In the course of thinking about metrics, I keep coming across cases of over-promoted research. An early case was “Why honey isn’t a wonder cough cure: more academic spin“. More recently, I noticed these examples.
“Effect of Vitamin E and Memantine on Functional Decline in Alzheimer Disease".(Spoiler -very little), published in the Journal of the American Medical Association. ”
and ” Primary Prevention of Cardiovascular Disease with a Mediterranean Diet” , in the New England Journal of Medicine (which had second highest altmetric score in 2013)
and "Sleep Drives Metabolite Clearance from the Adult Brain", published in Science
In all these cases, misleading press releases were issued by the journals themselves and by the universities. These were copied out by hard-pressed journalists and made headlines that were certainly not merited by the work. In the last three cases, hyped up tweets came from the journals. The responsibility for this hype must eventually rest with the authors. The last two papers came second and fourth in the list of highest altmetric scores for 2013
Here are to two more very recent examples. It seems that every time I check a highly tweeted paper, it turns out that it is very second rate. Both papers involve fMRI imaging, and since the infamous dead salmon paper, I’ve been a bit sceptical about them. But that is irrelevant to what follows.
Boost your memory with electricity
That was a popular headline at the end of August. It referred to a paper in Science magazine:
“Targeted enhancement of cortical-hippocampal brain networks and associative memory” (Wang, JX et al, Science, 29 August, 2014)
This study was promoted by the Northwestern University "Electric current to brain boosts memory". And Science tweeted along the same lines.
Science‘s link did not lead to the paper, but rather to a puff piece, "Rebooting memory with magnets". Again all the emphasis was on memory, with the usual entirely speculative stuff about helping Alzheimer’s disease. But the paper itself was behind Science‘s paywall. You couldn’t read it unless your employer subscribed to Science.
All the publicity led to much retweeting and a big altmetrics score. Given that the paper was not open access, it’s likely that most of the retweeters had not actually read the paper.
When you read the paper, you found that is mostly not about memory at all. It was mostly about fMRI. In fact the only reference to memory was in a subsection of Figure 4. This is the evidence.
That looks desperately unconvincing to me. The test of significance gives P = 0.043. In an underpowered study like this, the chance of this being a false discovery is probably at least 50%. A result like this means, at most, "worth another look". It does not begin to justify all the hype that surrounded the paper. The journal, the university’s PR department, and ultimately the authors, must bear the responsibility for the unjustified claims.
Science does not allow online comments following the paper, but there are now plenty of sites that do. NHS Choices did a fairly good job of putting the paper into perspective, though they failed to notice the statistical weakness. A commenter on PubPeer noted that Science had recently announced that it would tighten statistical standards. In this case, they failed. The age of post-publication peer review is already reaching maturity
Boost your memory with cocoa
Another glamour journal, Nature Neuroscience, hit the headlines on October 26, 2014, in a paper that was publicised in a Nature podcast and a rather uninformative press release.
"Enhancing dentate gyrus function with dietary flavanols improves cognition in older adults. Brickman et al., Nat Neurosci. 2014. doi: 10.1038/nn.3850.".
The journal helpfully lists no fewer that 89 news items related to this study. Mostly they were something like “Drinking cocoa could improve your memory” (Kat Lay, in The Times). Only a handful of the 89 reports spotted the many problems.
A puff piece from Columbia University’s PR department quoted the senior author, Dr Small, making the dramatic claim that
“If a participant had the memory of a typical 60-year-old at the beginning of the study, after three months that person on average had the memory of a typical 30- or 40-year-old.”
Like anything to do with diet, the paper immediately got circulated on Twitter. No doubt most of the people who retweeted the message had not read the (paywalled) paper. The links almost all led to inaccurate press accounts, not to the paper itself.
But some people actually read the paywalled paper and post-publication review soon kicked in. Pubmed Commons is a good site for that, because Pubmed is where a lot of people go for references. Hilda Bastian kicked off the comments there (her comment was picked out by Retraction Watch). Her conclusion was this.
"It’s good to see claims about dietary supplements tested. However, the results here rely on a chain of yet-to-be-validated assumptions that are still weakly supported at each point. In my opinion, the immodest title of this paper is not supported by its contents."
(Hilda Bastian runs the Statistically Funny blog -“The comedic possibilities of clinical epidemiology are known to be limitless”, and also a Scientific American blog about risk, Absolutely Maybe.)
NHS Choices spotted most of the problems too, in "A mug of cocoa is not a cure for memory problems". And so did Ian Musgrave of the University of Adelaide who wrote "Most Disappointing Headline Ever (No, Chocolate Will Not Improve Your Memory)",
Here are some of the many problems.
- The paper was not about cocoa. Drinks containing 900 mg cocoa flavanols (as much as in about 25 chocolate bars) and 138 mg of (−)-epicatechin were compared with much lower amounts of these compounds
- The abstract, all that most people could read, said that subjects were given "high or low cocoa–containing diet for 3 months". Bit it wasn’t a test of cocoa: it was a test of a dietary "supplement".
- The sample was small (37ppeople altogether, split between four groups), and therefore under-powered for detection of the small effect that was expected (and observed)
- The authors declared the result to be "significant" but you had to hunt through the paper to discover that this meant P = 0.04 (hint -it’s 6 lines above Table 1). That means that there is around a 50% chance that it’s a false discovery.
- The test was short -only three months
- The test didn’t measure memory anyway. It measured reaction speed, They did test memory retention too, and there was no detectable improvement. This was not mentioned in the abstract, Neither was the fact that exercise had no detectable effect.
- The study was funded by the Mars bar company. They, like many others, are clearly looking for a niche in the huge "supplement" market,
The claims by the senior author, in a Columbia promotional video that the drink produced "an improvement in memory" and "an improvement in memory performance by two or three decades" seem to have a very thin basis indeed. As has the statement that "we don’t need a pharmaceutical agent" to ameliorate a natural process (aging). High doses of supplements are pharmaceutical agents.
To be fair, the senior author did say, in the Columbia press release, that "the findings need to be replicated in a larger study—which he and his team plan to do". But there is no hint of this in the paper itself, or in the title of the press release "Dietary Flavanols Reverse Age-Related Memory Decline". The time for all the publicity is surely after a well-powered study, not before it.
The high altmetrics score for this paper is yet another blow to the reputation of altmetrics.
One may well ask why Nature Neuroscience and the Columbia press office allowed such extravagant claims to be made on such a flimsy basis.
What’s going wrong?
These two papers have much in common. Elaborate imaging studies are accompanied by poor functional tests. All the hype focusses on the latter. These led me to the speculation ( In Pubmed Commons) that what actually happens is as follows.
- Authors do big imaging (fMRI) study.
- Glamour journal says coloured blobs are no longer enough and refuses to publish without functional information.
- Authors tag on a small human study.
- Paper gets published.
- Hyped up press releases issued that refer mostly to the add on.
- Journal and authors are happy.
- But science is not advanced.
It’s no wonder that Dorothy Bishop wrote "High-impact journals: where newsworthiness trumps methodology".
It’s time we forgot glamour journals. Publish open access on the web with open comments. Post-publication peer review is working
But boycott commercial publishers who charge large amounts for open access. It shouldn’t cost more than about £200, and more and more are essentially free (my latest will appear shortly in Royal Society Open Science).
Hilda Bastian has an excellent post about the dangers of reading only the abstract "Science in the Abstract: Don’t Judge a Study by its Cover"
4 November 2014
I was upbraided on Twitter by Euan Adie, founder of Almetric.com, because I didn’t click through the altmetric symbol to look at the citations "shouldn’t have to tell you to look at the underlying data David" and "you could have saved a lot of Google time". But when I did do that, all I found was a list of media reports and blogs -pretty much the same as Nature Neuroscience provides itself.
More interesting, I found that my blog wasn’t listed and neither was PubMed Commons. When I asked why, I was told "needs to regularly cite primary research. PubMed, PMC or repository links”. But this paper is behind a paywall. So I provide (possibly illegally) a copy of it, so anyone can verify my comments. The result is that altmetric’s dumb algorithms ignore it. In order to get counted you have to provide links that lead nowhere.
So here’s a link to the abstract (only) in Pubmed for the Science paper http://www.ncbi.nlm.nih.gov/pubmed/25170153 and here’s the link for the Nature Neuroscience paper http://www.ncbi.nlm.nih.gov/pubmed/25344629
It seems that altmetrics doesn’t even do the job that it claims to do very efficiently.
It worked. By later in the day, this blog was listed in both Nature‘s metrics section and by altmetrics. com. But comments on Pubmed Commons were still missing, That’s bad because it’s an excellent place for post-publications peer review.