- The brain is a fragile organ that undergoes specific changes with age. Older people tend to be at higher risk of developing dementia.
- Researchers want to find out what interventions can delay dementia or even improve cognitive function.
- A recent study found that high-intensity interval training, or HIIT, in older adults may help improve hippocampal function and maintain that improvement years after the intervention.
Exercise offers many health benefits, and researchers are particularly interested in how it affects brain function in older adults.
A recent study published in Aging and disease The researchers looked at three levels of exercise in healthy older adults and how these interventions affected the functioning of the hippocampus, an area of the brain critical for memory consolidation. The researchers found that participants who engaged in high-intensity interval training (HIIT) saw improvements in hippocampal function. They also found that they continued to see this improvement up to five years after the intervention began.
As people age, some
Older adults are also at higher risk for dementia, making preventative measures and interventions even more crucial in this age group. The researchers of the current study note that age can affect the hippocampus.
So, looking at how interventions affect this area of the brain could prove very beneficial in combating cognitive decline in older adults and possibly preventing dementia.
“A key feature of age-related dementia is the decline in specific areas of cognitive function, including those related to spatial learning and memory. The hippocampus is a critical brain region that is responsible for consolidating spatial information into memories and is particularly sensitive to age, with reports of age-related declines in hippocampal volume and connectivity.”
– Authors of the study
Dr. Michele Longo, MD, a neurologist at the University Medical Center of New Orleans and a non-author of the study, offered the following insight: Today’s Medical News:
“Exercise-induced biomarker responses as predictors of improved hippocampal functional outcomes provide a quantifiable metric to inform an effective exercise program. The long-term improvement and retention of hippocampal learning capacity after HIIT exercise provides novel insight into how older adults may be protected from cognitive decline even though their exercise capacity may decline with age. This approach could greatly enhance clinicians’ ability to tailor personalized exercise paradigms, including for individuals at risk of cognitive decline.”
This study was a multidomain randomized controlled trial. The researchers recruited 194 participants aged 65 to 85 years. They excluded participants who had suffered a stroke, traumatic brain injury, or brain or heart surgery, as well as anyone at high risk of having a cardiac event such as a heart attack during exercise. Participants did not have diagnosed mental disorders or cognitive decline at baseline.
Participants were divided into three groups to undergo different levels of exercise intensity:
- Low-intensity training, including activities such as stretching, range of motion and balance exercises
- Moderate intensity training, which consisted of continuous walking on a treadmill
- High-intensity training, which included intervals of treadmill work, resulted in a more significant increase in heart rate than the medium-intensity training group
The high-intensity training group additionally combined aerobic and anaerobic exercises.
Participants completed exercise programs three days a week for six months under the supervision of exercise physiologists. The researchers administered a number of tests to examine cognitive and hippocampal function, such as the hippocampus-dependent paired associate learning (PAL) test. They also took monthly blood samples from participants to gain valuable biomarker information.
Researchers conducted cognitive tests every month during the intervention and followed up with participants every six months thereafter for five years.
The study results revealed that the high-intensity interval training group experienced improvement in hippocampus-dependent spatial learning. The other two groups remained stable rather than showing improvement. This improvement was maintained in the high-intensity interval training group during the five-year follow-up. It did not appear to be related to differences in lifestyle and physical activity during follow-up.
The researchers also found that participants who initially performed poorly on the PAL assessment showed the greatest improvement if they were in the high-intensity interval training group. Participants who performed poorly in the moderate-intensity interval training group also saw some improvement on these assessments, but less than the high-intensity interval training group. They also found that the high-intensity interval training group had stable right hippocampal volume, while the other groups experienced a decrease in this brain area.
The researchers found that brain structures in both the high- and medium-intensity groups were in better condition than those in the low-intensity group. They also observed “improved functional connectivity between multiple neural networks” in the high-intensity interval training group. However, after 12 months, the researchers did not observe any improvement in functional connectivity between pairs of networks compared to baseline in either group.
They also observed that changes in some biomarkers in the high-intensity interval training group were correlated with improvements in associated learning. The researchers did not find that exercise interventions helped improve working memory or emotional recognition.
The findings highlight the potential benefits of exercise on the brain, particularly for those who engage in high-intensity interval training.
Ryan Glatt, CPT, NBC-HWC, senior brain health coach and FitBrain program director at the Pacific Neuroscience Institute in Santa Monica, California, was not involved in the study. He noted the following clinical implications of the data: Today’s Medical News:
“The study suggests that high-intensity interval training (HIIT) can significantly improve hippocampus-dependent learning in healthy older adults. Although promising, the results should be interpreted with caution due to potential variability in individual responses to exercise and the specific study population. If further research corroborates these findings, they could inform exercise-based interventions for cognitive health in older adults, promoting HIIT as a non-pharmacological strategy to mitigate age-related cognitive decline.”
This study has some limitations. First, it involved a small number of participants, which means that future research could be done with larger samples to see if the results are the same.
The researchers were also limited by their inclusion and exclusion criteria, such as working only with participants who could communicate in English and had no medical history. They also did not include people who already had cognitive deficits and did not have a sedentary control group. Having this control group would have allowed them to see if social interactions had an effect on hippocampal function. Because the research included healthy older adults who could participate in these exercise interventions, it is unclear whether the intervention would be feasible for people with more health problems.
The researchers also acknowledge that more research is needed to understand whether exercise affects working memory and the differences seen in the high-intensity interval training group. Finally, the researchers acknowledge that it is unclear whether similar methods of high-intensity interval training would produce the same results, which could also be a topic of future research.
Study author Dr. Daniel G. Blackmore, PhD, of the University of Queensland Brain Institute, noted the following areas for continued research:
“There are many avenues of research in this area. We have shown that it is essential to have a highly controlled exercise intervention that takes into account multiple parameters. The use of biomarkers as a diagnostic tool for exercise requires further research and we are also currently investigating genetic factors that may regulate a person’s response to exercise to see if we can determine who will and who will not respond to this intervention.”