The study found that so-called super-agers — people 80 and up who have the memory ability of someone 30 years younger — had roughly twice as many new neurons as older adults with normal memory for their age, and 2.5 times more than people with Alzheimer’s disease. The research focused on an area of the brain called the hippocampus, which is important for learning and memory and is thought to be the primary birthplace of new neurons.