There are several longitudinal studies: one is The Victoria Longitudinal Study. They followed 250 adults over six years and generally had a population that was pretty high functioning and fairly well educated. They measured cognitive status on standard neuropsychological tests. They looked at activity levels and they separated that out to a cognitive activity level, mental tasks, and to physical activities such as hobbies and physical fitness. They looked at self-reported health and they looked at personality using the NEO.