The present study was the first study to examine how gender relates to emotion processing accuracy and speed in adults with MDD. The expectations that MDD status and gender would individually influence accuracy and speed of processing negative stimuli were not supported. In contrast, only women without MDD showed the expected advantage in emotion processing. Consistent with our hypothesis, emotion processing depended on the combined characteristics of MDD status and gender. During depressed states, women were less accurate than non-depressed women, as well as men with and without MDD, in processing non-verbal emotional cues (i.e., facial expressions). In contrast, depressed men showed equivalent performance in emotion processing during depressed states as compared to non-depressed men. Women with MDD also were slower to respond to negative emotions (i.e., showed greater response cost) than non-depressed women, whereas men with MDD were equivalent to non-depressed men in speed of processing negatively posed expressions. Women with MDD demonstrated a tendency to misclassify facial expressions of fear and sadness as representing anger, showing clear and specific processing biases or skill deficits that were not present in men with and without MDD. Misclassifying negative facial expressions as angry suggests that women with MDD may engage in threat-related processing of emotions more than men with MDD. It is not entirely clear why gender appears to modulate the relationship between MDD and emotion processing, although social cognitive, socioemotional, and neurobiological processes may provide plausible hypotheses for future study.
Women and men process emotions differently during non-depressed and depressed states. Non-depressed women have been shown to be more emotionally aware than non-depressed men; a finding that is related to women’s superiority over men in recognizing, expressing, and interpreting emotional stimuli(17
). During depressed states, however, the different cognitive strategies in which women and men engage may differentially affect their ability to process other’s emotions. For example, during depressed states, women are more likely to ruminate, whereas men are more likely to distract themselves(25
). Given that rumination has been shown to influence appraisal of the past, present, and future(26
), it is likely to lead to distorted perceptions of events, including those that arouse emotion. Rumination has also been shown to disrupt problem solving(28
), and may similarly disrupt emotion processing during depressed states in women. Although this hypothesis has not been tested, it might explain increased processing time and reduced accuracy for sad and fearful stimuli, such that they are incorrectly appraised as anger.
Research suggests that from very early in life, women are taught to place greater value in interpersonal relations than are men, who are more likely to strive for individualism(30
) and that interpersonal skill is strongly related to women’s self-esteem and well being(32
). Consequently, difficulties in interpersonal skill degrade self-esteem in women(34
), placing them at greater risk for MDD(36
). Men, on the other hand, are more likely to become depressed in response to status or occupational loss(39
Emotion processing is an essential component of interpersonal skill(41
). Thus, the observation that women with such deficits are more likely to be depressed than women without such deficits may reflect the increased importance of interpersonal relationships in the etiology of MDD in women. Premorbid deficits in emotion processing may place some women at increased risk for interpersonal difficulties, and subsequently for MDD, whereas this may not be the case for men. Furthermore, the types of events that foment MDD in women may be related to these pre-existing social expectation biases and foundational interpersonal skills such as emotion processing.
It is also possible that women’s and men’s abilities to process emotions develop differently, with greater dependence upon limbic functioning in women as compared to men(42
). Moreover, men do not rely as heavily as do women on inhibitory emotional repair strategies(43
) that are associated with activation of the prefrontal cortex, which modulates activity in subcortical limbic circuits(44
). Research on non-depressed samples indicates greater limbic activation among women than men during emotion perception tasks(42
) and sad states(46
). Thus, during depressed states, increased limbic activation may abrogate inhibitory emotional repair strategies in women, leading to greater emotion perception inaccuracy.
To our knowledge, this is the first study to demonstrate a disproportionately greater adverse outcome of MDD on emotion processing in women as compared to men. Important limitations are present for this study. First, the sample is composed of women and men who chose to seek treatment for MDD, which may have disproportionately sub-sampled distinct groups of men and women. Substance abuse was an exclusion criteria for this study, which may have biased the sample in unknown ways, particularly with higher comorbidity of substance abuse in men. There is also an increased potential for Type I error and inaccurate estimates of effect sizes with unequal cell sizes across sex and diagnostic groups. To address this potential limitation, we ran post hoc analyses with equal numbers of women and men controls (n = 35) and population gender-representative MDD samples (n = 36 women, n = 23 men), with the same main findings. Third, it is not clear from this cross-sectional design whether MDD adversely affects emotion processing or whether these women with MDD were premorbidly impaired in emotion processing, which then served as a risk factor for subsequently developing MDD. Specifically, we can not comment on whether these emotion processing difficulties are a state or trait phenomena. Longitudinal research tracking changes in emotion processing over the course of depressive episodes would best address these two alternative interpretations, including impact of developmental experiences such as trauma on emotion processing acuity.
During depressed states, women were less accurate in processing sad and fearful facial stimuli, whereas men tended to show preserved accuracy in processing these stimuli as compared to same-gender controls. These findings suggest the need for further research into the mechanisms and functional correlates behind emotional processing differences in women and men with MDD. Future research might address the aforementioned limitations through employing community-based samples, perhaps using a longitudinal design. Future research might also measure MDD subtypes, severity and chronicity (e.g., hospitalizations, and number of depressive episodes). Moreover, to test the hypotheses generated by our findings, it would be necessary to measure rumination and correlate this with performance on a non-verbal emotion recognition task in depressed and non-depressed women and men. Finally, functional activation studies might enhance understanding of the interaction between gender and MDD status in emotion processing, specifically the comparison between depressed and non-depressed women. It would be very valuable toward understanding biological bases for early onset MDD to demonstrate that emotion processing circuits are affected in younger adult women with MDD in one way, with perhaps no effect in younger adult men with MDD.