Aerobic exercise may reduce cognitive decline

According to the National Institute on Aging (NIA), Alzheimer’s disease is an irreversible and progressive neurological disorder.

At its mildest, it can affect a person’s ability to think or remember things. Moderate forms of the condition can affect a person’s brain areas and impair language, reasoning, sensory processing, and conscious thought.

When the disease progresses to become severe, it can stop a person from performing basic, everyday tasks and recognizing or communicating with friends or family.

According to the NIA, researchers estimate Alzheimer’s disease affects over 5.5 million people in the United States. It typically first appears in people in their mid-60s.

The Alzheimer’s Association highlight that there is no known cure for the condition, with treatments instead focusing on easing the symptoms of the disease or slowing its progression.

While various drugs are available in the treatment of Alzheimer’s disease, there is an emerging body of evidence suggesting that aerobic exercise may also be effective in reducing the progression of the disease.

However, as the authors of the present study note, randomized controlled trials that have put this to the test have produced inconsistent findings.

To begin to resolve this problem in existing research, the present authors devised a randomized controlled trial to act as a pilot study.

This study examined whether a group of older adults with Alzheimer’s disease would have less cognitive decline following 6 months of aerobic exercise compared with the expected level of cognitive decline they would experience if the disease progressed naturally.

The study involved 96 participants aged 66 years or older with Alzheimer’s disease.

Researchers randomly split these participants into two groups. One group of 64 people took part in supervised cycling exercise classes three times a week for 6 months.

The remaining 32 participants took part in supervised stretching and range of motion exercise classes, which the scientists matched to the cycling group in terms of the regularity of the classes and their length of time, but at low intensity. This latter group also acted as a control.

Researchers continually monitored participants’ heart rates in both groups. The team also supported the cycling group to achieve 50–75% heart rate reserve while helping the control group maintain less than 20% heart rate reserve.

In addition, the scientists measured participants’ cognition at the beginning of the intervention, as well as at months 3, 6, 9, and 12.

The researchers found that both the cycling group and the stretching or range of motion group scored significantly better than would have been predicted if they had continued with treatment as normal.

The researchers used the Alzheimer’s Disease Assessment Scale-Cognitive Subscale, a scaling system where a greater number reflects worse cognition.

According to this scale, after 6 months, the cycling group scored 1.0±4.6, and the control group 0.1±4.1. This compares with a score of 3.2±6.3, which would be in line with expectations given the natural progression of Alzheimer’s disease.

According to Prof. Fang Yu, Edson Chair in Dementia Translational Nursing Science at the Arizona State University Edson College of Nursing and Health Innovation, and corresponding author of the study, “our primary finding indicates that a 6-month aerobic exercise intervention significantly reduced cognitive decline in comparison to the natural course of changes for Alzheimer’s dementia.”

“However, we did not find a superior effect of aerobic exercise to stretching, which is likely due to the pilot nature of our trial. We do not have the statistical power to detect between-group differences, there was a substantial social interaction effect in the stretching group, and many stretching participants did aerobic exercise on their own.”

As a consequence, scientists need to conduct further research to corroborate these initial encouraging findings.