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Do PET scans improve dementia diagnosis? LA Times story overlooks harms of screening


3 Star


Is it Alzheimer’s or another dementia form? Why doctors need to distinguish and how they might do so

Our Review Summary

Sample PET scan of the brain. Credit: Jens Maus/Wikipedia

Sample PET scan of the brain. Credit: Jens Maus/Wikipedia

This Los Angeles Times story broaches the tricky terrain of improving dementia and Alzheimer’s diagnostics in a world where there are no treatments that effectively stop or reverse the disease. Still, researchers want to know how doctors and patients might change their treatment decisions with more refined knowledge that expensive PET scans can provide. The story explores three new studies within that frame with care. And yet, the findings were described only in very general terms, and the story doesn’t discuss the downsides of this screening test (such as the risk of a false positive result).


Why This Matters

The potential for more accurate diagnoses is important if there are treatments that vary according to the cause of dementia. This isn’t a settled issue–and news coverage needs to make that clear.


Does the story adequately discuss the costs of the intervention?


A close call here. The story does discuss costs, but perhaps not adequately. It cites a range of costs early on — “$3,000-5,000” — but it’s not clear whether that’s for PET scans or transcranial magnetic stimulation or whether that range covers both.

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

Not Satisfactory

The story misleads the reader by citing 19,000 patients in the IDEA study. However the results described actually refer to 3,979 patients from whom data were analyzed. (The story does mention that these are preliminary results, but we think it could have been much clearer on this point.)

The endpoint in the study was whether patients treatment plans changed after their PET scans were analyzed by doctors. The story says roughly two-thirds of patients “saw their medication regimens changed or were counseled differently by their doctors about what to expect.” We’d like to see the breakdown — how many changed medications? how many changed prognosis? Also, a change in prognosis might go in either direction — better or worse — and might be subtle or profound.

The story does include a patient whose faced a worse prognosis after his PET scan, but it’s not clear whether he’s representative. It’s a compelling patient narrative, but was it a common result?

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

Not Satisfactory

The story discusses the frustration of having a diagnosis with no known treatments. However, when it comes to the intervention specifically–the PET scan–there are the risks of false-positives and false-negatives. As in, what’s the risk someone is diagnosed when they don’t have the disease, or they’re not diagnosed when they do indeed have the disease? Every screening test has these risks–it’s important to know how likely they are.

And, PET scans themselves expose people to radiation and can cause allergic reactions to the tracer.

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

Not Satisfactory

There is not sufficient discussion of the details of the studies to help readers understand the quality of the evidence.

Does the story commit disease-mongering?


No over-the-top language to describe Alzheimer’s disease or other dementia conditions.

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

Not Satisfactory

The one expert source quoted is chief scientific offer at the Alzheimer’s Association, which ran the study. Readers would have benefitted from hearing a perspective from an expert or researcher who was not involved with the study.

Does the story compare the new approach with existing alternatives?


The story discusses the rise of imaging technology in diagnosing Alzheimer’s disease, which used to be only definitively diagnosed post-mortem. It also mentions another new experimental technique — transcranial magnetic stimulation. We think the story could have better discussed the relative accuracy of each option, though.

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


This was a close call. In general, PET scans are widely available, if costly. The story also made it clear that Medicare doesn’t cover this scan. But, the story could have gone a step further and explained without Medicare coverage, it’s unlikely to become widely available.

Does the story establish the true novelty of the approach?

Not Satisfactory

This isn’t a new area of research–we reviewed a Wall Street Journal story on nearly an identical topic more than 10 years ago. This LA Times story could have made that more clear, and talked about how this newer effort adds (or doesn’t) to what’s already known.

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


The story does not appear to be based on a news release.

Total Score: 5 of 10 Satisfactory


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