Cognitive Specificity Enhancement Training (CoST) in depressed patients with a history of childhood maltreatment: a pilot study on the feasibility and efficacy of CoST for reducing rumination, cognitive avoidance, and depressive symptoms.

Depression rates are rising globally, with traditional treatments often failing to address cognitive overgeneralization - a distortion that perpetuates negative thinking and depressive symptoms. This study aimed to evaluate the efficacy of Cognitive Specificity Enhancement Training (CoST) in reducing rumination, cognitive avoidance, and depressive symptoms, particularly in patients with childhood maltreatment. Using a quasi-experimental design, 40 depressed patients (Mage = 33.02 ± 10.69) with a history of childhood maltreatment were purposively sampled and randomly assigned to experimental (n = 20) or control (n = 20) groups. The experimental group underwent four CoST sessions, while the control group received no intervention. After dropouts, 35 participants (18 experimental, 17 control) completed the study. Beck Depression Inventory-II (BDI-II), Ruminative Response Scale (RRS-10), and Cognitive Avoidance Questionnaire (CAQ) were administered pre-intervention, post-intervention, and at a one-month follow-up. Repeated measures ANOVA revealed significant reductions in BDI-II and RRS-10 scores in the experimental group (p < .05), maintained at follow-up. No significant changes were observed for cognitive avoidance in either group. These findings highlight that the short-term intervention CoST may be effective in improving rumination and depression symptoms amongst depressed patients with history of childhood maltreatment as a vulnerable social group.