Predictors of improved mood over time in clinical trials for major depression

The objective of this exploratory analysis was to use a repeated measures modeling approach to identify potential predictors of improved mood over time in patients with major depression. Fifty-one subjects with major depressive disorder (MDD) were enrolled in a 1-week single blind placebo lead-in, followed by an 8-week, double-blind placebo-controlled treatment with either fluoxetine or venlafaxine. Hierarchical linear regression models were used to identify baseline and placebo lead-in predictors of change in repeated measures of the Hamilton Depression Rating Scale (HDRS) during treatment. Non-specific predictors of improved mood included decreased prefrontal activity during placebo lead-in as measured by quantitative electroencephalographic cordance, lower pretreatment depressed mood on the HDRS, shorter duration of current episode, increased verbalization of suicidal thoughts, no family history of mood disorders, less severe middle insomnia, higher guilt, lower somatic anxiety, and younger age. Moderators of improved mood included somatization, paranoid ideation, and self-reported depressed mood. We also found that change in prefrontal cordance after randomization mediated the effects of middle insomnia, suicidal thoughts, and family history of mood disorders. We recommend the use of repeated measures modeling, and the exploration of relationships among biological and psychological factors, for future analyses of clinical trial data.