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Building and maintaining your cognitive reserve


Building and maintaining your cognitive reserve

KAILAS ROBERTS looks at how a lifetime spent ‘using our brains’ can help protect against dementia.

When it comes to the brain at least, size does matter – but not as much as you think.

Although a contentious issue, there is some evidence linking bigger heads with protection against dementia.

Men might feel they can brag about this, as they do on average have brains roughly 10 per cent larger than women.

It is also the case that rates of dementia related to Alzheimer’s disease are lower in men than in women, but I suspect this is about a number of things other than the volume of their brains.

This notion of ‘brain reserve’ – referring to your neural real estate – is only one type of reserve, however, and in many ways not that interesting as it is not really amenable to change.

What is more engaging is the idea of ‘cognitive reserve’. This does not relate to the size of the brain but to its efficiency and connectivity. Software rather than hardware, perhaps.

Another analogy is that of a city. Cognitive reserve here may refer to the network of roads within.

Now let’s say you need to get a message from one side of town to the other. The more roads you have, the more chance you have of being able to transport the message effectively, even if some of the roads are blocked.

In a similar way, having plenty of networks of neurons in the brain allows you to transmit a message from A to B, even if some of these networks are damaged. So, cognitive reserve refers to the ability of the brain to function despite the damage that occurs to it.

Damage to the brain can be the consequence of all sorts of things, including the proteins whose accrual is associated with Alzheimer’s disease (amyloid and tau).

So, in theory, greater cognitive  reserve should be associated with less-severe symptoms. And this does appear to be the case.

There is a famous study known as the nun study in which, you guessed it, nuns were given memory tests throughout their lives and then their brains were examined after they passed away.

What the researchers found was that many of the nuns had substantial amounts of amyloid in their brain, even when they had normal memory during their lives.

One of the influencing factors as to whether they developed cognitive decline during their lives, regardless of how much amyloid they had, was their level of education.

There is a certain difficulty in defining cognitive reserve, as it is a bit nebulous: how do we measure it exactly?

Well, we tend to use proxy measures: that is, ones that are indirect measures, but which seem logically to be connected.

It makes sense that the more you use your brain, the higher the reserve might be. And so, measures include the educational level studied in the nuns, but also how cognitively stimulating one’s job is or was, and how much time we spend in cognitively engaging tasks such as learning new skills and participating in leisure activities.

Another important proxy is social contact. This might not seem intuitive but socialising is a great workout for  the brain and likely to enhance  cognitive reserve.

A recent study involving more than 200,000 people looked at the some of these cognitive reserve variables and found that those who had better measures of them were indeed protected against dementia.

This is empowering, as we can incorporate many of these things into  our lives.

The other variable was time spent watching TV. This was found to be inversely related to dementia risk: the more you watch, the greater the risk.

So, there’s an easy option here to protect your brain, I suppose. Switch off the gogglebox!

Kailas Roberts is a psychogeriatrician and author of Mind Your  Brain: The Essential Australian Guide to Dementia, now available  at all good bookstores  and online. Visit  or

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