Conducted by researchers at the University of Illinois at Chicago, the study examined how 26,000 people used their prescription medications over a nine-year period.
Researchers first asked the study’s participants to report on the drugs they’d taken in the past month, and then screened them for depression.
By 2014 (the last year of the study), 38% of all U.S. adults were taking at least one drug with adverse effects. Seven percent of the people who used one of those drugs, the study found, suffered from depression. Perhaps not surprisingly, depression increased with the number of drugs people take at the same time.
Depression was reported in 9% of the people who took two drugs and in 15% of adults who took three or more at the same time. (Only 5% of the people not taking any of the commonly used drugs had depression.)
The researchers described their study as the first to successfully prove that when common drugs are used at the same time (termed “polypharmacy”), the risk for adverse side effects rises.
“The takeaway message of this study is that polypharmacy can lead to depressive symptoms and that patients and health care providers need to be aware of the risk of depression that comes with all kinds of common prescription drugs—many of which are also available over the counter,” said Dima Qato, the study’s lead researcher. “Many may be surprised to learn that their medications, despite having nothing to do with mood or anxiety or any other condition normally associated with depression, can increase their risk of experiencing depressive symptoms, and may lead to a depression diagnosis.”
As ABC News observed, doctors and health care providers may be blind to depression and suicide risks because the drugs are so common.
Not everyone, however, is convinced the study makes its case.
“It’s hard to prove this link with this type of research. It could in fact be that the drugs are leading to depression. However, it could be that people had pre-existing depression,” Dr. Tara Narula told CBS This Morning. “It could be the chronic conditions they’re taking the medications for… [that is] what’s causing depression and not the drugs.”
And while Dr. Narula recommended that people read their drugs’ packaging, Dr. Qato counters that very few drugs actually carry warning labels, which only further puts people at risk.