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Strong look at evidence underlying saliva test for Alzheimer’s


3 Star

Could a Saliva Test Help Spot Alzheimer's?

Our Review Summary

Alzheimer'sThis story discusses a small study from the University of Alberta in Canada that looked for differences in the saliva of Alzheimer’s patients, individuals that have shown some mild cognitive impairment, and those whose mental skills are normal for their age.  An analysis of the saliva from these three distinct groups showed specific differences in certain compounds present.  The suggestion is that, if shown to be correct in a much larger controlled trial, a simple saliva test might offer an early warning for those people at higher risk for developing Alzheimer’s.

This story does a nice job of clarifying the small, preliminary nature of the study and describing its significant limitations. It also acknowledges that even a noninvasive saliva test has the potential to cause harm — context that’s not often provided with stories of diagnostic/screening studies. The main area where the coverage could have been deeper is in the description of the study results and in quantifying the accuracy of the test. Overall, though, the coverage was much more thorough and balanced than a competing story about the study from Time magazine.


Why This Matters

Alzheimer’s dementia is a debilitating and increasingly prevalent condition in our aging society. If the described simple, non-invasive screening test is truly effective (which will take much more testing to find out), it could have an enormous impact that is potentially positive if we develop better treatments for Alzheimer’s patients and can take action based on the results. There is also potential for negative impact resulting from false positive and false negative results, and from knowing about a frightening diagnosis without having the ability to do anything about it.


Does the story adequately discuss the costs of the intervention?

Not Satisfactory

There is no mention in this short story about the potential costs of such a test, if it proved to be viable. Of course, it’s too early to say anything definitive about cost, and offering a specific number might mislead readers by implying that the test is anywhere near ready to be used. But we think the story could have offered some sense of the technology behind the test and whether it’s advanced/expensive or cheap/widely available. Other tests using saliva are in use today and could offer a general comparison point to suggest the costs of a new test.

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

Not Satisfactory

The main investigator states, “Saliva is easily obtained, safe and affordable, and has promising potential for predicting and tracking cognitive decline,” which gives readers a sense of the potential benefits. But that’s only a partial account of what readers need to know. We think any story about diagnostic testing or screening should discuss the sensitivity and specificity of the test — numbers which tell us about how well the test finds people who actually have the disease and rules out people who don’t have it. But the closest the story comes to this is the following: “They found that the saliva of people with Alzheimer’s had different levels of certain substances compared to the saliva of healthy people or those with mild cognitive impairment.”

We’d note that another story about this study from the Wall Street Journal (which we didn’t review) had most of the details we were looking for here. It said, “Some 80% of the sample predicted by the biomarker combination to go on to develop abnormal memory problems truly went on to develop them, while 20% would have been classified as a false negative. The algorithm, 75% of the time, correctly predicted who wouldn’t go on to develop memory problems.”

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


While it’s hard to imagine harms from spitting in a cup, the story does bring up the possibility that patients might request the test even though they show no signs of being at risk for Alzheimer’s, and as with any tests, the risk of false positives is always present. The story meets our standard here. Another issue that could have been raised pertains to screening for a disease for which we do not have great treatments, and the harm that can occur when one is told they will get Alzheimer’s disease and can’t do much about it.

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


The story does a very nice job pointing to potential weaknesses in the study: ” . . . the current study lacks information on possible confounding factors — things such as ‘coexisting illnesses, medications, hydration state, tobacco use and multiple other variables’ that could influence what’s found in the saliva samples.”  A second source says, “There are many gaps in the evidence. It is uncertain whether the strength and consistency of the relationship between these metabolites [in saliva] and Alzheimer’s risk will be maintained in a large multicenter study.”  These caveats come half-way through the story and are substantive enough to meet our standard.

Does the story commit disease-mongering?


Fear of Alzheimer’s is real and pervasive, but this story didn’t get into disease-mongering territory.

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


Nice job here. Two of the three sources quoted in the story are apparently unaffiliated with the institution conducting the research, suggesting independent voices. A comparison with a Time story about the same study makes this story seem exceptionally well-sourced.

Does the story compare the new approach with existing alternatives?

Not Satisfactory

This story is about screening for Alzheimer’s, so it would have been useful to talk about other efforts to develop screening tools (and the lack of effective ones) or methods currently used to diagnose the condition.

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


At a number of different points in the story we are reminded of the preliminary nature of the research, suggesting that it is years away from prime time.

Does the story establish the true novelty of the approach?

Not Satisfactory

The research discussed here is novel in a general sense, but the story doesn’t establish this to a satisfactory degree. A number of previous studies have looked at saliva markers of Alzheimer’s, and there are probably dozens of other blood tests, scans, and other approaches currently in development to address the diagnosis of Alzheimer’s disease. The story does not allude to this research

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


This story does not rely solely on a news release.

Total Score: 6 of 10 Satisfactory


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