I'm sure everyone has heard that activities like Sudoku and doing lots of math can help maintain your cognitive function as you age. This is because these activities require increased "cognitive load", they are hard to do and therefore take more cognitive effort. Doing this as you age (and preferably starting long before you age) is thought to do things like preserve memory and cognitive abilities.
Now, I don't know about you, but I HATE Sudoku. I just really don't find putting numbers in order to be particularly fun. But what I do love to do is READ. I just got a Kindle (I love physical books, it was a tough decision, but you really can't beat the portability!) and it's already well loaded. I read on the train, at the gym, at home, on planes, car trips, you name it. Every time I see those articles about Sudoku (which, honestly, are not always that well supported), I try to tell myself that yeah, I don't do a lot of math, but I do do a lot of READING and that surely has to do something! But I never really had much support for it.
But as it turns out, I might be right!
Wilson et al. "Life-span cognitive activity, neuropathologic burden, and cognitive aging" Neurology, 2013.
The authors of this study were interested in looking at the role of cognitive activity across the lifespan, as measured by things like reading, and how that might affect the cognitive abilities of the aged, and the physical problems that occur in the brain with aging, including things like the buildup of plaques and tangles.
To look at this, they hooked up with the Rush Memory and Aging project, a very large ongoing longitudinal aging study that examines various aspects of aging in a group of people over a period of years. They ended up with the a sample of 294 people who had died around age 89. In the years before their passing, the subjects had taken several quizzes, asking how much they read, went to the library, or wrote letters. They were also asked how much they did these activities from childhood on. Then, every year of the study they were in, they were tested for measures of memory and visuospatial ability.
After the participants had passed on, their brains were examined for various neuropathies associated with aging, infarcts (areas of dead tissue, often associated with things like micro-strokes), beta amyloid build up, tau related tangles, etc.
They then correlated the measures of cognitive activity, memory abilities, and the amount of neuropathy in the brain.
What you can see above are changes in global cognitive ability in the elderly as compared to both their early life cognitive activity (top), and the late life cognitive activity (bottom). You can see that low levels of activity (red line) meant fast loss of cognitive ability, while high activity (green line) provided some protection.
The authors then corrected for the presence of neuropathies in the brains, and showed that there is a correlation between high cognitive activity and protected cognitive ability regardless of the presence of brain neuropathy. But the cognitive activities did not REDUCE neuropathy, they just protected from cognitive decline.
The study suggests that reading and other cognitive activities really are good for you, and may help slow cognitive decline. It's a nice study, the longitudinal design is a good one, and they were careful to work with participants only when they had complete sets of data.
But of course there are potential confounds here. Activities included reading books, visiting a library, and writing letters. While all of these are good measures of cognitive activity, I'm wondering if maybe they missed stuff that might have helped their data. For example, yes, this is an aging population, but it IS 2012, and many of the people in the study (who were required to be 55 or older and had a mean death age of 89) would have been exposed to the internet or other forms of reading. Or example, reading books is fine, but what about the newspaper or magazines? Those might not be rated, but they still count as cognitive activity. What about reading things on the internet and sending emails? The number of people who might have done so could have been low (considering the age involved), but it probably wasn't zero, and that could definitely count toward cognitive activity. I'd also be interested to see if social interaction (which can range very widely as you age) might help memory and cognitive performance later in life. Social interaction also requires some cognitive load.
Another (larger) confound is that higher education was associated with more reading, writing, etc, both in late and early life. This isn't exactly surprising, but with higher education comes other possible confounds. People of higher education tend to be of high socio-economic class. They eat different things, they have different levels of physical activity. I'd be interested to see what happened if they normalized for education and socio-economic status.
And of course, ARE you ok with just being a happy bookworm? Will reading and going to the library alone save your brain? Probably not by much. There's some evidence that it's overall activity, including mental and physical (walking, etc), that really makes a difference as we age. What can we really conclude from this? So far, it appears that reading doesn't hurt, and the kind of lifestyles that include reading may indeed help. But is the key factor how many of the top 100 books you've gone through? That's probably too much to say.