It is clear that there are differences between people in their cognitive reserve. In the face of disruption caused by ageing or disease, some people’s brains cope better than others. Why?

Research suggests that our level of intelligence, which traces back to childhood, and our set of lifetime experiences, help build cognitive reserve and may account for differences in cognitive reserve between us.

The lifetime experiences include education, having an engaging occupation and taking part in stimulating activities, the latter ideally combining leisure activities, learning and social interactions.

The evidence that lifetime experiences help build cognitive reserve comes from studies of large groups of people over long periods of time. Such studies have repeatedly found that these life experiences are associated with a slower rate of cognitive decline in normal ageing and reduced risk of developing Alzheimer’s disease. In other words, higher attainment and engagement appear to protect cognitive function in ageing.

Indeed, some studies have suggested that these life experiences may reduce the risk of Alzheimer’s disease by 35-40%. The changes in the brain that are seen in the disease may still occur, but these people cope better and won’t ever be diagnosed because they don’t present any symptoms.

The cognitive reserve explanation for these findings is that these life experiences help people maintain their cognitive function better in the face of age- or disease-related changes to the brain. Studies that have followed people since childhood have shown that different life experiences contribute to cognitive reserve differentially and in an additive manner.

A complementary idea is 'brain maintenance', which suggests that some of the same activities, as well as others such as exercise, actually help maintain the integrity of the brain itself in the face of ageing.