Regular exercise provides enormous benefits for both physical and mental health. In particular, aerobic exercise has been shown to have significant positive effects on brain structure and function. Here we will explore 3 of the main ways that exercise can improve cognition and brain health:
- Exercise increases brain volume
- Exercise improves memory
- Exercise reduces risk of dementia
Exercise increases brain volume
Numerous studies have demonstrated that aerobic exercise can increase the volume of critical brain regions. For example, a meta-analysis of 14 randomized controlled trials in older adults found that aerobic exercise significantly increased hippocampus volume by around 2%, reversing age-related atrophy in this memory-critical region.1 Increased hippocampus volume has been associated with improved spatial memory and learning.2
Aerobic exercise has also been shown to increase volume in the prefrontal cortex, a brain region involved in planning, decision-making and mood regulation.3 One randomized controlled trial had older adults perform one year of moderate intensity walking. The walking group showed a significant increase in prefrontal cortex volume compared to controls who did stretching and toning exercises.4
Some key ways that exercise may increase brain volume include:
– Increasing blood flow to the brain
– Stimulating neurotransmitter systems like serotonin and norepinephrine
– Upregulating growth factors like brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF)
– Promoting development of new neurons (neurogenesis)
– Reducing inflammation
By increasing the volume of critical brain regions, exercise provides the structural framework for improvements in cognitive abilities.
Mechanisms for increasing brain volume
Increasing blood flow: Exercise increases heart rate and respiration which elevates blood flow and oxygen delivery throughout the body, including the brain. Greater cerebral blood flow brings glucose, oxygen, and nutrients to neural tissue.5
Stimulating neurotransmitters: Exercise releases neurotransmitters like serotonin, norepinephrine and dopamine. These brain chemicals support neuroplasticity, learning, focus, mood and memory.6
Upregulating growth factors: Aerobic exercise increases levels of BDNF, VEGF, insulin-like growth factor-1 (IGF-1) and other growth factors that stimulate neurogenesis, synaptogenesis, angiogenesis and other facets of neural plasticity.7
Promoting neurogenesis: Aerobic exercise stimulates the birth of new neurons in the hippocampus and other brain regions involved in learning and memory.8 New neurons help sharpen cognitive abilities.
Reducing inflammation: Exercise helps reduce chronic inflammation in the body and brain. This provides a more favorable neural environment since inflammation can damage neurons and impair neuroplasticity.9
Exercise improves memory
A growing body of research confirms that exercise can boost memory function across people of different ages. For example:
– Young adults showed improved performance on memory tests after 30 minutes of moderate intensity exercise compared to after rest.10
– Middle-aged adults with memory complaints increased memory test performance by around 20% after 6 months of aerobic exercise training.11
– Dementia patients demonstrated improved verbal memory and language skills immediately after 20 minutes of moderate intensity cycling.12
Some of the ways exercise may improve memory include:
– Facilitating long-term potentiation which strengthens synaptic connections between neurons that store memories
– Increasing neurotransmitters like dopamine that are important for memory encoding and retrieval
– Stimulating hippocampal neurogenesis to sharpen declarative memory
– Improving sleep quality which supports memory consolidation
– Reducing cortisol levels that can interfere with memory when elevated
Let’s explore the mechanisms behind these memory-boosting effects in more detail:
Mechanisms for improving memory
Facilitating long-term potentiation (LTP): LTP describes the strengthening of synapses between neurons, a key mechanism of memory formation. Aerobic exercise promotes factors like BDNF that facilitate LTP.13 Strengthening neural connections via LTP improves the storage and recollection of memories.
Increasing dopamine: The neurotransmitter dopamine supports memory encoding and information retrieval. Exercise increases dopamine synthesis and release in memory centers like the hippocampus.14 This dopamine boost enhances memory function.
Stimulating hippocampal neurogenesis: As described earlier, exercise promotes the growth of new neurons in the hippocampus. These new neurons integrate into neural circuits supporting declarative and spatial memory.15
Improving sleep: Exercise can improve sleep quality, duration and efficiency,16 which facilitates memory consolidation during REM and deep NREM sleep stages. Better sleep = better memory.
Reducing cortisol: Chronically elevated cortisol, induced by high stress, impairs memory retrieval. Exercise lowers cortisol, removing this memory barrier.17
Exercise reduces risk of dementia
Dementia involves the progressive deterioration of cognitive abilities that interfere with daily functioning. Alzheimer’s disease is the most common form of dementia. Aerobic exercise helps prevent dementia by:
– Increasing growth factor levels like BDNF that protect neurons from damage.18
– Reducing chronic inflammation which can impair neuronal health.9
– Improving cardiovascular health which enhances blood delivery to the brain.19
– Stimulating the growth of new neurons to compensate for loss of damaged neurons.8
Many large observational studies show that greater amounts of exercise are associated with lower dementia risk. For example:
– One study of over 1,740 adults found that exercising 3 or more times per week reduced dementia risk by around 40% compared to exercising less than 3 times per week.20
– Another study reported that being very physically active was associated with a 38% lower risk of Alzheimer’s dementia compared to being least active.21
Intervention studies also demonstrate that adopting an exercise program can drive meaningful reductions in dementia risk among older adults. One randomized controlled trial had seniors with memory complaints take up a moderate intensity aerobic exercise program (45 minutes/day, 4 days/week) for 6 months. The exercise group showed improved memory scores along with a 16% reduction in tau protein, a biomarker indicating reduced Alzheimer’s risk.11
Mechanisms for reducing dementia risk
Here are some key ways exercise helps mitigate development of dementia:
Increasing BDNF: By boosting BDNF levels, exercise stimulates neuroplasticity and neurogenesis which help compensate for neuronal damage and death in dementia.18
Reducing inflammation: Exercise curbs inflammatory cytokines and increases anti-inflammatory factors to limit neuron-damaging inflammation in the brain.9
Improving cardiovascular health: Exercise enhances heart health and circulation which optimizes delivery of oxygen and nutrients to neurons, protecting them from damage.19
Stimulating neurogenesis: By prompting development of new hippocampal neurons, exercise facilitates regeneration of neurons lost in dementia diseases.8
Conclusion
In summary, aerobic exercise provides a host of benefits for brain structure and function. It increases the volume of critical brain regions, sharpens memory, and helps prevent dementia. Memory improvements stem from exercise enhancing neuroplasticity mechanisms including LTP, dopamine levels, neurogenesis and sleep quality. For reducing dementia risk, exercise promotes neuronal growth factors, decreases inflammation, boosts cardiovascular health, and stimulates neurogenesis. Incorporating regular aerobic exercise into your weekly routine can support optimal cognitive health across your lifespan. Even short workout sessions can deliver meaningful improvements in brain volume, memory and neural protection.
| Exercise Benefit | Mechanisms |
|---|---|
| Increases brain volume |
|
| Improves memory |
|
| Reduces dementia risk |
|
References
1. Firth, J., et al. (2018). Effect of aerobic exercise on hippocampal volume in humans: A systematic review and meta-analysis. NeuroImage, 166, 230-238. https://www.sciencedirect.com/science/article/pii/S1053811917307323
2. Erickson, K. I., et al. (2011). Exercise training increases size of hippocampus and improves memory. Proceedings of the National Academy of Sciences, 108(7), 3017-3022. https://www.pnas.org/doi/full/10.1073/pnas.1015950108
3. Colcombe, S. J., et al. (2006). Aerobic exercise training increases brain volume in aging humans. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 61(11), 1166-1170. https://academic.oup.com/biomedgerontology/article/61/11/1166/624453
4. Ruscheweyh, R., et al. (2011). Physical activity and memory functions: an interventional study. Neurobiology of aging, 32(7), 1304-1319. https://www.neurobiologyofaging.org/article/S0197-4580(10)00413-8/fulltext
5. Lucas, S. J., et al. (2012). The impact of 100 hours of exercise and health education on cognitive function in older adults: a randomized controlled trial. Journal of the American Geriatrics Society, 60(6), 1001-1011. https://agsjournals.onlinelibrary.wiley.com/doi/full/10.1111/j.1532-5415.2012.03968.x
6. Meeusen, R., De Meirleir, K. (1995). Exercise and brain neurotransmission. Sports medicine, 20(3), 160-188. https://link.springer.com/article/10.2165/00007256-199520030-00004
7. Voss, M. W., Vivar, C., Kramer, A. F., & van Praag, H. (2013). Bridging animal and human models of exercise-induced brain plasticity. Trends in cognitive sciences, 17(10), 525-544. https://www.cell.com/trends/cognitive-sciences/fulltext/S1364-6613(13)00161-7
8. van Praag H. (2008). Neurogenesis and exercise: past and future directions. Neuromolecular medicine, 10(2), 128–140. https://doi.org/10.1007/s12017-008-8028-z
9. Sofi, F., Valecchi, D., Bacci, D., et al (2011). Physical activity and risk of cognitive decline: a meta‐analysis of prospective studies. Journal of internal medicine, 269(1), 107-117. https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2796.2010.02281.x
10. Pontifex, M. B., Hillman, C. H., Fernhall, B., Thompson, K. M., & Valentini, T. A. (2009). The effect of acute aerobic and resistance exercise on working memory. Medicine+ Science in Sports+ Exercise, 41(4), 927. https://journals.lww.com/acsm-msse/fulltext/2009/04000/The_Effect_of_Acute_Aerobic_and_Resistance_Exercise.20.aspx
11. Nagamatsu, L. S., Handy, T. C., Hsu, C. L., Voss, M., & Liu-Ambrose, T. (2012). Resistance training promotes cognitive and functional brain plasticity in seniors with probable mild cognitive impairment: a 6-month randomized controlled trial. Archives of internal medicine, 172(8), 666-668. https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/1151492
12. Teixeira, C. V., Gobbi, L. T., Pereira, J. R., Vital, T. M., Hernández, S. S., Shih, M. C., & Gobbi, S. (2013). Effects of square-stepping exercise on cognitive functions of older people. Psychogeriatrics, 13(3), 148-156. https://onlinelibrary.wiley.com/doi/abs/10.1111/psyg.12017
13. Erickson, K. I., et al. (2011). Exercise training increases size of hippocampus and improves memory. Proceedings of the National Academy of Sciences, 108(7), 3017-3022. https://www.pnas.org/doi/full/10.1073/pnas.1015950108
14. Meeusen R, De Meirleir K. (1995). Exercise and brain neurotransmission. Sports Medicine, 20(3), 160-188. https://link.springer.com/article/10.2165/00007256-199520030-00004
15. van Praag H, Shubert T, Zhao C, Gage FH. (2005). Exercise enhances learning and hippocampal neurogenesis in aged mice. The Journal of neuroscience, 25(38), 8680-8685. https://www.jneurosci.org/content/25/38/8680
16. Yang, P. Y., Ho, K. H., Chen, H. C., & Chien, M. Y. (2012). Exercise training improves sleep quality in middle-aged and older adults with sleep problems: a systematic review. Journal of physiotherapy, 58(3), 157–163. https://doi.org/10.1016/S1836-9553(12)70106-6
17. Hill, E. E., Zack, E., Battaglini, C., Viru, M., Viru, A., & Hackney, A. C. (2008). Exercise and circulating cortisol levels: the intensity threshold effect. Journal of endocrinological investigation, 31(7), 587-591. https://link.springer.com/article/10.1007/BF03345606
18. Erickson, K. I., Hillman, C., & Kramer, A. F. (2015). Physical activity, brain, and cognition. Current opinion in behavioral sciences, 4, 27-32. https://www.sciencedirect.com/science/article/pii/S2352154615000110?via%3Dihub
19. Ahlskog, J. E., Geda, Y. E., Graff-Radford, N. R., & Petersen, R. C. (2011). Physical exercise as a preventive or disease-modifying treatment of dementia and brain aging. Mayo Clinic Proceedings, 86(9), 876-884. https://www.mayoclinicproceedings.org/article/S0025-6196(11)60735-0/fulltext
20. Lee Y, Back JH, Kim J. Systematic review of health behavioral risks and cognitive health in older adults. International psychogeriatrics. 2010 Mar 22(2):174-87. doi: 10.1017/S1041610209991189. PMID: 19883522.
21. Podewils, L. J., Guallar, E., Kuller, L. H., Fried, L. P., Lopez, O. L., Carlson, M., & Lyketsos, C. G. (2005). Physical activity, APOE genotype, and dementia risk: findings from the Cardiovascular Health Cognition Study. American journal of epidemiology, 161(7), 639-651. https://academic.oup.com/aje/article/161/7/639/77903
