Long-Term Effects of a 5-Year Randomized Controlled Exercise Trial on Brain Volumes and Cognitive Function in Older Adults: A 4-Year Post-Intervention Follow-Up Study.
Level 2 - randomized trial
Individual randomized controlled trial with extended 4-year post-intervention follow-up (9 years total).
PubMed 41999477 · doi:10.1007/s40279-026-02434-3
What was done
Researchers assessed 106 older adults (aged 70–77 at baseline) from the Generation 100 study randomized to 5 years of high-intensity interval training (HIIT), moderate-intensity continuous training (MICT), or a control group following national physical activity guidelines. Assessments occurred 4 years after the 5-year intervention ended (9 years total). Brain MRI was performed at baseline and after 1, 3, 5, and 9 years. Cognitive testing (verbal list learning, pattern separation, and odor identification) was conducted at baseline and 9 years. Linear mixed models and linear regressions examined group-by-time interactions on brain volumes, associations with cognitive performance, and the predictive value of baseline VO2peak.
What was found
The abstract reports directions of effect without reporting exact numerical values, effect sizes, confidence intervals, or p-values. The HIIT group experienced greater hippocampal volume loss over time compared with the guideline control group at 9 years, with the control group demonstrating the lowest hippocampal volume loss. Verbal memory and pattern separation scores did not differ significantly between intervention groups at 9 years, though MICT (and a trend for HIIT) showed higher odor identification scores. Across all participants, greater hippocampal volume loss was linked to poorer verbal memory at 9 years, and higher baseline VO2peak predicted larger cortical volume and superior pattern separation performance.
Why it matters
This study shows that long-term adherence to standard physical activity guidelines preserves hippocampal volume as well as or better than structured high-intensity exercise in older adults. It also demonstrates that initial cardiorespiratory fitness predicts preserved cortical volume and cognitive performance nearly a decade later.
Limits
The abstract provides no exact numerical data, effect estimates, or confidence intervals. The sample size is relatively small (n = 106) and restricted to fit older adults from a single trial, limiting generalizability. Exercise habits outside the intervention were measured via self-report, and attrition or selection bias over the 9-year study window is not detailed.
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