Investigators discovered that even in the best case, that is when an individual shows a distinct improvement after beginning medication, symptoms such as insomnia, sadness and decreased concentration are likely to persist.
“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,” said Shawn McClintock, Ph.D., of University of Texas Southwestern medical school.
Investigators studied 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.
Integral to the investigation was the use of data from the Sequenced Treatment Alternatives to Relieve Depression, or STAR*D study, the largest ever on the treatment of major depressive disorder and considered a benchmark in the field of depression research. The six-year, National Institute of Mental Health-sponsored 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 percent of participants reported five symptoms or more. Some of their symptoms included insomnia that occurs in the middle of the night (nearly 79 percent); sadness (nearly 71 percent); and decreased concentration and decision-making skills (nearly 70 percent).
Thoughts of suicide rarely persisted or emerged during treatment, researchers found.
“Some people fear that antidepressant medication increases thoughts of suicide,” McClintock said. “This provided counterevidence of that.”
Researchers discovered that depression medication such as SSRIs, or selective serotonin reuptake inhibitor, enabled only 33 percent of participants to resolve depression symptoms (go into remission) in the first three months of the study.
Fifteen precent of participants did not respond to the medication — with response defined as a 50 precent decrease in severity of depression. The average age of participants was 40, 73 percent were white, and 66 percent were female.
McClintock believes the research demonstrates the need to develop more targeted antidepressant therapies to decrease depressive symptoms, and to understand better the association between depression and concentration.
The study highlights the fact that while medication can assist recovery from depression, residual depressive symptoms need attention to help individuals return to normal and maintain in the long run.
The paper discussing the research findings is available in the April print issue of the Journal of Clinical Psychopharmacology.