Optimising exercise intensity for neuronal growth – Felicity Spencer

Felicity is a second-year PhD student based at University of Birmingham.

Dementia is a serious brain condition that produces a decline in cognitive ability and ultimately results in death. More than 55 million people have dementia across the world; with approximately 60-80% of those cases caused by Alzheimer’s disease¹. The global cost of dementia was 1.3 trillion US dollars in 2019¹; and there are currently no treatments that can cure dementia. Therefore, developing techniques that can reduce the risk of getting a diagnosis of dementia is important. My PhD is focusing on optimising the delivery of exercise-based interventions; as modifiable lifestyle factors, such as physical activity, diet, and smoking, can account for up to 40% of the risk of getting dementia².

Blood Derived Neurotrophic Factor (BDNF) is a blood-based protein that is responsible for the growth and maintenance of cells in the brain³. People with dementia typically have low levels of BDNF, but research has shown that exercise can increase BDNF levels³. However, the optimal intensity of exercise to increase BDNF levels is unclear.

Therefore, the study I’m running at the moment is aiming to determine the optimal intensity of exercise to increase levels of BDNF. Healthy male and female participants have been invited to the lab to complete four exercise sessions on an exercise bike. In the first session all participants complete a maximal exertion test, where they are encouraged to as cycle for as long as they can whilst the resistance on the bike increases. The following three sessions are completed in a random order by all participants:

1. Moderate Intensity: Participants cycle for 30 minutes at 65% of their maximum capacity.
2. High Intensity: Participants complete 4 bouts of intense cycling (4 minutes each) at 90% of their maximum capacity, interspersed with 3 minutes of recovery.
3. Very High Intensity: Participants complete 8 bouts of very intense cycling (30 seconds each) at 150% of their maximum capacity, interspersed with 3 and a half minutes of recovery.

Blood samples are collected from participants before the start of each session, straight away after they finish the exercise session, and then a final sample is taken after 30 minutes of rest. The blood samples are then processed to separate the blood into different parts, which we use to measure the levels of BDNF.

We’re still in the process of running exercise sessions and analysing the levels of BDNF in the blood from participants at the moment, but we hope to have completed this study by Autumn 2024!

References

1. World Health Organization. (2023, March 15). Dementia Fact Sheet. https://www.who.int/news-room/fact-sheets/detail/dementia#:~:text=Currently%20more%20than%2055%20million,injuries%20that%20affect%20the%20brain.
2. Livingston, G., Huntley, J., Sommerlad, A., Ames, D., Ballard, C., Banerjee, S., … & Mukadam, N. (2020). Dementia prevention, intervention, and care: 2020 report of the Lancet Commission. The Lancet, 396(10248), 413-446.
3. Ng, T. K. S., Ho, C. S. H., Tam, W. W. S., Kua, E. H., & Ho, R. C. M. (2019). Decreased serum brain-derived neurotrophic factor (BDNF) levels in patients with Alzheimer’s disease (AD): a systematic review and meta-analysis. International journal of molecular sciences, 20(2), 257.