Effect of 5 Years of Exercise Intervention at Different Intensities on Brain Structure in Older Adults from the General Population: A Generation 100 Substudy

Abstract

Purpose

The aim was to examine the effect of a 5-year exercise intervention at different intensities on brain structure in older adults from the general population partaking in the randomized controlled trial Generation 100 Study.

Participants and Methods

Generation 100 Study participants were invited to a longitudinal neuroimaging study before randomization. A total of 105 participants (52 women, 70–77 years) volunteered. Participants were randomized into supervised exercise twice a week performing high intensity interval training in 4×4 intervals at ~90% peak heart rate (HIIT, n = 33) or 50 minutes of moderate intensity continuous training at ~70% of peak heart rate (MICT, n = 24). The control group (n = 48) followed the national physical activity guidelines of ≥30 min physical activity daily. Brain MRI at 3T, clinical and cardiorespiratory fitness (CRF), measured as peak oxygen uptake, were collected at baseline, and after 1, 3, and 5 years of intervention. Brain volumes and cortical thickness were derived from T1 weighted 3D MRI data using FreeSurfer. The effect of HIIT or MICT on brain volumes over time was investigated with linear mixed models, while linear regressions examined the effect of baseline CRF on brain volumes at later time points.

Results

Adherence in each group was between 79 and 94% after 5 years. CRF increased significantly in all groups during the first year. Compared to controls, the HIIT group had significantly increased hippocampal atrophy located to CA1 and hippocampal body, though within normal range, and the MICT group greater thalamic atrophy. No other effects of intervention group were found. CRF across the intervention was not associated with brain structure, but CRF at baseline was positively associated with cortical volume at all later time points.

Conclusion

Higher baseline CRF reduced 5-year cortical atrophy rate in older adults, while following physical activity guidelines was associated with the lowest hippocampal and thalamic atrophy rates.

Keywords:

• CNS
• aging
• limbic
• brain reserve
• morphometry

Acknowledgments

The authors thank all the participants for taking part in the study. We thank Torill E Sjøbakk for help with the recruitment, our students Hanne Nikkels and Stine Bjøralt for help with data collection and the radiographers at 3T scanner. Testing of VO_2peak was performed at the core facility NeXt Move, Norwegian University of Science and Technology (NTNU). All other clinical measurements were performed at the Clinical Research Facility, St. Olavs Hospital.

Abbreviations

AD, Alzheimer’s disease; BMI, body mass index; CRF, cardiorespiratory fitness; CRP, C-reactive protein; DBP, diastolic blood pressure; FOV, field of view; HADS, hospital anxiety and depression scale; HbA1c, glycated hemoglobin; HDL, high density lipoprotein cholesterol; HIIT, high intensity interval training; ICV, intracranial volume; LDL, low-density lipoprotein cholesterol; MICT, moderate intensity interval training; MoCA, Montreal Cognitive Assessment; MRI, magnetic resonance imaging; RCT, randomized controlled trial; RHR, resting heart rate; SBP, systolic blood pressure; SF-8, Short Form health survey questionnaire; TC, total cholesterol; TE, echo time; TG, triglycerides; TR, repetition time.

Data Sharing Statement

Because privacy concerns and state regulations, the ethical and governance approvals for this study do not allow the MRI data to be made available in a public repository. Data in this manuscript can be accessed by qualified investigators after ethical and scientific review (to ensure the data is being requested for valid scientific research) and must comply with the European Union General Data Protection Regulations (GDPR), Norwegian laws and regulations, and NTNU regulations. The completion of a material transfer agreement (MTA) signed by an institutional official will be required.

Author Contributions

All authors made a significant contribution to the present article, either in one, more than one or all the following areas: conception of the study, acquisition of the data, analysis, interpretation of the results, drafting and critically reviewing the manuscript. All authors revised and critically reviewed the manuscript. There was a joint agreement on which journal the manuscript was submitted to, and all the authors agree to take responsibility and be accountable for the content of this article.

Disclosure

The authors have no conflicts of interest.