Are antidepressants effective?

Recently there has been a lot of media coverage of a paper by psychologist Irving Kirsch claiming antidepressants are not as effective as we thought.

Much of the news coverage reports antidepressants are no more effective than placebo and then adds as a much less prominent side bar that this is true in cases of mild to moderate depression.

Another popular angle claims pharmaceutical companies only publish positive studies while suppressing negative results and giving false optimism about these and other drugs on the market.

I find this story interesting for several reasons. First, the reason behind the media frenzy - there is a segment of the population that rejoices when news reports even hint toward undermining the 'evil empire' of the pharmaceutical industry. Another segment seems to have the same reaction when anything negative is reported about psychiatry.

Here we have a story that on its face appears to undermine both drug companies and psychiatry and it has unleashed a flurry of media hype.

In reality, there was nothing particularly new published in this paper. We have long known about the placebo effect and I have written about it several times in this column. This is when a person taking an inactive medication or sugar pill experiences improvement in symptoms.

We have also long known that psychiatric studies in general and depression studies in particular are very susceptible to this effect and this is one of the primary stumbling blocks faced by those conducting clinical trials for the treatment of depression.

As a psychiatrist who is heavily involved in clinical trials, I can tell you placebo response is discussed in detail at investigator meetings for every depression study. If the rate of placebo response in a particular study is high, it is very difficult to show a statistically significant effect of the drug being studied with the number of patients typically involved.

In any study the goal is to keep the placebo rate as low as possible by trying to eliminate as many factors as possible known to increase placebo response. A few such factors can include therapeutic time spent with the depressed person, other procedures or treatments directed at the depression, encouragement and empathy, and hyping the possible benefit of the medication.

A fine balance needs to be struck between ensuring the study volunteer feels cared for and creating an excessive placebo response which could mask benefits from medication.

When a new medication is compared with a proven one and a placebo, a common model in clinical research, if there is no difference between any of the three and a high placebo rate, this is a failed trial. In a case like this, the results may not be published because there would be a known problem making the study unhelpful.

Many studies (which are also included in Dr. Hirsch's analysis) are not meant to show an advantage of medication over placebo. Early studies with smaller numbers exist to find the best dose of medication, learn about side effects and prepare the way for later, larger scale studies. These support a new drug application, but are not necessarily for publication.

Even Dr. Hirsch did not say antidepressants are not effective. He said their effects in mild to moderate depression may not be as great as some people think based on the published studies. Again, this is not news.

Today, most clinical trials for depression are focusing on moderate to severe depression in order to minimize the effects of placebo response.

In cases of mild depression, clinicians and treatment guidelines know that antidepressants are only one of several treatment options.

Placebo response is not unique to psychiatric disorders or treatments and can be substantial in disorders of all kinds. It does not replace effective treatment in the long run unless the symptoms were time limited or transient in nature. Someone with a severe depression may have a temporary elevation of mood in response to hope generating influences such as the promise of new, effective treatments – but if these turn out to be placebos, the positive effects will eventually subside.

Only a few short months ago we had a publicity frenzy over antidepressant medications allegedly causing people to become suicidal and now we are asked to believe they are no more powerful than placebos. We can't have it both ways.

Antidepressants are effective medications that need to be used wisely under the supervision of experienced professionals in the context of an assessment and diagnosis. Other treatments are often also necessary.

 

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