Can sugar affect brain growth?

. . . especially in the absence of omega-3 fats

Do you sometimes wonder how "people can be so stupid?" We now have a clue as to why. Some unfortunate California rats were taught to negotiate a complicated maze. They were then deprived of omega-3 fatty acids in their diet and given water laced with high fructose corn syrup to duplicate two prominent features of the standard American diet. After six weeks on this regime, when placed back into the maze, they had become bumbling idiots, unable to recall what they had previously learned.

The UCLA researchers who devised this torture did it to prove a point -- that the standard American diet, which now includes 40 pounds a year of high fructose corn syrup (found in sodas and in almost all processed foods) -- causes brain dysfunction, and possibly permanent brain damage. Such a high-sugar diet produces "diabetes of the brain" -- too much insulin and consequent insulin resistance in the brain. This leads to "synaptic decline," or difficulties in brain cell-to-brain cell communication, and problems with learning and remembering.

A diet high in omega-3 fats, however, offered some protection against these effects. Another group of rats given the same sugar-water were also fed flax oil and DHA (omega-3 fats) and didn't have the same cognitive difficulties.

Source: Agrawal R. "Metabolic syndrome" in the brain: Deficiency in omega-3 fatty acid exacerbates dysfunctions in insulin receptor signaling and cognition. The Journal of Physiology. Published online before print April 2, 2012.