Lifting weights can help protect the brain from degeneration, and its benefits last for many months after training, according to Australian research.
A study by University of Sydney researchers has found that the areas of the brain affected by Alzheimer’s disease are protected for one year after training.
The research, published in NeuroImage: Clinical, found that six months of strength training led to cognitive improvements in people with mild cognitive impairment (MCI) and significantly slowed neurodegeneration linked with Alzheimer’s disease. Dementia affects 47 million people globally and there are estimates this figure will rise to 150 million by 2050.
Exercise is known to benefit cognition, but there is very little research into the effects on older adults with MCI who are able to go about their daily activities but are forgetful and are more vulnerable to developing dementia.
For the new study, 100 participants with MCI were randomly assigned to one of four different interventions.
The twice-weekly supervised sessions, which lasted for six months, comprised of strength and computerised cognition training, strength training (progressively increasing load using free weights and exercise machines) alone, computerised cognition training alone or a “double control condition” of stretching and watching videos.
The participants were assessed via MRIs, physical, metabolic and cognitive tests at the start of the study, at the end of the six months and then again at 18 months.
“At the end of the six months there was a significant effect on cognition … for anyone doing resistance exercise,” said senior author Professor Michael Valenzuela, leader of the Regenerative Neuroscience Group at the University of Sydney’s Brain and Mind Centre.
One year after the program ended, the researchers found the “cognitive benefits were preserved” and loss of volume in the hippocampus was largely prevented among those in the strength training group. It did not seem to matter whether or not participants kept up their training during that time.
“There seems to be a delayed effect on the brain that is specifically related to that six months of training,” Professor Valenzuela said.
The cognitive training group showed improvements in memory at six months, but the effect was “not as strong” at 18 months, while the group who did both cognitive and strength training did not have statistically significant results at the end of 18 months.
“We had been expecting the two things to be better than either, but we didn’t see that,” Professor Valenzuela said. “Our working hypothesis is that we may have overloaded participants with the double intervention of 45 minutes of strength training and then … 45 minutes of brain training. My perspective is you probably need to space these things out and have a rest day in between.”
Aerobic and strength training share common biological mechanisms but they also have some specific mechanisms to each other, Valenzuela explained, noting it was too early to tell whether one type of exercise was more beneficial than the other.
“Exercise stimulates a whole cocktail of biological changes in the bloodstream,” he said.
“Strength training specifically promotes anti-inflammatory types of mechanisms in the body … and it strengthens your bones more specifically than aerobic [but] how you get from lifting a dumbbell to an improvement in the hippocampus is not clear at the moment.”
Rodent studies have found that exercise stimulates the arousal and alertness centres in the brain.
“Those brain centres that underlie arousal or alertness are deep in the brain and they have direct connections to the same hippocampal areas that we found to be protected,” Valenzuela said, speculating that this pathway may help to explain the findings.
Rob Newton, a Professorial Research Fellow at Edith Cowan University’s Exercise Medicine Research Institute, says “this is an excellent piece of research”.
“Any physical activity is beneficial,” Newton added. “Heavy resistance training drives more mechanisms for potential neuroprotection such as BDNF and testosterone.”
Professor Valenzuela added: “The main message is we can reduce our risk for dementia through lifestyle changes. Exercise is very important.”