emotional reactivity (as indexed by a larger increase in negative affect after watching the valence-loaded stimuli) at baseline predicted reductions in depression symptoms after the intervention. On the other hand, higher emotional reactivity (as indexed by a decrease in positive affect) after the intervention was marginally associated with reductions in depression symptoms. To conclude, emotional reactivity increased after the neurocognitive antidepressant intervention and it was directly associated to the degree of depression improvement.

Transcranial electric stimulation and neurocognitive training in clinically depressed patients: a pilot study of the effects on rumination.

Rumination is a cognitive-affective thinking style that plays a key role in the onset and maintenance of depression. Recently, it was shown that clinically depressed patients who received a neurocognitive training - involving two weeks of repetitive cognitive control exercises that necessitate prefrontal engagement - are more able to control over ruminative negative thoughts than patients who only received treatment as usual. Transcranial Direct Current Stimulation (tDCS) is a biological technique that can directly modulate prefrontal excitability via the manipulation of neural membrane potentials. In this randomized double-blind trial, we investigated whether bifrontal tDCS (anode over the left/cathode over the right dorsolateral prefrontal cortex (DLPFC)) would enhance the influence of a neurocognitive training on depressive brooding, the maladaptive form of rumination. Major depressed patients were trained using a procedure based on the Paced Auditory Serial Addition Task (PASAT), a task that relies heavily on working memory and is found to engage the DLPFC. One group (n=19) completed the PASAT training together with active tDCS and another group (n=14) completed the same training together with sham (placebo) tDCS. In both groups, depressive brooding was reduced following the PASAT training. Moreover, we observed that improvement in working memory over the course of the training was associated with a greater reduction in depressive brooding post- versus pre-intervention. However, tDCS did not moderate this association between changes in working memory and changes in depressive brooding. Possible explanations for this absent moderation of tDCS, as well as avenues for future research to influence ruminative thinking in depression, are discussed.