Interesting piece in NY Times today, by Sandra Aamodt and Sam Wang, about whether doing Sudoku puzzles or other "brain exercises" really do keep your brain in shape. Their reporting on the research concludes: "Not so much." On the other hand, they found that physical exercise had a strong effect on mental performance:
How might exercise help the brain? In people, fitness training slows the age-related shrinkage of the frontal cortex, which is important for executive function. In rodents, exercise increases the number of capillaries in the brain, which should improve blood flow, and therefore the availability of energy, to neurons. Exercise may also help the brain by improving cardiovascular health, preventing heart attacks and strokes that can cause brain damage. Finally, exercise causes the release of growth factors, proteins that increase the number of connections between neurons, and the birth of neurons in the hippocampus, a brain region important for memory. Any of these effects might improve cognitive performance, though it’s not known which ones are most important.