By the way, doctor: Can the brain grow new neurons?

Q. A recent Health Letter urged us seniors to stay mentally active because that causes the growth of new neurons (brain cells). When my husband had a stroke 40 years ago, the doctors told me that the brain cannot make new cells in later life. What's the truth?

A. If I had been your husband's doctor 40 years ago, I would have told you the same thing, because that's what I was taught and what everyone believed: once a stroke kills a bunch of neurons, they can never be replaced.