Whether placebos are as good as antidepressant medications for most patients -- as a 60 Minutes segment argued on Sunday -- may depend on the placebo and the population. The CBS show highlighted what it called a war in the medical community over the research of Irving Kirsch, PhD, associate director of the Placebo Studies Program at Harvard Medical School.
In one study, his group found no difference in depression response between antidepressants, tranquilizers, and barbiturates.
In another, which pooled data from the published antidepressants trials with the large number of unpublished negative trials obtained through a Freedom of Information Act request, antidepressants were no better than placebo for mild to moderate depression. Only in severe depression did antidepressants break away with a clinically meaningful difference in benefit.
"People get better taking the drug but it's not the chemical ingredients of the drug that are making them better, it's largely the placebo effect," Kirsch explained on the program.
In response, the American Psychiatric Association (APA) called the segment "irresponsible and dangerous."
The association warned that "Kirsch's conclusions were widely discredited by the FDA, European Medicines Agency, and clinical psychiatrists" and stuck by its support of the efficacy of antidepressants.
Some experts in depression contacted by ABC News in collaboration with MedPage Today also voiced concern about the impact on patients.
"It is very easy for such information to be misinterpreted, especially with regard to illnesses that are already stigmatized in our society," cautioned Carol Bernstein, MD, of NYU Langone Medical Center in New York City and a past president of the APA.
But Kirsch's conclusions found a sympathetic ear with many, who largely blamed the way clinical trials have been set up rather than the drugs.
Changing Trial Demographics
"There is definitely an element of truth to this," P. Murali Doraiswamy MD, head of biological psychiatry at Duke University Medical Center in Durham, N.C., said in an email.
Placebo response rates in clinical trials over the past two decades have climbed to around 60% of patients getting partial improvement, with half showing remission. But the antidepressant response has not improved, so the drugs managed to beat placebo in only about half of studies over this period, he explained.
"This is in part due to the commercialization of the clinical trial recruitment process which has led to emphasis on rate of recruitment rather than quality of people recruited for trials," Doraiswamy explained. "Put in other words, a lot more mildly depressed people are put in trials nowadays, [which] results in greater rates of spontaneous improvement."
That mirrors what has been happening in clinical practice, Walter Brown, MD, of Brown University in Providence, R.I., noted in the TV segment.
"The number of antidepressant prescriptions over the last decade has increased, and most troublesome is that these increases are in the mildly depressed who are least likely to benefit from them," he told 60 Minutes.
The first-line strategy for mild to moderate depression should be psychotherapy, according to APA guidelines.
Its statement issued in response to the 60 Minutes segment acknowledged that "only after this approach falls short should the physician decide whether or not antidepressants are needed in conjunction with psychotherapy."
Depression typically doesn't arise solely from a deficiency of the neurotransmitter serotonin that antidepressants would theoretically fix, noted Jajnish Mago, MD, director of the mood disorders program at Thomas Jefferson University in Philadelphia.
He likened it to diluting the chances of finding a benefit of antibiotics by including both viral and bacterial illness in a treatment trial.
"Our field has no one to blame but ourselves," he wrote in an email to ABC News and MedPage Today. "We expanded the concept of depression to include less severe cases (so-called 'minor depression') and cases where the depression occurred after a significant life problem."
Not Just a Sugar Pill
The strong placebo effect in antidepressant trials doesn't mean depression is "all in your head," Kirsch noted.
Placebo does have real biologic impact that has been tracked with neuroimaging and shown in studies even when participants knew they were only getting an inert substance.
But placebo groups have been getting much more than just inert pills in the antidepressant trials.
Harold Koenig, MD, MHSc, who is running a randomized clinical trial for depression treatment at Duke University Medical Center, explained the "huge" effort to keep participants in trials like his.
"We listen, encourage, are compassionate, understanding -- in order to get them to continue," he told ABC News and MedPage Today. "They are volunteers, of course, and could drop out at any minute -- which threatens what may be a multi-million dollar study. ... This puts tremendous pressure on staff to provide support and care for patients in the study, which is probably the most effective treatment there is for milder forms of depression."
Placebo really ends up being low-dose supportive psychotherapy, agreed Gary Kennedy, MD, of Montefiore Medical Center in New York City.
"It is our capacity to enhance the placebo response that accounts for the finding rather than the limitations of antidepressant therapy, of which there are many," he wrote in an email.
So the placebo effect in the clinical trials shouldn't be surprising because it simply estimates the impact of recommended initial therapy for the majority of patients with clinical depression (mild to moderate cases).
"If insurance companies would support talk therapies, education and counseling at the same level they support medication, the entire field would be better off," said Thomas L. Schwenk, MD, of the University of Nevada in Reno.
February 24, 2012
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Placebos or Drugs for Depression Treatment?