Though a clear error in characterization (you cannot engage in "high-intensity aerobics" - it is an oxymoron), the point remains well-taken. (What you can do is engage in aerobics at the high-end of moderate intensity.

A high-intensity, supervised aerobic exercise program improves cognitive performance in older adults with mild cognitive impairment (MCI), a new study suggests. The effects are most pronounced in women despite comparable gains in cardio respiratory fitness and body fat reduction in both sexes.

The results, published in the January issue of the Archives of Neurology, showed that a 6-month aerobic exercise program improved performance on multiple tests of executive function in women with MCI. The same exercise regimen also improved insulin sensitivity and reduced stress hormones in women but had much less effect in men.

"What we know is that generally with age or disease, we use glucose less efficiently and then we see cognitive problems," Laura Baker, PhD, University of Washington School of Medicine, Seattle, told Medscape Neurology. "So if we can increase the efficacy of glucose metabolism, we may be improving the efficacy with which glucose gets to the brain and therefore improve cognition. This happened for women but not for men."

As to the glucose metabolism part, the primary fuel of aerobic training is fat.

Their explanation is a bit suspect to me.

If you want to improve the use of carbohydrate as primary fuel, anaerobic training is the consideration.

A study of proper weight training and cognition vs. aerobic training and cognition would seem in order.