A while back I wrote about the beneficial impacts that yoga has on the brain and it got me thinking about other sports. We have all heard of runners high, the phenomenon that occurs leading to feelings of euphoria during or after running. While runners high is incredibly unpredictable and not everyone will experience it, it suggests that running may not just be good for the body. For this blog post, I want to explore if running has any benefits for the brain, and if so, what are they?
Running and Neurodegeneration
Plasticity is defined as “the quality of being easily shaped or moulded”. Our brains have the amazing ability to rewire and reorganise how they work through experience; this is known as neuroplasticity or neural plasticity. Neuroplasticity occurs when we learn new things, form new behaviours, and retain new memories. Alongside this is neurogenesis, the process by which new neurons (brain cells) are formed in the brain. It is well understood that neurogenesis occurs throughout life and at all ages but not in all areas of the brain.
Running has been found to both influence neurogenesis and neuroplasticity, especially in the hippocampal areas of the brain. The hippocampus is an important area for learning and memory and has a crucial role in the development of neurodegenerative conditions. The hippocampus is also one of the only known areas of the brain where neurogenesis can occur. After the age of about 50 years, the volume of the hippocampus begins to atrophy (reduce in size) at about 1-2% per year in healthy adults. For adults with mild cognitive impairments or with dementia, this rate is much higher at about 3-5% per annum. As we know, the hippocampus is a primary place for memory and learning, so we see that with a decline in volume, a decline in function transpires and ultimately, a decline in volume is associated with dementia. However, hippocampal volume is hugely moderated by lifestyle factors, and one of those being fitness. For example, a study in 2009 demonstrated that higher aerobic fitness levels were associated with larger hippocampal volume and better memory performance.
Running has been shown to increase neurogenesis in the hippocampus and has been shown to increase neural connectivity in both rodents and humans . Running may in fact be a protective factor against the development of neurodegenerative conditions through its ability to stimulate neurogenesis in the hippocampus and neuroplasticity both within and outside of the hippocampus.
The UK National Institute for Health and Clinical Excellence (NICE) and the National Service Framework for Mental Health both suggest that exercise should be included as a treatment option for depression. Running has been found to be effective for depression and emotional wellbeing. It has also been found to be as effective, in many cases, as antidepressants however research still calls for more longitudinal evidence as the majority of the existing evidence is based on small numbers of participants.
It is not exactly known how exercise improves mental health, but there are many theories. For example, the same area implicated in the development of neurodegenerative diseases, the hippocampus, also plays a role in mental health conditions. Stress, one of the leading causes for depression, is associated with reduced neurogenesis in the hippocampal areas. Antidepressants like fluoxetine are effective in restoring this ability and we know from our research noted above that running can also encourage neurogenesis in the hippocampus. Running may also act as a distraction from negative thinking or in the cases of social running, like Parkruns, the social contact may act as a mechanism alone to promote mental wellbeing. Running is also know to illicit physiological and psychological effects such as runners high  which may contribute to more short term lifts in ones mental health.
While there does not seem to be a huge amount of evidence into the effects of running on the brain, the existing evidence shows a clear benefit of running in helping to protect from neurodegenerative diseases and as a treatment for depression. Running seems to have a large effect on neuroplasticity in the brain and neurogenesis in the hippocampus.
What is lesser known at the moment is the specifics, like how long to run for, where to run, and whether to run alone or with other people. Research seems to be ongoing which is great as it shows an interest in the neuroprotective effects of running and hopefully in the future, the evidence could establish more benefits of running for our brains and further establish the ones we already know about.
 Carmen Vivar, Benjamin D. Peterson, and Henriette van Praag, ‘Running Rewires the Neuronal Network of Adult-Born Dentate Granule Cells’, NeuroImage, 131 (2016), 29–41 <https://doi.org/10.1016/j.neuroimage.2015.11.031>.
 C’iana Cooper, Hyo Youl Moon, and Henriette van Praag, ‘On the Run for Hippocampal Plasticity’, Cold Spring Harbor Perspectives in Medicine, 8.4 (2018) <https://doi.org/10.1101/cshperspect.a029736>.
 Guo-li Ming and Hongjun Song, ‘Adult Neurogenesis in the Mammalian Brain: Significant Answers and Significant Questions’, Neuron, 70.4 (2011), 687–702 <https://doi.org/10.1016/j.neuron.2011.05.001>.
 Naftali Raz, Faith Gunning-Dixon, and others, ‘Aging, Sexual Dimorphism, and Hemispheric Asymmetry of the Cerebral Cortex: Replicability of Regional Differences in Volume’, Neurobiology of Aging, 25.3 (2004), 377–96 <https://doi.org/10.1016/S0197-4580(03)00118-0>.
 Naftali Raz, Ulman Lindenberger, and others, ‘Regional Brain Changes in Aging Healthy Adults: General Trends, Individual Differences and Modifiers’, Cerebral Cortex (New York, N.Y.: 1991), 15.11 (2005), 1676–89 <https://doi.org/10.1093/cercor/bhi044>.
 D. Mungas and others, ‘Longitudinal Volumetric MRI Change and Rate of Cognitive Decline’, Neurology, 65.4 (2005), 565–71 <https://doi.org/10.1212/01.wnl.0000172913.88973.0d>.
 Clifford R. Jack and others, ‘The Rate of Medial Temporal Lobe Atrophy in Typical Aging and Alzheimer’s Disease’, Neurology, 51.4 (1998), 993–99.
 Hyo Youl Moon and others, ‘Running-Induced Systemic Cathepsin B Secretion Is Associated with Memory Function’, Cell Metabolism, 24.2 (2016), 332–40 <https://doi.org/10.1016/j.cmet.2016.05.025>.
 James A. Blumenthal and others, ‘Exercise and Pharmacotherapy in the Treatment of Major Depressive Disorder’:, Psychosomatic Medicine, 69.7 (2007), 587–96 <https://doi.org/10.1097/PSY.0b013e318148c19a>.
 Yael Netz, ‘Is the Comparison between Exercise and Pharmacologic Treatment of Depression in the Clinical Practice Guideline of the American College of Physicians Evidence-Based?’, Frontiers in Pharmacology, 8 (2017) <https://doi.org/10.3389/fphar.2017.00257>.
 Petra Wollseiffen and others, ‘The Effect of 6 h of Running on Brain Activity, Mood, and Cognitive Performance’, Experimental Brain Research, 234.7 (2016), 1829–36 <https://doi.org/10.1007/s00221-016-4587-7>.
 Laura Micheli and others, ‘Depression and Adult Neurogenesis: Positive Effects of the Antidepressant Fluoxetine and of Physical Exercise’, Brain Research Bulletin, 143 (2018), 181–93 <https://doi.org/10.1016/j.brainresbull.2018.09.002>.