Group-Based Symptom Trajectory of Intramuscular Administration of Scopolamine Augmentation in Moderate to Severe Major Depressive Disorder: A Post-Hoc Analysis

OBJECTIVE: Developing new strategies for rapid and sustained relief of depressive symptom has been the focus of research in the field of major depressive disorder (MDD). Scopolamine exerts rapid antidepressant effect in recent years but is controversial. Therefore, we aimed to identify a sensitive patient who may respond to intramuscular injections of scopolamine added to antidepressants based on distinct trajectory patterns. METHODS: We analyzed longitudinal post hoc data collected from 66 MDD patients at Beijing Anding Hospital, Capital Medical University, over a 4-week period. In addition to demographics, depressive symptoms were assessed using the 16-item Quick Inventory of Depressive Symptomatology and Self-Report (QIDS-SR16) Scale and 17-item Hamilton Rating Scale for Depression (HRSD-17) following an i.m. injection of scopolamine. We explored different longitudinal patterns of depressive symptoms using a group-based trajectory model (GBTM). We used multiple logistic regression models to help identify predictors of different depressive symptom trajectories. RESULTS: A two-class GBTM was identified as optimal for classifying depressive symptoms: high/rapidly declining (39.4%) and moderate/gradually declining depression trajectories (60.6%) were distinguished based on the HRSD-17. The high/rapidly declining depression trajectory was characterized by high initial depression followed by a rapid decrease at the end of the study. The moderate/gradual decline trajectory was dominated by moderate depression and gradual decline over 4 weeks. There were no significant associations of age, gender, education, or age of onset with the two trajectory groups. CONCLUSION: Scopolamine added to antidepressants can effectively relieve the symptoms of patients with severe depression, and it decreases faster than patients with moderate depression.