High-intensity exercise isn’t just good for your muscles; it could also be the key to keeping your brain sharp as you age. Older adults who take part in high-intensity interval training (HIIT) can boost their cognitive function — and these benefits could last for up to five years, according to a new study from the University of Queensland. The study is published in the journal Neurology. Aging and Diseasewas one of the first studies to show that exercise can not only slow cognitive decline but also actively improve cognitive performance in healthy older adults.
Led by Emeritus Professors Perry Bartlett and Daniel Blackmore of the Queensland Brain Institute, the study involved participants aged 65 to 85 who underwent a carefully controlled exercise regimen. After six months of HIIT, participants saw improvements in their brain function that were maintained for years afterward. “Six months of high-intensity interval training is enough to flip the switch,” says Bartlett.
Many aspects of health naturally decline with age, and cognitive function is no exception. With more than 130 million people worldwide predicted to live with dementia by 2050, finding ways to slow, mitigate, or even reverse age-related cognitive decline is crucial. Current research suggests that lifestyle factors, particularly physical activity, may play an important role in maintaining cognitive health.
While much research focuses on preventing cognitive decline, researchers at the University of Queensland wanted to explore whether exercise could actively improve cognitive function in older people who are still healthy. They were particularly interested in how different intensities of exercise affect brain structure and function.
Researchers conducted a rigorous six-year study with 194 participants aged between 65 and 85. Participants were randomly assigned to one of three exercise groups: low-intensity training, moderate-intensity training, or HIIT.
The exercise plan for the study consisted of participants in the HIIT group performing short, intense bouts of exercise that reached 85-95% of their peak heart rate, followed by a reduced-intensity recovery period, three times per week for six months. This contrasted with the moderate-intensity training group, who continued to exercise at a reduced intensity, and the low-intensity group, who performed even gentler exercise.
To measure changes in cognitive performance, the researchers administered a battery of tests each month designed to assess different aspects of brain function, with a particular focus on a hippocampus-dependent task called paired-associate learning (PAL), which is a strong indicator of spatial memory, which tends to decline with age.
In addition to cognitive testing, the researchers also performed brain scans on a subset of participants before and after the exercise intervention and six months later to monitor changes in brain structure, particularly in the hippocampus, and took monthly blood samples to analyze changes in biomarkers that may be related to cognitive function.
The HIIT group showed improvements in the PAL task, indicating enhanced hippocampal function. These improvements were sustained over time, with the HIIT group maintaining their cognitive gains for up to five years after the initial six-month exercise intervention. In contrast, the lower-intensity exercise group did not see the same level of cognitive gains, indicating that exercise intensity played an important role in driving these benefits.
“In previous pre-clinical studies, we found that exercise activates stem cells, increases the production of neurons in the hippocampus, and improves cognition,” Bartlett explains. “In this study, a large cohort of healthy volunteers, aged 65-85, participated in a six-month exercise program, underwent biomarker and cognitive testing, and underwent high-resolution brain scans. We followed them up five years after the program and, incredibly, their cognition was still improving, even though they had stopped exercising.”
In addition to improving cognitive function, the HIIT group also showed stabilization of hippocampal volume. This is particularly noteworthy because the hippocampus is known to shrink with age and is associated with cognitive decline. The researchers found that participants in the low-intensity exercise group experienced a decrease in hippocampal volume over time, whereas participants in the HIIT group did not. This suggests that high-intensity exercise may help protect this region of the brain from age-related atrophy.
Additionally, the study found that HIIT also improved functional connectivity between different brain networks, particularly those associated with attention and motor function, which were strengthened in the HIIT group. These changes in brain connectivity were associated with the observed improvements in cognitive function and may explain how HIIT improves brain health in older adults.
“High-resolution MRI scans of this group showed changes in the structure and connectivity of the hippocampus, which is responsible for learning and memory,” Blackmore says, “and we also found blood biomarkers that changed in correlation with improved cognitive performance. Biomarkers can help predict the benefits of the exercise a person is doing.”
Although this study provides compelling evidence that HIIT can benefit cognitive function in older adults, it does have limitations. One major limitation is that the study only included healthy older adults who were able to participate in a rigorous exercise program. This raises the question of whether similar benefits would be seen in older adults who are less physically fit or who have pre-existing conditions.
Future studies could explore these questions by comparing different types of exercise across a wider range of participants. The researchers also suggested that further studies should investigate the mechanisms underlying these cognitive gains, particularly the role of biomarkers such as brain-derived neurotrophic factor (BDNF) and cortisol, two of which have been found to be associated with cognitive performance in HIIT groups.
“Our findings may inform exercise guidelines for older people and further research could evaluate different types of exercise that could be incorporated into aged care,” says Blackmore. “We are now looking at the genetic factors that influence a person’s response to exercise to see if we can distinguish between those who will and will not respond to this intervention. The use of biomarkers as diagnostic tools for exercise also requires further research.”
the study, “Long-term improvement of hippocampal-dependent learning ability in healthy older adults following high-intensity interval training” is written by Daniel G. Blackmore, Mia A. Schomberg, Mariam Ziaei, Samuel Belford, Xuan Vinh To, Imogen O’Keefe, Ann Bernard, Jules Mitchell, Emily Hume, Grace L. Rose, Thomas Shaw, Ashley York, Marcus Barth, Elizabeth J. Cooper, Tina L. Skinner, Fatima Nasrallah, Stephen Leake, and Perry F. Bartlett.
