I have just finished reading the book ‘Spark’ by John Ratey where the positive impact of aerobic exercise on brain function is described.
Based on what I read there, I would suggest aerobics exercise which should raise the heart rate to about 65 to 75 % of MHR. If you can find an activity that the person is quite familiar with, that would be ideal. But the main concern is safety.
However, I would definitely require a physician’s approval when working with this population.