In the study, young adult rats were divided into three dietary groups -- those fed high-fat foods derived from saturated fat (beef tallow) or polyunsaturated fat (soybean oil), and those on standard lab chow. Each of the rats underwent 21 days of training to learn a simple Go/No Go test. Basically they had to learn to alternate their response to a lever on a feeder. When it appeared the first time, they were to go and press it to be rewarded with a food pellet. When it appeared the next time, they were NOT to go and press it since they would not receive a pellet. The next time the lever appeared, they were to go and press it again to receive a food reward, and so forth. The interval delay between levers was 5, 10 and 20 seconds (to test short-term memory) and 40 and 80 seconds (to test long-term memory).
Those rats on the high-fat diet had difficulty learning the Go/No Go task and did poorly in the testing stage, especially when the interval delays were more than 20 seconds. The researchers then injected the high-fat rats with either a glucose or saline solution. Those who received the glucose showed a general improvement in performance that was greatest on the measures of long-term memory.
"While glucose administration clearly helps overcome those memory deficits associated with hippocampal function, this is not a long-term solution," cautions Dr. Winocur. "We should not fool ourselves into thinking that glucose from a glass of orange juice is all we need to protect our brains from clogging up from a high-fat diet."
Added Dr. Greenwood: "The one important message I hope people take away from this study is that modifying diet and lowering fat intake is good
Contact: Kelly Connelly