Changes in Depression and Anxiety Symptoms during Antidepressant Treatment in Adults

BACKGROUND: Antidepressant treatment response can be estimated by tracking the course of symptom change over a series of treatment sessions. However, many prognostic factors can influence response trajectories, and patients with depressive and anxiety symptoms may respond differently to the same antidepressant treatment. METHODS: Repeated measurements of Patient Health Questionnaire-9 (PHQ-9) and General Anxiety Disorder-7 (GAD-7) scores were used to track the symptoms and severity of depression and anxiety in patients for 12 weeks after initiating an antidepressant treatment. Group-based trajectory modeling was used to generate trajectories that cluster patients with similar trends in symptom progression. Finally, multinomial logistic regression was used to explore associations of various baseline patient characteristics with the different trajectories. RESULTS: Of the 577 participants, 373 (64.64%) were female, and the mean age was 39.34 (SD: 12.87) years. Six depression trajectory subgroups were identified, which included three subgroups that responded to antidepressant treatment and three other subgroups that showed nonresponse. In particular, for three responded subgroups: one group with severe baseline depression showed a steady, yet substantial improvement in symptoms (n=49, 8.49%). Two groups with moderate baseline depression showed more rapid response (n=93, 16.12%) and remission (n=106, 18.37%). For three nonresponse subgroups: one group had severe baseline symptoms (n=62, 10.75%), and two groups had moderate baseline symptoms (n=137, 23.74% and n=130, 22.53%). Similar patterns were also observed in anxiety trajectories, which included six trajectory subgroups. In particular, three subgroups demonstrated response to antidepressant treatment: two groups with severe baseline anxiety showed a rapid response (n=100, 17.33%) and remission (n=66, 11.44%), and one group with moderate baseline anxiety also achieved remission (n=93, 16.12%). The three nonresponse subgroups included one group with severe baseline anxiety (n=106, 18.37%) and two groups with moderate baseline anxiety (n=97, 16.81% and n=115, 19.93%). Anxiety nonresponse was typically associated with higher pre-treatment depression severity, poorer sleep quality, healthier lifestyle, lower pre-treatment anxiety severity, and non-white race. DISCUSSION: The observed trajectory patterns demonstrate one example of the various paths to improvement or maintenance in depression and anxiety. This analysis sheds light on the often overlooked heterogeneity between depression and anxiety and illustrates that treatments suitable for one condition alone may be insufficient for addressing symptoms of the other.