تتا میدلاین جدا برونگرایی اژنتیک و افسردگی فقدان لذت

The agency facet of extraversion is related to individual differences in reward anticipation and has been linked to the neurotransmitter dopamine. Dopamine has also been associated with components of anhedonia, which is one of the cardinal symptoms of depression and refers to lack of responsiveness to pleasurable stimuli. This raises the question whether low agency is associated with anhedonia symptoms in depression and if agency and anhedonia are characterized by similar neurobiological mechanisms. To address this hypothesis, we tested whether questionnaire measures of agency and anhedonia are correlated within depressed (n = 20) and non-depressed (n = 22) participants. Further, we investigated whether dopamine-related signatures in the EEG recorded during a gambling task (feedback-evoked theta activity, and frontal versus posterior theta activity) similarly relate to agency and anhedonia. Results indicated that anhedonia was significantly elevated in the depression group, and negatively correlated with agency. However, while theta activity evoked by negative vs. positive feedback was sensitive to anhedonia and depression status but unrelated to agency, frontal versus parietal theta activity predicted agency, but was unrelated to anhedonia and depression. Together, this double dissociation suggests that in spite of considerable phenotypical overlap, anhedonia and agency may be linked to partially distinct neurobiological markers.

Depression is a debilitating condition with a high prevalence and economic burden for society across cultures (Kessler & Bromet, 2013). In order to better understand its etiology and pathophysiology it has been recommended to study more narrowly defined phenotypes or symptoms of this complex and relatively heterogeneous mental illness. A core symptom of depression that has received increasing interest in this regard is anhedonia – the lack of responsiveness to pleasurable stimuli (Hasler et al., 2004, Meehl, 1975 and Pizzagalli, 2014). Although the personality dimensions that are specifically associated with an increased risk for anhedonia have not been systematically explored, early theories suggested that low extraversion relates to depression (e.g. Fig. 1 of Eysenck, 1944), or anhedonia in particular (Clark & Watson, 1991); in line with these early theories negative associations between extraversion and depression are well established (e.g. Jylha & Isometsa, 2006). However, extraversion is a relatively broad and heterogeneous construct capturing individual differences in agency, affiliation and impulsivity (Depue & Collins, 1999) and it is not known which of these facets are linked to anhedonia or depression. Furthermore, little is known about biological mechanisms that may link extraversion facets to anhedonia.

As shown in Table 1, patients with depression had significantly enhanced anhedonia scores. Moreover, anhedonia and agency were negatively correlated with each other (r(42) = −.39, p < .01; Table 1) and these correlations could also be observed within the depression group (r(20) = −.49, p < .05). Notably, among the depressed group, the correlations between anhedonia and agency remained significant when overall symptom severity (as measured with the Beck Depression Inventory) was partialled out (r(17) = −.67, p < .002). Together, these results indicate that agency and anhedonia capture common variance associated with a more specific aspect of depression that is independent of overall symptom severity.