The association of glutamate level in pregenual anterior cingulate, anhedonia, and emotion-behavior decoupling in patients with major depressive disorder.

Impairments of translating emotional salience into effortful behavior are core features of anhedonia in cohorts with major depressive disorder. Glutamate metabolism is considered to be involved in this process, but the empirical study is relatively few. Therefore, the present study aimed to examine the correlations between glutamate level in pregenual anterior cingulate, anhedonia, and emotion-behavior decoupling in patients with major depressive disorder. Fifteen individuals diagnosed with major depressive disorder and ten healthy individuals were recruited. All participants were asked to complete self-report instruments for anhedonia and the computerized anticipatory and consummatory pleasure task, and the in vivo glutamate levels were measured by proton magnetic resonance spectroscopy. Thus, a potential lower glutamate levels in pregenual anterior cingulate in individuals with major depressive disorder were founded to be positively correlated with the ability of pleasure experiencing. The mechanism of glutamate in pregenual anterior cingulate in anhedonia in patients with major depressive disorder may be reflected in the early pleasurable experience stage, rather than in the transformation of emotional experience to motivation or reward-seeking behavior, which may be different from that in schizophrenia.

Impairment of response inhibition to emotional face stimuli in individuals with subclinical depression.

Response inhibition, a crucial component of executive function, is closely related to personal impulse control, social adaption, and mental health. Previous studies have found response inhibition deficit in patients with major depressive disorder, but whether it also exists in individuals with subclinical depression (SD) remains unclear. This study aimed to identify the ability of response inhibition to emotional face stimuli both under explicit and implicit conditions in individuals with SD. Thirty-six subclinical depressed college students and 39 healthy individuals were recruited and administered the non-emotional, explicit, and implicit emotional stop-signal tasks (SSTs). Mixed-model analyses of variance were used to analyze the differences between and within groups. In implicit emotional SST, the results showed a significant longer stop-signal response time, a shorter stop-signal delay time, a shorter go reaction time, and a similar proportion of stop success in the SD group compared to healthy controls. However, the above indices showed no significant difference between the two groups in the non-emotional SST and explicit emotional SST. These findings suggest a possible defect of response inhibition in implicit emotional processing in individuals with SD, which may potentially serve as a marker of susceptibility to depression and thus be applied to early screening and intervention for major depressive disorder.