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Deeper Dive: Can regular exercise and a good diet attenuate age-associated cognitive decline?

This large four-year trial found surprisingly little benefit from diet and exercise on brain health of older people. Here, we explore some possible reasons for this finding.

Study under review: Exercise, diet, and cognition a 4-year randomized controlled trial: Dose-Responses to Exercise Training (DR’s EXTRA)

Introduction

Cognition is a combination of processes in the brain involved with the ability to learn, remember, and make judgements. Health and well being are affected when cognition is impaired. A decline in cognition can range from mild impairment to dementia, which is a form of decline in abilities that is severe enough to interfere with daily activities. The most common form of dementia is Alzheimer’s disease, which affects nearly 6 million people in the United States. Age is the primary risk factor for cognitive decline. Other risk factors include genetics and lifestyle factors.

There is some scientific evidence[1] indicating that healthy behaviors may help prevent cognitive decline, although there is not sufficient evidence[2] to justify encouraging people to adopt specific behaviors for the sole purpose of preventing dementia and cognitive decline. Studies suggest that aerobic exercise and resistance exercises[3] can lessen cognitive decline associated with aging. There are also studies[4] showing that a healthy diet may help prevent cognitive decline associated with aging. A couple of intervention studies have looked at the combined effects of exercise and a healthy diet on cognition. One study[5] involving many components, including exercise and a healthy diet, showed that these measures attenuated cognitive decline in middle-aged and older adults with an increased risk of dementia. Another study showed that aerobic and resistance training alone and combined with a calorie-controlled diet improved cognition in older, obese, frail, and sedentary individuals.

The authors of the study under review point to several systematic reviews and meta-analyses, such as a study looking at aerobic exercise[6] intended to improve cognitive function in older people without cognitive impairment, a study looking at physical activity[7] interventions for preventing cognitive decline and Alzheimer-type dementia, and a study looking at the impact of exercise[8] on the cognitive function of healthy older adults. These reviews concluded that there is a need for long-term randomized controlled trials conducted with large numbers of participants on the effects of aerobic and resistance exercise and a healthy diet on cognitive function. Such information could provide evidence-based recommendations for the general population in an effort to help prevent cognitive decline. To address this gap in the research, the authors conducted this four-year randomized controlled trial to examine whether aerobic or resistance exercise, a healthy diet alone, or combinations of exercise and diet can lessen age-related cognitive decline in a general population of middle-aged and older people.

The risk of cognitive decline increases with aging. It may be possible to decrease this risk through aerobic and/or resistance exercise, a healthy diet, or a combination of these lifestyle factors. This study examined the effects of interventions using these factors on cognitive decline in middle-aged and older people over the course of four years.

What was studied?

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What were the findings?

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The bigger picture

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