Exercise is the best thing you can do for your body besides getting eight hours of sleep and maintaining a healthy diet. You may not know, though, that exercise is one of the best things you can do for your brain. because it can help to increase the number of new brain cells.
Brain Cell Growth
For years it was assumed that the adult brain did not grow any new brain cells, which are known as neurons. Then scientists reported in 1958 that new neurons had formed from a pool of adult stem cells in a mouse brain. New neuron birth was confirmed in the human brain by P.S. Eriksson in 1998. This was considered to be an exciting development because it raised the possibility that these new neurons could be used to repair the diseased brain in conditions such as Alzheimer's or Parkinson's Disease, or to heal an injured brain. The study of the birth of new brain cells, called neurogenesis, is a relatively new field of science and many questions remain to be answered. These include what do these new neurons do, how do we increase the number of new neurons, and are more neurons better for brain function?
Exercise Increases Neurogenesis
According to a study conducted in 1999 at The Salk Institute, rodents that voluntarily exercise by using a running wheel have increased neurogenesis in the hippocampus, an area of the brain used for learning and memory. Voluntary is key here, because forced running causes stress to the rodents, and stress can decrease neurogenesis. To quantify neurogenesis, rodents were sacrificed after exercise and their brain tissue was stained with a marker that identifies only new neurons. The neurons were counted under a microscope. For living human studies, this method is not possible. So a less accurate method, MRI imaging of cerebral blood volume (CBV) was used in a 2007 study at Columbia University. Increased CBV is associated with increased neurogenesis. This study found that exercise increases CBV and thus increases adult neurogenesis.
Mechanism of Exercise-induced Neurogenesis
Exercise increases growth factors in the brain, such as vascular endothelial growth factor (VEGF) and brain-derived neurotrophic factor (BDNF), according to a 2007 literature review by Henriette van Praag. Both factors make it easier for new neurons to grow VEGF by increasing blood vessels and blood flow to new neurons, and BDNF by increasing the rate of neurogenesis.
Benefits of Increased Neurogenesis
Adult neurogenesis may be important for some types of spatial and contextual learning and memory according to van Praag. Adult neurogenesis may also regulate mood. Exercise increases neurogenesis and is an antidepressant.
Exercise Does not Increase Intelligence
If exercise increases adult neurogenesis and enhanced adult neurogenesis may be associated with increased learning and memory, then why aren't all athletes geniuses? Athletes may have better contextual memory, for example, of the playing field they are on, which may aid in performance of the sport. Intelligence includes many other factors besides contextual memory. Increased adult neurogenesis has not been linked to increased intelligence.
References
- "Nature Medicine"; Neurogenesis in the Adult Human Hippocampus; Eriksson PS, Perfilieva E, Bjork-Eriksson T, Alborn AM, Nordborg C, Peterson DA, and Gage FH; November 1998
- "Experimental Cell Research"; Presence of DNA Synthesis and Mitosis in the Brain of Young Adult Mice; Messier B, Leblond CP, and Smart I; February 1958
- "Trends in Neuroscience"; Exercise and the Brain: Something to Chew on"; van Praag H; April 2009
- "Nature Neuroscience"; Running Increases Cell Proliferation...; van Praag H et. al; March 1999
- "Proceedings of the National Academy of Sciences of the United States of America"; An in vivo Correlate of Exercise-induced Neurogenesis in the Adult Dentate Gyrus; Pereira AC, Huddleston DE, Brickman AM, Sosunov AA, Hen R, McKhann GM, Sloan R, Gage FH, Brown TR, and Small SA; March 2007
