This Simple Workout Could Keep Your Brain Sharp for Decades

Why People Over 50 Can’t Afford to Ignore It

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My Longevity Experiment
February 27, 2025

HIIT for Brain Health: How High-Intensity Interval Training Preserves Cognitive Function

Cognitive decline is a major concern associated with aging, but new research suggests that high-intensity interval training (HIIT) may help preserve brain function. A recent study indicates that HIIT improves spatial learning while maintaining brain volume and connectivity.

The Aging Brain and Cognitive Decline

One of the primary cognitive functions that deteriorates with age and in conditions like dementia is spatial learning and memory. The hippocampus, a critical region of the brain, is primarily responsible for these functions.

Previous studies have demonstrated that hippocampal volume and connectivity decline over time. While research in rodents has shown that physical activity can counteract hippocampal-dependent spatial learning deficits, there has been a lack of studies examining how exercise affects hippocampal function in older humans.

To bridge this knowledge gap, researchers conducted a study to assess the impact of exercise on brain function in healthy elderly individuals.

Exercise Intensity and Brain Benefits

In the study, 151 participants aged 65 to 85 were divided into three groups based on exercise intensity:

  • Low-intensity training (LIT)

  • Medium-intensity training (MIT)

  • High-intensity interval training (HIIT)

Each participant engaged in exercise sessions three times per week for six months. To assess cognitive function, researchers administered a hippocampal-dependent paired associated learning (PAL) test, which measures spatial learning and the ability to create a mental representation of the environment.

By the end of the study, the HIIT group exhibited significant improvement in PAL test scores compared to their baseline measurements. The improvements were also notably greater in the HIIT group compared to both the MIT and LIT groups, which remained stable.

However, the study did not stop there. Follow-up tests conducted six months after the exercise program, and then regularly over the next four years, demonstrated that the HIIT group continued to perform better in cognitive assessments. Their improved test scores persisted for up to five years, whereas scores for the MIT and LIT groups remained largely unchanged from baseline.

Interestingly, participants who had the lowest initial test scores benefited the most from HIIT. These individuals exhibited the most significant improvements in cognitive function, and these benefits were sustained over the follow-up period. While the MIT group also showed some improvement, the effect was more modest. According to the study authors, "HIIT intervention was specific to the hippocampal-dependent spatial learning task."

Brain Volume and Connectivity

Beyond cognitive test results, the study also examined brain volume changes. One of the most significant findings was that after six months, both the LIT and MIT groups exhibited a decrease in right hippocampal volume—a brain region strongly associated with spatial learning. In contrast, the HIIT group maintained hippocampal volume at six- and twelve-month follow-ups.

The hippocampus was not the only region affected. The study also found that HIIT helped preserve volume in brain areas involved in motor functions, language processing, learning, and memory. Additionally, HIIT participants displayed enhanced connectivity between brain networks associated with attention, movement, and vision while at rest. These connectivity improvements were not observed in the LIT or MIT groups.

Biomarkers and Cognitive Improvement

The study also explored how exercise influences blood biomarkers associated with cognitive function. The researchers observed a correlation between increased levels of brain-derived neurotrophic factor (BDNF) and cortisol in the HIIT group, which aligned with improved hippocampal-dependent cognition.

While chronically elevated cortisol levels have been linked to cognitive decline, acute elevations—such as those triggered by exercise—have been reported to have beneficial effects. The study authors explained, "HIIT intervention was specific to the hippocampal-dependent spatial learning task."

In the MIT group, a different biomarker response was noted. Decreased prolactin levels were associated with improved hippocampal-dependent cognition, suggesting that different types of exercise may trigger distinct neurobiological responses. The study authors hypothesized that these differences were likely due to the nature of the workouts, with the HIIT group performing both aerobic and anaerobic exercises, while the MIT group focused primarily on aerobic training. Further research is needed to explore these mechanisms in greater depth.

Long-Term Implications of HIIT for Brain Health

The study’s findings reinforce the potential of HIIT as an effective strategy for preserving cognitive function in older adults. "Our results highlight the specificity of HIIT in significantly improving hippocampal-dependent spatial learning in the healthy elderly," the authors concluded.

One of the most significant takeaways is the long-term effectiveness of HIIT. Given that older adults often struggle with high-intensity exercise, the study underscores the importance of adopting such regimens earlier in life. The findings suggest that "a relatively acute, six-month HIIT intervention can maintain the improvement in hippocampal function for at least 4.5 years with no diminution of performance."

Despite these promising results, the study did have limitations. It lacked a non-exercise control group, and differences in exercise modalities between groups were not fully addressed. Furthermore, the participants were all healthy older adults with no cognitive deficits, meaning the findings may not be applicable to individuals with existing cognitive impairments.

Nevertheless, this research underscores the potential of HIIT as a protective measure against cognitive decline. By integrating HIIT into a regular exercise routine, older adults may be able to maintain brain function and reduce the risk of age-related cognitive deterioration.

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