The Guardian is claiming a new study "links" drinking a can of artificially sweetened to dementia and stroke, then putting a disclaimer that the study does not show a "causal" connection.

While technically they say the right words, the whole article seems to be skewed with weasel words to indicate that such a causal connection exists—after all a correlation without a causation means that they could title the article "an early sign of dementia is being more thirsty for soft drinks", and be equally technically correct.

Furthermore, the study is cited without context. Studies can find correlation between cheese consumption and people dying tangled in bedsheets, but this does not tell us anything real. What is the current state of the evidence regarding the safety of these ingredients? Have they been tested for safety in regards to these diseases?

I would like to know what the actual evidence says:

  1. Did the study actively look at causation? If so, did they find any evidence of it? Did they find evidence of no causation?
  2. What does the rest of the literature say on this link? Have the same sweeteners been studied before? How good is the rest of the evidence?
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    "Any claim coming from an observational study is most likely to be wrong" this paper should be included as a caveat in all Sk.SE claims based on observational studies
    – matt_black
    Commented Apr 21, 2017 at 11:40
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    Saw the report on this on CBS news last night. At the end the reporter says: this method cannot prove causation. Perhaps those who drink diet soda tend to be those who were already at risk for dementia because of other causes: like obesity or diabetes.
    – GEdgar
    Commented Apr 21, 2017 at 12:10
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    I have no idea of what you want. They openly say there is no causal link: "However, they admitted that they could not prove a causal link between intake of diet drinks and development of either medical condition because their study was merely observational...". They quote another researcher saying it shouldn't be interpreted as causal: "This research does not show that artificially sweetened drinks cause dementia...".
    – KAI
    Commented Apr 21, 2017 at 13:43
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    They quote another researcher saying there could be confounding factors messing with the correlation/causation: " The results could have been skewed by people who had already become ill before switching to low- or no-sugar drinks, Sattar added." They quote soft drink people as protesting that there is no causation. Given that the article itself answers your own question over and over, what are you looking for? Those aren't weasel words, those are explicit and repeated statements that it isn't causal.
    – KAI
    Commented Apr 21, 2017 at 13:45
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    A single study isn't going to be dispositive. The "weasel words" are probably because the scientists, being scientists, are being very careful in the words they choose and very cautious about claims. With a single study they'd say that their findings "suggest" or "could" show something, but need to be reviewed, replicated and verified. That's scientists being scientists. Reporters and editors being who they are, will slap on a very dramatic-sounding headline that in no way reflects the actual impact of the single study, because that's what they do. Commented Apr 21, 2017 at 14:40

1 Answer 1


I'm very doubtful, as KAI noted, not even the researchers are speaking of this study with certainty. NCBI, which is extremely reputable notes "evidence does not support links between aspartame and cancer, hair loss, depression, dementia, behavioural disturbances, or any of the other conditions appearing in websites." In the following study pertaining to aspartame: Aspartame and its effects on health.

The sweetener has been demonised unfairly in sections of the press and several websites.

As for other artificial sweeteners, who knows. But aspartame is extremely prevalent and is one of the few artificial sweeteners with conclusive scientific research in this area, at least to my knowledge.

  • it is a rather old study, however it is the best I could readily find specifically citing "dementia" "artificial sweeteners" and they will have done their homework. The lack of chatter in scientific community versus the media leads me to conclude that this study hasn't definitively verified anything different from the null
    – Nik
    Commented Apr 21, 2017 at 22:35

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