Antidepressants have completely changed the way we treat depression, and largely for the better. But they are not a cure-all. They can have side effects and may worsen feelings of depression in some.

The idea that depression may respond better to meds and talk therapy together has been gaining ground in recent years. Now, a new study adds a layer of understanding to that idea, suggesting that severe acute depression — the kind brought on by difficult events — may be the only type of depression that requires both treatments in tandem.

For people who experience chronic mild or moderate depression, the medication-therapy combo doesn’t seem to offer any particular benefit over antidepressants alone.

Combining cognitive therapy with antidepressant medicine can make a much bigger difference than we had thought [for] about one-third of patients suffering from major depressive disorder…

In the study, the authors studied 452 adult participants who had chronic (recurring) depression, and assigned them to take antidepressant medication (ADM) or to take antidepressants as well as have cognitive therapy (CT). They followed the participants for as long as took them to recover (that is, to be symptom-free for six months), which in some cases was up to three and a half years.

In the end, the recovery rate with antidepressants and talk therapy together was 72%, compared to antidepressants alone, which was 63%. For mild or moderate depression, the recovery rates were no different between the two types of treatment.

“Our results indicate that combining cognitive therapy with antidepressant medicine can make a much bigger difference than we had thought to about one-third of patients suffering from major depressive disorder,” study author Steven Hollon said in a news release. “On the other hand, it does not appear to provide any additional benefit for the other two-thirds.”

Antidepressants are known to help some people, but they may run a greater risk of relapse than talk therapy over the long term. An additional point to keep in mind is that the study didn’t assess the effectiveness of talk therapy (or cognitive therapy) alone, which is known to be useful for many people.

If you are suffering from depression talk with a mental health care provider. He or she can explain the different types of treatment. It may take some time to arrive at the best type of therapy and/or medication, but the important point to remember is that there are effective treatments out there. It’s often just a matter of finding the one that works best for you.

The study was carried out by a team at Vanderbilt University and published in the journal JAMA Psychiatry.