Summary

Patients with mild memory problems were assigned to either a physical activity program consisting mainly of extra walking, or to usual care. When they were tested on tasks such as word recall and word fluency, those in the exercise group showed an overall modest improvement.

Introduction

The aging of the population means that there will be in increase in the number of cases of Alzheimer's disease from the current 26.6 million worldwide to 106.2 million in 2050. If the onset of Alzheimer's could just be delayed by 12 months, then this increase would at least be less dramatic and the demands on health services eased. Therefore, there is much interest in both identifying those at risk of Alzheimer's disease and finding ways that might slow the onset and progress of the disease.

Some studies have suggested that medication can delay Alzheimer's. But lifestyle changes might be important as well. Previous research has suggested that people who are physically active seem to be less likely to experience cognitive decline and dementia in later life. There is evidence that this is so even when people do not take up exercise until they are older. But the positive link between physical activity and reduced risk of dementia has been not yet been confirmed.

What was done

Researchers at the University of Melbourne recruited a group of 138 adults aged 50 years or older who reported memory problems but did not actually have dementia. They were considered to be at risk of developing the condition, however. They were allocated randomly to either a usual care group or to a 24-week home based program of physical activity.

The aim was to encourage the participants to undertake at least 150 minutes of moderately intense physical activity every week in three 50 minute sessions for 24 weeks. The most frequently recommended activity was extra walking, but some chose light strength training. They used a diary to record their activity levels and received support like follow-up calls and newsletters. All the participants took a range of tests on cognitive ability and depression levels at six months and 12 months.

What was found

Those in the physical activity group did better on the standard ADAS-cog test and delayed recall memory test. They also had a lower Clinical Dementia rating. These findings suggest better cognitive functioning in the physical activity group. The benefits of physical activity were apparent at six months and persisted for at least a further 12 months.

What this study means

This is the first study that shows that exercise can improve cognitive function in older adults at risk of dementia because they report memory problems. The targets achieved in this work are realistic for anyone - extra walking up to 50 minutes a day three times a week. We don't know exactly how exercise improves cognitive function - it may be that it increases blood flow to the brain which can, in itself, improve brain function. Studies have shown that this particularly improves functioning in the parts of the brain relating to attention which would tend to improve memory.