The didn't tell us what kind of fat they used which is REALLY important. Its a scientific fact that omega 3 fats are GOOD for memory and mental performance. It sounds to me like this is a less than well conducted study which is trying to counter the good publicity fats are getting for mental performance.
Without disclosure of the type of fat fed to the rats I suspect they deliberately used transfats which is just one of those dirty little things they do. When they claim that the high fat diet may have a negative effect on insulin levels then thats DEFINITELY the result of transfats. It is know that transfats have a negative effect in this regard hence there undesirability in our diets. Natural fats, saturated included cause NO such problems. I did read the article to try and find out what kind of fat they fed to the rats but they left that bit out. Probably quite deliberately.
Anthony