The War Against Fat
Prior studies have shown increased risk for Alzheimer's and cognitive decline in individuals whose diets were high in saturated and trans fats. The idea for this current study came about from an accidental finding: rabbits on a high cholesterol diet who were fed water with trace amounts of copper had a faster decline in memory function than those drinking regular water. At autopsy, the rabbits on copper water had a substantial accumulation of amyloid beta plaques in their brains - plaques that are found in the brains of Alzheimer's patients.
This study look at this association in humans. More than 3000 people, 65 years and older, were included in the study. All study participants had cognitive testing and completed a food questionnaire that included questions about copper, zinc, and iron intake. Cognitive function was reassessed at three and six year follow-up interviews.
The results showed that in general, average cognitive abilities declined somewhat with age. However, within the "high bad fat" group, the 16% of people with the highest intake of saturated and trans fats, cognitive function declined faster in those with a higher copper intake - with up to a 143% increase in the rate of decline. But copper alone is not the problem - individuals with a high copper intake and a low consumption of saturated and trans fats did not show an increased rate of cognitive decline.
This type of study has inherent limitations due to the study type and design. Most importantly, it can only suggest an association between two things. But it does raise interesting hypotheses about possible environmental causes of Alzheimer's that may be further investigated with randomized, controlled trials.
Update on "Don't Eat This Book" - Apparently during Super Size Me, Morgan Spurlock did an experiment to see how long McDonald's food would last before rotting. He took the Big Mac, Fillet O'Fish, a McD chicken burger, McD fries, regular burger and regular fries, placed each food item into a glass jar, and watched them decompose with time. The experiment was ended at 10 weeks because of the overwhelming stench of rotting burgers (and regular fries), but the McD french fries NEVER developed any mold or decomposed. They looked a little dehydrated, like cold leftover McD fries bought the day before. Disgusting!