Most of what this library covers is a question the evidence has not settled. This one it has. A drug class widely reported to protect the brain was tested in the population that matters, at scale, for two years, and it did nothing measurable. That is a more useful result than a positive one, and it is also the kind that gets far less coverage — which is itself a pattern worth recognizing when reading any claim on a seller’s page.
What was tested
evoke and evoke+ ran across 566 sites in 40 countries [1]. Participants were aged 55 to 85 with mild cognitive impairment or mild dementia due to Alzheimer’s disease, confirmed by amyloid imaging or cerebrospinal fluid analysis — not self-reported memory complaints. They were randomized 1:1 to once-daily oral semaglutide at up to 14 mg or placebo for up to 156 weeks. evoke+ additionally included people with significant small vessel pathology.
Between May 2021 and September 2023, 9,981 people were screened and 3,808 randomized: 1,855 in evoke and 1,953 in evoke+. Mean age was 72.2 years and the mean baseline dementia rating score was 3.7.
What they found
The primary endpoint was the change in the Clinical Dementia Rating – Sum of Boxes score from baseline to week 104. In evoke, scores worsened by 2.3 points on semaglutide and 2.3 on placebo, an estimated difference of −0.08 (95% CI −0.35 to 0.20, p=0.57). In evoke+, 2.2 against 2.1, a difference of 0.10 (95% CI −0.17 to 0.38, p=0.46).
Both intervals sit symmetrically around zero. This is not an underpowered trial that missed a small effect; it is a very large trial that found no effect. The investigators’ own conclusion is that oral semaglutide was not efficacious in slowing clinical progression, and both trials were discontinued.
What it did not find, either
Safety was unremarkable. Treatment-emergent adverse events were reported in 91.2% of 1,896 participants on semaglutide against 84.8% of 1,902 on placebo, and the investigators judged five deaths treatment-related — one in the semaglutide group and four in the placebo group. Tolerability was consistent with what the drug does in its other indications, described in titration and nausea.
How to use a negative trial
A well-run trial that finds nothing closes a question, and closing questions is the scarcer service. It means anyone still telling you these drugs help with memory is working from evidence that has been superseded — and, on current publishing incentives, may not know it.
It also tells you what to do with the next observational headline in this category. The pattern here is exactly the pattern that ran for other outcomes: a real correlation, a plausible mechanism, and no effect when tested. That is worth holding onto while reading what the semaglutide trials are worth, and while reading any seller’s summary of them — most publish nothing about which claims rest on trials and which on cohorts, a silence counted in what sellers will not tell you.