EXERCISE AND THE PREVENTION OF DEMENTIA

Dementia, a modern pandemic

Dementia is an advancing modern scourge and has recently been reported to have overtaken coronary heart disease (CHD) as the most frequent cause of death for women in the UK. For men it is still in second place after CHD. The two most common forms of dementia are Alzheimer’s disease (AD) and vascular dementia (VD).

How big a problem is it?

There are about 47 million people in the world living with dementia and this number is projected to rise to about 130 million by 2050. The figures for the UK are 850,000 rising to 2 million by 2050. This represents one in every 79 (1.3%) of the entire UK population and 1 in every 14 (7%) of the population aged 65 years and over.

For any particular age group, dementia is getting less common, perhaps the result of the steady decline of vascular disease with less smoking and better treatment of raised blood pressure and lipid levels. However this effect is overwhelmed by the steady increase in the age of the population, so demented people are becoming more numerous, though not as numerous as might be expected.

And its impact?

The devastation caused by this epidemic is hard to overstate – the ill effects are seen in every aspect of our lives. Most families will sooner or later have to face the emotional, financial and social problems brought by a relative with dementia. The cost to the health service and to the social services of this rising tide of dependence is astronomical. The Alzheimer’s Society has estimated that the cost to the nation is £24 billion annually, that by 2025 this will rise to £32.5 billion and by 2050 it could be costing the UK economy £59.4 billion at today’s prices. The economic impact of caring for each sufferer is currently some £ 28,500 per annum.

Exercise in the prevention of dementia

The evidence that dementia is delayed and reduced in severity by regular exercise is growing. Meta-analyses of all the prospective studies of the effects of midlife exercise have confirmed that it significantly reduces the risk of dementia and of milder forms of cognitive impairment in later life. For those who have a mild degree of cognitive impairment, regular exercise reduces the rate of progression to dementia.

As an example a recent study used the Swedish Twin Registry to identify 264 individuals with dementia who were compared with 2870 unimpaired controls matched for age and sex and a number of other features. All had been normal at baseline, average age 49, and were followed up for an average of 30 years.  Compared with those who did virtually no exercise, those who performed light exercise had less than half the risk of developing dementia while those who performed moderate exercise had one third the risk. Other studies have put the reduction of risk of dementia from regular exercise to a level of between a half and two thirds the risk found for inactive people.

Higher levels of physical fitness in mid-life are also associated with lower risk of dementia in later life – those in the upper fifth for fitness having two thirds the risk of dementia of those in the lowest fifth in a long-term study of nearly 20,000 middle aged Americans.  A number of studies have confirmed that having high level of physical fitness delays the onset of dementia by around a decade. For instance the Gothenburg study of fitness and dementia bicycle tested 200 women aged 38 to 60 and followed them up for 44 years. By this time only 5% of the fittest group had developed dementia compared 32% in the least fit group.

Underlying this benefit of regular exercise and high fitness level is the finding that the fitter you are, the greater the volume of grey matter in your brain.

Healthy living

To achieve the lowest possible risk of dementia an overall healthy lifestyle does seem to be the best option and the more aspects of healthy behaviour the better. The Caerphilly Cohort Study looked at five different behaviours – exercise, maintaining normal weight, eating a healthy diet, not smoking and avoiding excess alcohol – and examined the rate of dementia over the following decades. Adhering to all five of these behaviours was associated with just one third the risk of dementia. The biggest contributor to lowering the risk of dementia was regular exercise which, on its own, reduced risk by about 60%. However you will not be surprised to hear that less than 1% followed all five and only 5% followed four out of the five behaviours.

PS
Exercise is cheap!

A recent analysis of the cost of bringing new drugs to the market has found that, on average,  this amounts to $985 million per drug¹! When you consider that exercise has equivalent or superior effects to drugs in the management of many chronic conditions, it makes you wonder why the governments of the world don’t put more money into encouraging and facilitating physical activity for their populations. Just saying….

1. doi:10.1001/jama.2020.1166