Sugar and the Mind


By Nancy Appleton, Ph.D.

Nancy Appleton, Ph.D.
Nancy Appleton, Ph.D.
Nancy Appleton Ph.D. started writing and lecturing about health in the late 1970s as a reaction to her own poor health. Her discoveries about sugar and other common diet mistakes led to her first book Lick the Sugar Habit, which is still chugging along as a 25-year bestseller. Six more books have followed. Her latest, available now online and in stores in August, is Suicide by Sugar. Dr. Appleton has also encapsulated her life's work into the movie Sweet Suicide. She is semi-retired and living in San Diego.

(Source: - Reprinted with permission from the authors)

Does sugar impair memory? According to rat studies conducted at Georgia State University, apparently so. Adult rats were given diets of either 0-percent or 60-percent fructose and ran through a water maze to test performance. The short version: the fructose impaired the rats’ ability to remember the location of the target platform.

First, all the rats were put into a maze sunk into a tank and set free to find a platform on which a lever or other device to get the rodents out of the water had been placed. Then, a few days later, the rats were put in the same maze only without the platform. The differences between the high fructose diet and the zero fructose diet were recorded.

“What we discovered is that the fructose diet doesn’t affect their ability to learn,” said Marise Parent, the head researcher. “But, they can’t seem to remember as well where the platform was when you take it away. They swam more randomly than rats fed a control diet.”[i]

The researchers didn’t find any effect on the first time trial and error learning process that enabled the rats to find the platform, just the ability to employ the abstract spatial memory that says, “the platform should be here based on yesterday’s results.” If a rat or person, for that matter, learns a task, but can’t prove they learned the task by reproducing it at some point in the future, is it really learning?

Other studies have indicated that sugar affects other aspects of the mind, which typically shows up in the classroom. The knowledge that bad diet and lower test scores have gone hand in hand has existed for some time.[ii] Some of the reasons why sugar consumption have an inverse relationship, sugar goes up and scores go down, may have to do with behavioral changes, which are also linked to sugar.

In our article 141 Reasons Why Sugar is Ruining Your Health, we have made statements that “sugar can cause hyperactivity, anxiety, inability to concentrate and crankiness in children.”[iii] We also said flat out that “sugar can cause juvenile delinquency in children.”[iv]

Apparently, a child will suffer a variety of mental effects in a high-sugar environment that will feed each on other. Decreased memory retention leads to lower scores leads to acting out behavior and so the chicken and egg cycle continues until someone changes the diet.

Our recommendation at this point is some form of a whole food diet to arrest the mental decline with sugar and the modern diet. Allergies play a part in this process. It’s quite simple: stop hurting your mind and you too will find your way through the maze.


[i] Ross, AP, et. al. “A High Fructose Diet Impairs Spatial Memory in Male Rats” Neurobiol Learn Mem. 2009 Jun 12. [Epub ahead of print]

[ii] Fu M.L., et al. “Associatation Between Unhealthful Eating Patterns and Unfavorable Overall School Performance in Children.” J Am Diet Assoc. 2007;107(11): 1935-1942.

[iii] Goldman, L et al. “Behavioral Effects of Sucrose on Preschool Children.” J Abnorm Child Psy. 1986; 14(4): 565-577.

[iv] Schauss, A. Diet, Crime and Delinquency. (Berkley, CA: Parker House, 1981).

Knowledge Search