How effective are antidepressants?

Antidepressants, including serotonin reuptake inhibitors and serotonin-norepinephrine reuptake inhibitors, are widely used in the United States despite a number of unknowns related to their clinical performance. One of the biggest unknowns stems from the dearth of evidence on the efficacy of the drugs over the long term, as most studies have followed up with participants for only 8 to 12 weeks. Researchers also do not know much about how antidepressants affect mental and physical quality of life over time.

A new study in PLOS One examined the effects of antidepressant use on patient-reported health-related quality of life for individuals with depression from 2005 to 2016. The study, based on data from more than 17 million Americans participating in the U.S. Medical Expenditures Panel Survey, found no substantial differences in the changes in quality of life among patients who used antidepressants and those who did not. However, potential limitations to the findings include that the study compared groups of people who may have been experiencing different levels of depression, and the people who were taking antidepressants may have been taking them for a while and may have already experienced quality of life improvements before the study began.

The literature to date suggests that individuals do register modest improvement in symptoms in the initial months of antidepressant use, but the jury is still out on whether these small changes have a noticeable effect on mood or overall function. It is also up for debate whether the small improvements are worth the possible adverse effects, which may include nausea, agitation, weight gain, reduced libido, and indigestion. Additionally, the benefits of antidepressants appear to be much less pronounced in people with mild versus severe depression. That raises a red flag, too, because by one estimate nearly three-quarters of Americans who take the drugs have not even been diagnosed with depression.