Clinical tests on new antidepressant medications often exclude many people with depression, a new study finds.

More than 80 percent of people with depression in the general population aren't eligible for clinical trials of antidepressant drugs because they don’t meet inclusion criteria, the study says.

Researchers, whose work was published in the Journal of Psychiatric Practice, found that about 82 percent of people suffering depression would not be eligible for enrollment in current clinical trials on antidepressant medications. They believe the percentage could be as high as 90 percent because many trials have even stricter criteria.

The excluded were patients older than 65, people with slight depression, those with other medical condition, and women not using birth control.

The findings could explain why the side effects of antidepressants are often underestimated and benefits overestimated before they are used in the “real world,” researchers said.