Mental activity and the brain

Introduction

As we get older, our ability to receive, process and remember information tends to decline. This is a normal part of ageing. We may regularly have trouble retrieving information like people’s names or telephone numbers, for example. However, those of us with normal age-related memory lapses will eventually recall the information we had problems remembering, whereas those with dementia are unlikely to.

Having an ageing brain is not necessarily a bad thing. With age comes experience and knowledge that allow us to consider and reflect on situations and adapt to circumstances in ways we could not have done at a younger age.

Some studies(63)(64) have found that cognitive training through various brain exercises can improve older people’s ability to reason and to process data, at least in the short term. But can mental stimulation have a preventative effect? Is it a case of ‘use it or lose it’ for the brain as well as the body?

What’s the evidence about mental activity and dementia?

Cognitive reserve
It has been suggested that more intelligent, better educated people possibly have more brain cells and connections between brain cells in reserve - so that even if some are destroyed there are more left to work with. This is generally described as ‘cognitive reserve’.

Cognitive reserve has also been suggested as the reason why some people don’t show any signs of dementia while others with the same amount of brain damage do(65). When some people’s brains have been examined after death, they have shown significant amounts of plaques and tangles which would suggest that they must have had Alzheimer’s disease, yet they apparently showed no symptoms. To explain this, researchers have suggested that the brains of such people must be able to compensate for the damage in some way.

Some research has suggested that people with larger brains are less likely to develop dementia (66) but others say that it’s how they use their brains that matters, and so a lot of research has concentrated on brain imaging to examine brain activity. If imaging can show how the brain is working when it compensates for any damage, it might give some clues as to how the disease could be slowed down or treated, perhaps through some form of cognitive training.

A recent review of 22 studies of cognitive reserve found that greater brain reserve was associated with a decreased risk of dementia(63). People who took part in complex mental activity in their work or education or through stimulating leisure activities throughout their lives had an almost 50% reduced risk of developing dementia. The review also suggested that the more intellectual activity that people had, the lower their risk of developing dementia; and that it was never too late to build cognitive reserve.

The concept of cognitive reserve is controversial though. Some may say that it is just common sense. Is it just the case that people who peak higher have further to drop? (68) If you have a bigger brain, or more brain cells and more connections between cells, is it not obvious that any damage your brain receives will have less impact?

However, even if cognitive reserve helps to compensate, it still doesn’t mean that an individual will not develop dementia.

Education and intelligence
A number of studies have suggested that people with fewer years of formal education have a higher incidence of dementia or at least cognitive decline. This may be because better-educated people are somehow able to compensate for any problems due to cognitive decline (see previous section) or they may be more experienced in doing the kinds of tests used to measure dementia and so can cover up any difficulties they have.

A long-term study in the United States, commonly known as the Religious Orders Study or ROS, has followed more than 1,000 priests, nuns and brothers since 1993, studying various aspects of cognitive decline and Alzheimer’s disease. This is a useful group to study, because many of them have shared very similar lifestyles, for example nuns living together in a convent, and because information is available about the participants going back over many years.

One feature of the ROS study programme is that they have been able to study the brain tissue of participants after they have died. They found that the more years of formal education a person has had, the better it seems to be for his or her memory (69). Comparing post-mortem brain tissue of participants with the results of earlier brain function tests, the researchers found that in some brains where there were the plaques associated with Alzheimer’s disease, there seemed to be little impact on brain function. They also found that people with more years of education retained a higher level of brain function even where there was considerable damage to the brain.

However, it is not all good news for the better educated. A recent study suggested that people with Alzheimer’s disease who had higher levels of education got worse more quickly(70). It may be that more highly educated people seem to show a faster decline because their brains have already suffered more damage by the time symptoms become noticeable. At that stage, the disease may have progressed so much that when the cognitive reserve runs out, the visible decline is dramatic.

Mentally stimulating activities
One American study asked subjects to look back on their 20s, 30s, 40s, and 50s and report on which leisure activities they had taken part in and for how long each month. People who had done more intellectual activities in their 20s and 30s were at a lower risk for Alzheimer's disease. Intellectual activities included things like reading, doing jigsaws and other puzzles, playing a musical instrument, writing letters, playing board games, doing crafts or home repairs. Those who had increased their intellectual activities after their 30s also reduced their risk of Alzheimer's disease(71).

Another widely-reported study of leisure activities and dementia(72) led to media headlines like ‘Dancing wards off dementia ’ (70) and ‘Leisure activities protect against dementia’(73). 469 people aged over 75, all without dementia at the start of the study, were asked about how often they took part in certain activities involving mental stimulation – reading, writing, crosswords, playing board games, playing a musical instrument and taking part in group discussions. They were also asked about their participation in physical activities which included dancing, housework, babysitting, and various sports. Participants were followed for an average of 5.1 years.

The level of risk reduction found was linked to how often the people took part in an activity. For example, those who did crossword puzzles four days a week had a 47% lower risk than those who did crosswords once a week. In all, those who did the most mentally stimulating activities per week had a 63% lower risk of developing dementia. Contrary to other research into the role of physical activity in dementia (see Chapter 5), this study found that the only physical activity that seemed to be beneficial was ballroom dancing, possibly because it involves both physical activity and the mental effort of remembering the dance steps and doing them with a partner, in time to the music.

Despite their findings, the researchers were reluctant to suggest a direct link between taking part in these leisure activities and risk of dementia. It may be that people in the early, undiagnosed stages of dementia cut down on mentally stimulating activities; or perhaps people who do intellectually stimulating activities also do other things that are good for their brain like exercise and eating healthily. More research is needed.

One piece of research coming from the Religious Orders Study mentioned above supports the findings about mental stimulation and reduction of dementia risk. Brain stimulating activities like listening to the radio, reading, doing crosswords and visiting museums were found to protect against cognitive decline and Alzheimer’s disease (70). Each activity was rated depending on how often each person did it in a week, from 5 points for every day down to 1 point for once a year or less. The scores for each activity were then averaged to give a composite measure. Each one-point increase was associated with a 47% lower risk of cognitive decline and a 33% reduced risk of Alzheimer’s disease, again suggesting that the more you take part in mentally stimulating activities, the better.

There are a number of theories about possible reasons for these results:

• doing mentally stimulating activities may protect the brain, possibly giving the individual a ‘cognitive reserve’ to draw upon
• maybe doing these things helps the brain to adapt more in some areas to make up for areas in the brain where there is damage
• it may be that people who don’t do these sorts of activities are already showing the very early signs of dementia
• maybe people who do mentally stimulating things also do other things that reduce their risk, such as eating healthily or being physically active.

The only way to test any of these theories would be to conduct long-term randomised controlled trials – not very likely due to the complexity and expense involved.

The future?

Early in 2006, there were reports of a new computer craze supposedly taking Japan by storm. A package produce by Nintendo called Brain Training for Adults is aimed at the over 45 market. The exercises in the package are said to ‘improve mental agility and even slow the onset of dementia and Alzheimer’s disease’. Whether these ‘mental workouts’ help or whether it is just playing on the fears of people worried about developing dementia has still to be determined in clinical trials.

So-called ‘smart drugs’ or nootropics are also receiving a lot of press interest because they claim to boost cognitive abilities. A number of nootropics already exist as cognitive enhancers licensed for other purposes such as treatment of narcolepsy (where people suddenly fall asleep) or attention deficit disorder. Some people are taking these drugs, not for the purpose for which they are intended, but to keep them awake and alert. Other nootropics are natural substances rather than manufactured drugs – Gingko biloba is probably the best known of these – see Chapter 8 for evidence about Gingko.

How to keep mentally active

Think of your brain as if it was a muscle – ‘use it or lose it’ could apply to your brain as well as your body. Although its protective effect hasn’t been proven, mental activity is enjoyable, no-one has ever suggested that there is any harm in it, and the evidence there is so far does suggest that it may be helpful in reducing the risk of dementia.

We don’t know for sure but it is possible that mental activities stimulate more brain cell connections. That might mean that if brain cells are damaged, the brain can keep working well for much longer, and the person may not show symptoms of dementia.

It doesn’t really matter what you do as long as it engages you and stimulates your brain. Try new things to keep your brain active. Carry on doing things you already enjoy that stimulate your brain.

• Read magazines, newspapers and books. Joining a book group will add social contact to what is normally a solitary activity
• Play cards or board games
• Play bingo
• Do crosswords and other puzzles like Sudoku
• Try a day or evening class – learn to use a computer, take photographs
• Attend lectures and talks
• Learn a musical instrument or a language
• Develop new skills at work

Some of these activities can be done on your own, but others can involve social interaction with other people - which may give additional protection against dementia (see Chapter 7).

Although more research is needed to determine if mental activity helps prevent or delay dementia, there's no harm in keeping yourself busy and active. It might just help your brain.

Next section: Social activity and the brain
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