Depression, exercise, research and the media

A recent study on treating depression with exercise encouragement and advice has caused quite a stir. Check out the headlines.

But the paper itself says the following:

The main implication of our results is that advice and encouragement to increase physical activity is not an effective strategy for reducing symptoms of depression. Although our intervention increased physical activity, the increase may not have been sufficiently large to influence depression outcomes.

An article tackling the coverage of the study quotes the pay-walled editorial from the same issue of the medical journal:

Or, as the BMJ’s own editorial points out: “Patients in both groups therefore already received high quality care, and 57% were taking antidepressants at recruitment. It may have been difficult for the addition of a physical activity intervention to make an appreciable difference.” Further, about 25 per cent were already meeting Government exercise guidelines, so there may have been “little room for the intervention to make a difference”. The BMJ says that there has still been insufficient research.

I think that this is a very important point. It would be interesting to compare the following groups:

  1. exercise/no medication
  2. exercise/medication
  3. no exercise/medication
  4. no exercise/no medication

Further, look at the effect of exercise rather than the effect of advice and support. AND, follow them for at least a year. Then, if we establish exercise is helpful, we can look at whether it helps some but not others, what dose and frequency is needed, whether it’s helpful as an adjunct to other treatments, and THEN explore strategies for getting patients to exercise.

Another blog summarizes the study this way:

So, what did the study actually find? Two groups of depressed individuals were kept on their standard treatment plan and one of those groups was mildly encouraged to do more exercise through a few short telephone calls and a couple of face to face meetings. There was no minimum amount of exercise required for inclusion in the study, nor were any facilities for exercise provided. Over half of the participants were on anti-depressant medication that may provide some of the benefits of exercise alone, thus negating the benefit of exercise on self reported happiness.

At the four month follow up, exactly the same number of people in the treatment group had participated in physical activity as had done so in the control group (though it should be noted that there were seventeen more people in the control group than in the treatment group). Over the course of the study there was only a fifteen percent difference in the amount of exercise between the two groups! This study shows that the current exercise based treatment plan of telling people to exercise is not effective. It does not assess the outcomes of enabling people to exercise, or indeed of actually exercising.

“EXERCISE DOES NOT HELP DEPRESSION” is a good headline, but it’s not that simple and it’s not true.