Contrary to popular belief, the mental decline older people experience (I'm one of them) is not due to the steady death of nerve cells. Instead, it results from the thinning out of the so-called dendrites, the branches on nerve cells that receive and process information from other nerve cells. Dendrites receive information across connections called synapses. If connections aren't regularly switched on, the dendrites can atrophy. Growing new dendrites was long thought to be possible only in the brains of children. More recent work has shown that old neurons can grow dendrites to compensate for losses. So let our nerve cells keep communicating!