There are several studies that show adult neurogenesis from aerobic exercise, particularly running, in rats and mice.
Example:
Physical exercise increases adult hippocampal neurogenesis in male rats provided it is aerobic and sustained.
https:/www.ncbi.nlm.nih.gov/pubmed/26844666
A review article here:
https://www.researchgate.net/publication/5566493_Neurogenesi...
There is at least one study that allows us to infer that the same effects may occur in humans (quoted below).
Please let us know if there are more studies like this. It looks like a very practical approach to improve your cognition and prevent dementia with little risk.
From: http://www.dana.org/Publications/Brainwork/Details.aspx?id=4...
"Columbia neuroscientist Scott Small and colleagues appear to have found a way around this problem. First, they put mice that had been running voluntarily for two weeks into a magnetic resonance imager to map exercise-induced changes in cerebral blood volume, a measure of increased blood vessel formation in the dentate gyrus. Then, by sacrificing the animals and counting new neurons, they were able to correlate the neuronal proliferation they observed with changes in blood volume.
The researchers then conducted magnetic resonance tests on a small group of middle-aged people who had been exercising about an hour a day, four times a week, for three months. By charting exercise-induced changes in cerebral blood volume in the human hippocampal region and applying the same algorithms used in the mice, they were able to deduce that neurogenesis was also occurring in the humans. Changes in blood volume in the dentate gyrus, they concluded, provide a correlate of neurogenesis in humans."
Anecdotal, yet may not be completely coincidental: Alan Turing was an avid marathon runner. This is not part of the argument--so please don't take it into account when responding. ;)