Strength training can help protect the brain from degeneration

Researchers have found that six months of strength training (lifting weights) can help protect brain areas especially vulnerable to Alzheimer’s disease up to one year later.

The team, led by researchers at the University of Sydney, conducted a clinical trial for older people at high risk of Alzheimer’s disease due to mild cognitive impairment. 

Mild cognitive impairment involves a decline in memory and other thinking skills despite generally intact daily living skills, and is one of strongest risk factors for dementia. People with mild cognitive impairment are at a one-in-10 risk of developing dementia within a year. 

Study participants were randomly allocated to do computerised brain training, strength training, combined computer and strength training, which they did for just six months followed by their usual  activity for 12 months.

The long-term study found that strength training led to overall benefits to cognitive performance, benefits linked to protection from degeneration in specific subregions of the hippocampus. The hippocampus is a complex structure in the brain with a major role in learning  and memory. 

The hippocampus subregions targeted by the strength training were those especially vulnerable to Alzheimer’s disease. In the control condition, where no strength training was undertaken hippocampal subregions shrunk by 3-4 percent over the 18-months, whilst those undergoing strength training saw only 1-2 percent reductions, and in some areas, none at all. 

The findings have been published this month in the specialist journal Neuroimage: Clinical.

Strength training is a type of physical exercise that requires repetitive contraction of the major muscle groups against an opposing force, typically a free weight or using gym equipment. Participants in this study did supervised strength training for just 90 minutes in total each week, over two or three weekly sessions.

Dr Kathryn Broadhouse, now with the University of the Sunshine Coast, who led the analysis while at the University of Sydney, said the data showed that strength training could exert important biological effects. 

“Our research shows that strength training can protect some hippocampal subregions from degeneration or shrinkage for up to 12-months after the training has stopped,” Dr Broadhouse said.

To arrive at their conclusions, the team conducted MRI brain scans of the participants three times over an 18-month period and used some of the latest advances in image analysis to quantify changes to subregions within the hippocampus, the brain’s memory hub.

“Hippocampal segmentation is difficult because the borders between structures are sometimes unclear and even anatomists will debate where to draw the line, so we restricted our analysis to those subregions where the data is consistent,” Dr Broadhouse said.

Professor Michael Valenzuela, leader of the Regenerative Neuroscience Group at the University of Sydney’s Brain and Mind Centre and the senior author of the study, believes the finding should change the dementia prevention message.

“This is the first time any intervention, medical or lifestyle, has been able to slow and even halt degeneration in brain areas particularly vulnerable to Alzheimer’s disease over such a long time,” said Professor Valenzuela, from the Sydney Medical School in the Faculty of Medicine and Health. 

“Given this was also linked to protection from cognitive decline, the message is clear: resistance exercise needs to become a standard part of dementia risk-reduction strategies,” he said.

Professor Valenzuela is one of the leaders of the multi-million-dollar Australian Maintain your Brain online trial (www.maintainyourbrain.org) that will test if a tailored program of lifestyle modification, including resistance exercise, can prevent cognitive loss in a group of 6,000+ older adults. 

About the study

One hundred participants were randomised to one of four training groups: (1) Combined high intensity progressive resistance and computerised cognitive training (PRT+CCT), (2) PRT+Sham CCT, (3) CCT+Sham PRT, (4) Sham physical+sham cognitive training (SHAM+SHAM). PRT but not CCT or PRT+CCT led to global long-term cognitive improvements above SHAM intervention at 18-month follow-up.

What is the difference between cognitive impairment and dementia? 

These concepts tend to lie along a continuum of cognitive function. 

Most cognitive domains decline as we get older but there is great variability between individuals and even within our own trajectories over time. This variability increases in later life and so can make the distinction between normal and impaired, or between impaired and dementia, challenging. 

Neuropsychological testing can then be useful to find out how they compare to the average person of their age, sex and level of education. If multiple tests for a given cognitive domain point to a result less than the 10th percentile, then they may have an impairment in that domain. 

For a diagnosis of dementia, four main conditions need to be satisfied: 

1. impairment on multiple cognitive domains
2. a definite decline in cognitive function
3. exclusion of any possible medical causes for this decline, and
4. the person is no longer able to carry out day-to-day tasks. 

In practice, the last criterion – being able to do one’s daily activities independently – is pivotal to distinguishing between cognitive impairment and dementia.