(CBS News) More than 29 million Americans have experienced depression, and the drugs available to treat them haven't changed much in 25 years. But two studies out Thursday focus on a new class of drugs that may offer new hope.
Jim Staples, 58, has suffered from depression since his twenties.
"I tried to commit suicide, and it wasn't a hearty attempt," Staples says. "It was just screaming out for help."
When he gets to the point where he feels like he wants to hurt himself, Staples says he feels frightened.
"Scared because I don't want to hurt my family," he says.
"The medicines that I had been taking over the years, they only work for two to three years and then they just fizzled out," Staples adds.
In depressed patients such as Jim Staples, brain cell communication breaks down. Current medications target a chemical called serotonin to help brain cells talk to each other. But it's present in just five percent of those cells.
These new drugs target a different chemical called glutamate, present in 80 percent of brain cells. Researchers believe these new drugs restore the lost communication better than older drugs, which can take months to kick in.
"The exciting part of some of these newer medications is that they might, in fact, produce very rapid antidepressant effects, within hours or days," says Dr. Gerard Sanacora of Yale University, who is leading one of the trials.
The new approach was discovered by accident, when doctors noticed that an anesthesia drug -- ketamine, which targets glutamate -- relieved depression. But it also caused symptoms that mimicked schizophrenia.
Dr. Ron Burch has been developing Glyx-13, one of these new medications.
"We found it has a very nice antidepressant effect, lasts for several days after a single dose and with no side effects of schizophrenia at all," says Burch.
In one study, patients taking an experimental drug had a 40-percent improvement in symptoms, compared to 24 percent on placebo. Jim Staples participated in the trial.
"My hope is that the trial drug will in time to be the last one I'll ever have to take. I'd take the drug for the rest of my life, but it might be the last one I have to switch to," Staples says.
The drugs are still in trials, and even if they continue to show promise, FDA approval is still three to five years away.
For those interested in more information about enrollment eligibility in glutamate drug trials for depression:
Astra Zeneca's AZD6765
Click here OR call: 1.877.860.4646