Memory bias in euthymic bipolar disorder: The disruptive effect of happiness

The aim of this study was to examine the implicit effect of facial emotional expressions on identity memorization in euthymic bipolar disorder. In the encoding condition, neutral, happy and sad faces were presented to the participants. In the recalling condition, half of the identities presented during encoding and half new identities were presented with neutral expressions. Participants were then asked to carry out an explicit facial emotional expressions recognition task. In healthy controls (CRT), recall was lower for faces encoded with a sad expression, while in euthymic patients suffering from bipolar disorder type I (EBIP1), recall was lower for faces encoded with a happy expression. Moreover, only the recall performance for happy faces was significantly lower in the EBIP1 group when compared to the CRT group. Thus, the EBIP1 patients exhibit a memory deficit for positive stimuli in euthymia that could constitute a factor of emotional vulnerability by contributing to the instigation or maintenance of the affective symptoms.