An experimental paradigm for triggering a depressive syndrome

Research investigating whether depression is an adaptation or a disorder has been hindered by the lack of an experimental paradigm that can test causal relationships. Moreover, studies attempting to induce the syndrome often fail to capture the suite of feelings, thoughts, and behaviors that characterize depression. An experimental paradigm for triggering depressive symptoms can improve our etiological understanding of the syndrome. The present study attempts to induce core symptoms of depression, particularly those related to rumination, in a healthy, nonclinical sample through a controlled social experiment. These symptoms are sad or depressed mood, anhedonia, feelings of worthlessness or guilt, and difficulty concentrating. One hundred and thirty-four undergraduate students were randomly assigned to either an exclusion (E) or control (C) group. Participants in the exclusion group were exposed to a modified Cyberball paradigm, designed to make them feel socially excluded, followed by a dual-interference task to assess whether their exclusion interfered with their working memory. Excluded participants: (a) self-reported a significant increase in sadness and decrease in happiness, but not anxiety or calmness; (b) scored significantly higher in four of five variables related to depressive rumination; and (c) performed significantly worse on a dual-interference task, suggesting an impaired ability to concentrate. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Empathy, Defending, and Functional Connectivity While Witnessing Social Exclusion

Peers are present for most bullying episodes. Peers who witness bullying can play an important role in either stopping or perpetuating the behaviour. Defending can greatly benefit victimized peers. Empathy is strongly associated with defending. Yet, less is known about defenders' neural response to witnessing social distress, and how this response may relate to the link between empathy and defending. Forty-six first-year undergraduate students (M_age = 17.7; 37 women), with varied history of peer defending, underwent fMRI scanning while witnessing a depiction of social exclusion. Functional connectivity analysis was performed across brain regions that are involved in cognitive empathy, empathetic distress, and compassion. History of defending was positively associated with functional connectivity (Exclusion > Inclusion) between the left orbitofrontal cortex (OFC) - medial prefrontal cortex (MPFC), and right OFC - left and right amygdalae. Defending was negatively associated with functional connectivity between the left OFC - anterior cingulate cortex. The relationship between history of defending and empathy (specifically, empathetic perspective taking) was moderated by functional connectivity of the right OFC - left amygdala. These findings suggest that coactivation of brain regions involved in compassionate emotion regulation and empathetic distress play a role in the relationship between empathy and peer defending.

B-36 Effects of Electroconvulsive Therapy on Cognitive Performance and Depressive Symptoms: A Naturalistic Study

Objective

1) Examine the short- and long-term effects of electroconvulsive therapy (ECT)—conducted in a naturalistic treatment setting—on objective and subjective cognitive functioning. 2) Examine the long-term effects of naturalistic ECT on depressive symptoms.

Method

Participants (N = 108) were outpatients (aged 18-65) diagnosed with a Major Depressive Episode who received ECT at St. Joseph’s Healthcare Hamilton, Ontario. Parameters of ECT varied clinically. Participants completed a cognitive and psychological test battery at baseline (n = 108), mid-treatment (n = 82), 2–6-weeks post-ECT (n = 52), 6-months post-ECT (n = 24), and 12-months post-ECT (n = 14) that included Repeatable Battery for Assessment of Neuropsychological Status (RBANS), Squire Subjective Memory Questionnaire (SSMQ), Beck Depression Inventory-II (BDI-II), and WHO Disability Assessment Schedule (WHODAS-2).

Results

Overall cognitive performance (total RBANS scaled scores) did not improve from baseline to 2-6 weeks post-ECT (p = 0.156), significantly improved from baseline to 6-months post-ECT (t(22) = -2.34, p = .026, CI: = -8.93– -0.63), but were not maintained at 12-months post-ECT (p = 0.20). SSMQ scores significantly worsened from baseline to mid-ECT (t(75) = -5.04, p < .001, CI: -17.53– -7.60), but returned to baseline levels by 2–6-weeks post-ECT. Depressive symptoms (BDI-II) significantly improved by the 4th ECT session and gains were maintained across all timepoints (p < 0.004). WHODAS-2 scores significantly improved from baseline and were maintained across follow-up (t < 0.05).

Conclusion

ECT was effective at improving depressive symptoms in a naturalistic setting with diverse patient presentations. Preliminary findings show minimal, if any, gains in cognitive performance–although, functioning did not appear to worsen following ECT. RBANS may not be sufficiently sensitive. Developing recommendations for conducting and evaluating ECT in naturalistic settings marks an essential next step.

Functional connectivity across social inclusion and exclusion is related to peer victimization and depressive symptoms in young adults

BACKGROUND

Peer victimization is associated with increased risk for depression, as well as increased neural response to social exclusion in the anterior cingulate cortex (ACC) and the amygdala. Altered functional connectivity (FxC) of fronto-limbic circuitry is associated with risk for various affective disorders. The present study examined the relationship between fronto-limbic FxC during social exclusion, prior peer victimization experience and depressive symptoms.

METHODS

Three mutually exclusive groups were formed: peer victimized (with a history of peer victimization), defenders (history of defending peers), and controls (no prior peer victimization experience) (n = 15/group; M_age = 17.7 years). Functional Magnetic Resonance Imaging data were collected while participants completed the Cyberball paradigm (simulating the experience of social exclusion). FxC between the Medial Prefrontal Cortex (MPFC), ACC, right insula and left amygdala, was compared between groups and examined in relation to depressive symptoms.

RESULTS

Prior peer victimization experience was associated with differences in fronto-limbic FxC across social inclusion and exclusion. Defenders displayed distinct shifts in FxC across the transition from being included to excluded. Peer victimized individuals exhibited a unique pattern of amygdala-specific FxC during inclusive interaction with peers, and in the continuous FxC across inclusion and exclusion. FxC of the MPFC-amygdala across inclusion and exclusion moderated the relationship between peer victimization and depressive symptoms.

LIMITATIONS

Small sample size and cross-sectional design limit interpretation of the findings.

CONCLUSIONS

Peer victimized individuals who exhibit continuous positive FxC of the MPFC-left amygdala across inclusion and exclusion may be at greater risk for depressive symptoms.