Comparing the temporal pattern of symptom change across multiple treatments for depression

Depression is increasingly understood as a complex dynamic network of individual depressive symptoms that change over time and are causally related to each other. Directed dynamic time warping (DTW) is a novel method for examining the temporal pattern of symptom change, hereby identifying symptoms that tend to remit earlier and those that improve at later stages of treatment. We compared directed depressive symptom dynamics across psychotherapy, pharmacotherapy and electroconvulsive therapy (ECT).

Time series data from three observational studies (on ECT) and two randomized trials (one on pharmacotherapy and one on psychotherapy) were included, comprising a total of 549 patients. Across these cohorts, individual depressive symptoms were assessed using validated depressive symptom rating scales. Time series data were analyzed using DTW to calculate a directed symptom network yielding the temporal lead or temporal lag for each symptom.

Patients were on average 62 years old and 60% were female. The dynamic symptom changes were largely similar across all treatment modalities. Somatic symptoms and suicidal ideation showed significant temporal lead, indicating that remission of these symptoms tended to precede remission of other symptoms. Mood symptoms showed the strongest temporal lag values, suggesting that remission of these symptoms tended to occur last during treatment.

The current results suggest that improvements in depressive mood symptoms are preceded by improvements in somatic symptoms and suicidal ideation, irrespective of treatment modality. This may have some important clinical implications. Future research, however, should elucidate whether baseline symptom severity affects the directed DTW network.