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Research Review

Antidepressants May Not Improve All Symptoms of Depression

Even people who show a clear treatment response with antidepressant medications continue to experience symptoms like insomnia, sadness, and decreased concentration, researchers at the University of Texas (UT) Southwestern Medical Center have found after analyzing data from the largest study on the treatment of depression.

“Widely used antidepressant medications, while working overall, missed these symptoms. If patients have persistent residual symptoms, these individuals have a high probability of incomplete recovery,” says Shawn McClintock, PhD, an assistant professor of psychiatry and lead author of the analysis available in the Journal of Clinical Psychopharmacology.

UT Southwestern researchers tracked a wide range of symptoms of depression, including sadness, suicidal thoughts, and changes in sleep patterns, appetite/weight, concentration, outlook, and energy/fatigue, at the start of the trial and at the end of the antidepressant treatment course.

McClintock’s research used data from the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) study, the largest ever on the treatment of major depressive disorder. The six-year study initially included more than 4,000 patients with major depressive disorder from clinics across the country. All responders reported between three to 13 residual depressive symptoms, and 75% of participants reported five symptoms or more.

Some of their symptoms included insomnia that occurs in the middle of the night (nearly 79%); sadness (nearly 71%); and decreased concentration and decision-making skills (nearly 70%). Moderately severe midnoctural insomnia was reported in nearly 60% of participants, more than twice as frequently as other symptoms.

Thoughts of suicide rarely persisted or emerged during treatment, researchers found. “Some people fear that antidepressant medication increases thoughts of suicide,” McClintock says. “This provided counterevidence of that.”

Researchers in the STAR*D trial found that only 33% of people go into remission in the first 12 weeks of treatment with a selective serotonin reuptake inhibitor (SSRI). Individuals on SSRIs often still exhibit symptoms of depression. For one of the first times, researchers sought with this analysis in a large sample to identify residual symptoms of the disease and whether these symptoms began before or during treatment.

McClintock and colleagues looked at data from the 2,876 STAR*D participants who completed the first phase of the trial—treatment with an SSRI for 12 weeks. About 15% of those participants, or 428 people, responded to treatment with no remission. Response was defined as a 50% decrease in severity of depression. The average age of participants was 40, 73% were white, and 66% were female.

The next step, Dr. McClintock said, will be to develop more targeted antidepressant therapies to decrease depressive symptoms, and to understand better the association between depression and concentration.

— Source: University of Texas Southwestern Medical Center