The date of the article is November, 2007 - but the evidence seems strong that exercise improves cognitive function - and it is doubtful that it has been overturned.
According to the authors (see below): "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."
Sandra Aamodt is the editor in chief of Nature Neuroscience. Sam Wang is an associate professor of molecular biology and neuroscience at Princeton. They are the authors of the forthcoming “Welcome to Your Brain: Why You Lose Your Car Keys but Never Forget How to Drive and Other Puzzles of Everyday Life.”