There is a group of people that longevity researchers call “SuperAgers,” who are in their 80s and beyond, but have the cognitive function of those decades younger. Conversely, it’s possible for your brain to be older than your chronological age, which is what we want to avoid. As a neuroscience researcher and author of “The Age-Proof Brain,” I’ve found that it’s our behaviors, not just our genes, that have a powerful impact on our brain’s destiny. So what sets SuperAgers apart from people who...