OLD(ER), FAT AND HAPPY – BUT NOT DUMB

This is part one of two blogs regarding two recent studies, both of which are being touted in the media as proof that fat people are dumber than not-fat people.

The first study has to do with cognitive decline in old(er) people, and whether being fat speeds up that process.

http://www.neurology.org/content/79/8/755.abstract

And the headlines are screaming that fat makes you dumber

http://www.onmedica.com/NewsArticle.aspx?id=c41a06dd-8d4d-46b7-b1c3-bc4b91a217e7

http://now.msn.com/being-obese-leads-to-lower-cognitive-function-and-skills-according-to-a-new-study

The results of the study actually says:

Among the obese, the global cognitive score at baseline (p = 0.82) and decline (p = 0.19) over 10 years was similar in the metabolically normal and abnormal groups. In the metabolically normal group, the 10-year decline in the global cognitive score was similar (p for trend = 0.36) in the normal weight (−0.40; 95% confidence interval [CI] −0.42 to −0.38), overweight (−0.42; 95% CI −0.45 to −0.39), and obese (−0.42; 95% CI −0.50 to −0.34) groups. However, in the metabolically abnormal group, the decline on the global score was faster among obese (−0.49; 95% CI −0.55 to −0.42) than among normal weight individuals (−0.42; 95% CI −0.50 to −0.34), (p = 0.03).

Say what?  I really had to stop and wrap my brain around this.  This seems to be what the results actually say (based on the foregoing):

Obese participants’ decline stayed  about the same whether or not they were metabolically normal or abnormal.

The decline for metabolically normal participants (fat and non-fat) decline was similar.

The obese and metabolically abnormal participants had a faster decline than average sized participants; but looking at the numbers (-0.49 for obese versus -0.42 for average weight), it doesn’t look like there is all that much difference.

Also, this study  is over 10 years; starting with the youngest participants at 39 and the oldest 63 and we don’t know how the age group versus metabolic status was spread – were most of the younger people metabolically normal and most of the older participants metabolically abnormal?  Nor do we know what other medical issues may be arising (particularly for the older participants who were going from age 63 to 73 during the study).

Serious medical issues could skew the results significantly as well, since hospitalization substantially speeds up cognitive decline, even after controlling for illness severity and pre-hospital cognitive decline.

http://www.neurology.org/content/early/2012/03/21/WNL.0b013e31824d5894.abstract

Based on a 10-year study in England, cognitive decline is estimated to begin at age 45 with older people having greater and faster cognitive decline.  Also almost 2/3 of the participants were men and older men have faster cognitive decline than women.

http://www.bmj.com/content/344/bmj.d7622

So depending on how the deck was “stacked” (and I use that phrase advisedly), it would be pretty easy to come up with the results – and those “results” don’t stack up to a whole lot of difference between fat and non-fat people.

 

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5 thoughts on “OLD(ER), FAT AND HAPPY – BUT NOT DUMB

  1. Nice try to obfuscate the science. The study was a gold standard longitudinal study that controlled for a wide range of variables, and which was then data matched with another longitudinal study. The results were clear – the obese who were metabolically compromised had a faster cognitive decline than all others.

    The salient point is that they were metabolically abnormal. The take away shouldn’t be that fat people are being discriminated against, but that fat people should adopt HAES and avoid being metabolically compromised.

    • I wasn’t trying to obfuscate anything. I was trying to make sense of the research from an abstract (the wording of which I found unclear); and I was offering some thoughts on what I thought were valid issues that may or may not have been taken into consideration (such as non-metabolic medical issues, hospitalization, and gender differences).

      Also, I still think the increase in the rate of decline for metabolically abnormal obese participants was quite small – certainly not enough to warrant the alarmist claims being made in articles based on this study.

      And while I support the HAES(R) approach and I believe it may improve metabolic outcomes for come people, I do not believe it is a guaranty of metabolic normality.

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