Wednesday, June 11, 2014

DG VI: Doctor Susan

I knew that the Journal of Chess Research was coming. I’m indebted to EJH for the knowledge that one of things that Polgie’s magazine is intending to investigate is the issue of chess and Alzheimer’s Disease (Unlearned Journal).

Chess and dementia (Alzhiemer’s Disease is the most common form of dementia) is an important subject, but try to find out something about it and chances are you’ll end up misinformed. The internet being awash with just as much ignorance and nonsense on this particular topic as it is for everything else, anything which helps cut through the confusion is to be welcomed. It’s just a pity that Susan Polgar is herself one of the highest profile generators of that confusion.

Exhibit A of the Polgarian chess/dementia misinformation: the article that she reproduces on her website which has the headline, "Playing Chess Can Lower the Risk of Dementia by 74%" even though the claims turn out to be based on the Verghese research which actually concludes, " ... our findings do not establish a causal relation between participation in leisure activities and dementia ...."

Susan Polgar: once part of problem, and now - apparently - the solution. Well, if it gives us nothing else, the Journal of Chess Research has at least put to bed the claim that folks on the other side of the Atlantic don’t do irony.

Let’s return to the Verghese journal article 'Leisure Activities and the Risk of Dementia in the Elderly'. That’s the one that supposed to prove that playing chess prevents dementia but doesn’t actually mention chess. It’s time to have a close look at what the authors actually said that they’d discovered.

This prospective, 21-year study demonstrates a significant association between a higher level of participation in leisure activities at base line and a decreased risk of dementia.
(p. 2514)

That certainly sounds promising. Let’s dig a little deeper.

The 'leisure activities' were a mixture of 'cognitive' and 'physical':-

Cognitive Activities
  • "reading books or newspapers";
  • "writing for pleasure";
  • "doing crossword puzzles";
  • "playing board games or cards";
  • "participating in organised group discussions";
  • "playing musical instruments".

Physical Activities
  • "playing tennis or golf";
  • "swimming";
  • "bicycling";
  • "dancing";
  • "participating in group exercises";
  • "playing team games such as bowing";
  • "walking for exercise";
  • "climbing more than two flights of stairs";
  • "doing housework and baby sitting";

with Verghese and his co-authors concluding:-
Among cognitive activities, reading playing board games, and playing musical instruments were associated with a lower risk of dementia ... Dancing was the only physical activity associated with a lower risk of dementia.


Because of the observational nature of our study, there is a possibility of residual or unmeasured confounding.

Ultimately, then,

 ... our findings do not establish a causal relation between participation in leisure activities and dementia ... our findings do not imply that subjects who were less active cognitively increased their risk of dementia.
(p. 2515)

You may remember Joseph T. Coyle M.D. from the end of  DGII: de nous jours. We’ll return to his NEJM article 'Use it or Lose It - Do Effortful Mental Activities Protect against Dementia?' for a summary of Verghese’s findings.

The Leisure Activities article , he says,

... suggests that participation in cognitively demanding leisure activities in late life may provide protection against dementia.
New England Journal of Medicine 2003; 348: 2489-2490

The key words being suggests and may. That 'provides protection against’ dementia is preferred to 'prevents’ is also important**, as is the inclusion of in late life***. Of course, it goes without saying that the word "chess" does not appear.

"Bringing you updated, timely, fair and objective chess daily news from around the globe"

The story on the Polgar website is rather different. There you’ll find an article by Michael Gelb with the headline, "Playing chess can lower the risk of dementia by 74%"

... did you know that playing chess or other challenging mind sports can lower the risk of developing dementia by as much as 74 per cent, according to a study conducted by researchers at the Albert Einstein College of Medicine?
(emphasis from the original)

Gelb asks, before continuing with the claim that the research findings,

... demonstrate that continuing participation in a range of mentally stimulating activities serves to protect the health of the brain.

Apparently he is unaware that the Verghese and his colleagues explicitly stated that their study doesn’t "demonstrate" anything at all. Neither, for that matter, does he seem to know that the paper he is referencing doesn’t make any mention of chess (DG III: Dogs That Don’t Bark).


The conclusions of the Verghese research are not unclear. They do not require interpretation, nor do they depend on point of view. They are not difficult to understand.

The authors did not find that playing board games - let alone chess - prevents dementia and they explicitly stated that a causal relationship between activity and outcome had not been proved.

So, how did Gelb come to write his nonsense? How did Polgar come to reproduce it without even so much as a cursory check of the claims made? What does the fact that she did say about the credibility of the Journal of Chess Research.

I leave those questions for the reader. The appraisal of Verghese’s article in the New England Journal of Medicine I’ll do myself: nothing in it proves that participating in cognitively stimulating leisure activities prevents dementia. Any suggestion to the contrary is simply factually incorrect.

Chess and Dementia Index

* For this and all other references to Verghese:-

Verghese J, Lipton RB, Katz MJ, Hall CB, Derby CA, Kuslansky G, Ambrose AF, Sliwinski MS; Buschke H
Leisure Activities and the Risk of Dementia in the Elderly
New England Journal of Medicine 2003; 348: 2508-16

** 'Prevents dementia’ implies the certainty of immunisation. 'Protects against ...' is the preferable term because it suggests that while the intervention may help there are no guarantees.

*** I’ll return to the importance of this qualifier on a later date.


Andrew Gelman said...

You're such a party pooper! I bet you'll be going after the Journal of Dancing Research next. For example, there's this, from Stanford University:

Jonathan B said...

Bloody dancers. Where are the Taliban when you need them?