Dr. Rao is completing his own study comparing exercise and cognitive training in a different group of people.

WSJ: Exercise Might Beat Puzzles for Protecting the Aging Brain

Significantly increased hippocampal LTP activity was only recorded in the enriched-environment mice, possibly because exploring novel objects provided both physical exercise and cognitive stimulation, researchers said.

WSJ: Why Young Children Don't Notice Coming Cars

Early environmental enrichments that include better nutrition, more exercise and cognitive stimulation from ages 3 to 5 both improves brain functioning at age 11 and also reduces crime at age 23 by 35%.

CNN: Opinion: Unlocking crime using biological keys

Practices like meditation, exercise, and cognitive therapy have shown comparable short-term efficacy to medication.

WSJ: Mind-Controlled Videogames Become Reality

Few studies have compared exercise to drug treatment, but two randomized trials have shown that vigorous exercise combined with cognitive treatment is just as good as spinal fusion surgery, with fewer complications.

FORBES: On The Cover/Top Stories

New research published in the journal Neuron suggests stimulating cognitive activities may be more effective than exercise alone in protecting the brain against Alzheimer's disease.

WSJ: Why Young Children Don't Notice Coming Cars

The researchers noted, however, that "the direction of causation is unclear, " meaning they couldn't tell if a healthier brain was a result of physical activity, or if people showing signs of cognitive decline weren't able to exercise.

WSJ: Exercise Might Beat Puzzles for Protecting the Aging Brain