Although previous studies have suggested that combination therapy may be more effective than monotherapy, researchers at UT Southwestern Medical Center have now shown this is not the case. The condition, which affects approximately 19 million Americans each year, is a mood disorder in which feelings of sadness, loss, anger, or frustration interfere with everyday life for a long period of time. While the exact cause of depression is not known many researchers believe it is caused by chemical imbalances in the brain, which may be hereditary or caused by events in a person’s life.
The Combining Medication to Enhance Depression Outcomes, studied 665 patients aged 18-75 with major depressive disorder. It randomized patients into 3 groups who were then prescribed FDA approved antidepressant medications.
- One group received escitalopram (a selective serotonin reuptake inhibitor [SSRI]) and a placebo.
- The second group received escitalopram together with bupropion (a non-tricyclic antidepressant)
- The third group took different antidepressants: venlafaxine (a tetracyclic antidepressant) and mirtazapine (a serotonin norepinephrine reuptake inhibitor).
After 12 weeks of treatment, remission rates were similar across the three groups: 39%, 39% and 38%, respectively. Response rates were about 52% in all three groups. After seven months of treatment, remission and response rates across the three groups remained similar, but side effects were more frequent in the third group.
These results show that, “Clinicians should not rush to prescribe combinations of antidepressant medications as first-line treatment for patients with major depressive disorder,” said Dr. Madhukar H. Trivedi, Principal Investigator of the study and Professor of Psychiatry and Chief of the Division of Mood Disorders at UT Southwestern. “The clinical implications are very clear – the extra cost and burden of two medications is not worthwhile as a first treatment step,” he concluded.
The next step is to study biological markers of depression to see if it is possible to predict response to antidepressant medication and, thus, improve overall outcomes.