Physical activity and the brain

Introduction

The expression ‘use it or lose it’ is most often associated with the view that being physically active helps the body remain healthy and mobile by keeping joints and muscles in good condition and keeping the heart and blood circulation system in good order.

But physical activity is not just good for your body – it’s also good for your brain. It is still not clear exactly why this is the case but it’s likely to be something to do with improving the blood flow to the brain, which may in turn help the brain carry out its function.

Getting your heart pumping and your circulation going increases blood flow, which carries nutrients and oxygen to the brain. It also helps reduce the risk of heart attack, stroke and diabetes, which are all risk factors for dementia.

We have deliberately called this chapter Physical activity and the brain rather than Exercise and the brain because ‘exercise’ often conjures up off-putting images of people in lycra sweating it out at the gym or pounding the pavements in all weathers. But this chapter aims to show that it is not necessary to take up those kinds of physical activity (unless you want to of course) to benefit your health and, particularly, your brain.

Many people also say they ‘don’t have time for that sort of thing’ but it is possible to build regular activities into the normal working day which will lead to a more active, and healthier, lifestyle.

What is physical activity?

Generally speaking, physical activity is any everyday activity, but done in an active way. So walking the children to school, gardening, using the stairs, cleaning the windows, dancing, and more traditional forms of exercise like swimming, cycling or jogging, all count.

The recommended minimum level of physical activity for adults is at least 30 minutes of moderate activity, most days. Moderate activity is something like brisk walking or strenuous gardening – enough to make you warmer, make your heart beat faster and make you breathe more deeply. At the moment, six out of 10 Scots don’t do this much physical activity, putting their health at risk.

What’s the evidence about physical activity and dementia?

It is unlikely that there will ever be a long-term randomised controlled trial of the benefits of physical activity on brain health because it would be too expensive and complicated to recruit the thousands of people needed to give meaningful results, and impractical and unethical, given what is known already, to instruct some of them not to be physically active. Following up a large group over the years in a longitudinal trial would also be difficult and costly; but other kinds of research has been carried out.

While a lot of early research was done on animals like rats and mice, we now have a body of evidence from human studies. Some of these have looked at a single type of physical activity like walking while others have examined the effect of a range of everyday activities and types of exercise(55)(56).

What has the research found?

One American study(57) of more than 2,200 older men aged between 71 and 93 found that those who walked less than a quarter of a mile a day had almost twice the risk of dementia of those who walked more than two miles a day. This observation was part of a longitudinal study called the Honolulu-Asia Aging Study. The men’s walking activity was assessed for two years, and they had a neurological assessment on two occasions over the next six years to determine who had developed dementia.

Another study(58) of 3,375 men and women over 65 found that those who took part in four or more different kinds of physical activity had about half the risk of developing dementia of those who did just one or none of these activities. Activities included walking, housework, gardening, golfing and swimming.

The Nurses’ Health Study is one of several large epidemiological studies which are looking at participants’ past behaviours to relate these to their health now. This study signed up nearly 122,000 American nurses who were aged between 30 and 55 in 1976. This large group has been used as the basis of a number of smaller studies. In one of these, more than 18,000 women aged between 70 and 81 who reported taking part in moderate exercise, including walking, for 30 minutes five times a week scored better on cognitive tests than those who exercised less (59).

One recent study has received a lot of press coverage in Britain. In this study (60), 1740 people were asked about their activity levels at the beginning of the study then followed up for six years. Participants were asked to record the number of times a week when they spent at least 15 minutes on any exercise, including walking, hiking, cycling, weight training and swimming. Those who exercised for 15 minutes at least three times a week were found to have a 32% reduction in risk for dementia of any kind. The authors of this study go on to suggest that, even if exercise does not prevent dementia, it may be associated with a delay in onset of the disease, giving older people more dementia-free years. The researchers also found that those assessed at the start of the study as being the least physically able had an even greater reduction in risk through exercise than those with higher levels of physical function.

Another Swedish study(61) caused a number of dramatic headlines in the press – Regular exercise in younger years ‘reduces Alzheimer’s risk by 60%’ was the headline in the Scotsman on 5 October 2005. In this study, 1449 people aged 65 to 79 were asked questions about their levels of physical activity and other aspects of their lifestyles during the 1970s and 1980s when they were in their 40s and 50s. Those people who exercised for 20-30 minutes twice a week were between 50 and 60% less likely to develop dementia than those who were less active at that age. The level of exercise had to be vigorous enough to cause the person to perspire and breathe hard. Walking and cycling were the most common forms of exercise in the study.

While most studies seem to support the view that physical activity is good for the brain as well as the body, some have found no association. One American study(62) which looked at a range of mental and physical leisure activities and the risk of dementia found that dancing was the only physical activity associated with a reduced risk of dementia. Dancing may have been beneficial because of the mental activity required to remember the steps.

Does physical activity reduce the risk of dementia?

While the evidence is encouraging, it is not conclusive. Although physical activity does not prevent dementia, there is starting to be evidence that points towards it reducing the risk.

It should be borne in mind that there are other possible reasons for the findings of the research studies. For example, it could be that people with early, as yet undiagnosed, dementia start to become less active. It could also be that people who exercise have healthier lifestyles generally; however the Swedish study described above took other factors like diet or smoking behaviour into account in determining that exercise was what seemed to make the difference.

There is also a problem with asking people to report on what they did often many years ago. People may not be able to remember accurately, or there may be a tendency to exaggerate the ‘good’ behaviours and play down the ‘bad’. But a well-constructed study should take these factors into account.

The available research suggests that physical activity may help to protect against dementia. It certainly does not appear to do any harm or make matters worse. It need not be expensive and can be easily introduced into everyone’s daily routine.
Even if physical activity cannot actually prevent dementia, it may play a part in delaying the onset of the disease. The research also indicates that modest levels of activity may make a difference even in the more physically frail, suggesting that any physical activity is better than none at all.

How to get started

Any increase in physical activity is beneficial. The important thing is to do something active that you enjoy – that way, you are more likely to stick to it and make it part of your routine. You don’t need to run marathons - unless you want to!

If you are unsure about what to do, talk to your doctor about how much and what type of exercise would be suitable, especially if you have any kind of medical condition. The recommended level of physical activity is to build up at least 30 minutes a day, most days, of moderate to vigorous activity, such as brisk walking – enough to make you warmer and make your heart beat faster.

Aim to build up gradually if you’re not used to exercise. You can break the 30 minutes into smaller amounts such as 10 minutes, 3 times a day or 15 minutes twice a day, until you build up to a full 30 minutes – for example, a brisk 10 minute walk to work and another one home again, along with 10 minutes of vigorous vacuuming, could get you to the target. If you’re not currently very active, start by aiming to increase your physical activity by a few minutes a day.

Remember to listen to your body – if you feel dizzy or sick or develop pain, slow down or stop. Talk to your doctor.

Try building active travel into your day – take a walk at lunchtime; get off the bus a stop or two earlier; try cycling to work or walking to the shops for a paper instead of jumping in the car; take a walk at lunchtime; climb the stairs instead of using the lift.

If you’d rather not walk alone, you could join a walking group. Not only will you be more active, you’ll meet new people. See www.pathstohealth.org.uk for health walking groups near you.

As well as walking or cycling, you might want to take up a new activity such as dancing, swimming or bowls, or join a gym. Your local council or local library should be able to tell you about groups and classes in your area.

Try teaming up with a friend, relative or workmate to encourage you both to get started and keep going.

Switch off the TV and go for a walk or do some gardening; have a dance while you are doing the dusting or vacuuming.

For more advice and an information pack on physical activity, see www.healthyliving.gov.uk or phone 0845 2 78 88 78.

Next section: Mental activity and the brain
References
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Useful links:

Information about dementia
Healthy living with dementia
Paths to Health
Healthy Living