Long-Term Improvement in Hippocampal-Dependent Learning Ability in Healthy, Aged Individuals Following High Intensity Interval Training.
Level 2 - randomized trial
Individual randomized controlled trial with three parallel exercise intensity arms and 5-year follow-up.
PubMed 39012673 · doi:10.14336/AD.2024.0642
What was done
Healthy adults aged 65–85 years without baseline cognitive deficits (151 completers) were randomized to one of three 6-month supervised exercise interventions: low-intensity training (LIT), medium-intensity training (MIT), or high-intensity interval training (HIIT), each comprising 72 sessions. Hippocampal function was assessed monthly for up to 5 years using a paired associative learning (PAL) task alongside monthly blood collection for brain-derived neurotrophic factor (BDNF) and cortisol. Structural and functional 7-Tesla MRI scans were collected at baseline, 6 months, and 12 months.
What was found
The abstract does not report numerical values, effect sizes, or p-values. It states that after 6 months, only the HIIT group exhibited significant gains in PAL performance, which persisted for at least 5 years. 7-Tesla MRI demonstrated that HIIT prevented age-associated volume reduction in the hippocampus and related cortical areas and improved neural network functional connectivity relative to LIT and MIT. Changes in circulating BDNF and cortisol correlated with cognitive gains in the HIIT group.
Why it matters
These findings suggest that exercise intensity is a critical determinant of neuroprotection in aging, indicating that a discrete 6-month HIIT intervention can yield durable structural and cognitive benefits in the hippocampus lasting multiple years.
Limits
The abstract omits quantitative point estimates, confidence intervals, and per-group sample sizes. The study enrolled only cognitively intact older adults, limiting direct generalizability to individuals with mild cognitive impairment or dementia. The abstract does not detail whether participants maintained unsupervised exercise during the post-intervention 4.5-year follow-up.