Remaining a bookworm into old age reduced the rate of memory decline by 32 percent

From Being a Lifelong Bookworm May Keep You Sharp in Old Age by Marina Koren

The findings, published online today in Neurology, suggest that reading books, writing and engaging in other similar brain-stimulating activities slows down cognitive decline in old age, independent of common age-related neurodegenerative diseases. In particular, people who participated in mentally stimulating activities over their lifetimes, both in young, middle and old age, had a slower rate of decline in memory and other mental capacities than those who did not.

[snip]

Using information from the questionnaire and autopsy results, the researchers found that any reading and writing is better than none at all. Remaining a bookworm into old age reduced the rate of memory decline by 32 percent compared to engaging in average mental activity. Those who didn’t read or write often later in life did even worse: their memory decline was 48 percent faster than people who spent an average amount of time on these activities.