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Mediterranean diet may help prevent dementia, study says


3 Star

Mediterranean diet may help prevent dementia, study says

Our Review Summary

This is a story about a study that won’t be presented for two months yet – about a health benefit that is seen in individuals who self-report consuming a Mediterranean diet.  It was good that the story pointed out "The study shows association, not causation" but the explanation of this was a bit awkward and incomplete. It also never answered what "36% less likely to have areas of brain damage" really meant.  36% of what?  And what clinical significance might that have? There can be a difference between being able to find something and whether that something has significance in people’s lives.


Why This Matters

 Dementia is a major concern for older people.  However, the gist of the story  – that the "Mediterranean diet may help prevent dementia" – as the headline states – is something an observational study can’t prove.  That’s what the story could have better explained.


Does the story adequately discuss the costs of the intervention?

Not Applicable

Another not applicable criterion for this story.  Costs not mentioned, but also hard to pin down costs of this diet.

Does the story adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

 The story specified that those following a Mediterranean diet were ‘36% less likely to have areas of brain damage’.  This is an inadequate presentation of information because the reader has no sense of how common the thing prevented might be (36% of what?) and also how well this measurement of brain damage correlates with a clinical parameter of concern to real people. There can be a difference between being able to find something and whether that something has significance in people’s lives.

Does the story adequately explain/quantify the harms of the intervention?

Not Applicable

 There was no discussion of harms, but we’re not sure of any from this diet – so we judge this criterion Not Applicable in this case.

Does the story seem to grasp the quality of the evidence?

Not Satisfactory

The story highlighted the results of a study to be presented two months from now.  This means that the results have not been peer reviewed. This should have been explained. Even then there are weaknesses in stories about presentations at scientific meetings. See our primer.  We appreciate that the story stated that the study showed an association but does not prove causality – but think the story could have used better language to explain this, such as: 

“But readers shouldn’t jump to the conclusion that this diet can prevent dementia.  That’s a conclusion that such an observational study can’t reach.  Other factors in the study subjects’ lives may have explained the findings.  Only a randomized clinical trial can establish cause-and-effect. That doesn’t mean that the statistical link (association) isn’t real; it just means a study like this can’t prove that the diet had a preventive effect.”

The story came close at times – dancing around these messages – but never quite clearly communicating the significance of the limitation of an observational study.

Does the story commit disease-mongering?


 No disease-mongering of Alzheimer’s disease or vascular dementia in this story.

Does the story use independent sources and identify conflicts of interest?


 The story has a quote from a clinician who does not appear to be associated with the research to be presented that was reported on.

Does the story compare the new approach with existing alternatives?

Not Satisfactory

The story could have at least briefly mentioned other approaches to risk reduction.  For example, control of hypertension and use of daily aspirin to reduce risk of vascular disease in the brain.  It doesn’t require many words in a story to put one area of research into context of other research in the field.

Does the story establish the availability of the treatment/test/product/procedure?

Not Applicable

There isn’t any question about the availability of the ‘mediterranean diet’ so this criterion is not applicable for this story.

Does the story establish the true novelty of the approach?


 The story appropriately tried to put this research into the context of other resarch on the Mediterranean diet and health.

Does the story appear to rely solely or largely on a news release?


Although there is some language in the story that is very similar to that found in a news release, we rule this satisfactory because an independent expert was quoted, indicating that the story didn’t rely solely or largely on a news release.

Total Score: 4 of 7 Satisfactory


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