Millions of Americans swallow antidepressants each day. Many are people who struggle with terrible, debilitating depressions, but some are people who have only mild or moderate symptoms. They are often prescribed antidepressants anyway with the expectation that the drugs will help them feel better.
Although antidepressants have been around for decades, relatively few studies have focused directly on how the pills affect people with milder symptoms. A new study published in the Journal of the American Medical Association this week looked directly at this group and concluded that antidepressant medications don't seem to work well for people who struggle with mild or moderate symptoms.
A Peculiar Truth About Research Design
Since Prozac was introduced to the American public in 1987, there's been a huge amount of research on antidepressants. Small armies of patients have offered themselves up for testing and gone through a complex screening process.
One part of that process is a standardized test that measures a patient's level of depression, says Robert DeRubeis, a psychological researcher at the University of Pennsylvania.
"The interviewer asks a series of questions and the patient responds to those questions, and on each of those items the interviewer assigns a rating of zero — if it's not present — up to the maximum number of 4," says DeRubeis.
According to the test, any score over 19 means that the patient is severely depressed, and DeRubeis says that in most cases, the people who run antidepressant trials won't accept you unless you're actually higher than 20.
"It's just been the practice of pharmaceutical trials that studies of antidepressant medication include patients with severe or very severe depression," he says.
The odd thing is that a huge number of people who actually take antidepressant medications fall into the mild or moderate category.
"My best guess would be that about half the people treated by doctors in the community fall into the moderate or even mild range," says Gregory Simon, a mental health researcher at the Group Health research institute in Seattle. Simon researches the way that mental health clinicians actually practice.
In fact a recent survey showed that almost 70 percent of depressed patients on medication had moderate to mild symptoms.
So why study only those with very serious problems?
"Because drug companies fund the vast majority of clinical trials, and obviously drug companies are interested in having their clinical trials show the efficacy of their antidepressant medications," says Brett Deacon, a psychologist at the University of Wyoming who has done research on depression treatments. "And everyone knows that they are more likely to have that outcome if they recruit very severely depressed patients."
But it's not just about drug companies getting striking results so they can get a drug approved by the FDA. Simon says it's also about doing right by the patients involved in research.
"Ethically there's some obligation to say how can we do this research most efficiently so that we don't enroll a lot more people in a study than we need to, in a study where they're randomly assigned to get a placebo," Simon says.
The Results Of The New Study
In the recent study DeRubeis compared people who took real pills with people who got placebo pills at all levels of depression. He says that in severe cases it appears that antidepressants do genuinely improve mood.
But people with mild depression didn't do so well. According to DeRubeis, in mild and moderate depression, "The difference of the benefit of the medication was rather small, nearly zero."
DeRubeis is careful to say that consumers and clinicians shouldn't conclude from this research that they should not pursue any kind of treatment for depression.
Dr.Philip Wang, deputy director of the National Institute of Mental Health, agrees. Even consumers with mild symptoms shouldn't necessarily be scared off of drugs, he says.
"They don't not work for everyone, and they don't work for everyone," Wang says. "I think buried within the group are people who do respond if they have mild or moderate depression."
And so Wang says clinicians just need to closely monitor patients who don't seem to respond to medication and give them an alternative treatment if necessary.