There are 3 known types of depression—and SSRIs don’t work for one of them

For some people suffering from depression, SSRIs (selective serotonin reuptake inhibitors), the most common form of antidepressants—are true life-savers. The only problem? Unfortunately, they don’t work for everyone, and new research has revealed why that might be.

In a study published in the journal Scientific Reports, researchers looked at the health data—which included sleeping patterns, life history, and gene expression and was gathered from blood tests and questionnaires—from 134 individuals, half of whom had been recently diagnosed with depression and the other half a history of the mental illness. What they found was what they’ve always suspected: Depression is crazy complex, and there’s not just one standard type that everyone perfectly fits into. In fact, they’ve now found, there are three.

According to the researchers, those three sub-types of depression are characterized by two factors: level of functional connectivity of the brain (or, how well the different areas of the brain sync with one another) and whether you’ve experienced childhood trauma. And those factors play a big role in determining whether SSRIs will be able to treat the mental illness or not. While SSRIs worked for sub-type D3 (low functional connectivity of the brain and no childhood trauma) and D2 (high functional connectivity of the brain and no childhood trauma), they didn’t for sub-type D1 (those who have high functional connectivity of the brain and a history of childhood trauma).

“There has been a growing body of evidence—not just this study—that some people with depression who have experienced childhood trauma do not respond as well to medication as those that haven’t.” —Dr. Gail Saltz, psychiatrist

“There has been a growing body of evidence—not just this study—that some people with depression who have experienced childhood trauma do not respond as well to medication as those that haven’t,” says Gail Saltz, MD, associate professor of psychiatry at New York Presbyterian Hospital Weill-Cornell School of Medicine (who was not affiliated with the new study). “The good news is this same subgroup does appear to respond to certain psychotherapies. Psychotherapy has no side effects and can make permanent changes that also help prevent relapse later.”

Now with this new knowledge on sub-types of depression, medical professionals will have a better idea of how to treat future patients the first time around. “The value here is that taking a good history of the depressed patient can help determine what type of treatment is more likely to be effective rather than assuming incorrectly that one size fits all,” Dr. Saltz explains. “Over time, as our diagnostic techniques get better, it’s likely that we will find there are numerous different types of depression and that different types of treatment may be beneficial depending on which type you have.” And hopefully, you’ll be able to find some relief much quicker—and with less experimenting—than before.

Here’s how one hour of exercise per week can help ward off depression. Or, find out the holistic ways you can help ease the symptoms of depression—no meds, included.