I'm hesitant to take this at face value. I found a few snippets in the comments that I thought worth noting:
"There's no history here, and no clear indication of cause and effect. Maybe the small brains led to the obesity in some manner (habitual differences). Maybe both the brain size and obesity are symptoms of a separate underlying cause.
Unless we have brain scans from these same individuals from 30 years ago, how can we know how badly their brains degenerated? Hell, how can we even know these people didn't recently become obese, or that some of the "normal-weight" individuals weren't formerlly obese, and simply lost a lot of weight as they aged?"
"I am not a doctor, but even a three year old can connect the dots. With that said, research has shown that the avarage American's weight has increased by forty-two punds since the introduction of High Fructose Corn Syrup in sodas and foods in the early eightys. I just connected the first two dots.
Many studies have also shown that as many as seven out of ten foods or sodas with H.F.C.S. sampled had mercury present. The mercury contamination is believe to be cause do to out dated equipment used in the processing of corn into H.F.C.S. Research has also proven mercury causes brain neuron degeneration. Wow, just connected two more dots! So, let's review, you consume H.F.C.S., you will become obese, and as the toxic effect of mercury start to take effect, brain degneration will begin. Next time you enjoy that Coca-Cola, remember that Mercury is the second most toxic metal known to man; second only to plutonium! Enjoy!"
" The used definition for obesity is faulty, because it ignores the three body types medical science recognizes - it is more an index for body type;
mesomorph people will have a greater muscle mass and thereby more neural mass.
Tall people will be more ectomorph and therefor have a greater muscle mass and thereby more neural mass. The last category of body type, the endomorph will therefore have less neural mass, and so will women (who have more body fat and are shorter, on average). This does not indicate neural loss at all."
I'm no expert, but I was a little suspicious as well. Grain of salt. Still, it's interesting and worth noting... any legitimate data is good data. When I die, perhaps they should dissect my brain - terrible diet rife with HFCS, low body weight. Pity I won't be around to see the results.
On an irrelevant but cool note, a few pearls of wisdom. Ignore some of the feminist stuff at the front, it gets better.