Benton D (2010) Nutr Rev. 68 Suppl 1: S6-10.
Rather than being an inevitable consequence of age, cognitive decline can occur with marked variation among individuals. In this context, nutrition is one factor that is believed to be influential. When considering the potential role of diet, two factors need to be considered.
First, cognitive or brain reserve is said to decrease the incidence of dementia; that is, it has been suggested that those with larger brains and better intellectual functioning have a greater capacity to resist the effects of the biological changes that define dementia. As such, the adequacy of nutrition before birth and in the early formative years may have long-term consequences.
Second, shrinkage of the brain begins in young adulthood, suggesting that any insidious influence of diet will take place from that time onward over a period of many decades. The marked decline in the weight of the brain associated with advanced dementia suggests it will be easier to slow that decline than to repair the brain.
If this model is accurate, diet is influential throughout the entire lifespan, and this has substantial methodological implications for the study of the topic.